JPH1014111A - System-linked power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system-linked power supply system which can continue the operation of good solar battery modules when some are out of order and which can extract the maximum power from each solar battery module even if the solar battery modules are in different power generating conditions and thereby provides a high converting efficiency. SOLUTION: In a system-linked power supply system wherein a single-phase three-wire distribution line 3 which is constituted of two voltage lines and one neutral line and which has an R phase and a T phase is connected to an AC module 5 (5a-5d) which is constituted of a solar battery module PVM and an inverter unit VTU which outputs single-phase AC, a plurality of AC modules 5a, 5b, 5c,... are connected to each of the R phase and the T phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grid-connected power supply system in which an AC module is connected to a single-phase three-wire distribution line, and an AC module used for the system.

[0002]

2. Description of the Related Art In recent years, a grid-connected power supply system has been proposed which interconnects a solar cell with a single-phase three-wire commercial power system via an inverter device and supplies generated power of the solar cell to loads such as home appliances. It has been put into practical use (Japanese Unexamined Patent Publication No.
No. 80).

For example, six solar cell modules that output a DC voltage of about 30 V are connected in series to 180 V, and an AC voltage of 100 V is applied by an inverter device using this as an input voltage.
And then connected to the R-phase or T-phase of the single-phase three-wire distribution line.

[0004]

In a conventional grid-connected power supply system, a DC input voltage to an inverter
V or about 360 V, a plurality of sheets, for example, 6
Or about 12 solar cell modules are used in series. However, in that case, when one solar cell module fails, all the solar cell modules connected in series with it become unusable.

[0005] Further, depending on the installation location of the solar cell module, depending on the time zone, a part of the plurality of solar cell modules may be shaded by a building or the like, and the output may decrease. In this case, since the power generation status of each solar cell module is different from each other, even when the optimum operating point tracking control is performed, the maximum power cannot be extracted from each solar cell module, and the conversion efficiency decreases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and when some of the solar cell modules have failed, it is possible to continue the operation with the non-failed solar cell modules, It is an object of the present invention to provide a grid-connected power supply system capable of extracting maximum power from each solar cell module and obtaining high conversion efficiency even when the power generation states of the modules are different from each other.

[0007]

According to a first aspect of the present invention, there is provided a system comprising an AC module including a solar cell module and an inverter device for outputting a single-phase AC, two voltage lines and one neutral line. A system interconnection power system comprising a single-phase three-wire distribution line composed of an R-phase and a T-phase, wherein a plurality of ACs are provided for each of the R-phase and the T-phase. The module is connected.

According to a second aspect of the present invention, each of the AC modules has at least three connection poles for connecting the output to the R phase or the T phase and is connected in parallel with each other. Two fixed-side connectors are provided, and each of the AC modules is sequentially connected to each other by a connection cable provided at both ends with a cable-side connector connected to the fixed-side connector. The two AC modules are connected to the distribution line by an interconnection cable having the cable-side connector provided at least at one end.

According to a third aspect of the present invention, in each of the AC modules, the connection between the output and the connection terminal of the fixed connector is switched to either the R phase or the T phase. Switching means for selectively connecting is provided.

A system according to a fourth aspect of the present invention provides the system according to the fourth aspect,
The outputs of all of the AC modules connected to the T-phase and the T-phase have the same specifications, and the number of AC modules connected to the R-phase and the number of A-modules connected to the T-phase
The number of C modules is the same.

An AC module according to a fifth aspect of the present invention comprises:
It is composed of a solar cell module and an inverter device,
An AC module for a grid-connected power supply system connected to a single-phase three-wire distribution line composed of an R phase and a T phase composed of two voltage lines and one neutral line, wherein the inverter is Two fixed-side connectors having at least three connection poles and connected in parallel with each other are provided for connecting the output of the device to the R-phase or the T-phase; Switching means for selectively connecting to either the R-phase or the T-phase by switching the connection with the connection pole of the fixed-side connector is provided.

