JP6420717B2 - Power plant in-house power supply system - Google Patents

Description

  The present invention relates to an in-house power supply system of a power plant, and more particularly, to an in-house power system of a power plant equipped with a large capacity electric motor that starts up directly.

  Thermal power plants are equipped with large-capacity motors such as boiler ventilators and circulating water pumps as operational loads in the plant, and nuclear power plants are large-capacity motors such as reactor water pumps and circulating water pumps as operational loads within the plant. It has. When a rated voltage is directly applied to such a large-capacity motor and started (direct start), a starting current containing a large amount of reactive current flows, and this reactive current greatly reduces the voltage of the in-house power supply, and other operations There is a possibility that an instantaneous load stop, lighting flicker, etc. may occur.

  As a method of suppressing the voltage drop that accompanies the start-up of large-capacity motors, a method of reducing the starting current by installing starters (inverters, etc.) in each large-capacity motor can be considered. However, it is not realistic to provide a starter for all large capacity motors.

  On the other hand, as a method for suppressing the voltage drop of the in-house power supply, a load tap changer (hereinafter referred to as “LTC”) is installed in a transformer (in-house transformer) that supplies power to the in-house operating load. There is. In the case of a transformer not equipped with LTC, the secondary side voltage of the transformer decreases according to the power supply (operating capacity) of the transformer, but in the case of a transformer with LTC, the transformation ratio is adjusted by LTC. As a result, the secondary voltage can be maintained at the rated voltage. However, since the response speed of LTC is on the order of several seconds, it is not possible to compensate for an instantaneous voltage drop (second order or less) accompanying the start of the motor.

  Therefore, in the in-house power supply system of recent power plants, an LTC is installed in the in-house transformer, and the voltage drop at the start of the in-house load motor having the maximum capacity is within the voltage fluctuation allowable range of the in-house equipment. A method is adopted in which the impedance of the in-house transformer is kept low so that it does not fall below the minimum starting voltage of the load motor.

  However, lowering the impedance of the transformer is a major factor in increasing the cost, such as increasing the winding thickness of the transformer. Further, in the nuclear power generation plant, the plant output is expected to further increase in the future, and when the capacity of the on-site load motor increases in proportion to the plant output, the voltage drop at start-up further increases. Therefore, it is expected that it becomes difficult in terms of technology and cost to suppress the voltage drop at start-up only by reducing the impedance of the in-house transformer.

  Patent Document 1 discloses a voltage fluctuation that suppresses a relatively gradual voltage fluctuation by LTC in a substation and a voltage drop (instantaneous voltage drop) at the start of a large capacity motor by a static reactive power compensator (SVC). A suppression method is disclosed. The SVC includes a semiconductor switch, a reactor, a capacitor, and the like, and reactive power can be instantaneously supplied by switching the semiconductor switch at high speed (several ms order).

Japanese Patent Laid-Open No. 2006-166683

  During the operation of the SVC, a surge is applied to the bus bar due to the high-speed switching of the semiconductor switch, and the current waveform of the bus bar is distorted due to the insertion of the reactor or the capacitor, thereby generating harmonic noise. Therefore, when the voltage fluctuation suppression method of Patent Document 1 is applied to an in-house power supply system of a power plant, harmonic noise is continuously generated even during plant operation by always operating the SVC.

  Therefore, when the voltage fluctuation suppression method is applied to an on-site power supply system of a nuclear power plant, a device that handles weak signals, such as a neutron monitor that monitors the amount of neutrons in a nuclear reactor, is affected by harmonic noise. May interfere with driving.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to suppress a voltage drop during start-up of the on-site load motor and to maintain a favorable operating environment of the on-site equipment during plant operation. It is to provide an on-site power system of a power plant.

