JP2019149861A - Engine power generator system, control method of the same and co-generation system - Google Patents

Abstract

To provide an engine power generator system which uses a variable speed engine power generator, in which a protection circuit of a power converter is miniaturized and miniaturization and low cost of the converter are realized, and to provide a control method of the system and a co-generation system.SOLUTION: An engine power generator system comprises: an engine; a power generator driven by the engine; and a converter which comprises a DC circuit and performs AC/AC conversion. In the engine power generator system, one end of the converter is connected to one of a rotor or a stator of the power generator, and the other end is connected to a power system to be operated. The engine power generator system comprises first means which connects a resistor to a DC circuit of the converter in parallel upon a power system accident; and second means for reducing the amount of fuel supplied to the engine upon the power system accident.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine generator system that supplies electric power simultaneously with a variable speed engine generator, a control method thereof, and a cogeneration system, and more particularly, in a system in which a converter for frequency conversion is essential for a variable speed generator. The present invention relates to an engine generator system, a control method therefor, and a cogeneration system that protect a converter against an excessive current generated at the time of an accident and that can continue operation without disconnecting the generator from the system.

  The engine generator system according to the present invention can be used as a cogeneration system that further supplies heat using the exhaust heat. For this reason, in the following description of the present invention, a cogeneration system will be described as an example.

  A cogeneration system using an engine generator has good overall energy efficiency because it can effectively use the exhaust heat of the engine. However, since the cogeneration system is generally operated at a rated output with good electrical conversion efficiency of the engine, the supply amount of heat and electric power is constant. When power is generated according to demand, the heat supply capacity also changes, but the thermoelectric ratio cannot be changed, and there is excess or deficiency for either.

  For this reason, as shown in Patent Document 1, a method has been proposed in which an AC excitation generator is used as the engine generator to achieve variable speed. This utilizes the fact that the amount of exhaust heat of the engine changes by changing the ratio of engine torque and rotational speed even with the same electrical output.

  The AC excitation generator uses a converter to supply alternating current to the rotor, and by changing the alternating frequency, the rotational speed of the engine is made variable and the power generation frequency is kept constant to match the system. Such an AC excitation generator is described in Patent Document 2, for example.

  Patent Document 2 relates to a technique related to converter protection when a voltage drop such as a power failure occurs in a power system in a wind power generation system using an AC excitation generator. The conventional main power source is a synchronous generator directly connected to the system, and the speed of the prime mover is constant. Synchronous generators are designed so that they do not break down due to overcurrent generated by an instantaneous voltage drop that occurs during an abnormality such as a grid fault.

  On the other hand, in order to change the prime mover to a variable speed, a frequency conversion converter is essential for the generator. However, since converters are prone to failure against overcurrent, protection against them is essential. This is a problem common to asynchronous generators using converters such as solar power generation, wind power generation, and batteries, and the early asynchronous generators were disconnected from the system and protected in the event of a system failure.

  In recent years, with the rapid spread of renewable energy such as solar power generation and wind power generation, the proportion of these asynchronous power generation devices has increased, and it cannot be ignored compared with conventional synchronous generators that are main power sources. If all asynchronous power generators are disconnected for self-protection at the same time in the event of a system failure, the system failure may increase due to chain disconnection, leading to a large-scale power outage.

  Therefore, in order to stabilize the system, an asynchronous generator device using a converter must have a function called FRT (Fault Ride Through) or LVRT (Low Voltage Ride Through) as a grid connection requirement. Specifically, the rate of voltage decrease and its duration are specified, and in the event of a system fault that is less than the specified, it is obliged to continue operation.

Patent No. 5868170 JP 2010-213563 A

  Since conventional engine generators used for cogeneration used synchronous generators, the FRT regulations were not applied, but when using a variable speed engine, a converter is indispensable. The FRT function is indispensable. Patent Document 1 has no description for this countermeasure.

  Patent Document 2 discloses an FRT-compatible technique related to a wind power generator. According to this, the converter has a DC circuit between the system side converter and the rotor side converter, detects the voltage rise of the DC circuit, and realizes continuation of operation by the overcurrent consumption device provided in parallel there How to do is shown.

  Since this overcurrent consuming device is specifically a resistor, the larger the consumed energy, the larger the physique. In other words, the overcurrent consuming device has a larger physique because it consumes more energy as the generator has a higher output and the longer the time required to withstand the voltage drop is required. This is a cause of hindering cost reduction and downsizing of the entire converter. Moreover, in a society where renewable energy will increase in the future, the time required to withstand a voltage drop as a grid connection requirement may be longer, but not shortened.