One solar cell module has, for example, about 30
V DC voltage is output. The inverter device, for example, converts the output of the solar cell module into a DC / DC converter 18
After the DC voltage is converted to about 0 V, the voltage is converted to AC power of 50/60 Hz and 100 V by a voltage-type current control type inverter. By connecting a number of AC modules to the R-phase or T-phase of the distribution line 3 by the same number, interconnection with the commercial power system is achieved.

When two fixed connectors are provided on an AC module, adjacent AC modules are sequentially connected by a connection cable, and the AC module at the end is connected to a distribution line by an interconnection cable.

When the switching means is provided in the AC module, the AC module can be easily switched to the R-phase or the T-phase without performing the work for changing the connection with the distribution line. Therefore, A for R phase or T phase
The arrangement and number of C modules can be easily set. As the switching means, for example, a jumper wire circuit or a changeover switch is used.

[0015]

FIG. 1 is a block diagram showing a circuit of a grid-connected power supply system 1 according to the present invention, FIG. 2 is a schematic view of an AC module 5, FIG. 3 is a block diagram showing a circuit of the AC module 5, 4 is a block diagram for explaining a connection state of the AC module 5, FIG. 5 is a diagram for explaining a connection state of the AC module 5, and FIG. 6 is a diagram showing an arrangement state of the AC module 5.

In FIG. 1, a grid-connected power supply system 1
Is a single-phase three-wire distribution line 3, which is one form of a commercial power system, an interconnection protection device 4, and AC modules 5a, 5b, and 5c.
.., An independent operation control device 6 and a personal computer 7. AC modules 5a, 5b, 5
All or part of c may be described as an AC module 5.

The distribution line 3 is composed of an R phase and a T phase composed of two voltage lines R and T and one neutral line N. Each of the R phase and the T phase is a single-phase AC 100 V, and the voltage lines R,
During T, single-phase 200 VAC.

The interconnection protection device 4 includes a switch 11, a system abnormality detection circuit 12, an interconnection control circuit 13, and the like. The switch 11 is closed or opened in response to a signal from the system abnormality detection circuit 12, and connects the AC module 5 and the distribution line 3 to be in an interconnected state, or is disconnected to be in an off-line state.

The system abnormality detection circuit 12 has an OVR / UV
It includes R, OFR / UFR, monitors the presence or absence of abnormality in the voltage and frequency of the commercial power system, and outputs a signal for opening the switch 11 when the abnormality is detected. The system abnormality detection circuit 12 has a passive system and an active system independent operation prevention function, detects when the AC module 5 is in the island operation state due to a power failure of the commercial power system or the like, and switches the switch 11. Outputs an open signal.

The interconnection control circuit 13 controls the entire interconnection protection device 4. The interconnection control circuit 13 is an RS-232C
It has a communication function by the interface of. When the system abnormality detection circuit 12 detects an abnormality and opens the switch 11, the interconnection control circuit 13 outputs a gate block command signal to all the AC modules 5 and stops their operation. A switching state signal SK indicating the state of the switch 11
And outputs it to the independent operation control device 6. The interconnection control circuit 13 receives information on each power generation state and operation state from each AC module 5.

The interconnection control circuit 13 communicates with the personal computer 7. The personal computer 7 receives information from the interconnection protection device 4 and performs monitoring such as detection of the power generation state of each AC module 5 or the presence or absence of a failure.

The AC module 5, as shown in FIG.
One solar cell module PVM is integrated with one inverter unit VTU. One solar cell module PVM outputs a DC voltage of about 30V.
The inverter unit VTU is a solar cell module PV
M output to DC / DC converter (converter circuit 2
After being converted to a DC of about 180 V in 1), the voltage is converted to 5 V by a voltage-source current control type inverter (the inverter circuit 23).
Convert to 0/60 Hz AC power.