  In order to solve the above problems, the present invention includes a generator, a main transformer connected to the generator, an in-house transformer connected to a circuit branched from the generator and the main transformer, An internal high-voltage bus connected to the in-house transformer and supplying power to the in-house load motor necessary for the operation of the power plant, a load tap changer capable of changing the secondary side voltage of the in-house transformer, a capacitor, and In a power plant in-house power system comprising a semiconductor switch, and comprising a static type reactive power compensator configured to supply reactive power from the capacitor to the in-house high voltage bus by switching control of the semiconductor switch, The static reactive power compensator includes a first control unit that determines whether or not the on-site load motor is being started, and the on-site load motor is being started by the first control unit. If it is determined, the semiconductor switch switching control is executed, and if the on-site load motor is determined not to be started by the first control unit, the semiconductor switch switching control is not executed. It is assumed that the second control unit is configured.

  According to the in-house power supply system of the power plant according to the present invention, it is possible to suppress a voltage drop at the start of the large-capacity electric motor while maintaining a good operating environment of the in-house electronic equipment during plant operation.

1 is a diagram illustrating an overall configuration of an in-house power supply system of a nuclear power plant according to an embodiment of the present invention. It is a figure which shows schematic structure of the on-load tap changer (LTC) provided in the in-house transformer. It is a figure which shows schematic structure of a static reactive power compensation apparatus (SVC). It is a figure which shows the control logic of a static type reactive power compensation apparatus (SVC). It is a figure which shows the whole structure of the in-house power supply system of the nuclear power plant by a prior art.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same member and the overlapping description is abbreviate | omitted suitably.

  In this embodiment, the on-site power supply system of a power plant according to the present invention is applied to a nuclear power plant. In a nuclear power plant, steam heat energy generated in a nuclear reactor is converted into rotational energy by a turbine, and electric power is generated by converting the rotational energy into electrical energy by a generator directly connected to the turbine. The electric power output from the generator is boosted to a predetermined voltage via the main transformer and supplied to the power transmission system.

  FIG. 1 shows the overall configuration of an in-house power supply system of a nuclear power plant according to this embodiment. The in-house power supply system 100 includes a generator 1, a main transformer 2, an in-house transformer 3, a start-up transformer 4 (also referred to as “backup transformer” or “auxiliary transformer”), and a plurality of in-house high voltage. And buses 5, 6, 7, and 8 and a plurality of static var compensators (hereinafter referred to as “SVC”) 9, 10, 11, and 12.

  The main transformer 2 is connected to the generator 1 via a power supply circuit 14 that can be opened and closed by a generator load switch 13. The primary side of the in-house transformer 3 is connected to a feeding circuit 15 branched from between the generator load switch 13 of the feeding circuit 14 and the main transformer 2. In-house high voltage buses 5 and 6 are connected to one secondary side circuit 32 of the in-house transformer 3 via power receiving circuit breakers 3a and 3b, respectively. In the other secondary side circuit 33 of the in-house transformer 3, In-house high-voltage buses 7 and 8 are connected via power receiving circuit breakers 3c and 3d, respectively.

  The in-house high-pressure bus 5 includes an electric motor (hereinafter referred to as “reactor water pump motor”) 51 for driving a reactor water pump (not shown), and an electric motor for driving a high pressure condensate pump (not shown). (Hereinafter referred to as “motor for high pressure condensate pump” as appropriate) 52, motor for driving low pressure condensate pump (not shown) (hereinafter referred to as “motor for low pressure condensate pump” as appropriate) 53 and high pressure drain pump An electric motor (not shown) (hereinafter referred to as “high-pressure drain pump motor”) 54 is connected to each other via a plurality of load circuit breakers 5a, 5b, 5c, 5d, and SVC 9 is an SVC circuit breaker. 5e is connected.

  The in-house high-pressure bus 6 includes an electric motor (hereinafter referred to as “circulating water pump motor”) 61, a high-pressure condensate pump motor 62, and a high-pressure drain pump electric motor 63 that drive a circulating water pump (not shown). Are connected via a plurality of load circuit breakers 6a, 6b, 6c, respectively, and the SVC 10 is connected via an SVC circuit breaker 6d.

  The in-house high-pressure bus 7 includes a reactor water pump motor 71, a circulating water pump motor 72, a low-pressure condensate pump motor 73, and a motor for driving a low-pressure drain pump (not shown) (hereinafter referred to as “low-pressure drain pump” as appropriate). 74 ”is connected via a plurality of load circuit breakers 7a, 7b, 7c, 7d, and SVC 11 is connected via an SVC circuit breaker 7e.

