CN106849679A - For the grid-connected wide range input converting means of distributed power source and method - Google Patents

Abstract

The invention provides a wide-range voltage input conversion device and method for distributed power grid connection, and relates to the technical field of power system control. The device includes a microprocessor unit, a full-bridge high-frequency array unit, a composite buffer protection unit, a power conversion unit, a MOSFET/IGBT drive unit, a voltage detection unit, a current detection unit, a wireless communication unit, an LC filter and a host computer. The processor unit processes the current and voltage information collected by the current and voltage detection unit, and then drives the MOSFET/IGBT drive unit to control the on-off of MOSFET and IGBT devices, and at the same time transmits the collected current and voltage information to the host computer. The invention can broaden the voltage input range of distributed power grid-connected, classify the grid-connected output power levels, avoid the impact of voltage fluctuations caused by the environment or other factors on the distributed power generation system, and meet the requirements for output grid-connected power in different environments needs, and has the function of enhancing man-machine dialogue.

Description

Wide-range voltage input conversion device and method for distributed power grid connection

technical field

The invention relates to the technical field of power system control, in particular to a wide-range voltage input conversion device and method for distributed power grid connection.

Background technique

With the increasing energy consumption, non-renewable fossil fuels will eventually be exhausted, so green and clean energy such as wind power, photovoltaic power generation, and fuel cells have been rapidly developed. As an effective way to connect clean energy to the grid, distributed power generation technology has attracted more and more attention. Due to the regulation method of the distributed power generation system and the inherent characteristics of its own structure, the input energy of the distributed power generation system using wind energy, solar energy, etc. has natural fluctuations. Therefore, the output power of the distributed power generation fluctuates greatly, and its output voltage is mostly in a very large range. Changes in a wide range, high degree of uncertainty, easy to cause flicker caused by grid voltage fluctuations, and the distributed power generation system cannot classify the output power through relevant measures. Therefore, for the voltage input range of the distributed power generation system and The classification of multi-terminal output power levels puts forward higher requirements. At present, the distributed power generation system mainly uses the Boost-Buck buck circuit to improve the measures for widening the input voltage range of the distributed power supply. When it comes to the improvement of the power level, components with extremely high power levels are often required. The Boost-Buck buck circuit Inherent device characteristics limit the classification of voltage input ranges and power levels for DG systems. For distributed power generation systems, not only a wide range of voltage input is required, but also simple and reliable measures are needed to classify power levels to meet the needs of distributed power generation systems in different environments.

Contents of the invention

Aiming at the defects of the prior art, the present invention provides a wide-range voltage input conversion device and method for distributed power grid-connected, aiming at increasing the voltage input range of distributed power grid-connected and improving the grid-connected output power level Classification, combined with hardware auxiliary circuits, control methods and control system hardware structure, can broaden the voltage input range of distributed power grid-connected, classify the grid-connected output power level, and avoid voltage fluctuations caused by the environment or other factors. The impact of the system can meet the needs of output grid-connected power in different environments, and has the function of enhancing man-machine dialogue.

On the one hand, the present invention provides a wide-range voltage input conversion device for distributed power grid connection, including a microprocessor unit, a full-bridge high-frequency array unit, a composite buffer protection unit, a power frequency conversion unit, and a MOSFET/IGBT drive unit , voltage detection unit, current detection unit, wireless communication unit, LC filter and host computer;

The microprocessor unit is used to process the current and voltage information collected by the current detection unit and the voltage detection unit, and then drive the MOSFET/IGBT drive unit to control the on-off of MOSFET and IGBT devices, and at the same time transmit the collected current and voltage information To the upper computer, the PC terminal records the voltage and current information to provide protection for broadening the voltage input range and output power level classification of distributed power grid-connected; the microprocessor unit includes a main control chip, a first buffer chip and a second buffer chip; the MOSFET/IGBT drive unit is connected to the main control chip through the first buffer chip, the current detection unit and the voltage detection unit are connected to the main control chip through the second buffer chip, and the wireless communication unit is directly connected to the Main control chip connection;

The full-bridge high-frequency array unit includes five full-bridge high-frequency voltage stabilizing circuits with the same structure, which are arranged on two DC buses for widening the voltage input range of distributed power grid-connected; the full-bridge high-frequency The array unit includes three input terminals and one output terminal. The first input terminal of the high-frequency array unit is connected to an energy storage conversion battery as a distributed grid-connected power supply through a current detection unit and a voltage detection unit. The full bridge is high The second input end of the frequency array unit is connected to the output end of the MOSFET/IGBT drive unit, the third input end of the full-bridge high-frequency array unit is connected to the second output end of the microprocessor unit, and the full-bridge high-frequency array unit The output end of the unit is connected to the first input end of the composite buffer unit;

The composite buffer protection unit includes two first composite buffer circuits and second composite buffer circuits with the same structure, which are respectively arranged on two bus bars I and II to suppress the peak voltage on the bus when the IGBT device is turned on and off; the The composite buffer protection unit includes two input terminals and two output terminals, the first input terminal of the composite buffer protection unit is connected to the output terminal of the high-frequency array unit, and the second input terminal of the composite buffer protection unit is connected to the MOSFET / the output terminal of the IGBT drive unit, the first output terminal of the composite buffer protection unit is connected to the input terminal of the current detection unit, and the second output terminal of the composite buffer protection unit is connected to the first input terminal of the power conversion unit;

The power frequency conversion unit is used to convert the DC voltage at the busbar side to the AC voltage at the grid side, and includes 6 subunits with the same structure, and the circuit structure of each subunit is the same as that of the first or second composite buffer circuit ;

The MOSFET/IGBT drive unit includes a drive chip and a peripheral protection circuit, which is used to boost the output signal of the microprocessor unit, and then achieve the required voltage for controlling the gates of MOSFET and IGBT devices;

The voltage detection unit is used to detect the voltages of the composite buffer protection unit, the first input terminal of the high-frequency array unit and the three output terminals of the power frequency conversion unit, including two sets of voltage detection circuits with the same circuit structure;

The current detection unit is used to detect whether the current at the point to be detected in the conversion device exceeds or is lower than a preset current threshold range, and includes a bridge arm through current detection unit, a bus current detection unit and a load current detection unit, and the bridge arm through current detection unit The detection circuit of the fault current detection unit is a decentralized overcurrent protection circuit, which is used to detect whether the bridge arm direct current at the point to be detected in the composite buffer unit and the power frequency conversion unit exceeds the preset current value. The bus current detection unit and the load current detection The detection and protection circuits of the unit are centralized overcurrent protection circuits. The bus current detection unit is used to detect whether the current at the point to be detected on the DC bus exceeds the preset current threshold range, and a bus current detection unit is respectively installed on the two buses. unit, the load current detection unit is set on the load connection line, and is used to detect whether the current at the point to be detected on the load connection line exceeds the preset current threshold range;

The wireless communication unit is used to wirelessly transmit the signal of the micro-processing unit to the host computer;

The LC filter is used to filter out the harmonics generated by the power frequency conversion unit, including three groups of LC filter circuits, the input ends of the three groups of LC filter circuits are respectively connected to the three output terminals of the power conversion unit, and the three groups The output ends of the LC filter circuit are respectively connected to the three-phase lines of the power grid;

The upper computer is a mobile phone and a computer PC, which are used to monitor the voltage, current and power information of the device in real time, and can control the on-off of the IGBT device by sending instructions.

Further, the full-bridge high-frequency voltage stabilizing circuit includes a high-voltage bus filter capacitor, a first MOSFET device, a second MOSFET device, a third MOSFET device, a fourth MOSFET device, a high-frequency full-bridge step-up transformer, a first selection switch, The first reverse diode, the second reverse diode, the third reverse diode and the fourth reverse diode; the two ends of the high-voltage bus filter capacitor are used as the first input end of the high-frequency array unit, connected as a distributed The energy storage device of the power generation system is connected to the input terminal of the voltage detection unit at the same time; the drains of the first MOSFET device and the second MOSFET device are connected to one end of the high-voltage bus filter capacitor at the same time, and the source of the first MOSFET device is connected to the The input end of the different name of the high-frequency full-bridge step-up transformer and the drain of the fourth MOSFET device, the source of the second MOSFET device is connected to the input end of the same name of the high-frequency full-bridge step-up transformer and the drain of the third MOSFET device, so The sources of the third MOSFET device and the fourth MOSFET device are connected to the other end of the high-voltage bus filter capacitor at the same time; the gates of the first MOSFET device, the second MOSFET device, the third MOSFET device and the fourth MOSFET device are used as high-frequency The second input terminal of the array unit is connected to the output terminal of the MOSFET/IGBT drive unit; the output terminal of the same name of the high-frequency full-bridge step-up transformer is connected to the cathode of the third reverse diode and the anode of the fourth reverse diode at the same time, and the high-frequency full-bridge The different-name output end of the bridge step-up transformer is connected to the first input end of the first selector switch; the signal pin 2 of the first selector switch is used as the third input end of the high-frequency array unit, and is connected to the microprocessor unit The second output terminal; the output terminal of the first selector switch is simultaneously connected to the anode of the first reverse diode and the cathode of the second reverse diode; the cathode of the first reverse diode is connected to the cathode of the fourth reverse diode The cathode is connected as the first output terminal of the full-bridge high-frequency voltage stabilizing circuit, and the anode of the second reverse diode is connected to the anode of the third reverse diode as the second output of the full-bridge high-frequency voltage stabilizing circuit end; five full-bridge high-frequency stabilizing circuits with the same structure are connected to the first output terminal of the next adjacent full-bridge high-frequency stabilizing circuit through the second output terminal of the previous full-bridge high-frequency stabilizing circuit The method is connected in series, and the series transfer terminal 1 of the first selection switch of the previous full-bridge high-frequency voltage stabilizing circuit is connected with the same-named output terminal of the high-frequency full-bridge step-up transformer in the next full-bridge high-frequency voltage stabilizing circuit; the first The first output end of the first full-bridge high-frequency voltage stabilizing circuit and the second output end of the fifth full-bridge high-frequency voltage stabilizing circuit are jointly used as a pair of output ends of the full-bridge high-frequency array unit, and are connected to the first of the composite buffer unit. input.