  Even if a system failure does not occur, the system voltage becomes unstable due to the fluctuating output of renewable energy. At this time, the function of maintaining the voltage is necessary as a power generation system for cogeneration. Conventionally, it has been possible to control the power generation end voltage by exciting current control of the synchronous generator, but in this system, a control method for stabilizing the voltage is not shown.

  The present invention has been made in view of the above problems, and an object of the present invention is to reduce the power converter protection circuit in an engine generator system using a variable speed engine generator, thereby reducing the size and cost of the converter. Is to provide an engine generator system, a control method thereof, and a cogeneration system.

  In view of the above, in the present invention, “the engine, a generator driven by the engine, and a converter that has a DC circuit and performs AC-AC conversion, the converter is a rotor or stator of the generator. An engine generator system that is operated with one end connected to either side and the other end connected to the power system, and a first means for connecting a resistor in parallel to the DC circuit of the converter in the event of a power system fault; And an engine generator system comprising a second means for reducing the amount of fuel supplied to the engine in the event of a power system accident.

  In the present invention, a “cogeneration system including an exhaust heat recovery device that recovers exhaust heat from the engine” is used.

  Further, in the present invention, “the engine, a generator driven by the engine, and a converter having a DC circuit and performing AC-AC conversion, the converter is either a rotor or a stator of the generator. A control method for an engine generator system in which one end is connected and the other end is connected to a power system, and a resistor is connected in parallel to a DC circuit in the event of a power system fault and the engine in the event of a power system fault The engine generator system control method is characterized in that the amount of fuel supplied to the engine is reduced.

  According to the present invention, in an engine generator system using a variable speed engine, a short circuit (overcurrent consuming device) for protecting an excitation power converter of an AC excitation generator from an overcurrent is reduced when a system abnormality occurs. can do. Moreover, a system | strain can be stabilized by controlling the voltage of a generator end.

The figure which shows the structural example of the cogeneration system which concerns on Example 1 of this invention. The figure which shows the time passage of the voltage drop at the time of an electric power system failure. The figure which shows the time change of the surplus output and surplus energy at the time of a system | strain accident. The figure which shows the time change of the temperature of the resistor at the time of a system | strain accident. The figure which shows the state of each part in normal FRT operation | movement. The figure which shows the control flow of this invention. The figure which shows the relationship between the rotational speed after the electric power system failure generation | occurrence | production in the flow of FIG. 6, and a fuel. The figure which shows the state of each part by the control flow of FIG. The figure which shows the structural example of the cogeneration system which concerns on Example 2 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In all the drawings for explaining the embodiments, the same reference numerals are given to the same members in principle, and the repeated explanation is omitted as appropriate.

  A configuration example of the cogeneration system according to the first embodiment of the present invention will be described with reference to FIG.

  The cogeneration system 4 includes an engine 1, an AC excitation generator 3, a converter 2, and an exhaust heat recovery device 5 as main elements. The controller includes an integrated control device 6, an engine control unit 601 (hereinafter referred to as ECU), and a converter control device 602.

The integrated control device 6 is provided with an active power command p ^* , a reactive power command q ^*, and a thermal command Q ^* as the command signal CMD, and also supplies the power of the power system (the active power command p and the reactive power command q). Obtained from the wattmeter 21, along with these, an engine speed command ω ^* is determined and sent to the ECU 601, and power commands (active power command p ^* and reactive power command q ^* ) are given to the converter control device 602.

The engine 1 controls the shaft output by adjusting the intake amount of the mixture of the fuel 11 and the air 10 with the throttle valve 8. The ECU 601 receives feedback of the rotational speed ω of the engine from the speedometer 30 and controls the throttle valve 8 so as to obtain the rotational speed target value ω ^* given by the integrated control device 6.

  The engine exhaust 12 is heat-exchanged by the exhaust heat recovery device 5 to heat the water 13 to the steam 14 and supply heat to a heat load (not shown).

  The shaft output of the engine 1 is converted into electric power through the AC excitation generator 3. Normally, when an engine generator controls electric power, heat cannot be controlled independently. However, as disclosed in Patent Document 1, the amount of heat supplied can be increased by increasing the rotational speed of the engine.