  The in-house high-pressure bus 8 includes a circulating water pump motor 81, a high-pressure condensate pump motor 82, a high-pressure drain pump motor 83, a low-pressure condensate pump motor 84, and a low-pressure drain pump motor 85. , 8b, 8c, 8d, and 8e, and the SVC 12 is connected through the SVC circuit breaker 8f.

  During operation of the nuclear power plant, the generator load switch 13 is turned on to connect the generator 1 to the on-site transformer 3, and a part of the power output from the generator 1 is converted to the on-site transformer 3 and the in-house high voltage. It supplies to in-house loads (electric motors 51 to 54, 61 to 63, 71 to 74, 81 to 85, etc.) via buses 5, 6, 7, and 8.

  When starting or stopping the nuclear power plant, the generator load switch 13 is opened to disconnect the generator 1 from the on-site transformer 3, and the main transformer 2, the on-site transformer 3 or the starting transformer 4 from the transmission system, In addition, power is supplied to the in-house load via the in-house high-voltage buses 5, 6, 7, and 8.

  The in-house high-voltage buses 5 and 6 are also connected to one secondary circuit 42 of the starting transformer 4 via the power receiving breakers 4a and 4b, and the in-house high-voltage buses 7 and 8 are connected via the power receiving breakers 4a and 4b. The other secondary side circuit 43 of the starting transformer 4 is also connected. Thereby, when it becomes impossible to supply power from the generator 1 to the in-house high voltage buses 5, 6, 7, and 8 through the in-house transformer 3 due to an electrical failure (short circuit) of the main transformer 2, in-house transformer 3, etc. Power can be supplied from the power transmission system to the in-house high-voltage buses 5, 6, 7, and 8 through the starting transformer 4.

  In the power transmission system, there is a possibility that a voltage fluctuation of about ± 5% occurs with respect to the rated voltage. The in-house transformer 3 and the start-up transformer 4 are provided with an in-house transformer 3 and a start-up transformer 4 in order to reduce the influence on the in-house power supply system 100 due to the voltage fluctuation of the power transmission system. In order to compensate for the voltage drop, load tap changers (hereinafter referred to as “LTCs”) 31 and 41 are provided, respectively.

  FIG. 2 shows a schematic configuration of the LTC 31 provided in the in-house transformer 3. In addition, since LTC41 provided in the starting transformer 4 has the structure similar to LTC31, the description is abbreviate | omitted.

  In FIG. 2, the on-site transformer 3 includes a primary winding 34, a secondary winding 35, an iron core (not shown), and the like. The LTC 31 is provided on the primary side of the on-site transformer 3 and changes the transformation ratio when the transformer is operating (when the load current is energized) by selecting one of the plurality of taps 36 drawn from the primary winding 34. can do.

  Switching control of the tap 36 is performed by the LTC control unit 37. The LTC control unit 37 monitors the voltage on the secondary side of the transformer via the voltage detection circuit 38 provided on the secondary side of the transformer, and the voltage on the secondary side of the transformer is maintained at a set value (rated). The tap 36 is switched as follows.

  Specifically, the voltage drop in the in-house transformer 3 increases due to a decrease in the primary voltage of the in-house transformer 3 or an increase in the operation amount of the in-house load, and the secondary voltage of the in-house transformer 3 increases. Is lower than the set value (rated), the tap is switched to the tap 36 on the side (upper side in the drawing) where the number of turns of the primary winding 34 of the in-house transformer 3 is reduced. Thereby, the transformation ratio of the in-house transformer 3 becomes small, and the voltage on the secondary side of the transformer rises.

  On the other hand, when the primary voltage of the in-house transformer 3 increases or the operation load of the in-house load decreases, the voltage drop in the in-house transformer 3 decreases, and the secondary voltage of the in-house transformer 3 becomes the set value. When it becomes higher than (rated), the tap 36 is switched to the side (lower side in the figure) where the number of turns of the primary winding 34 of the in-house transformer 3 is increased. Thereby, the transformation ratio of the in-house transformer 3 is increased, and the voltage on the secondary side of the transformer is lowered.