Further, the first composite snubber circuit includes a first IGBT device, a first resistor, a sixth capacitor, a first inductor, a twenty-first reverse diode, and a twenty-second reverse diode; the first inductor One end is used as the first input end of the composite buffer protection unit, connected to the output end of the full-bridge high-frequency array unit, and connected to the cathode of the twenty-first reverse diode, and the other end of the first inductor is connected to the first IGBT device The collector of the first resistor, one end of the first resistor, the anode of the twenty-first reverse diode and the anode of the twenty-second reverse diode, the emitter of the first IGBT device is connected to the cathode of the twenty-second reverse diode, The other end of the first resistor, the positive pole of the sixth capacitor, and the first input terminal of the power conversion unit, the negative pole of the sixth capacitor is used as the second output terminal of the composite buffer protection unit, connected to the emitter of the first IGBT device and the power The first input end of the frequency conversion unit, the gate of the first IGBT device is used as the second input end of the composite buffer protection unit, connected to the output end of the MOSFET/IGBT drive unit; the collector of the first IGBT device is used as a composite buffer unit The first output end of the first output end is connected with the input end of the current detection unit and the output end of the high-frequency array unit.

Further, the power frequency conversion unit also includes an eighth capacitor; the gates of the IGBT devices of each subunit are used as the second input terminal of the power frequency conversion unit, and are connected to the output terminal of the IGBT drive unit; one end of the inductor in each subunit respectively serve as the input terminals of the corresponding subunits; the emitters of the IGBT devices in each subunit respectively serve as the output terminals of the corresponding subunits; the first subunit, the third subunit, and the first subunit among the six subunits with the same structure The input ends of the five subunits are connected at one point, as the positive pole of the first input end of the power conversion unit, connected to the second output end of the first composite buffer circuit connected to the bus I; the first of the six subunits with the same structure The output terminals of the second subunit, the fourth subunit and the sixth subunit are connected at one point, as the negative pole of the first input terminal of the power frequency conversion unit, connected to the second output terminal of the second composite buffer circuit connected to the bus II; the said The eighth capacitor is connected between the input terminal of the first subunit and the output terminal of the second subunit; the output of the first subunit, the third subunit, and the fifth subunit among the six subunits with the same structure The terminals are correspondingly connected to the input terminals of the second subunit, the fourth subunit, and the sixth subunit, and serve as three output terminals of the power frequency conversion unit respectively.

Further, the peripheral circuit of the MOSFET/IGBT drive unit includes a first diode, a ninth capacitor, a tenth capacitor, a current limiting resistor, a buffer resistor, a feedback resistor, a transistor and an optocoupler; the 6 pins of the driver chip are connected to the first The anode of the diode, the cathode of the first diode are connected to the collector of the driven IGBT device and the drain of the MOSFET device, and the pin 2 of the driver chip is connected to the 15V power supply, the positive pole of the ninth capacitor and one end of the feedback resistor, and the driver chip Pin 3 of the 10th capacitor is connected to the positive pole of the tenth capacitor and one end of the snubber resistor; the other end of the snubber resistor is used as the output end of the IGBT drive unit, and is connected to the gate of the driven IGBT device and the gate of the MOSFET device; the ninth capacitor and the tenth The negative electrode of the capacitor is connected to the emitter of the driven IGBT device, the source of the MOSFET device, and pin 1 of the driver chip. Pin 15 of the driver chip is connected to one end of the current-limiting resistor, and the other end of the current-limiting resistor is connected to a 15V power supply. Pin 14 is connected to the collector of the transistor, the emitter of the transistor is connected to pin 1 of the optocoupler, the gate of the transistor is connected to the first buffer chip of the microprocessor unit, pin 5 of the driver chip is connected to pin 4 of the optocoupler, and the optocoupler Pin 3 of the optocoupler is connected to the other end of the feedback resistor, and pin 2 of the optocoupler is connected to the microprocessor unit.

Further, the voltage detection unit includes an iron core and a signal processing circuit, wherein a Hall element is provided at the separation opening of the iron core to convert the magnetic flux signal of the iron core into an electrical signal, and the signal processing circuit includes an operational amplifier chip , the first triode, the second triode, and the measuring resistance; the same input end of the op amp chip is connected to one end of the Hall element, the inverting input end of the op amp chip is connected to the other end of the Hall element, and the op amp chip The positive pole of the power supply is connected to the power supply +VCC and the collector of the first triode at the same time, the 4 pins of the op amp chip are connected to the power supply -VCC and the emitter of the second triode at the same time, and the 5 pins of the op amp chip are connected to the first and third transistors at the same time. The base of the pole tube and the base of the second triode, the emitter of the first triode are connected to one end of the secondary coil of the iron core and the collector of the second triode, and the other end of the secondary coil of the iron core Ground through the measuring resistor.

Further, the distributed overcurrent protection circuit is used to detect the through current of the bridge arm formed by the composite buffer unit and the IGBT device in the power conversion unit, including a first voltage comparator, a third resistor, a fourth resistor, a fifth resistor and The sixth resistor, the second diode, the third diode, and the first adjustable potentiometer; the same input end of the first voltage comparator is connected to one end of the fourth resistor and the anode of the second diode, The cathode of the second diode is used as the input terminal of the distributed overcurrent protection circuit, and is connected to the collectors of the IGBT devices in the power conversion unit; one end of the third resistor is connected to the +15V DC power supply, and the other end is connected to the other end of the fourth resistor and One fixed end of the first adjustable potentiometer; the other fixed end of the first adjustable potentiometer is grounded, the sliding end of the first adjustable potentiometer is connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to the first The negative input terminal of the voltage comparator; the positive pole of the power supply of the first voltage comparator is connected to the 15V DC power supply, one end of the sixth resistor, and pin 2 of the driver chip of the MOSFET/IGBT drive unit; the negative pole of the power supply of the first voltage comparator is grounded , the signal output terminal of the first voltage comparator is connected to the other end of the sixth resistor and the cathode of the third diode, and the anode of the third diode is used as the output terminal of the distributed overcurrent protection circuit, connected to the MOSFET/IGBT drive unit The pin 6 of the driving chip, the signal output end of the first voltage comparator is connected with the second buffer chip of the microprocessor unit.

Further, the centralized overcurrent protection circuit includes a Hall current sensor, a seventh resistor, an eighth resistor, a ninth resistor, a second adjustable potentiometer, an eleventh capacitor, a twelfth capacitor and a second voltage comparator The Hall current sensor is installed on the connection line of the detected point, and the signal output end of the Hall current sensor is connected with the same input end of the second voltage comparator; the seventh resistor is connected in parallel with the twelfth capacitor and then one end is grounded, and One end is connected to the same input end of the second voltage comparator for signal filtering; one fixed end of the second adjustable potentiometer is connected to the 15V power supply, the other fixed end is grounded, and the sliding end is connected to the reverse input end of the second voltage comparator connected to provide feedback voltage; one end of the eighth resistor is connected to a 5V power supply as a pull-up resistor, and the other end is connected to the signal output end of the second voltage comparator and one end of the ninth resistor; the other end of the ninth resistor is used as a centralized overcurrent protection circuit An output port is connected to the second buffer chip of the microprocessor unit, and is connected to one end of the eleventh capacitor, and the other end of the eleventh capacitor is grounded; the ninth resistor and the eleventh capacitor form an RC delay circuit.

Further, the power supply of each unit in the wide-range voltage input conversion device for distributed power grid connection is provided by a switching power supply with multiple voltage outputs (output ±15V, 5V, 3.3V voltage).