  The AC excitation generator 3 outputs electricity from the stator 302 when the rotor 301 is driven by the engine 1. The electrical output end of the stator 302 is connected to the power system 100 via the switch 50 and the circuit breaker 52.

  In the converter 2, the rotor-side converter 201 and the system-side converter 202 are connected by a DC circuit 203, and a capacitor 204 for absorbing voltage fluctuations in the DC circuit 203 and a protection circuit 7 are connected. The converter 2 having such a configuration performs AC-AC conversion as a whole of the converter 2. Thus, the converter 2 is a converter having a DC circuit 203 and a function of performing AC-AC conversion.

  The protection circuit 7 includes a resistor 51 and a switching element 71. The rotor-side converter 201 energizes the rotor 301 by energizing AC. The system side converter is connected to the system via the filter circuit 53. Therefore, the generated power of the AC excitation generator 3 is the total output of the output of the stator 302 and the power that enters and exits the system side converter 202.

  The operation at the variable speed of the AC excitation generator will be described. A rotating magnetic field is generated when the rotor-side converter 201 supplies alternating current to the three-phase winding of the rotor 301. However, since the rotor 301 itself is also rotating, the rotational speed of the magnetic field as seen from the stator 302 is That sums up.

Assuming that the rotation direction of the shaft and the direction of the rotating magnetic field generated by the rotor 301 coincide, the AC frequency of the rotor 301 is f _rotor , the rotor speed N (r / min), and the number of pole pairs is P / 2. frequency _{f stator} of the alternating magnetic field experienced by the stator 302 can be expressed by the following equation (1).
[Equation 1]
f _stator = N / 60 * (P / 2) + f _rotor : (1)
If the AC frequency _front is zero, that is, if direct current is supplied, the operation is the same as that of the synchronous generator. The rotor-side converter 201 can give an alternating current having an arbitrary voltage, phase, and alternating current frequency f _rotor . Thereby, even if the rotational speed N of the engine 1 changes, the same frequency as the alternating current of the external electric power system 100 and synchronous power generation are possible.

  Such an AC excitation generator 3 can control the torque, that is, the effective power p of the AC excitation generator 3 by changing the energization phase to the rotor 301. Further, the exciting magnetic flux can be changed by changing the current value of the rotor 301, and the voltage of the stator 302 can be changed, that is, the reactive power q can be controlled. The rotor-side converter 201 controls the AC side to an arbitrary frequency and voltage, and the voltage of the DC circuit unit 203 in that case is assumed to be constant.

  On the other hand, the system side converter 202 performs control so that power is input to and output from the system side by switching so that the voltage Vdc of the DC circuit unit 203 is constant. At this time, the system side converter 202 can change the system side voltage independently, that is, can control the reactive power q.

  In this way, the reactive power q of the generator can be adjusted by the rotor side converter and the reactive power q can be adjusted by the system side converter. Therefore, the system using this AC excitation generator 3 supplies a larger reactive power q than before. can do.

Converter control device 602 appropriately controls rotor side converter 201 and system side converter 202 in order to achieve the given power command (active power command p ^* and reactive power command q ^* ). The control target in this case is the above-described energization phase to the rotor 301, the current value of the rotor 301, and the system side voltage in the system side converter 202.

  Next, the FRT operation at the time of a system fault in the configuration of FIG. 1 will be described.

  The rotor-side converter 201 and the system-side converter 202 that constitute the converter 2 are generally configured by semiconductor devices such as IGBTs. However, since there are upper limits on the energizable amount and the withstand voltage, there are limits set in normal operation. I'm driving below. This is in order to prevent the semiconductor device from breaking down beyond its withstand voltage and from being damaged due to temperature rise due to overcurrent. The tolerance of the converter against overcurrent and overvoltage is very low compared to the generator that is the main role of the conventional system power supply. Therefore, it is essential to protect the converter in case of an abnormality such as a system short circuit.

  For this reason, the AC excitation generator 3 using the converter 2 is often designed to be easily disconnected in the event of a system failure. However, if power sources that use converters, such as solar power generation, wind power generation, and storage batteries, increase in the future, if all of them are disconnected at the time of an accident, there is a possibility that power outages will spread in a chain. In order to avoid this, the system operator provides a continuation of operation (FRT) regulation for each generator against an instantaneous voltage drop.