  By the switching control of the tap 36 described above, the voltage on the secondary side of the transformer can be maintained at the set value (rated) against the voltage fluctuation on the primary side of the transformer and the change in the operation amount of the on-site load. In the present embodiment, the LTC 31 is provided on the primary side of the in-house transformer 3, but the present invention is not limited to this and may be provided on the secondary side of the in-house transformer 3.

  As shown in FIG. 2, the LTC 31 changes the secondary side voltage of the in-house transformer 3 by mechanically switching a plurality of taps 36 drawn from the primary winding 34. Therefore, the response speed is on the order of several seconds. Therefore, the LTC 31 can suppress relatively gradual voltage fluctuations due to voltage fluctuations in the power transmission system and increase / decrease in the amount of operation of the on-site load, but cannot cope with instantaneous voltage fluctuations.

  As a factor causing such instantaneous voltage fluctuation, there is a start of a large capacity motor. In the case of the nuclear power plant according to the present embodiment, the circulating water pump motors 61, 72, 81 for driving the circulating water pump that takes seawater into the condenser, and the seawater in which steam generated in the nuclear reactor is fed into the condenser The low-pressure condensate pump, the high-pressure condensate pump, and the reactor feed water pump for driving the low-pressure condensate pump, the high-pressure condensate pump, and the reactor feed water pump, respectively, The electric motors 52, 62, and 82, the reactor water pump electric motors 51 and 71, and the like correspond to large-capacity electric motors.

  In the case of a system that starts by applying a voltage directly to the electric motor without using a starter or the like (a direct-injection starting system), a starting current that is 6 times or more of the rated current flows to the motor. This starting current includes a large amount of reactive current. On the other hand, the impedance of the transformer is composed of a reactance component (L) and a resistance component (R). However, in the case of a large class such as the in-house transformer 3 and the starting transformer 4, most of the components are reactance components ( L), and the voltage drop in the transformer also increases in proportion to the magnitude of the reactive current. Therefore, when the large capacity motor is started, a very large voltage drop instantaneously occurs in the in-house transformer 3. At this time, it is difficult to compensate for the voltage drop at the start of the large-capacity motor with the LTC 31 and 41 having a response speed on the order of several seconds.

  In the in-house power supply system 100 according to the present embodiment, the SVCs 9, 10, 11, and 12 are installed in the in-house high-voltage buses 5, 6, 7, and 8 in order to compensate for the voltage drop at the start of the large-capacity motor. As described above, the SVC can be efficiently compensated by installing the SVC in the vicinity of the device that consumes the reactive power. However, the present invention is not limited to this, and the in-house transformer 3 or the starting transformer It is also possible to install an SVC in the secondary side circuits 32, 33, 42, 43 of the device 4.

  Here, the SVCs 9, 10, 11, and 12 do not need to target all large capacity motors, for example, only motors that can cause a voltage drop that is lower than the startable voltage, that is, only large capacity motors, are targeted for compensation. Just do it. In the present embodiment, as an example, only the reactor water pump motors 51 and 71 and the circulating water pump motors 61, 72, and 81 are targeted for compensation. That is, the SVC 9 compensates for the start-up voltage drop of the reactor water pump motor 51, the SVC 10 compensates for the start-up voltage drop of the circulating water pump motor 61, and the SVC 11 compensates for the reactor water pump motor 71 and the circulating water pump. The start-up voltage drop of the motor 72 is compensated, and the start-up voltage drop of the circulating water pump motor 81 is compensated by the SVC 12.