On the other hand, the present invention also provides a method for wide-range voltage input conversion for distributed power grid-connected, the method is realized by a wide-range voltage input conversion device for distributed power grid-connected, including the following steps:

Step 1. Use the microprocessor unit to control the internal components of the full-bridge high-frequency array unit, composite buffer protection unit, power frequency conversion unit and MOSFET/IGBT drive unit, so that the entire voltage input conversion device is in operation. The specific method is:

Step 1.1, adopt microprocessor unit to send SPWM (being sinusoidal pulse width modulation) signal;

Step 1.2, carry out boost processing through the MOSFET/IGBT drive unit, and increase the amplitude of the SPWM voltage signal to 15V;

Step 1.3, respectively drive the MOSFET device of the full-bridge high-frequency array unit, the composite buffer unit and the IGBT device of the power conversion unit, so that each MOSFET and IGBT device are turned on alternately, and a wide-range voltage input conversion device for distributed power grid connection is used in normal operation;

Step 2, carry out data collection and recording of current and voltage, the specific method is:

Step 2.1, use the voltage detection unit, the decentralized overcurrent protection circuit in the current detection unit, and the centralized overcurrent protection circuit to monitor the voltage at the front end of the full-bridge high-frequency array unit, the current and voltage of the composite buffer protection unit and the power frequency conversion unit in real time collection;

The voltage detection unit generates a signal and sends it to the microprocessor unit. When the voltage fluctuates beyond the first preset input voltage range, the duty cycle of the MOSFET device is changed, and the output voltage of the full-bridge high-frequency array unit is changed to avoid the The impact of input voltage fluctuations on output voltage;

The level signal generated by the centralized overcurrent protection circuit in the bus current detection unit and the load current detection unit is sent to the drive chip and microprocessor unit of the MOSFET/IGBT drive unit after being delayed by the RC delay circuit;

Step 2.2, the microprocessor unit collects and records the current and voltage data of each channel, and constructs the relationship curve between the voltage of the terminal to be detected and the detection branch in real time;

Step 3, the microprocessor unit judges whether the current value exceeds the first preset current threshold, whether the voltage at the terminal to be detected exceeds the first preset input voltage range, if any of the first preset current threshold and the first preset input voltage range If one is exceeded or both are exceeded at the same time, it means that there is a fault in the system. If the fault type is judged to be a voltage fault or a current fault, go to step 4; otherwise, the system works normally and go back to step 2;

Step 4. When a voltage failure occurs, the microprocessor unit generates a control signal and sends it to the corresponding MOSFET device of the full-bridge high-frequency array unit. According to the voltage variation range, the signal duty cycle of the driving MOSFET device is linearly adjusted, and the full-bridge height is adaptively changed. The output voltage of the frequency array unit; when a current fault occurs, the microprocessor unit generates a control signal and sends it to the corresponding unit where the fault occurs, and slowly reduces the grid voltage of the IGBT device of the faulty unit; the microprocessor unit simultaneously records Check the position of the fault current, generate the corresponding number, send the fault record to the mobile phone through the wireless communication unit, report the fault information judged by the microprocessor unit, and send out a fault intermediate alarm signal, and transmit the fault to the computer PC host computer; The computer PC host computer compares the existing faults with the faults stored in the computer database to determine the type and location of the fault current;

Step 5, the microprocessor further judges the fault current and voltage detection, and judges whether the current value exceeds the second preset current threshold, and whether the voltage at the terminal to be detected exceeds the second preset voltage threshold range, wherein the second preset current threshold is greater than the first The preset current threshold, the end value of the second preset input voltage range is greater than the end value of the first preset input voltage range, if any one of the second preset current threshold and the second preset input voltage range is exceeded or both If both are exceeded at the same time, it is determined that a serious undervoltage, short circuit or overcurrent fault has occurred at the corresponding position, and perform step 6, otherwise return to step 2;

Step 6. The microprocessor unit sends a control signal, blocks the input signal, shuts off the MOSFET or IGBT device in the unit that has a serious undervoltage, short circuit or overcurrent fault, and continuously sends the fault information to the user through the wireless communication unit At the same time, the microprocessor unit generates a serious fault alarm signal, and transmits the fault to the computer PC host computer.

It can be seen from the above technical solution that the beneficial effect of the present invention lies in that the wide-range voltage input conversion device and method for distributed power grid connection provided by the present invention is aimed at improving the voltage input range of distributed power supply grid connection And the classification of grid-connected output power levels. First, a full-bridge high-frequency array unit is added to the DC bus of the distributed power supply. When the input voltage of the distributed power supply fluctuates, it can adaptively adjust the stable output voltage, and at the same time, it can also classify the output power level according to the needs of the user; secondly, add A composite buffer unit is added, which can preferentially suppress and reduce the surge voltage amplitude on the bus when the IGBT device on the bus is turned on or off; in addition, a current and voltage detection unit is added to respectively monitor the through current of the IGBT bridge arm, the voltage and current of the bus side, and the load Monitor the side voltage and current, record the relevant current and voltage data, analyze the data through the computer PC host computer, establish the relationship curve between voltage, current and power, and provide the basis for the classification of wide-range voltage regulation and power level; finally through the current detection The unit monitors and locates the overcurrent fault location of the power frequency conversion unit, slowly reduces the grid voltage through the hardware auxiliary circuit and the microprocessor unit, prolongs the fault protection time of the action circuit, and uses the wireless communication unit to communicate with the mobile phone and computer to realize the mobile phone and computer. Data sharing between the devices, enhancing man-machine dialogue, and avoiding secondary damage to device converter devices, DC lines and systems. The invention combines the hardware auxiliary circuit, the control method and the hardware structure of the control system, which can broaden the voltage input range of the grid-connected distributed power supply, classify the output power levels of the grid-connected power supply, and avoid the voltage fluctuation caused by the environment or other factors from affecting the distributed power supply. The impact of the power generation system meets the needs of output grid-connected power in different environments, and has the function of enhancing man-machine dialogue.

Description of drawings

Fig. 1 is a schematic structural diagram of a wide-range voltage input conversion device for distributed power grid connection provided by an embodiment of the present invention;

Fig. 2 is the circuit schematic diagram of the microprocessor unit that the embodiment of the present invention provides;

3 is a schematic circuit diagram of a full-bridge high-frequency array unit provided by an embodiment of the present invention;

4 is a schematic circuit diagram of a composite buffer circuit provided by an embodiment of the present invention;

FIG. 5 is a schematic circuit diagram of a power conversion unit provided by an embodiment of the present invention;

6 is a schematic diagram of the connection circuit of the distributed power supply, energy storage and conversion, full-bridge high-frequency array unit, composite buffer unit, power frequency conversion unit and LC filter provided by the embodiment of the present invention;

7 is a schematic circuit diagram of a MOSFET/IGBT drive unit provided by an embodiment of the present invention;

FIG. 8 is a schematic circuit diagram of a voltage detection unit provided by an embodiment of the present invention;

9 is a schematic diagram of the working principle of the decentralized overcurrent protection circuit provided by the embodiment of the present invention;

10 is a schematic diagram of a decentralized overcurrent protection circuit connected to an IGBT driver chip provided by an embodiment of the present invention;

Fig. 11 is a schematic circuit diagram of a centralized overcurrent protection circuit on a DC bus of a distributed power supply provided by an embodiment of the present invention;

FIG. 12 is a flow chart of a method for wide-range voltage input transformation suitable for grid-connected distributed power sources provided by an embodiment of the present invention;

Fig. 13 is a circuit schematic diagram of the composite buffer unit IGBT turn-off time provided by the embodiment of the present invention;

Fig. 14 is a circuit schematic diagram of the composite buffer unit IGBT turn-on time provided by the embodiment of the present invention;

Fig. 15 is a graph of three-phase current RMS before installing a wide-range voltage input conversion device provided by an embodiment of the present invention;

Fig. 16 is a graph of three-phase current RMS after installation of a wide-range voltage input conversion device provided by an embodiment of the present invention.

In the figure: 1. Distributed power supply; 2. Energy storage and conversion device; 3. Full-bridge high-frequency array unit; 4. Composite buffer unit; 5. Power frequency conversion unit; 6. LC filter; 7. Power grid; 8. Iron core; 9, Hall element.

detailed description

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

As shown in Figure 1, a wide-range voltage input conversion device for distributed power grid connection, the device includes a microprocessor unit, a full-bridge high-frequency array unit, a composite buffer protection unit, a power conversion unit, MOSFET/IGBT Drive unit, voltage detection unit, current detection unit, wireless communication unit, LC filter and host computer. In this embodiment, the wireless communication unit adopts the SIM808 wireless module, which is used to wirelessly transmit the signal of the microprocessing unit to the upper computer. For mobile phones and PCs, it is used to monitor the voltage and current information of the device in real time, and at the same time, it can control the IGBT on and off by sending commands. The power supply of each unit in the device is provided by a switching power supply with multiple voltage outputs (output ±15V, 5V, 3.3V voltage).

The microprocessor unit is used to process the voltage and current information collected by the voltage detection unit and the current detection unit, and then drive the IGBT drive unit to control the on-off of the IGBT device, and at the same time transmit the collected information to the host computer to upgrade the full-bridge high-frequency array. Provide a basis for voltage regulation. In this embodiment, the microprocessor unit includes a TMS320F28335 main control chip, a first buffer chip 74HC245 and a second buffer chip 743384, and the MOSFET/IGBT drive unit, current detection unit and voltage detection unit are all connected to the main control chip through the buffer chip , the wireless communication unit is directly connected with the main control chip. TMS320F28335 main control chip is a processor with a main frequency up to 150MHZ, with 12 channels of complementary symmetrical pulse width modulation ports PWM1-12, built-in 2*8 channel 12-bit ADC converter, and 3 channel SCI communication interface.