  FIG. 2 shows the time lapse (horizontal axis) of voltage drop (vertical axis) at the time of a power system failure. In this example, the voltage 81 is reduced due to the occurrence of a power system failure at time t0, the accident is removed at time t10, and then restored to the original voltage at time t20. The AC excitation generator 3 that uses the converter 2 shown in FIG. 1 is expected to continue the operation of the converter 2 until the voltage is restored.

  In FIG. 2, the FRT rule for continuing operation is indicated by a dotted line 80. In the FRT rule of the dotted line 80, the minimum voltage 83 after the system fault and its duration 82, the allowable range 84 of the voltage drop after the fault convergence, the convergence time of the system fault, etc. are defined. If the voltage at the time of an actual system fault is, for example, the voltage waveform 81, it is regarded as a system fault that is lighter than the FRT rule indicated by the dotted line 80, and the operation must be continued for a voltage drop that falls within this range.

  At the time of a grid fault, the voltage at the fault point decreases, but since the stator 302 voltage is high, an overcurrent flows through the power grid. Further, an overcurrent tends to flow from the rotor 301 to the converter 2. In both cases, the energy received from the shaft of the engine 1 tends to be converted into electric power. Therefore, the current must increase as the voltage decreases, but the converter 2 cannot pass overcurrent.

  In such a state, when a protective relay device (not shown) opens the circuit breaker 52 in order to eliminate the power system accident, the electric circuit is cut off, so that the energy is lost and the rotation speed ω of the rotor 301 is reduced. Rises and is converted into kinetic energy, or energy is accumulated in the capacitor 204 of the DC circuit unit 203, and if the capacitor capacity is exceeded, it will burst. There is also concern about damage caused by over-rotation in rotating machines. Moreover, there is a concern about the destruction of the semiconductor elements constituting the converter 2.

  In normal operation, the system side converter 202 controls the AC current on the system side so as to keep Vdc constant. However, since the converter has an upper limit of current capacity, when the voltage decreases, power cannot be released to the system, and the voltage of the DC circuit 203 increases. In order to avoid this, the protection circuit 7 is installed in parallel with the DC circuit section. The protection circuit 7 detects the voltage of the DC circuit with the voltmeter 20A, and consumes energy when the voltage exceeds a predetermined voltage. The protection circuit 7 is composed of a resistor and a switching element 71. Normally, the switching element 71 is turned off. When an overvoltage is applied, the switch is turned on, and the resistor 51 consumes energy.

  However, as the resistor 51 consumes energy, the temperature rises. Resistors also have heat resistance limitations. A short-time temperature rise of a few seconds at most, such as FRT, can only be absorbed by the heat capacity of the device, and therefore the resistor is enlarged. This has a problem that the cost is high and the device cannot be downsized. In the future, as the number of power supplies with converters connected to the system increases, the requirements for FRT will become stricter, and the resistor becomes larger as the voltage drop time that can continue operation becomes longer.

  Therefore, in the present invention, in order to reduce the resistor of the protection circuit 7, the fuel control of the engine is also adjusted so as to reduce the energy input from the engine shaft to the generator 3 during the FRT operation. Energy consumption is reduced. A specific operation example will be described below.

  FIG. 3 shows temporal changes in surplus output and surplus energy at the time of a system fault. The surplus output 86 has a shape obtained by inverting the power generation end voltage of FIG. Under normal conditions, the mechanical input from the shaft is output as the product of the generator current and voltage and is in a steady state, but when the generator voltage drops, the current does not increase suddenly due to inductance, etc. Cannot output. This is called surplus power. The surplus energy 86 is obtained by accumulating the surplus output 86 over time.

  This surplus energy 87 is converted as it is into the heat of the resistor 51, and its average temperature is equal to the surplus energy curve when considered by a short time adiabatic approximation, and the temperature of the resistor becomes a temperature rise curve 90A shown in FIG. . FIG. 4 shows the time change of the temperature of the resistor at the time of a system fault. The temperature rise curves 90B and 90C are two parallel and three parallel resistors, and the temperature decreases as the number of parallel increases. However, this increases the protection circuit and hinders downsizing of the converter itself.

  FIG. 5 shows the state of each part during normal FRT operation. Specifically, a time change of the temperature rise curve 90A of the resistor, the DC voltage 95A, the rotation speed 93A, the mixer flow 92A, and the power generation end voltage 81 at the time of a system fault is shown.