  The SVC 9 includes the state of the load circuit breaker 5a (the on state or the open state) and the current value of the motor 51 detected by the current converter (CT) 21 and the current detector 22 provided in the power supply circuit of the motor 51 to be compensated. Based on the above, it is determined whether or not the motor 51 is starting, and when it is determined that the motor 51 is starting, a voltage converter (PT) 23 and a voltage detector provided in the in-house high voltage bus 5 Reactive power that compensates for the voltage drop detected by 24 is supplied to the in-house high-voltage bus 5. Whether or not the motor is being started may be determined using a start SW signal, an automatic start signal, or the like of the motor, but the signal from the load breaker 5a and current detection as in the present embodiment. By using the signal from the device 22, it can be easily determined. Since the operations of the SVCs 10, 11, and 12 are the same as those of the SVC 9, their descriptions are omitted. Also in FIG. 1, illustration of current converters (CT), current detectors, voltage converters (PT) and voltage detectors provided in the in-house high voltage buses 6, 7 and 8 is omitted.

  A schematic configuration of the SVC 9 is shown in FIG. In FIG. 3, the SVC 9 includes a step-down transformer 91, a variable reactor 92, a plurality of capacitors 93, a plurality of static switches (semiconductor switches) 94, a SVC circuit breaker controller 95, and a static switch controller 96. And.

  The secondary side of the step-down transformer 91 is connected to the in-house high voltage bus 5 via the SVC circuit breaker 5e. A variable reactor 92 and a plurality of capacitors 93 are disposed in parallel between the primary side of the step-down transformer 91 and the ground. Static switches 94 are provided between the plurality of capacitors 93 and the primary side of the step-down transformer 91, respectively.

  The SVC circuit breaker controller 95 performs opening / closing control of the SVC circuit breaker 5e based on inputs from the load circuit breaker 5a and the current detector 22. The static switch control unit 96 performs switching control (high-speed switching) of the static switch 94 based on the input from the voltage detector 24. The SVC circuit breaker 5e is turned on to connect the SVC 9 to the in-house high voltage bus 5, and the switching control of the static switch 94 is performed, so that the reactive power necessary for the in-house high voltage bus 5 is supplied from the capacitor 93. There are other SVC control methods such as a reactor control method, a self-excited inverter method, and the like. By using a static switch as described above, reactive power can be instantaneously supplied. It becomes possible.

  On the other hand, when the SVC 9 is in operation, an open / close surge due to switching control of the static switch 94 is applied to the in-house high-voltage bus 5, and the current waveform of the in-house high-voltage bus 5 is distorted by the reactive current supplied from the SVC 9. The current waveform of the high-voltage bus 5 includes harmonic components, and high-frequency noise is generated (the same applies to the in-house high-voltage buses 6, 7, and 8). Especially in nuclear power plants, there are many devices that handle weak signals such as neutron monitors that detect the state of the reactor, and these devices may be subject to false detection due to the effects of harmonic noise. Therefore, it is not desirable to continuously operate the SVC 9.

  The SVC 9 according to the present embodiment is controlled by the SVC control unit 95 and the static switch control unit 96 so as to operate only when the electric motor 51 to be compensated is started. The control logic of the SVC 9 by the SVC circuit breaker control unit 95 and the static switch control unit 96 is shown in FIG.

  The SVC circuit breaker control unit 95 includes a circuit breaker state determiner 95a, a current determiner 95b, an AND calculator 95c, and a circuit breaker control signal generator 95d. The circuit breaker state determiner 95a determines the state (loading state or open state) of the load circuit breaker 5a based on the state signal input from the load circuit breaker 5a, and uses the determination result (1 or 0) as an AND computing unit. Output to 95c. The current determiner 95b determines whether or not the current value of the electric motor 51 input from the current detector 22 is greater than the rated current value, and outputs the determination result (1 or 0) to the AND calculator 95c.

  The AND calculator 95c performs an AND operation on the determination result (1 or 0) input from the circuit breaker state determiner 95a and the determination result (1 or 0) input from the current determiner 95b, and the calculation result ( 1 or 0) is output to the circuit breaker control signal generator 95d and the AND calculator 96b (described later) of the static switch control unit 96. The circuit breaker control signal generator 95d generates a control signal (an input signal or an open signal) corresponding to the calculation result (1 or 0) input from the AND calculator 95c, and outputs the control signal to the SVC circuit breaker 5e.