Taking a group of detection units as an example, as shown in Figure 2, the specific connection structure between the microprocessor unit and other peripheral units is: the pulse width modulation ports PWM1, PWM2, PWM3, PWM4, PWM5, PWM6, PWM7, PWM8 of the main control chip , PWM9, PWM10, PWM11, and PWM12 are respectively connected to ports A0, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, and A12 of the first buffer chip 74HC245 in one-to-one correspondence, and the first buffer The B0 and B1 of the chip 74HC245 are connected to the S3 and S4 ports of the MOSFET/IGBT drive unit, the B6 and B12 of the 74HC245 buffer chip are connected to the IN1 and IN2 ports of the MOSFET/IGBT drive unit, and the ADCINA0 and ADCINA7 ports of the TMS320F28335 main control chip are respectively connected to the second The A0 and A1 ports of the buffer chip 743384 are connected, the D0 and D18 ports of the TMS320F28335 main control chip are respectively connected to the A8 and A15 ports of the second buffer chip 743384, and the B0 and B7 of the second buffer chip 743384 are respectively connected to the OC1 and OC2 of the current detection unit The ports are connected, B8 and B15 of the second buffer chip 743384 are respectively connected to the two output ports S1 and S2 of the voltage detection unit; the SCITXD port of the wireless communication unit SIM808 module is connected to the SCIRXD port of the TMS320F28335 main control chip, and the wireless communication unit SIM808 module The SCIRXD port of the TMS320F28335 main control chip is connected with the SCITXD port of the TMS320F28335 main control chip.

The full-bridge high-frequency array unit includes five full-bridge high-frequency boost circuits with the same structure, which are arranged on two busbars, and are used to widen the voltage input range of distributed power grid-connected. The full-bridge high-frequency array unit includes three inputs terminal and an output terminal, the first input terminal of the full-bridge high-frequency array unit is connected to the energy storage conversion battery as a distributed grid-connected power supply through the current and voltage detection unit, and the second input terminal of the high-frequency array unit is connected to the MOSFET/IGBT drive The unit output terminal, the third input terminal of the high-frequency array unit is connected to the second output terminal of the microprocessor, and the output terminal of the high-frequency array unit is connected to the first input terminal of the composite buffer unit.

The five full-bridge high-frequency boost circuits on the two buses have the same structure. Taking the first full-bridge high-frequency boost circuit as an example, as shown in Figure 3, it includes high-voltage bus filter capacitor C1 and four MOSFETs with high-frequency disconnection functions. Devices Q1, Q2, Q3, Q4, a high frequency full bridge step-up transformer TR1, selector switch K1, reverse diodes VD1, VD2, VD3 and VD4. The two ends of the high-voltage bus filter capacitor C1 are used as the first input end of the high-frequency array unit, connected to the energy storage device as a distributed power generation system (that is, connected to two buses), and connected to the input end of the voltage detection unit. The drains of the first MOSFET device Q1 and the second MOSFET device Q2 are connected to one end of the high-voltage bus filter capacitor C1 at the same time, and the source of the first MOSFET device Q1 is connected to the different-name input terminal of the high-frequency full-bridge step-up transformer and the fourth MOSFET device at the same time. The drain and the source of the second MOSFET device Q2 are simultaneously connected to the input terminal of the same name of the high-frequency full-bridge step-up transformer and the drain of the third MOSFET device Q3, and the sources of the third MOSFET device Q3 and the fourth MOSFET device Q4 are connected to the high-voltage bus at the same time The other end of the filter capacitor C1. The gates of the first MOSFET device Q1, the second MOSFET device Q2, the third MOSFET device Q3 and the fourth MOSFET device Q4 serve as the second input terminal of the high frequency array unit and are connected to the output terminal of the MOSFET/IGBT drive unit. The same-name output terminal of the high-frequency step-up transformer is connected to the cathode of the third reverse diode VD3 and the anode of the fourth reverse diode VD4 at the same time, and the different-name output terminal of the high-frequency step-up transformer is connected to the first input terminal of the selection switch K1, and the selection switch K1 The signal pin 2 of the high-frequency array unit is used as the third input terminal of the high-frequency array unit, which is connected to the second output terminal of the microprocessor unit, and the output terminal of the selection switch K1 is connected to the anode of the first reverse diode VD1 and the second reverse diode at the same time The cathode of VD2, the cathode of the first reverse diode VD1 and the fourth reverse diode VD4 are used as the first output terminal of the full-bridge high-frequency voltage regulator circuit, the anode of the second reverse diode VD2 and the third reverse diode VD3 The anode is connected as the second output terminal of the full-bridge high-frequency voltage stabilizing circuit. Five full-bridge high-frequency stabilizing circuits with the same structure are implemented by connecting the second output terminal of the previous full-bridge high-frequency stabilizing circuit to the first output terminal of the next adjacent full-bridge high-frequency stabilizing circuit. In series, that is, the second output terminal of the first full-bridge high-frequency voltage regulator circuit is connected to the first output terminal of the second full-bridge high-frequency voltage regulator circuit, and the second output terminal of the second full-bridge high-frequency voltage regulator circuit The output terminal is connected to the first output terminal of the third full-bridge high-frequency voltage regulator circuit, and so on, and finally, the first output terminal of the first full-bridge high-frequency voltage regulator circuit is connected to the fifth full-bridge high-frequency voltage regulator circuit. The second output terminal of the voltage stabilizing circuit is jointly used as a pair of output terminals of the full-bridge high-frequency array unit, which is connected to the first input terminal of the composite buffer unit; then, the first selection switch of the previous full-bridge high-frequency voltage stabilizing circuit The series transfer terminal 1 is connected with the same-named output terminal of the high-frequency full-bridge step-up transformer in the next full-bridge high-frequency voltage stabilizing circuit.

The composite buffer protection unit includes two composite buffer circuits with the same structure, which are respectively arranged on the two bus bars I and II to suppress the peak voltage on the bus bars when the IGBT is turned on and off. The composite buffer protection unit includes two input terminals and two output terminals, the first input terminal of the composite buffer protection unit is connected to the output terminal of the high-frequency array unit, and the second input terminal of the composite buffer protection unit is connected to the output terminal of the MOSFET/IGBT drive unit , the first output end of the composite buffer protection unit is connected to the input end of the current detection unit, and the second output end of the composite buffer protection unit is connected to the first input end of the power frequency conversion unit.

The first composite snubber circuit and the second composite snubber circuit with the same composite snubber circuit structure on the two buses, taking the first composite snubber circuit on the bus I as an example, as shown in Figure 4, includes a high-frequency breaking function IGBT device VT1, resistor R1, sixth capacitor C6, inductor L1, twenty-first reverse diode VD21 and twenty-second reverse diode VD22, the specific connection structure is: one end of inductor L1 is used as the input end of the composite buffer circuit , that is, the first input terminal of the composite buffer protection unit is connected to the output terminal of the high-frequency array unit, and at the same time connected to the cathode of the twenty-first reverse diode VD21, and the other end of the inductor L1 is connected to the collector of the IGBT device VT1 and the resistor R1 One end, the anode of the twenty-first reverse diode VD21 and the anode of the twenty-second reverse diode VD22, the emitter of the IGBT device VT1 is connected to the cathode of the twenty-second reverse diode VD22, the other end of the resistor R1, and the capacitor C6 The positive pole of the capacitor C6 is connected to the first input terminal of the power conversion unit, and the negative pole of the capacitor C6 is used as the second output terminal of the composite buffer protection unit, which is connected to the emitter of the IGBT device VT1 and the first input terminal of the power conversion unit; the gate of the IGBT device VT1 As the second input terminal of the composite buffer protection unit, it is connected to the output terminal of the MOSFET/IGBT driving unit. The collector of the IGBT device VT1 is used as the first output terminal of the composite buffer unit, connected to the input terminal of the current detection unit and the output terminal of the high-frequency array unit; the emitter of the IGBT device VT1 is used as the second output terminal of the composite buffer unit, connected to the power The first input terminal of the frequency conversion unit.