A number of the AC modules 5 configured as described above are connected to the R-phase or the T-phase of the distribution line 3 by the same number, so that interconnection with the commercial power system is achieved. Each AC module 5 is arranged, for example, as shown in FIG. 6, and is installed outdoors. Such an interconnection system has the following advantages. (1) Since each solar cell module PVM generates power according to each condition, each solar cell module PV
The effect of environmental conditions such as azimuth, shadow, and temperature on M can be minimized, and MPPT control (optimum operating point tracking control) for each solar cell module PVM
Can be performed to improve the efficiency of the entire system. (2) Since a system can be constructed by connecting a plurality of solar cell modules PVM in parallel for the R phase or the T phase, the entire installation space can be effectively used, and design and construction are easy. (3) Since the output of one AC module 5 is as small as about 100 W, by increasing or decreasing the number of AC modules 5, it is possible to easily cope with a small system of about 100 W to a medium-sized system of about several kW. It is. Basically, an even number of AC modules 5 are required to maintain the phase balance between the R phase and the T phase of the distribution line 3, but even in the case of an odd number, the unbalance is 100 W at the maximum. There is a practically negligible range. (4) Since there is no DC circuit, a backflow prevention diode or the like is unnecessary, and there is no DC loss due to the diode. Further, wiring work is performed only with an AC circuit, and can be performed by ordinary indoor wiring work. (5) The number of inverter units VTU used increases,
For example, the number of used inverters is ten times or more as compared with the case of a 3 kW inverter device, so that cost reduction can be achieved by mass production effect. (6) Only the self-protection function is built into the AC module 5, and the control is complicated and the advanced interconnection protection function and the independent operation control function are not built-in, so the circuit configuration of the AC module 5 is simplified and the number of parts is reduced. Thus, cost reduction and high reliability can be achieved. (7) The main circuit of the AC module 5 can be made into an IC using a thick film IC or the like, and the size can be reduced. (8) The output voltage of the inverter unit VTU is 100 V
Since the voltage is half that of the case where the voltage is connected between the voltage lines of the distribution line 3 (output voltage is 200 V), the overall conversion efficiency of the inverter unit VTU is high.

Referring to FIG. 3, inverter unit VTU
Are a converter circuit 21, an MPPT circuit 22, an inverter circuit 23, a gate control circuit 24, an operational amplifier 25, a multiplier 26, operational amplifiers 27 and 28, a bandpass filter 29, an interface 30, a current transformer 31, and a transformer 3
2 etc.

The converter circuit 21 outputs a signal from the solar cell module PVM by high-frequency switching.
A DC voltage of about 0 V is converted to a DC voltage of about 180 V. At that time, the MPPT circuit 22 performs a known optimal operating point tracking control for extracting the maximum power from the solar cell module PVM.

The inverter circuit 23 comprises a plurality of bridge-connected switching elements. The gate control circuit 24 has a microprocessor, and supplies a pulse width modulated switching control signal to the inverter circuit 23.

Voltage V1 input to inverter circuit 23
1 is input to the operational amplifier 25 and the voltage command value Vref
Is generated as an input error signal Sa. The input error signal Sa is one input signal of the multiplier 26. The signal S12 is input as the other input signal of the multiplier 26. The signal S12 is obtained by adding the fundamental frequency component S11 of the interconnection point voltage V3 extracted by the bandpass filter 29 and the voltage control signal S13 given by the signal SC by the operational amplifier. Input error signal Sa
And a signal S12 to generate a current command value signal Si indicating a control target value. A current command value signal Si,
The actual output current value detected by the current transformer 31 and the current control signal S14 given by the signal SC are input to the operational amplifier 27, and a current error signal SΔi is generated. The current error signal SΔi is input to the gate control circuit 24.

In the gate control circuit 24, the current error signal S
By comparing Δi with a reference triangular wave signal of about 20 kHz, a switching signal whose pulse width is adjusted is generated and output to the inverter circuit 23.

The interface 30 performs digital serial communication with an external device via an RS-232C interface, inputs the above-described voltage control signal S13 and current control signal S14 from outside, and operates the inverter unit VTU. Output information about

By such feedback control, an AC power having an appropriately set current value and a power factor of 1 having the same current phase as the system voltage is supplied from the inverter circuit 23 to the R-phase or T-phase load of the distribution line 3. Output to

As can be understood from the above description, even if the interconnection point voltage V3 is zero, that is, for example, if the switch 11 of the interconnection protection device 4 is open, the interconnection point voltage V3
The control can be performed by the voltage control signal S13 instead of the control signal S3.
Further, the magnitude of the output current can be controlled by the current control signal S14.