  Thereby, when the load circuit breaker 5a is turned on, the electric motor 51 is connected to the in-house high voltage bus 5 and a starting current exceeding the rating flows through the electric motor 51, that is, when the electric motor 51 is starting, the SVC circuit breaker 5e is turned on, and the SVC 9 is connected to the in-house high voltage bus 5. On the other hand, when the load circuit breaker 5a is opened and the electric motor 51 is disconnected from the in-house high voltage bus, or when the electric current value of the electric motor 51 becomes lower than the rated value, that is, when the electric motor 51 is not started, the SVC circuit breaker 5e. Is opened and the SVC 9 is disconnected from the in-house high voltage bus 5.

  The static switch control unit 96 includes a voltage determiner 96a, an AND calculator 96b, and a static switch control signal generator 96c. The voltage determiner 96a determines whether or not the voltage value of the in-house high voltage bus 5 input from the voltage detector 24 is smaller than the rated voltage value, and outputs the determination result (1 or 0) to the AND calculator 96b. .

  The AND calculator 96b performs an AND operation on the determination result (1 or 0) input from the AND calculator 95c of the SVC circuit breaker control unit 95 and the determination result (1 or 0) input from the voltage determiner 96a. The calculation result (1 or 0) is output to the static switch control signal generator 96c. The static switch control signal generator 96 c generates a control signal (ON / OFF signal) corresponding to the calculation result (1 or 0) input from the AND calculator 96 b and outputs the control signal (ON / OFF signal) to the static switch 94.

  Thereby, when the electric motor 51 is starting and the voltage value of the in-house high-voltage bus 5 falls below the rated voltage value, the switching control of the static switch 94 is performed to compensate for the voltage drop in the in-house high-voltage bus 5. Reactive power is supplied from the capacitor 93 to the in-house high voltage bus 5. On the other hand, when the electric motor 51 is not being started or the voltage value of the in-house high voltage bus 5 is equal to or higher than the rated voltage value, the switching control of the static switch 94 is not performed.

  In the on-site power supply system 100 configured as described above, the SVCs 9, 10, 11, and 12 do not operate during normal operation in which the voltage fluctuation is relatively gentle, and the voltage fluctuation is suppressed only by the LTC31 or the LTC41. Only when starting 51, 61, 71, 72, 81, the SVCs 9, 10, 11, 12 are operated, and the voltage drop during starting of the specific electric motors 51, 61, 71, 72, 81 is suppressed.

  Further, since the operation of the SVCs 9, 10, 11, and 12 is limited at the time of starting the specific electric motors 51, 61, 71, 72, and 81, high-frequency noise associated with the operation of the SVCs 9, 10, 11, and 12 is generated during normal operation. Without being able to maintain the working environment of the on-site equipment installed in the nuclear power plant. Further, since the SVCs 9, 10, 11, and 12 are disconnected from the internal high-voltage buses 5, 6, 7, and 8 except when the specific electric motors 51, 61, 71, 72, and 81 are started, the SVCs 9, 10, 11, Even when 12 malfunctions, the generation of high frequency noise can be suppressed.

  Further, since the SVCs 9, 10, 11, and 12 need only be able to compensate for the voltage drop during startup of the specific motors 51, 61, 71, 72, and 81, the capacity of the SVCs 9, 10, 11, and 12 is set to the specific motors 51. , 61, 71, 72, 81, the SVCs 9, 10, 11, 12 can be downsized by appropriately setting the capacity.

  In addition, the SVC 9, 10, 11 and 12 suppress the voltage drop at the start of the specific electric motors 51, 61, 71, 72 and 81 in the in-house high-voltage buses 5, 6, 7 and 8 to thereby start the in-house transformer 3 and start-up. Since the required specifications (such as low impedance) for the transformer 4 can be relaxed, the cost of the in-house transformer 3 and the start-up transformer 4 can be reduced. Furthermore, since voltage fluctuations of a downstream (low voltage side) bus (not shown) connected to the internal high voltage buses 5, 6, 7, 8 are also suppressed, the internal high voltage buses 5, 6, 7, 8 and the downstream side (low voltage) The allowable voltage fluctuations of the load equipment fed from the side bus) (about −20% of the rated voltage in normal load equipment of a nuclear power plant) can be mitigated, and the cost of these load equipment can be reduced.