The power conversion unit is used to convert the DC voltage on the busbar side to the AC voltage on the grid side, as shown in Figure 5, including the filter support capacitor C8 and 6 subunits with the same structure, and the circuit structure of each subunit is the same as that of the first or second The circuit structure of the compound snubber circuit is the same. The IGBT device VT3 and its peripheral circuit are used as the first subunit of the power conversion unit, the IGBT device VT4 and its peripheral circuit are used as the second subunit of the power conversion unit, and the IGBT device VT5 and its peripheral circuit are used as the third subunit of the power conversion unit , IGBT device VT6 and its peripheral circuit as the fourth subunit of the power frequency conversion unit, IGBT device VT7 and its peripheral circuit as the fifth subunit of the power frequency conversion unit, IGBT device VT8 and its peripheral circuit as the sixth subunit of the power frequency conversion unit unit. Taking the first subunit as an example, it includes an IGBT device VT3 with a high-frequency breaking function, a resistor R3, a capacitor C9, an inductor L3, a reverse diode VD24, and a reverse diode VD25; one end of the inductor L3 is connected to the cathode of the reverse diode VD24 , the other end of the inductor L3 is connected to the collector of the IGBT device VT3, one end of the resistor R3, the anode of the reverse diode VD24 and the anode of the reverse diode VD25, and the emitter of the IGBT device VT3 is connected to the cathode of the reverse diode VD25 and the resistor R3 The other end is the positive pole of the capacitor C9, the negative pole of the capacitor C9 is connected to the emitter of the IGBT device VT3, and the gate of the IGBT device VT3 is used as the second input terminal of the power conversion unit and connected to the first output terminal of the IGBT drive unit. One end of the inductance L3, L4, L5, L6, L7, L8 connected to the cathode of the reverse diode in each subunit is respectively used as the input end of the corresponding subunit, and the IGBT devices VT3, VT4, VT5, VT6, VT7 in each subunit , The emitters of VT8 are respectively used as the output terminals of the corresponding subunits. The input terminals of the first subunit, the third subunit and the fifth subunit of the power frequency conversion unit are connected at one point, as the positive pole of the first input terminal of the power frequency conversion unit, and connected with the first composite buffer circuit connected to the bus I at the same time. Two output terminals, the output terminals of the second subunit, the fourth subunit, and the sixth subunit are connected at one point, as the negative pole of the first input terminal of the power frequency conversion unit, and connected with the second composite buffer circuit connected to the bus II at the same time. Two output terminals. The capacitor C8 is connected between the input terminal of the first subunit and the output terminal of the second subunit. The output terminals of the first subunit, the third subunit, and the fifth subunit of the power frequency conversion unit are respectively connected to the input terminals of the second subunit, the fourth subunit, and the sixth subunit of the power frequency conversion unit, and serve as power frequency conversion units respectively. Three outputs of the unit.

The connection circuit of distributed power supply, full-bridge high-frequency array unit, composite buffer unit, power frequency conversion unit and LC filter is shown in Figure 6.

The MOSFET/IGBT drive unit is used to boost the output signal of the microprocessor unit to achieve the voltage required to control the gate of MOSFET and IGBT devices, including EXB841 drive chip and peripheral protection circuit, as shown in Figure 7, in which the peripheral circuit Including ERA34-10 diode D1, capacitors C10, C11, current limiting resistor Re, buffer resistor RG, feedback resistor Rf, transistor TCR and TLP251 optocoupler. Each IGBT drive unit drives a set of half-bridges composed of two IGBTs. Take driving an IGBT circuit as an example, the pin 6 of the driver chip EXB841 is connected to the anode of the ERA34-10 diode D1, the cathode of the ERA34-10 diode D1 is connected to the collector of the driven IGBT device, and the pin 2 of the driver chip EXB841 is connected to the 15V power supply, The positive pole of capacitor C10 is connected to one end of feedback resistor Rf, and the positive pole of capacitor C11 is connected to pin 3 of driver chip EXB841 and one end of buffer resistor RG; The gate, the cathode of capacitor C10 and capacitor C11 are simultaneously connected to the emitter of the driven IGBT and pin 1 of the driver chip EXB841, pin 15 of the driver chip EXB841 is connected to one end of the current limiting resistor Re, and the other end of the current limiting resistor Re is connected to the 15V power supply , pin 14 of the driver chip EXB841 is connected to the collector of the transistor TCR, the emitter of the transistor TCR is connected to pin 1 of the TLP251 optocoupler, and the gate of the transistor TCR is used as the IGBT drive unit to connect the input terminal IN1 of the microprocessor control signal to the microprocessor The B6 end of the first buffer chip 74HC245 of the device unit is connected; the pin 5 of the driver chip EXB841 is connected to the pin 4 of the TLP251 optocoupler, the pin 3 of the TLP251 optocoupler is connected to the other end of the feedback resistor Rf, and the pin 2 of the TLP251 optocoupler is used as The S3 port is connected to the B0 port of the first buffer chip 74HC245 of the microprocessor unit. The gates of all IGBT devices in the composite buffer unit and the power conversion unit are connected to the output terminal of the IGBT drive unit.

The voltage detection unit is used to detect the voltages of the compound buffer protection unit, the first input terminal of the full-bridge high-frequency array unit and the three output terminals of the power conversion unit, and includes two sets of voltage detection circuits with the same circuit structure.

Taking a group of voltage detection unit circuits as an example, as shown in Figure 8, it includes an iron core and a signal processing circuit, wherein a Hall element is arranged at the separation of the iron core, and the function is to convert the magnetic flux signal of the iron core into an electrical signal. The signal processing circuit includes an op amp U0, two transistors Qs1, Qs2 and a measuring resistor RM. The op amp model is LM358. The input terminals (pin 2) are respectively connected to both ends of the Hall element. The pin 3 of the operational amplifier U0 is used as the first input terminal of the voltage detection unit, and is connected to the +15V power supply and the collector of the transistor Qs1. The operational amplifier U0 The pin 4 of the pin 4 is used as the second input terminal of the voltage detection unit, and it is connected to the -15V power supply and the emitter of the triode Qs2 at the same time, and the pin 5 of the operational amplifier chip is connected to the base of the first triode and the base of the second triode at the same time. The emitter of the triode Qs1 is connected to the collector of the triode Qs2 and one end of the iron core secondary coil at the same time, the other end of the iron core secondary coil is connected to one end of the measuring resistor RM, the other end of the measuring resistor RM is grounded, and the iron core The input terminal of the side coil is used as the third input terminal of the voltage detection unit, which is connected to the first input terminal of the high-frequency array unit, and one terminal S1 of the measuring resistor RM is used as the output terminal of the voltage detection unit. The two resistors on the primary coil side in Figure 8 refer to the internal resistance of the access wire, which is a virtual equivalent value and has no practical meaning in the circuit. The left end is connected to the voltage input to the terminal to be detected.

The current detection unit is used to detect whether the current of the point to be detected in the device exceeds or is lower than the preset current threshold range, including a bridge arm through current detection unit, a bus current detection unit and a load current detection unit. The detection circuit of the bridge arm through current detection unit is a decentralized overcurrent protection circuit, which is used to detect whether the bridge arm through current formed by the IGBT device at the point to be detected in the composite buffer unit and the power conversion unit exceeds the preset current value, and is used to detect the composite buffer The distributed overcurrent protection circuit structure in the unit and the power conversion unit is the same. The detection circuits of the bus current detection unit and the load current detection unit are both centralized overcurrent protection circuits. The bus current detection unit is used to detect whether the current at the point to be detected on the bus exceeds the preset current value, and there are A bus current detection unit, the load current detection unit is used to detect whether the current at the point to be detected on the load connection line exceeds a preset current value. The detection position of the bridge arm through-fault current detection unit is shown in ③ and ④ in Figure 5 or 6, the detection position of the bus current detection unit is shown in ① and ② in Figure 5 or 6, and the detection position of the load current detection unit is shown in Figure 5 or 6 ⑤ in 6.

The working principle of the decentralized overcurrent protection circuit is shown in Figure 9. Vref is used as the set threshold voltage of the decentralized overcurrent protection circuit. When the comparator detects that the voltage at point 0 is greater than the set threshold voltage, the comparator outputs a high level The AND gate AND outputs a high-level signal to the micro-processing unit, and then sends out a pulse control signal to control the on-off of the IGBT to prevent the device from suffering secondary damage.

Taking the decentralized overcurrent protection circuit set at the point to be detected in the power conversion unit as an example, Figure 10 is a working principle diagram of the decentralized overcurrent protection circuit connected to the IGBT driver chip provided by this embodiment, and the specific structure of the decentralized overcurrent protection circuit Including voltage comparator U1, resistors R9, R10, R11 and R12, Schottky diodes D2 and D3, blue and white adjustable potentiometer RP1 (used to adjust the set voltage threshold). The same input end of LM339 voltage comparator U1 is connected to one end of resistor R10 and the anode of Schottky diode D2, and the cathode of Schottky diode D2 is connected to the collector of power frequency conversion unit IGBT device VT3 as the input end of distributed overcurrent protection circuit ; One end of the resistor R9 is connected to +15V DC power supply, the other end of the resistor R9 is connected to the other end of the resistor R10 and a fixed end of the adjustable potentiometer RP1; the other fixed end of the adjustable potentiometer RP1 is grounded, and the adjustable potentiometer RP1 The sliding end of the resistor R11 is connected to one end of the resistor R11, and the other end of the resistor R11 is connected to the reverse input end of the voltage comparator U1; one end of the resistor R12 is connected to a 15V DC power supply, and at the same time connected to the positive pole of the voltage comparator U1 power supply, MOSFET/IGBT driver The pin 2 of the driver chip EXB841 of the unit and one end of the decoupling capacitor C12. The decoupling capacitor C12 is a decoupling capacitor added after connecting to the distributed over-current protection circuit. Add a decoupling capacitor C12 between pin 1) and the negative pole of the power supply (GND); the negative pole 14 of the power supply of the voltage comparator U1 is grounded, and the signal output terminal of the LM339 voltage comparator U1 is connected to the other end of the resistor R12 and the Schottky diode The cathode of D3 is connected, the anode of Schottky diode D3 is used as the output terminal of the distributed overcurrent protection circuit, connected to pin 6 of the drive chip of the MOSFET/IGBT drive unit, and the signal output terminal OUT of the voltage comparator U1 is the current detection unit and The ADOC1 port where the second buffer chip of the microprocessor unit is connected. Resistor R9 is connected in series with blue and white adjustable potentiometer RP1, and through adjustable potentiometer RP1, feedback voltage Vref is provided to LM339 voltage comparator U1 through resistor R11. The collector voltage is collected and compared with the preset Vref value to determine whether the bridge arm of the IGBT device has an overcurrent fault.