  In this case, it is assumed that the output is not adjusted by the throttle valve 8 of the engine 1 at the time of a system failure, and the air-fuel mixture amount 92A input to the engine is constant. In this case, when the AC terminal voltage waveform drops as shown by 81 due to a system fault, the voltage Vdc of the DC circuit unit 203 rises as shown at 95A, for example, a protection circuit so as to be constant when it rises to a threshold of 105%. 7 operates the switching element 71. Meanwhile, energy is consumed by the resistor 51 and the temperature rises to 90A. Since all excess energy is consumed by the protection circuit 7, the rotation speed can be kept constant as shown by 93A. When the system fault is settled, the surplus energy disappears, so the DC voltage Vdc decreases and the operation returns to the steady operation.

  On the other hand, the control flow of the present invention is shown in FIG. In the first processing step S1 of FIG. 6, it is confirmed that the DC voltage Vdc rises at the time of a system fault and exceeds a threshold value of, for example, 105%. When the threshold value is exceeded, energization of the protection circuit 7 is started in processing step S2. The energization of the protection circuit 7 means that the resistor 51 is connected to the DC circuit 203 by the switching element 71 in FIG. 1, and heat is generated due to power consumption at the resistor. In the process step S3, the temperature of the protection circuit 7 is monitored. When the temperature exceeds the threshold value T7 of 60 ° C., the throttle valve 8 is once closed in the process step S4 to make the fuel of the air-fuel mixture almost zero. Since the fuel cut causes no input to the generator 3 from the engine shaft, the DC voltage is lowered, so that the energization to the protection circuit 7 is stopped in the processing step S5, and at the same time, the rotational speed starts to decrease. Note that the energization stop of the protection circuit 7 means that the resistor 51 is disconnected from the DC circuit 203 by the switching element 71 of FIG.

  In processing step S6, the rotational speed is continuously observed, and in the determination of processing steps S7 and S8, control according to the magnitude of the rotational speed is executed.

  First, in process step S7, when the rotational speed has not decreased to 100%, the process proceeds to process step S12, and thereafter, the fuel cut in process steps S4 and S5 and the stop process of the protection circuit 7 are repeatedly executed. Thus, when the rotational speed exceeds 100%, the protection circuit 7 is operated, the fuel is cut, and the rotational speed is controlled.

  If it can be confirmed in processing step S7 that the rotational speed is 100% or less, it is further confirmed in processing step S8 whether the rotational speed is 95% or more. If the rotation speed is in the range of 95 to 100%, the fuel is set to 50% in processing step S9, and if the rotation speed is 95% or less, 100% fuel is commanded in processing step S10.

  In processing step S11, the time ΔT after the energization of the protection circuit 7 is measured, and if the protection circuit 7 does not work for 2 seconds, for example, it is assumed that the system fault has ended and the FRT mode is ended. Thereafter, as usual, the engine output is controlled at a constant rotational speed by droop control.

  FIG. 7 shows the relationship between the rotational speed and the fuel after the occurrence of a power system accident in the flow of FIG. 6, for example, in the first stage st1 where the rotational speed is 100% or more, the fuel is 0% and the rotational speed is 100%. To 95% of the second stage st2, the fuel is 50%, and the third stage st3 of which the rotation speed is 95% or less is 100% fuel. That is, the lower the rotation speed, the more the fuel amount is increased. In addition, although the reduction in the rotational speed after the control is delayed depending on the case, the control shifts to the control determined by the ECU 601 after the time ΔT has elapsed since the energization of the protection circuit 7 has ended.

  Note that the flow of FIG. 7 is basically an AC excitation generator by connecting a resistor to the DC circuit 203 to cause heat consumption in the event of an AC system failure to continue operation of the converter 2 and by cutting or reducing fuel. The difference between the machine input 3 and the electrical output 3 is suppressed.

  In FIG. 6, as an example of a condition for connecting a resistor to the DC circuit 203, an increase in the DC voltage Vdc of the DC circuit 203 is illustrated, but this can be selected as appropriate from events that occur in response to the occurrence of an accident in the power system. Is possible. For example, it is directly the voltage drop of the power system, the output of a protective relay that detects an accident, and the like. Further, as a condition for stopping or reducing the supply of fuel, the fact that the temperature of the protection circuit 7 exceeds the threshold value T7 of 60 ° C. is used. Events such as temperature rise due to operation and DC current rise in the DC circuit 203 can be used. The reason why the temperature is adopted in the embodiment of FIG. 6 is that the temperature is information that can be detected inside the engine generator system, and an interlock for taking in from the outside is unnecessary.