  In addition, this invention is not limited to above-described embodiment, Various modifications are included. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described.

DESCRIPTION OF SYMBOLS 1 ... Generator, 2 ... Main transformer, 3 ... In-house transformer, 3a, 3b, 3c, 3d ... Receiving circuit breaker, 4 ... Starting transformer, 4a, 4b, 4c, 4d ... Receiving circuit breaker, 5, 6 , 7, 8 ... In-house high-voltage bus, 5a, 5b, 5c, 5d ... Load breaker, 5e, 6d, 7e, 8f ... SVC breaker, 6a, 6b, 6c ... Load breaker, 7a, 7b, 7c, 7d ... load circuit breaker, 8a, 8b, 8c, 8d, 8e ... load circuit breaker, 9, 10, 11, 12 ... static compensator (SVC), 13 ... generator load switch, 14, 15 ... power supply circuit, DESCRIPTION OF SYMBOLS 21 ... Current converter (CT), 22 ... Current detector, 23 ... Voltage converter (PT), 24 ... Voltage detector, 31, 41 ... On-load tap changer (LTC), 32, 33, 42, 43 ... secondary side circuit, 34 ... primary winding, 35 ... secondary winding, 36 ... tap, 37 ... LTC control unit 38 ... Voltage detection circuit, 51, 71 ... Reactor feed pump motor (specific motor), 52, 62, 82 ... High pressure condensate pump motor, 53, 73, 84 ... Low pressure condensate pump motor, 54, 63, 83 ... high pressure drain pump motor, 61, 72, 81 ... circulating water pump motor (specific motor), 74, 85 ... low pressure drain pump motor, 91 ... step-down transformer, 92 ... variable reactor, 93 ... Capacitor, 94 ... Static switch (semiconductor switch), 95 ... SVC circuit breaker controller (first controller), 95a ... Circuit breaker state determiner, 95b ... Current determiner, 95c ... AND calculator, 95d ... Breaker Generator control signal generator, 96 ... static switch control unit (second control unit), 96a ... voltage determiner, 96b ... AND operator, 96c ... static switch control signal generator, 100 House power supply system

Claims (2)

A generator,
A main transformer connected to the generator;
An on-site transformer connected to a circuit branched from between the generator and the main transformer;
An in-house high-voltage bus connected to the in-house transformer and supplying power to the on-site load motor required for operation of the power plant,
A load tap changer capable of changing the secondary side voltage of the internal transformer;
In an in-house power supply system of a power plant having a capacitor and a semiconductor switch, and comprising a static reactive power compensator configured to supply reactive power from the capacitor to the in-house high-voltage bus by switching control of the semiconductor switch ,
A current detector for detecting the current of the on-site load motor;
A voltage detector for detecting the voltage of the internal high voltage bus;
The in-house load motor is connected to the in-house high voltage bus via a load circuit breaker,
The static reactive power compensator is
When the load circuit breaker is turned on and the current value detected by the current detector is larger than the rated current value of the on-site load motor, it is determined that the on-site load motor is being started, and the load breaker is Is opened, or when the current value detected by the current detector is equal to or less than the rated current value of the on-site load motor, a first control unit that determines that the on-site load motor is not being started ; and
When it is determined by the first control unit that the on-site load motor is being started and the voltage value detected by the voltage detector is smaller than the rated voltage value of the on-site high voltage bus, the switching of the semiconductor switch When the control is performed and it is determined that the on-site load motor is not being started by the first control unit , or the voltage value detected by the voltage detector is equal to or higher than the rated voltage value of the on-site high voltage bus , An on-site power supply system for a power plant, comprising: a second control unit configured not to execute switching control of the semiconductor switch. In the in-house power supply system of the power plant according to claim 1,
The static reactive power compensator is connected to the internal high-voltage bus via an SVC circuit breaker,
The first control unit turns on the SVC circuit breaker when it is determined that the on-site load motor is being started, and turns on the SVC circuit breaker when it is determined that the on-site load motor is not being started. An in-house power supply system of a power plant characterized by being opened.

Images