Taking the centralized overcurrent protection circuit on the DC bus of the distributed power supply as an example, as shown in Figure 11, the specific structure of the centralized overcurrent protection circuit takes bus I as an example, including Hall current sensor H1, resistors R13, R14, R15, Blue and white adjustable potentiometer RP2, capacitors C14, C15 and LM339 voltage comparator U2, among them, the Hall current sensor H1 adopts the direct-measurement Hall effect current sensor HAP8-200/4 of Japan HINODE Company, the sensor needs positive and negative 15V dual power supply for power supply. The specific connection structure of the circuit is: the signal output terminal of the Hall current sensor H1 is connected to the same input terminal (pin 3) of the LM339 voltage comparator U2; one end of the resistor R13 is connected in parallel with the capacitor C15 to ground, and the other end is connected to the LM339 voltage comparator The same input terminal (pin 3) of the potentiometer U2 is used for signal filtering; one fixed terminal of the adjustable potentiometer RP2 is connected to the 15V power supply, the other fixed terminal is grounded, and the sliding terminal is connected to the reverse input terminal of the LM339 voltage comparator U2. Pin 2 is connected to provide feedback voltage; one end of resistor R14 is connected to a 5V power supply as a pull-up resistor, and the other end is connected to the signal output end (pin 1) of LM339 voltage comparator U2 and one end of resistor R15, which is used to improve the voltage of LM339 voltage comparator U2 The current driving capability of the signal output terminal, the other end of the resistor R15 is used as an output port OC1 of the centralized overcurrent protection circuit, that is, the ADOC2 port connected to the second buffer chip of the current detection unit and the microprocessor unit, and one end of the capacitor C14 is connected at the same time. The other end of the capacitor C14 is grounded, and the resistor R15 and the capacitor C14 form an RC delay circuit. The LM339 voltage comparator U2 signal output terminal (pin 1) outputs the level signal OC1 to the microprocessor through the buffer resistor R15 to record the current data. When the threshold value is seriously exceeded, all IGBT drive signals are blocked, and the resistor R15 The delay circuit composed of the capacitor C14 is an anti-jamming measure to prevent the malfunction of the blocking circuit. A centralized over-current protection circuit with the same structure is set on the other bus, and its output port is OC2.

The LC filter is used to filter out the harmonics generated by the power frequency conversion unit, including three sets of LC filter circuits. The three-phase lines of the grid.

A method for wide-range voltage input transformation for distributed power grid-connected realized by the above-mentioned wide-range voltage input conversion device for distributed power grid-connected, as shown in Figure 12, specifically includes the following steps:

Step 1. Use the microprocessor unit to control the internal components of the full-bridge high-frequency array unit, composite buffer protection unit, power frequency conversion unit and MOSFET/IGBT drive unit, so that the entire voltage input conversion device is in operation. The specific method is:

Step 1.1, adopt microprocessor unit to send SPWM (sinusoidal pulse width modulation) signal;

Step 1.2, carry out boost processing through the MOSFET/IGBT drive unit, and increase the amplitude of the SPWM voltage signal to 15V;

Step 1.3, respectively drive 20 MOSFET devices in the full-bridge high-frequency array unit, two IGBT devices in the IGBT composite buffer unit and 6 IGBT devices in the power conversion unit, so that each MOSFET and IGBT device are turned on alternately, and are used in distributed power supply and The wide-range voltage input conversion device of the network is in normal operation;

Step 2. Simultaneously use the measurement resistor RM in the voltage detection unit, the decentralized overcurrent protection circuit in the current detection unit, and the centralized overcurrent protection circuit to control the voltage at the front end of the full-bridge high-frequency array unit, the composite buffer protection unit, and the power conversion unit. Real-time acquisition of current and voltage;

The voltage detection unit generates a signal and sends it to the microprocessor unit. When the voltage fluctuates beyond the first preset input voltage range, the duty cycle of the MOSFET device is changed, and the output voltage of the full-bridge high-frequency array unit is changed to avoid the The impact of input voltage fluctuations on output voltage;

The level signal generated by the centralized overcurrent protection circuit in the bus current detection unit and the load current detection unit is sent to the EXB841 drive chip of the MOSFET/IGBT drive unit and the ADCINAO-A7 port of the microprocessor unit after being delayed by the RC delay circuit;

The microprocessor unit collects and records the current and voltage data of each channel, and constructs the relationship curve between the voltage of the terminal to be detected and the detection branch in real time;

Step 3. The microprocessor unit judges the position of the fault current, judges whether the current value exceeds 1.2 times the set value, and whether the input voltage of the terminal to be detected exceeds 48-198V. If any one of them exceeds or both exceed at the same time, it means that there is a Fault, the corresponding unit is the faulty unit, go to step 4, otherwise the system is working normally, go back to step 2, and continue testing;

Step 4. When a voltage failure occurs, the microprocessor unit generates a control signal and sends it to the corresponding MOSFET device of the full-bridge high-frequency array unit. According to the voltage variation range, the signal duty cycle of the driving MOSFET device is linearly adjusted, and the full-bridge height is adaptively changed. The output voltage of the frequency array unit; when a current fault occurs, the microprocessor unit is used to generate a control signal and sent to the corresponding unit where the fault occurs, and the gate voltage of the IGBT device of the faulty unit is slowly reduced; the microprocessor unit simultaneously records The location of the fault current will generate corresponding numbers, number 1 is bus current fault, number 2 is bridge arm through fault, number 3 and 5 are load short-circuit faults, and the fault record will be sent to the mobile phone through the SIM808 wireless communication unit, and the report micro The processor unit judges the fault information, sends out a fault intermediate alarm signal, and transmits the fault to the computer PC host computer; the computer PC host computer compares the existing faults with the faults stored in the computer database, and determines the type of fault current and Location;

Step 5. The microprocessor further judges the fault current and voltage detection, and judges whether the current value exceeds 1.5 times the set value, and whether the input voltage exceeds 50-200V. If any one exceeds or both exceed at the same time, it is determined that a serious fault has occurred at the corresponding position. Undervoltage, short circuit or overcurrent fault, go to step 6, otherwise go to step 2;

Step 6. The microprocessor unit sends a control signal, blocks the input signal, turns off the MOSFET or IGBT device in the unit where a serious short circuit or overcurrent fault occurs, and continuously sends the fault information to the user's mobile phone through the SIM808 wireless communication unit. At the same time, the microprocessor unit generates a serious fault alarm signal, and transmits the fault to the PC host computer to avoid secondary damage to the inverter.

In this embodiment, when the voltage input conversion is completed, the IGBT device is turned off to form a composite snubber circuit structure as shown in Figure 13, the current in the inductor L1 is released through the diode VD21, and the energy stored in the stray inductance in VT1 passes through Capacitor C6 and resistor R1 are released, buffering the overcurrent generated when the IGBT device is turned off, and avoiding damage to the IGBT device.

In this embodiment, when the voltage input conversion device starts to operate, the IGBT device is turned on to form a composite snubber circuit structure as shown in Figure 14. The inductance L1 suppresses the current rise rate on the collector side at the moment the IGBT is turned on, reducing the collector side. The surge peak voltage, and the surge current at the moment of VT1 opening is released through VD22 and C6, as shown in the dotted line path in the figure, which buffers the surge current generated at the moment of turning on the IGBT to avoid damage to the IGBT device.

The effective value of the three-phase voltage before the installation of the voltage input conversion device is shown in Figure 15, and the effective value of the three-phase voltage is shown in Figure 16 after the installation of the voltage input conversion device. During the period from the last 5ms to 35ms, the voltage fluctuation phenomenon after installation has been significantly improved. After 42ms, the AC side voltage waveform has been significantly improved, and the output voltage tends to be stable.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some or all of the technical features; these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope defined by the claims of the present invention.