  In short, the conditions for connecting a resistor to the DC circuit 203 or the conditions for reducing the supply of fuel are appropriately selected from incidental events that occur when the power system voltage drops due to the occurrence of a power system accident. do it. In the present invention, by performing both energy consumption by connecting a resistor to the DC circuit 203 in the event of an accident and suppressing machine input to reduce the difference between machine input and electrical output in the engine and generator, It enables stable operation after an accident.

  FIG. 8 shows the state of each part according to the control flow of FIG. Here, the DC voltage 95B, the rotation speed 93B, the protection circuit temperature 90D, the fuel flow rate 92B, and the power generation end voltage 81 at the time of a system fault are illustrated as a time change.

  First, when the system voltage 81 decreases at time t0, the DC voltage Vdc 95B increases and the energization of the protection circuit 7 starts, so that the temperature of the protection circuit 7 increases as 90D. When the temperature of the protection circuit 7 reaches the threshold value 60 ° C. at time t1, the fuel flow rate 92B is set to zero by the process of process step S3 of FIG. As a result, there is no shaft input to the generator, so the DC voltage 95B and the rotation speed 93B are reduced.

  When the rotational speed is not less than 95% and not more than 100% according to the determination process in the process step S8 of FIG. 6, the process step S9 acts to set the fuel to 50% at the time t2. Thereby, since the shaft input exceeds the electrical output, the rotation speed increases.

  When the rotational speed exceeds 100% at the time t3 by the determination process in the process step S7 of FIG. 6, the protection circuit 7 starts to be energized (process step S12) and simultaneously the fuel is throttled (process step S4). Thereby, a rotational speed falls. This operation is repeated.

  After time t3, when the system voltage 81 recovers, the energy that can be output to the system is increased, so the engine output must be restored. This is because the time after the last energization of the protection circuit 7 is completed is measured in the processing step S11 in FIG. 6, and for example, if the protection circuit does not operate even after 2 seconds, the system fault has converged. The FRT mode is terminated. As a result, the engine performs a droop control on the frequency so as to achieve a normal constant rotation speed control.

  In the above example, the temperature of the protection circuit 7 is determined to control the throttle valve. However, it is also easy to estimate the temperature by time integration of the current value of the circuit 7, and the same can be obtained by measuring this. An effect can be obtained.

  FIG. 9 shows a configuration example of a cogeneration system according to the second embodiment of the present invention. The difference from FIG. 1 is that the generator 3B connected to the engine is not an AC excitation generator but a magnet field generator. In this case, the converter capacity of the converter 2 needs to be the same capacity as the maximum output of the engine, and since all the output of the generator passes through the converter 2, there is a disadvantage that the loss of the converter becomes large. However, in this case as well, the overcurrent protection circuit 7 is similarly installed as a circuit for protecting the converter 2. The operation is the same as that shown in the first embodiment.

  The generator 3 of the first and second embodiments is a generator 3 in which a rotor 301 is driven by an engine, and either the rotor 301 or the stator 302 has a DC circuit 203 and is AC- It is connected to the electric power system 100 via the converter 2 having a function of performing AC conversion. Converter 2 is a converter provided with DC circuit 203 between two sets of converters 201 and 202.

1: Engine 2: Converter 3: AC excitation generator 3B: Magnet field generator 4: Cogeneration system 5: Waste heat recovery device 6: Integrated control device 7: Protection circuit 8: Throttle valve 9: Switch:
10: Air 11: Fuel 12: Exhaust 13: Water 14: Steam 20A: Voltmeter 20B: Voltmeter 21: Power meter 30: Tachometer 40: Integrated controller 50: Switch 51: Resistor 52: Circuit breaker 53 : Filter circuit 71: Switching element 80: FRT regulation 81: Example of power generation end voltage at the time of system fault 82: FRT regulation minimum voltage duration 83: FRT regulation minimum voltage 84: FRT regulation voltage convergence tolerance 85: FRT regulation System failure convergence time 86: surplus output 87: accumulated surplus energy 90A: temperature rise curve of resistor, number of parallel circuits 1
90B: Resistor temperature rise curve, number of parallel circuits 2
90C: Resistor temperature rise curve, 1 parallel circuit
90D: Temperature rise curve 92A of the resistor according to the present invention 92A: Fuel flow rate 92B during FRT of the conventional engine generator: Fuel flow rate 93A during FRT of the engine according to the present invention: Engine rotational speed 93B during conventional FRT Engine rotation speed 95A during FRT of the present invention: Vdc voltage curve 95B during conventional FRT: Vdc voltage curve 100 during FRT of the present invention 100: Power system 201: Rotor side converter 202: System side converter 203: DC circuit 204 : DC capacitor 301: AC excitation generator rotor 302: AC excitation generator stator 601: Engine control unit (ECU)
602: Converter control device