Next, distribution line 3 (or distribution line 3a) and AC
A wiring connection method with the module 5 will be described. FIG.
In the above, each inverter unit VTU is connected to an R-phase or a T-phase by an
Two fixed-side connectors 41a, 41b having two connection poles R, N, T, PO, E and connected in parallel with each other
Is attached.

Here, the fixed connectors 41a, 41
b may be one having only three connection poles R, N and T, and the other two connection poles PO and E may be connected by different lines. Alternatively, a plurality of poles may be provided in addition to the poles PO and E.

The output of the inverter circuit 23 and the connection poles R, T
A jumper wire circuit 42 is provided between
By changing the connection of the jumper wire 42a, the output of the inverter circuit 23 can be selectively connected to either the R phase or the T phase.

Referring also to FIG. 5, each inverter unit V
The TUs are sequentially connected to each other by a connection cable 50 having cable-side connectors 51a and 51b provided at both ends. That is, each cable side connector 5
1a and 51b have five connection poles R, N, T, PO and E connectable to the fixed-side connectors 41a and 41b, respectively, and the cable-side connectors 51a and 51b are provided in the adjacent inverter unit VTU. Each fixed side connector 4
1b, 41a, which are connected to each other, whereby all the inverter units VTU, that is, the AC module 5
Are sequentially connected to each other.

The fixed connector 41a of the first inverter unit VTU1 has a cable connector 5 at one end.
The interconnection cable 55 provided with 1a is connected. The interconnection cable 55 has three wires R,
N and T are connected to the distribution line 3, and two electric wires PO and E are connected to the interface circuits of the interconnection protection device 4 and the independent operation control device 6.

Thus, the output of each AC module 5 is connected to the R phase or T phase of the distribution line 3, and the signal SC of the interface 30 of each AC module 5 is connected to the electric wire or the pole P.
Interconnection protection device 4 and independent operation control device 6 via O and E
Connected to.

As shown in FIG. 6A, a large number (24 in this example) of AC modules 5 are arranged in a matrix, and the respective AC modules 5 are adjacent to each other as shown by a chain line in the figure. The AC modules 5 are sequentially connected by a connection cable 50. Each AC module 5
The AC modules 5 connected to the R phase and the AC modules 5 connected to the T phase are arranged in a zigzag pattern by selective connection of the respective jumper wires 42a.

In the case of arrangement in a zigzag pattern as shown in FIG. 6A, even when the sunlight shades a building or the like, the R-phase and T-phase are substantially averaged. Because it becomes a shadow, R
No large imbalance occurs between the phase and the T phase.

As described above, by adopting the common connector system in which adjacent AC modules 5 are sequentially connected by the common connection cable 50 irrespective of the R-phase or T-phase, the AC module 5 is connected to the distribution line 3a. Wiring work for connection is extremely easy, the work can be performed in a short time, and there is no risk of incorrect wiring. In addition, by changing the connection of the jumper wire 42a of each AC module 5, it is possible to easily change to either the R-phase or the T-phase, without changing the actual position of the AC module 5. These arrays can be set arbitrarily.

In FIG. 6B, the upper AC module 5
Are used for the R phase, and the lower AC module 5 is used for the T phase. In the case of such an arrangement, since the R-phase and the T-phase are grouped together, the management is easy.
It is more likely that the shadow will be offset to either the phase or the T phase, in which case an imbalance will occur between the R and T phases.

If any one of the AC modules 5 fails, if the load is unbalanced,
In the case of increasing or decreasing the number, the connection of the jumper wire 42a of any one of the AC modules 5 can be changed to achieve the overall balance.

Further, as can be understood from FIG. 6, all the AC modules 5 are connected by sequentially connecting the shortest distances by three wires of the connection cable 50. The length is shortened, so that cost reduction, high reliability, and easy maintenance can be achieved. Actually, for example, when the R-phase or T-phase AC modules 5 are separately connected in order to realize the arrangement of FIG. 6A, two R-phase and T-phase AC modules 5 are respectively connected. Since the four electric wires are stretched over the entire surface, the required electric wires are lengthened, the possibility of erroneous wiring is high, and the maintenance is not easy.