Claims (10)

1. a kind of wide range input converting means grid-connected for distributed power source, it is characterised in that：Including microprocessor Unit, full-bridge high-frequency array element, composite buffering protection location, power converter unit, MOSFET/IGBT driver elements, voltage Detection unit, current detecting unit, radio communication unit, LC wave filters and host computer；

Described microprocessor unit is used to process electric current and voltage letter that current detecting unit and voltage detection unit are collected Breath, and then the break-make of MOSFET/IGBT driver elements control MOSFET and IGBT device is driven, while the electric current electricity that will be collected Press information transfer to host computer, PC ends recording voltage and current information, the input voltage range grid-connected to widen distributed power source Provided safeguard with power output grade separation；The microprocessor unit includes that main control chip, the first buffer chip and second are slow Rush chip；The MOSFET/IGBT driver elements are connected by the first buffer chip with main control chip, the current detecting unit Be connected with main control chip by the second buffer chip with voltage detection unit, the radio communication unit directly with the master control Chip is connected；

The full-bridge high-frequency array element includes five structure identical full-bridge high-frequency mu balanced circuits, located at two dc bus On, the input voltage range grid-connected for widening distributed power source；Described full-bridge high-frequency array element includes three inputs With an output end, the first input end of described HF array unit passes through current detecting unit and voltage detection unit is connected Battery is converted as the energy storage of distributed grid-connected power supply, the second input connection of the full-bridge high-frequency array element is described MOSFET/IGBT driver element output ends, the 3rd input connection microprocessor unit of the full-bridge high-frequency array element Second output end, the output end of the full-bridge high-frequency array element connects the first input end of composite buffering unit；

The composite buffering protection location includes two structure identical the first composite buffering circuits and the second composite buffering circuit, It is respectively arranged on two buses I and II, for suppressing during IGBT device break-make peak voltage on bus；The composite buffering protection Unit includes two inputs and two output ends, the first input end connection HF array list of the composite buffering protection location The output end of unit, the second input of the composite buffering protection location connects the output of the MOSFET/IGBT driver elements End, the first output end of the composite buffering protection location connects the input of current detecting unit, the composite buffering protection Second output end of unit connects the first input end of power converter unit；

The power converter unit is used to for bus bar side DC voltage to be changed into grid side alternating voltage, including 6 structures are identical Subelement, the circuit structure of the circuit structure of each subelement with the described first or second composite buffering circuit is identical；

The MOSFET/IGBT driver elements include driving chip and peripheral protection circuit, for microprocessor unit to be exported Signal carries out boosting treatment, and then reaches control MOSFET and voltage needed for IGBT device grid；

The voltage detection unit is used to detect composite buffering protection location, HF array unit first input end and power frequency conversion The voltage of the tunnel output end of unit three, including two groups of circuit structure identical voltage detecting circuits；

The current detecting unit is used to detect whether the electric current of measuring point to be checked in converting means exceeds or falls below predetermined current threshold Value scope, including bridge arm direct pass current detecting unit, bus current detection unit and load current detection unit, the bridge arm are straight The detection circuit of logical fault current detection unit is dispersion current foldback circuit, for detecting composite buffering unit and power frequency conversion Whether the bridge arm direct pass electric current of measuring point to be checked exceedes pre-set current value, the bus current detection unit and load current in unit The detection protection circuit of detection unit is concentration current foldback circuit, and the bus current detection unit is used to detect that direct current is female Whether the electric current of line measuring point to be checked exceedes predetermined current threshold scope, and a bus current inspection is respectively equipped with two buses Unit is surveyed, the load current detection unit is used to detect whether the electric current of measuring point to be checked on load connecting line to exceed predetermined current Threshold range；

The radio communication unit is used to for the signal of microprocessing unit to radio to host computer；

The LC wave filters are used to filter the harmonic wave of power converter unit generation, including three groups of LC filter circuits, three groups of LC The input of filter circuit connects three tunnel output ends of the power converter unit, the output of three groups of LC filter circuits respectively End connects the triple line of power network respectively；

The host computer is mobile phone and computer PC, voltage, electric current and power information for real-time monitoring device, while can pass through Send the break-make of instruction control IGBT device.

2. the wide range input converting means grid-connected for distributed power source according to claim 1, its feature exists In：The full-bridge high-frequency mu balanced circuit includes high voltage bus filter capacitor, the first MOSFET element, the second MOSFET element, the Three MOSFET elements, the 4th MOSFET element, high frequency full-bridge boost transformer, first choice derailing switch, the first backward dioded, Second backward dioded, the 3rd backward dioded and the 4th backward dioded；The two ends conduct of the high voltage bus filter capacitor The first input end of the HF array unit, connects as the energy storage device of distributed generation system, while connecting voltage inspection Survey the input of unit；The drain electrode of first MOSFET element and the second MOSFET element connects high voltage bus filtered electrical simultaneously One end of appearance, the source electrode of first MOSFET element connects the different name input and of high frequency full-bridge boost transformer simultaneously The drain electrode of four MOSFET elements, the source electrode of second MOSFET element connects the of the same name defeated of high frequency full-bridge boost transformer simultaneously Enter to hold the drain electrode with the 3rd MOSFET element, the source electrode of the 3rd MOSFET element and the 4th MOSFET element connects height simultaneously Press the other end of bus filter capacitor；First MOSFET element, the second MOSFET element, the 3rd MOSFET element and the 4th The grid of MOSFET element connects the output end of MOSFET/IGBT driver elements as the second input of HF array unit； The output end of the same name of the high frequency full-bridge boost transformer connects negative electrode and the 4th reverse two pole of the 3rd backward dioded simultaneously The anode of pipe, the different name output end of the high frequency full-bridge boost transformer connects the first input end of first choice derailing switch；Institute The signal pins 2 of first choice derailing switch are stated as the 3rd input of HF array unit, the of connection microprocessor unit Two output ends；The output end of the first choice derailing switch connects anode and second reverse two pole of the first backward dioded simultaneously The negative electrode of pipe；The negative electrode connection of the negative electrode and the 4th backward dioded of the first described backward dioded, as the full-bridge high-frequency First output end of mu balanced circuit, the anode connection of the anode and the 3rd backward dioded of second backward dioded, as Second output end of the full-bridge high-frequency mu balanced circuit；Five structure identical full-bridge high-frequency mu balanced circuits are high by previous full-bridge The mode that second output end of frequency mu balanced circuit is connected with the first output end of adjacent next full-bridge high-frequency mu balanced circuit Connected, series connection change-over terminal 1 and next full-bridge high-frequency of the first choice derailing switch of previous full-bridge high-frequency mu balanced circuit The output end of the same name connection of mu balanced circuit medium-high frequency full-bridge boost transformer；First the first output of full-bridge high-frequency mu balanced circuit End and the 5th the second output end of full-bridge high-frequency mu balanced circuit connect collectively as a pair of output of full-bridge high-frequency array element Connect the first input end of composite buffering unit.

3. the wide range input converting means grid-connected for distributed power source according to claim 2, its feature exists In：The first composite buffering circuit includes the first IGBT device, first resistor, the 6th electric capacity, the first inductance, the 21st anti- To diode, the 22nd backward dioded；One end of first inductance is used as the first of the composite buffering protection location Input, connects the output end of full-bridge high-frequency array element, while connecting the negative electrode of the 21st backward dioded, described first The other end of inductance connects colelctor electrode, one end of first resistor, the anode of the 21st backward dioded of the first IGBT device With the anode of the 22nd backward dioded, the moon of emitter stage the 22nd backward dioded of connection of first IGBT device Pole, the other end of first resistor, the positive pole of the 6th electric capacity, the first input end of power converter unit, the 6th electric capacity it is negative Pole as composite buffering protection location the second output end, connect the first IGBT device emitter stage and power converter unit the One input, the gate pole of the first IGBT device connects MOSFET/IGBT and drives as the second input of composite buffering protection location The output end of moving cell；The colelctor electrode of the first described IGBT device connects electricity as the first output end of composite buffering unit Flow input, the output end of HF array unit of detection unit.

4. the wide range input converting means grid-connected for distributed power source according to claim 3, its feature exists In：The power converter unit also includes the 8th electric capacity；The gate pole of the IGBT device of each subelement is as power converter unit The second input, connect IGBT driver elements output end；One end of inductance in each subelement is single respectively as corresponding son The input of unit；Output end of the emitter stage of the IGBT device in each subelement respectively as corresponding subelement；6 structures The first subelement, the 3rd subelement in identical subelement, the input of the 5th subelement are connected to a bit, become as power The positive pole of the first input end of frequency unit, the second output end of the first composite buffering circuit that connection is connected with bus I；Described 6 The second subelement, the 4th subelement in individual structure identical subelement, the output end of the 6th subelement be connected to a bit, as The negative pole of the first input end of power converter unit, the second output of the second composite buffering circuit that connection is connected with bus II End；8th capacitance connection is between the input of the first subelement and the output end of the second subelement；6 structure phases With subelement in the first subelement, the 3rd subelement, the output end of the 5th subelement be connected respectively the second subelement, 4th subelement, the input of the 6th subelement, and respectively as three tunnel output ends of power converter unit.

5. the wide range input converting means grid-connected for distributed power source according to claim 4, its feature exists In：The peripheral circuit of the MOSFET/IGBT driver elements includes the first diode, the 9th electric capacity, the tenth electric capacity, current limliting electricity Resistance, buffer resistance, feedback resistance, transistor and optocoupler；6 pin of driving chip connect the anode of the first diode, the one or two pole The negative electrode connection of pipe connects 15V simultaneously by the drain electrode of the colelctor electrode of driving IGBT device and MOSFET element, 2 pin of driving chip One end of power supply, the 9th capacitance cathode and feedback resistance, 3 pin of driving chip connect the positive pole and buffering electricity of the tenth electric capacity simultaneously One end of resistance；The other end of buffer resistance as IGBT driver elements output end, connection by the gate pole of driving IGBT device and The grid of MOSFET element；The negative pole of the 9th electric capacity and the tenth electric capacity connect simultaneously by the emitter stage of driving IGBT device, The source electrode of MOSFET element and 1 pin of driving chip, 15 pin of driving chip connect one end of current-limiting resistance, current-limiting resistance it is another One end connects 15V power supplys, and 14 pin of driving chip connect the colelctor electrode of transistor, the emitter stage of transistor and 1 pin phase of optocoupler Even, the grid of transistor connects the first buffer chip of microprocessor unit, and 5 pin of driving chip are connected with 4 pin of optocoupler, light 3 pin of coupling connect the other end of feedback resistance, the 2 pins connection microprocessor unit of optocoupler.

6. the wide range input converting means grid-connected for distributed power source according to claim 1, its feature exists In：The voltage detection unit includes iron core and signal processing circuit, and wherein iron core to separate and be provided with a Hall element at mouth, uses In the magnetic flux signal of iron core is converted into electric signal, signal processing circuit includes amplifier chip, the first triode, the two or three pole Pipe, measurement resistance；The input in the same direction of amplifier chip connects one end of Hall element, and the inverting input connection of amplifier chip is suddenly The other end of your element, the positive source of amplifier chip connects the colelctor electrode of power supply+VCC and the first triode, amplifier core simultaneously 4 pin of piece connect the emitter stage of power supply-VCC and the second triode simultaneously, and 5 pin of amplifier chip connect the first triode simultaneously The base stage of base stage and the second triode, the emitter stage of the first triode connects one end and the two or three pole of iron core secondary coil simultaneously The colelctor electrode of pipe, the other end of iron core secondary coil is by measuring resistance eutral grounding.

7. the wide range input converting means grid-connected for distributed power source according to claim 5, its feature exists In：The dispersion current foldback circuit is used to detect the bridge that the IGBT device in composite buffering unit and power converter unit is constituted Arm through current, including first voltage comparator, 3rd resistor, the 4th resistance, the 5th resistance and the 6th resistance, the second diode With the 3rd diode and the first adjustable potentiometer；The input in the same direction of the first voltage comparator connects one end of the 4th resistance With the anode of the second diode, the negative electrode of the second diode is used as the input for disperseing current foldback circuit, connection power frequency conversion The colelctor electrode of each IGBT device in unit；One end connection+15V dc sources of 3rd resistor, the other end connects the 4th resistance One fixing end of the other end and the first adjustable potentiometer；Another fixing end ground connection of the first adjustable potentiometer, first is adjustable The sliding end of potentiometer is connected with one end of the 5th resistance, and the other end of the 5th resistance connects the reverse defeated of first voltage comparator Enter end；The positive source connection 15V dc sources of first voltage comparator, one end of the 6th resistance, MOSFET/IGBT drive list The pin 2 of the driving chip of unit；First voltage comparator power cathode ground connection, the signal output part of first voltage comparator with The other end of the 6th resistance and the negative electrode of the 3rd diode are connected, and the anode of the 3rd diode is used as dispersion current foldback circuit Output end, connects the pin 6 of the driving chip of MOSFET/IGBT driver elements, and the signal output part of first voltage comparator connects Connect the second buffer chip of microprocessor unit.

8. the wide range input converting means grid-connected for distributed power source according to claim 5, its feature exists In：The concentration current foldback circuit includes Hall current sensor, the 7th resistance, the 8th resistance, the 9th resistance, second adjustable Potentiometer, the 11st electric capacity, the 12nd electric capacity and second voltage comparator；Hall current sensor is installed on the company of tested measuring point In wiring, the signal output part of Hall current sensor is connected with the input in the same direction of second voltage comparator；7th resistance with 12nd electric capacity is in parallel and then one end is grounded, and the other end connects the input in the same direction of second voltage comparator, carries out signal filtering； Second fixing end of adjustable potentiometer one accesses 15V power supplys, another fixing end ground connection, sliding end and second voltage comparator Reverse input end is connected, there is provided feedback voltage；5V power supplys are accessed as pull-up resistor, other end connection second in 8th resistance one end The signal output part of voltage comparator and the 9th resistance one end；The other end of the 9th resistance is used as the one of concentration current foldback circuit Individual output port, is connected with the second buffer chip of microprocessor unit, while one end of the 11st electric capacity is connected, the 11st electricity The other end ground connection of appearance；9th resistance and the 11st electric capacity constitute RC retardation ratio circuit.

9. the wide range input converting means grid-connected for distributed power source according to claim 1, its feature exists In：The power pack of each unit is exported (output ± 15V, 5V, 3.3V voltage) by with plurality of voltages in the device Switching Power Supply is provided.

10. a kind of method that wide range input grid-connected for distributed power source is converted, the method passes through claim 1 institute The wide range input converting means grid-connected for distributed power source stated is realized, it is characterised in that：The method includes following Step：

Step 1, using microprocessor unit control full-bridge high-frequency array element, composite buffering protection location, power converter unit With the inner member of MOSFET/IGBT driver elements, whole control source converting means is set to be in running status, specific method For：

Step 1.1, SPWM (i.e. sinusoidal pulse width modulation) signal is sent using microprocessor unit；

Step 1.2, boosting treatment is carried out by MOSFET/IGBT driver elements, SPWM voltage signal magnitudes are raised to 15V；

Step 1.3, the respectively MOSFET element of driving full-bridge high-frequency array element, composite buffering unit and power converter unit IGBT device, makes each MOSFET and IGBT device alternate conduction, is used in the grid-connected wide range input of distributed power source and becomes Changing device is in normal operating condition；

Step 2, the data acquisition and the record that carry out electric current and voltage, specific method is：

Step 2.1, while using the dispersion current foldback circuit in voltage detection unit, current detecting unit, concentrate excessively stream protect Electric current and voltage of the protection circuit to the voltage, composite buffering protection location and power converter unit of full-bridge high-frequency array element front end Carry out Real-time Collection；

Voltage detection unit produces signal all the way, gives microprocessor unit, when voltage fluctuation occurs more than the first default input During voltage range, promote the change of MOSFET element dutycycle, change the output voltage of full-bridge high-frequency array element, it is to avoid due to Influence of the fluctuation of input voltage to output voltage；

The level signal that current foldback circuit is produced of concentrating in bus current detection unit and load current detection unit is passed through The driving chip and microprocessor unit of MOSFET/IGBT driver elements are given in the delay of RC retardation ratio circuit；

Each road electric current of step 2.2, microprocessor unit acquisition and recording and voltage data, build terminal voltage to be detected with detection in real time The graph of relation of branch road；

Whether step 3, microprocessor unit judge current value more than the first predetermined current threshold, and whether the voltage at end to be detected surpasses The first default input voltage range is crossed, if any one is surpassed in the first predetermined current threshold and the first default input voltage range Cross or both while exceed, then illustrate that system breaks down, failure judgement classification is voltage failure or current failure, performs step 4, otherwise system is working properly, returns and performs step 2；

Step 4, when there is voltage failure, microprocessor unit produce control signal simultaneously be sent to full-bridge high-frequency array element phase MOSFET element is answered, according to voltage change range, linear regulation drives MOSFET element signal dutyfactor, adaptively changing full-bridge The output voltage of HF array unit；When there is current failure, microprocessor unit produces control signal and sends to appearance In the corresponding units of failure, the IGBT device of the unit to breaking down carries out slow drop grid voltage；Microprocessor unit is recorded simultaneously The position of lower fault current, produces corresponding numbering, and failure logging is sent into short message to mobile phone, report by radio communication unit Failed transmission is given computer PC host computers by the fault message that microprocessor unit is judged, intermediate alarm signal of being concurrently out of order； Computer PC host computers are contrasted the failure stored in existing failure and computer data, determine fault current type and Position；

Whether step 5, microprocessor further differentiate to fault current voltage detecting, judge current value more than the second predetermined current Threshold value, whether terminal voltage to be detected is more than the second predetermined voltage threshold scope, wherein the second predetermined current threshold is pre- more than first If current threshold, the end value of the second default input voltage range presets input voltage range more than first, if the second predetermined current Any one is exceeded or both while be exceeded in threshold value and the second default input voltage range, then assert correspondence position generation Serious under-voltage, short-circuit or over current fault, performs step 6, otherwise return to step 2；

Step 6, microprocessor unit send control signal, block input signal, and shut-off occurs serious under-voltage, short-circuit or excessively stream event MOSFET or IGBT device in the unit of barrier, short message to use is continuously sent by fault message by radio communication unit Family mobile phone, while microprocessor unit produces failure Critical alerts signal, computer PC host computers is given by failed transmission.