Claims (14)

An engine, a generator driven by the engine, and a converter that has a DC circuit and performs AC-AC conversion, and one end of the converter is connected to either the rotor or the stator of the generator An engine generator system operated with the other end connected to the power system,
A first means for connecting a resistor in parallel to the DC circuit of the converter in the event of a power system fault, and a second means for reducing the amount of fuel supplied to the engine in the event of a power system fault. Engine generator system. The engine generator system according to claim 1,
The condition for connecting a resistor in parallel to the DC circuit in the event of a power system failure and / or the condition for reducing the amount of fuel supplied to the engine in the event of a power system failure is that the voltage of the power system has dropped due to the occurrence of a power system accident. An engine generator system characterized by being selected from incidental incidental events. The engine generator system according to claim 1 or claim 2,
An engine generator system characterized in that the conditions for connecting a resistor in parallel to the DC circuit in the event of a power system fault are an increase in DC voltage of the DC circuit, a voltage drop in the power system, and an output of a protective relay that detects an accident. . The engine generator system according to claim 1 or claim 2,
The engine for reducing the amount of fuel supplied to the engine in the event of a power system failure is an increase in DC voltage of the DC circuit, a temperature increase due to parallel connection of resistors, and an increase in DC current of the DC circuit. Generator system. The engine generator system according to any one of claims 1 to 4,
One end of the converter is connected to a rotor of the generator, and the other end of the converter and a stator of the generator are connected to an electric power system. The engine generator system according to any one of claims 1 to 4,
The converter has one end connected to a stator of the generator, and the other end of the converter is connected to an electric power system. The engine generator system according to any one of claims 1 to 6,
The engine generator system according to claim 2, wherein the second means reduces the amount of fuel supplied to the engine in the event of a power system accident according to the rotational speed of the engine. The engine generator system according to any one of claims 1 to 7,
A third means for controlling the amount of fuel supplied to the engine from the rotational speed command of the engine and the rotational speed of the engine;
The first means disconnects the resistance connected in parallel to the DC circuit after the fuel quantity is reduced by the second means, and further controls the fuel quantity by the third means after a predetermined time has elapsed. The engine generator system, characterized in that The engine generator system according to any one of claims 1 to 8,
The converter has the DC circuit connected between a generator-side converter and a power system-side converter, and changes the power factor of the stator end of the generator by the generator-side converter to convert the power system-side converter. By controlling the reactive power on the power system side, the voltage at the output end of the generator is controlled. The engine generator system according to any one of claims 1 to 9,
The condition for connecting a resistor in parallel to the DC circuit at the time of a power system fault is a voltage rise in the DC circuit, and the condition for reducing the amount of fuel supplied to the engine at the time of a power system fault is connected in parallel to the DC circuit. An engine generator system characterized by heat generated by resistance.   A cogeneration system comprising the engine generator system according to any one of claims 1 to 10 and an exhaust heat recovery device that recovers exhaust heat from the engine. An engine, a generator driven by the engine, and a converter that has a DC circuit and performs AC-AC conversion, and one end of the converter is connected to either the rotor or the stator of the generator And a control method of an engine generator system operated with the other end connected to the power system,
A control method for an engine generator system, wherein a resistance is connected in parallel to the DC circuit in the event of a power system failure, and the amount of fuel supplied to the engine is reduced in the event of a power system failure. A method for controlling an engine generator system according to claim 12,
A control method for an engine generator system, characterized in that when the amount of fuel supplied to the engine in the event of a power system failure is reduced, the amount is reduced in accordance with the rotational speed of the engine. A control method for an engine generator system according to claim 12 or claim 13,
A third means for controlling the amount of fuel supplied to the engine from the rotational speed command of the engine and the rotational speed of the engine;
After the amount of fuel is reduced, the resistance connected in parallel to the DC circuit is disconnected, and after a predetermined time has passed, the control proceeds to control of the amount of fuel according to the difference between the engine speed command and the engine speed. A control method for an engine generator system.

Images