When the switch 11 of the interconnection protection device 4 is opened and the interconnection is released, the independent operation control device 6 operates the AC module 5 independently of the commercial power system and outputs the output. It is intended to be used as an emergency power supply. The independent operation control device 6 includes a reference signal supply unit 61, a charger 62, an emergency inverter 63, an overall control unit 64, a battery 65, an output switch 66, and an outlet 67.

When the interconnection is released, the reference signal supply unit 61 supplies the AC module 5 with the same voltage as the commercial power system to the distribution line 3a in order to supply the AC module 5 with the fundamental frequency component S11 of the interconnection point voltage V3. And frequency signals. Therefore, the reference signal supply unit 61 only needs to output the same waveform as the interconnection point voltage V3, and does not need to supply power. However, power sufficient to charge the distribution line 3a and other stray capacitance, for example, several It is preferable that a power of about ten to several hundred mW can be output.

The charger 62 rectifies the output of the AC module 5 and converts it to a direct current to charge the battery 65. Each value of the input current, the input voltage, the output current, and the output voltage of the charger 62 is detected by a detection device (not shown) and input to the overall control unit 64. The charger 62 has an internal distribution line 3a so that it operates only when the interconnection is released.
And an electromagnetic switch for opening and closing between them. The operation may be electronically controlled without providing such an electromagnetic switch. The charger 62 is controlled by the overall control unit 64 so that the battery 65 is not overcharged.

The emergency inverter 63 includes a battery 65
Is converted to single-phase AC 100V commercial power, and supplied to the outlet 67 or the distribution line 3b according to the connection of the output switch 66. The emergency inverter 63 is of a surge-compatible type, and can output a surge current about 10 times the rated current value instantaneously. Therefore, it is possible to operate an inductive load having a large starting current such as an electric motor, and a refrigerator, a washing machine, an air conditioner, and the like can be connected to the outlet 66 or the distribution line 3b.

When the switch 11 is opened and the connection between the commercial power system and the AC module 5 is released, the overall control unit 64 controls the independent operation control device 6 so that the AC module 5 operates in an independent state. Take control of the whole. Overall control unit 64
Outputs a command signal SC1 as a basis of a current control signal S14 for controlling the output current of each AC module 5 so that the charging current of the battery 65 becomes appropriate. The command signal SC1 is output to each AC module 5 via the RS-232C interface, for example, every second. Each AC module 5 generates a current control signal S14 based on the command signal SC1.

As described above, since the command signal SC1 for controlling the output current of the AC module 5 may be output at a slow speed on the order of seconds, it is possible to perform sufficient control by serial communication. .

As can be understood from the above description, the independent operation control device 6 uses the generated power of the AC module 5 as an emergency power source when the interconnection is released due to a power outage of the commercial power system or the like. Things. Since power generation by sunlight alone is not stable as a power supply device, the battery 65 is charged thereby, and the power stored in the battery 65 is converted to commercial power and supplied to a load.
Thereby, the power generated by the solar cell module PVM is stably supplied to the load, and the effective use of sunlight is achieved. Further, an electrical product connected to the distribution line 3 or 3a, for example, a home computer, can be used as an uninterruptible power supply system for the computer by switching the connection to the distribution line 3b at the same time as the disconnection of the interconnection. Moreover, since such complicated control is performed by the independent operation control device 6, the control is realized without complicating the circuit configuration of each AC module 5.

According to the above-described embodiment, even if some of the solar cell modules PVM fail, the AC
The operation of the module 5 is stopped, and the jumper wire circuit 42 is stopped.
By balancing the R-phase and the T-phase, the operation by the solar cell module PVM without failure can be continued. Since each solar cell module PVM operates independently of each other, even when the power generation statuses of each solar cell module PVM are different from each other, the maximum power can be extracted from each solar cell module PVM, and a high conversion as a whole can be achieved. Efficiency can be obtained.

In the above-described embodiment, the interconnection protection device 4, the AC module 5, and the independent operation control device 6 are connected by the RS-232C interface to exchange signals SC bidirectionally. But RS-232
An interface other than C may be used, and an analog signal may be used. A changeover switch may be provided as the jumper wire circuit 42. At the normal time when the connection between the commercial power system and the AC module 5 is performed, a small amount of power may be obtained from the commercial power system to trickle charge the battery 65. Commercial power system and AC
When the connection with the module 5 is released, the independent operation control by the independent operation control device 6 may be automatically performed, or a switch or the like may be provided to manually start the independent operation control. Is also good. In the case of manual operation, an indicator light indicating that the interconnection has been released, a warning sound generator, or the like may be provided.

In the above embodiment, the output voltage of the solar cell module PVM, the configuration of the inverter unit VTU, the total number of the AC modules 5, the configuration of the interconnection protection device 4, the configuration of the independent operation control device 6, Communication method, overall configuration of grid-connected power supply system 1, operation details,
The operation order and the like can be appropriately changed according to the gist of the present invention.

[0054]

According to the first to fifth aspects of the present invention,
When some of the solar cell modules have failed, the operation with the non-failed solar cell modules can be continued, and even when the power generation status of each solar cell module is different from each other, each solar cell module , The maximum power can be extracted from the power supply, and high conversion efficiency can be obtained.

According to the second and fifth aspects of the present invention, A
The wiring connection between the C modules is simple, and the length of the wire is shortened, so that cost reduction, high reliability, and easy maintenance can be achieved.

According to the third and fifth aspects of the present invention, A
Since the C module can be easily changed to either the R phase or the T phase, the arrangement of the R phase or the T phase can be arbitrarily set without changing the actual position of the AC module.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit of a grid-connected power supply system according to the present invention.

FIG. 2 is a schematic view of an AC module.

FIG. 3 is a block diagram showing a circuit of the AC module.

FIG. 4 is a block diagram for explaining a connection state of an AC module.

FIG. 5 is a diagram for explaining a connection state of an AC module;

FIG. 6 is a diagram showing an arrangement state of AC modules.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Grid connection power supply system 3 Distribution line 5 AC module 41a, 41b Fixed side connector 42 Jumper wire circuit (switching means) 50 Connection cable 51a, 51b Cable side connector 55 Interconnection connection cable PVM Solar cell module VTU Inverter unit (Inverter device) )

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hitoshi Kishi 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (5)

[Claims] An AC module comprising a solar cell module and an inverter device for outputting a single-phase AC;
A system interconnection power supply system comprising a single-phase three-wire type distribution line composed of an R phase and a T phase each including one voltage line and one neutral line, wherein the R phase and the T phase are connected to each other. For each of the phases, a plurality of AC
A grid-connected power supply system, comprising a module connected. 2. Each of the AC modules has two fixed side connectors having at least three connection poles and connected in parallel with each other to connect the output to the R phase or the T phase. The AC modules are connected to each other sequentially by a connection cable provided at both ends with a cable-side connector connected to the fixed-side connector, and any one of the AC modules is connected to the cable. The system interconnection power supply system according to claim 1, wherein the side connector is connected to the distribution line by an interconnection cable provided at least at one end. 3. A switch for selectively connecting to either the R-phase or the T-phase by switching a connection between the output and a connection pole of the fixed-side connector. The grid-connected power supply system according to claim 1 or 2, further comprising means. 4. The output of all of the AC modules connected to the R-phase and the T-phase has the same specifications as each other, and the number of AC modules connected to the R-phase and the connection to the T-phase. The grid-connected power supply system according to any one of claims 1 to 3, wherein the number of AC modules is the same as the number of AC modules. 5. A system comprising a solar cell module and an inverter device and connected to a single-phase three-wire distribution line composed of an R-phase and a T-phase composed of two voltage lines and one neutral line. An AC module for an interconnected power supply system, comprising at least three connection poles for connecting the output of the inverter device to the R phase or the T phase, and connected in parallel with each other. Two fixed-side connectors are provided, and switching for selectively connecting to either the R-phase or the T-phase by switching a connection between the output and a connection pole of the fixed-side connector. An AC module for a grid-connected power supply system, comprising: