JP2012075211A - Power generator voltage control system of power generation plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable in-station isolated operation to continue by suppressing the amount of generated overvoltage caused by a control overshoot after removal of an accident in a power generation plant that migrates to the in-station isolated operation due to the external accident such as a transmission system.SOLUTION: The invention is characterized in that when the power generator is in normal operation, the power generator output voltage is monitored by an instrument transformer placed on the output side of the power generator, and a thyristor is controlled so that the output voltage of the power generator is a prescribed voltage value, and when an electric accident occurs in a transmission system or switchyard, a power generator voltage control device switches to control making a field winding of the power generator generate a no-load field voltage based on an accident detection signal of a protector detecting the accident. The invention enables the in-station isolated operation to continue by suppressing the amount of generated overvoltage caused by a control overshoot after removal of the accident in a power generation plant that migrates to the in-station isolated operation due to the external accident such as the transmission system.

Description

  The present invention relates to a generator voltage control system for a power plant.

  FIG. 6 shows an outline of a conventional generator voltage control device for a power plant. This figure describes, as an example, a high-voltage synchronous plant in which the generator 1 is synchronized with the transmission system side by turning on the main transformer breaker 2 on the high-voltage side of the main transformer 3. During operation of the generator 1, the electric power generated by the generator 1 is output to an external power transmission system via the main transformer 3, the main transformer circuit breaker 2 and the switch station 14 provided on the generator 1 output side. In addition, the in-house high-voltage bus 6 is connected to the in-house transformer 4 connected to the circuit branched from between the generator 1 and the main transformer 3 and the in-house transformer power receiving breaker 5 connected to the in-house transformer 4. Power is supplied. The in-house high-voltage bus 6 is connected to an in-house load motor 7 required for operation of the power plant.

  In addition, the excitation power source of the generator 1 necessary for the output operation of the generator 1 is a direct current by a thyristor 9 connected from the circuit branched from the generator 1 and the main transformer 3 via the excitation power transformer 8. The electric power is converted into electric power, and the DC electric power is supplied to the field winding 11 via the field breaker 10 connected to the thyristor 9.

  Note that the instrument transformer 12 provided on the output side of the generator 1 measures the generator output voltage, the generator voltage control device 13 takes in this voltage signal, and the generator 1 output voltage becomes a predetermined voltage value. The field current supplied to the field winding 11 is controlled by controlling the thyristor 9 as described above.

  When an electrical accident such as a short circuit or ground fault occurs in the power transmission system or the switch station 14 while the generator 1 is connected to the power transmission system and is operating for output, the point of the accident is detected when the protective device 15 detects the electrical accident. The protective device 15 outputs an open signal to the main transformer breaker 2 for the purpose of disconnecting the power plant. Thereby, the main transformer circuit breaker 2 is opened and the power plant is disconnected from the accident point. The power plant shifts to an in-house single operation that supplies power only to the in-house load necessary for the operation of the power plant, and continues the operation.

Japanese Patent Laid-Open No. 11-113296

  As described above, when an electrical accident such as a short circuit or a ground fault occurs in the power transmission system or the switch station 14 and the output voltage of the generator 1 decreases, the generator voltage control device 13 is connected to this via the instrument transformer 12. Detects a decrease in generator output voltage. And the generator voltage control apparatus 13 is controlled to the direction which raises the output voltage of the generator 1 so that the generator 1 may output a predetermined voltage.

  On the other hand, when the protective device 15 detects an accident and opens the main transformer circuit breaker 2, the accident point is removed and the generator output voltage is restored. At this time, the generator voltage control apparatus 13 is controlling in the direction which raises the generator 1 output voltage which fell. Therefore, since there is a control delay before the generator 1 output voltage returns to the rated value by feedback, the generator 1 output voltage overshoots the rated value, and the in-house transformer 4 of the power plant or the in-house transformer 4 may cause an overvoltage to be applied to an electrical facility such as an in-house load supplied with power via 4 and may cause equipment damage. In addition, such an overvoltage causes a transformer such as the in-house transformer 4 to be overexcited, and the increased excitation current may cause the ratio differential relay 20 installed to protect the transformer to malfunction. There was a problem that it was impossible to continue the in-house independent operation.

  As described above, in the conventional power plant configuration, when an accident occurs in the power transmission system, etc., an overvoltage occurs due to overshoot of the generator voltage control, and damage to the on-site electrical equipment and the ratio differential relay for transformer protection There was a problem that it may become impossible to continue the in-house independent operation due to a malfunction.

  Therefore, the object of the present invention is to suppress the occurrence of overvoltage due to control overshoot after the accident is removed in a power plant that shifts to in-house single operation due to an external accident such as a power transmission system, etc. It is to do.

  The present invention monitors the generator output voltage by an instrument transformer provided on the generator output side during normal operation of the generator, and controls the thyristor so that the output voltage of the generator becomes a predetermined voltage value. Control that causes the generator voltage control device to generate a no-load field voltage in the field winding of the generator based on the accident detection signal of the protective device that detects the accident when an electrical accident occurs in a power transmission system or switching station The control mode is switched to the above.

  According to the present invention, in a power plant that shifts to in-house single operation due to an external accident such as a power transmission system, it is possible to suppress the amount of overvoltage generated due to control overshoot after the accident is removed, and to continue in-house single operation.

It is a block diagram of the generator voltage control apparatus for power plants of Example 1. FIG. It is a block diagram of the generator voltage control apparatus for power plants of Example 2. FIG. It is a block diagram of the generator voltage control apparatus for power plants of Example 3. FIG. It is a block diagram of the generator voltage control apparatus for power plants of Example 4. FIG. It is a block diagram of the generator voltage control apparatus for power plants of Example 5. FIG. It is a block diagram of the conventional generator voltage control apparatus for power plants.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a configuration of a generator voltage control system of a power plant that is an embodiment employing the present invention.

  FIG. 1 shows the configuration of the on-site power supply facility of a high-voltage synchronous power plant in which the generator 1 is placed in parallel with the power transmission system side by turning on the main transformer circuit breaker 2 on the high-voltage side of the main transformer 3. During operation of the generator 1, the electric power generated by the generator 1 is output to an external power transmission system via the main transformer 3, the main transformer circuit breaker 2 and the switch station 14 provided on the generator 1 output side. In addition, the in-house high-voltage bus 6 is connected to the in-house transformer 4 connected to the circuit branched from between the generator 1 and the main transformer 3 and the in-house transformer power receiving breaker 5 connected to the in-house transformer 4. Power is supplied. The in-house high-voltage bus 6 is connected to an in-house load such as an in-house load motor 7 necessary for the operation of the power plant.

  In addition, the excitation power source of the generator 1 necessary for the output operation of the generator 1 is a direct current by a thyristor 9 connected from the circuit branched from the generator 1 and the main transformer 3 via the excitation power transformer 8. The electric power is converted into electric power, and this electric power is supplied to the field winding 11 through the field breaker 10 connected to the thyristor 9.

  When the generator 1 is operated, an instrument transformer 12 provided on the output side of the generator 1 measures the generator output voltage, and this voltage signal is taken into the generator voltage control device 13. The generator voltage control device 13 controls the field current supplied to the field winding 11 by controlling the thyristor 9 so that the generator output voltage becomes a predetermined voltage value.

  Here, when an electrical accident such as a short circuit occurs in the power transmission system or the switch station 14, the protection device 15 that monitors the state of the power transmission system or the switch station 14 detects the accident. When an electrical accident is detected by the protective device 15, the protective device 15 transmits an open command to the main transformer circuit breaker 2 and transmits an electrical accident occurrence signal to the generator voltage control device 13. The electrical accident is removed by opening the main transformer circuit breaker 2, but once the protective device 15 detects the accident, the accident signal output is continued until the reset operation is performed after confirming the removal of the cause of the accident. ing.

  At this time, when the main transformer circuit breaker 2 is opened, the power plant is disconnected from the power transmission system, and the generator 1 has an on-site load such as the on-site load motor 7 necessary for the output operation of the generator 1 and excitation. The operation shifts to the in-house single operation in which the operation is continued while supplying power only to the excitation power transformer 8 as a power source. In addition, the electric power required for the output operation of the generator 1 during the in-house single operation is about several percent of the rated output capacity of the generator 1.

  When the generator voltage control device 13 receives a signal indicating the occurrence of an electrical accident, the generator voltage control device 13 switches from the predetermined voltage value mode to the no-load field voltage mode. The predetermined voltage value mode is a mode in which the generator output voltage is monitored by an instrument transformer 12 provided on the output side of the generator 1 and controlled so that the generator output voltage becomes a predetermined voltage value. Note that, due to the occurrence of an electrical accident, the power plant shifts to in-house single operation. As described above, the output of the generator 1 during in-house single operation is very small compared to the rated capacity. Therefore, the no-load field voltage mode is a mode in which the field winding 11 is controlled to generate the no-load field voltage of the generator 1, and the operation of the generator 1 is continued in this mode.

  Here, the allowable fluctuation range of the output voltage of the generator 1 is defined in “Electrical Society of Japan Electrical Standards Survey Standard Standard Synchronous Machine JEC-2130”. For example, if the generator has a rated output of 10 MVA or more, ± 5% or less. Therefore, even after switching to the no-load field voltage mode in which the field winding 11 is controlled to generate the no-load field voltage of the generator 1, the instrument transformer 12 provided on the output side of the generator 1 is Monitor generator output voltage. And the time when the output voltage of the generator 1 is outside the range of the set value (the allowable range of voltage fluctuation is ± 5%, so set the fluctuation range below this) (for example, the set value is set at ± 4%) When the voltage fluctuation of ± 4% is less than the time allowed by the on-site power supply equipment such as the generator 1), the generator output voltage is adjusted by the instrument transformer 12 provided on the output side of the normal generator 1. Monitor and return to the predetermined voltage value mode in which the generator output voltage is controlled to a predetermined voltage value, and continue the in-house single operation.

  As described above, in this embodiment, during the normal operation of the generator, the generator output voltage is monitored by the instrument transformer provided on the generator output side, and the output voltage of the generator becomes a predetermined voltage value. When an electrical accident occurs in the power transmission system or switching station by controlling the thyristor, an unloaded field voltage is applied to the field winding of the generator based on the accident detection signal of the protective device that the generator voltage control device detects the accident. It is characterized by switching to the generated control. By this control, the occurrence of overvoltage due to control overshoot after the accident is removed is suppressed, and the in-house independent operation can be continued. In addition, it is possible to suppress the transient fluctuation amount of the generator voltage, converge the duration in a short time, and continue the stable in-house operation alone.

  FIG. 2 shows a configuration of a generator voltage control system of a power plant that is an embodiment employing the present invention. The generator voltage control device 13 according to the first embodiment is a no-load control that controls the field winding 11 to generate a no-load field voltage of the generator 1 only by inputting an accident signal transmitted from the protection device 15. Switching to field voltage mode. On the other hand, in this embodiment, the generator voltage controller 13 switches the control mode only when an electrical accident occurs in the power transmission system or the switch station 14 while the generator 1 is connected to the power transmission system. When the AND condition of the accident signal transmitted from the device 15 and the signal indicating that the main transformer breaker 2 is opened by the command from the protection device 15 is established, the control mode of the generator voltage control device 13 is switched.

  FIG. 3 shows a configuration of a generator voltage control system of a power plant that is an embodiment employing the present invention. The generator voltage control device 13 according to the first embodiment is a no-load control that controls the field winding 11 to generate a no-load field voltage of the generator 1 only by inputting an accident signal transmitted from the protection device 15. Switching to field voltage mode. On the other hand, in this embodiment, the generator voltage controller 13 switches the control mode only when an electrical accident occurs in the power transmission system or the switch station 14 while the generator 1 is connected to the power transmission system. The control mode of the generator voltage control device 13 is switched when an AND condition is established between the fault signal transmitted from the device 15 and the signal of the instantaneous operation and time limit return timer 17 provided for the closing signal of the main transformer circuit breaker 2. Note that the set value of the instantaneous operation and time recovery timer 17 is set to such a length that the signal output can be continued until the control mode switching of the generator voltage control device 13 is completed by the accident signal transmitted from the protection device 15.

  FIG. 4 shows a configuration of a generator voltage control system of a power plant that is an embodiment employing the present invention. The power plant shown in FIG. 4 is a low-voltage synchronous power plant in which the generator 1 is placed in parallel with the power transmission system by inserting a generator load switch 16 provided on the output side of the generator 1 and on the low-voltage side of the main transformer 3. It is. In the third embodiment, the protection device 15 is configured so that the generator voltage control device 13 switches the control mode only when an electrical accident occurs in the power transmission system or the switching station 14 with the generator 1 connected to the power transmission system. The switching condition of the control mode is that the AND condition of the fault signal transmitted from the signal and the signal of the operation of the closing signal of the main transformer circuit breaker 2 with the instantaneous operation and the time recovery timer 17 is established. On the other hand, in the present embodiment, the generator voltage control device 13 is controlled only when an electrical accident occurs in the power transmission system or the switch station 14 in a state where the generator 1 is connected to the power transmission system even in the low-voltage synchronous plant. As the mode is switched, a closing signal of the generator load switch 16 is added to the conditions of the third embodiment, and the control mode of the generator voltage control device 13 is switched when the AND condition of the three conditions is satisfied. In FIG. 4, the condition indicating the open / close state of the main transformer circuit breaker 2 is the same as that in the third embodiment, but may be the same as that in the second embodiment.

  FIG. 5 shows a configuration of a generator voltage control system of a power plant that is an embodiment employing the present invention. In the first embodiment, the generator voltage control device 13 is switched to a mode in which the field winding 11 is controlled to generate the no-load field voltage of the generator 1 by the input of the accident signal transmitted from the protection device 15. It was. On the other hand, in the present embodiment, an in-house transformer instrument current transformer 18 installed on the primary side of the in-house transformer 4, an exciting power transformer instrument current transformer 19 provided on the primary side of the exciting power transformer 8, and The difference is that an electric signal obtained from the instrument transformer 12 installed on the output side of the generator 1 is taken into the generator voltage control device 13. The generator voltage control device 13 monitors the power consumption of the in-house load and the power consumption of the excitation power source based on the electrical signal, and when an accident signal is input from the protection device 15, the power consumption of the power plant is calculated. The mode is switched to a mode for controlling the field winding 11 to generate a field voltage suitable for generating power.

  In FIG. 5, as an example of a method for measuring the power consumption of the in-house transformer circuit and the excitation power transformer circuit, the current transformer for the instrument provided on the primary side of the in-house transformer 4 and the primary side of the excitation power transformer 8 In addition, although the configuration in which the in-house power consumption is monitored by the instrument transformer 12 provided on the output side of the generator 1 has been described, other methods can be applied as the in-house power consumption measurement method. Moreover, as a structure which takes in the accident signal from the protection apparatus 15 in the generator voltage control apparatus 13, it can also be set as the structure of Examples 2-4. In addition, after switching to a control mode in which an appropriate field voltage is generated in the field winding 11 in order to generate power consumption of the power plant, the configuration of monitoring the generator voltage control device 13 and re-switching the control mode is as follows. The same as in the first embodiment.

  Thus, in this embodiment, when an electrical accident occurs in the power transmission system or switching station, the generator voltage control device captures the accident detection signal of the protective device that detects the accident, and when the accident detection signal is input, By having a configuration that switches the field winding to control that generates an appropriate field voltage while the generator supplies the measured in-site power consumption, it is possible to apply an overvoltage to the on-site power supply equipment. It is possible to prevent the transient fluctuation of the generator voltage from being converged in a short time and to continue the stable in-house operation.

DESCRIPTION OF SYMBOLS 1 Generator 2 Main transformer circuit breaker 3 Main transformer 4 In-house transformer 5 In-house transformer receiving circuit breaker 6 In-house high voltage bus 7 In-house load motor 8 Excitation power transformer 9 Thyristor 10 Field breaker 11 Field winding 12 Instrument transformers,
13 Generator Voltage Control Device 14 Switch Station 15 Protection Device 16 Generator Load Switch 17 Instantaneous Operation, Time-Return Timer 18 Current Transformer Current Transformer 19 Excitation Power Transformer Current Transformer 20 Ratio Differential Relay

Claims (6)

A generator, a main transformer provided on the generator output side, a main transformer circuit breaker connected to the main transformer high-voltage side, and a power transmission system connected via a switch station, the switch station and the power transmission system A protective device for detecting electrical accidents,
Necessary for operation of a power plant connected via an in-house transformer connected to a circuit branched from the generator and the main transformer, and an in-house transformer power receiving breaker connected to the in-house transformer An on-site power system consisting of an in-house high-voltage bus that supplies power to the in-house load,
Furthermore, a thyristor for converting AC power supplied from an excitation power transformer connected to a circuit branched from the generator and the main transformer to DC power, and connected to the thyristor output side, is excited in the event of an accident. A field breaker that breaks the circuit;
Generator voltage control device for controlling a generator field current by controlling the thyristor, and generator voltage control of a power plant having an instrument transformer for transmitting the generator output voltage signal to the generator voltage control device In the system,
During normal operation of the generator, the generator output voltage is monitored by an instrument transformer provided on the generator output side, and the thyristor is controlled so that the output voltage of the generator becomes a predetermined voltage value. When an electrical accident occurs at a switch or in a switching station, the generator voltage control device controls the generator coil to generate a no-load field voltage based on the accident detection signal of the protective device that detects the accident. A generator voltage control system for a power plant characterized by switching.   In Claim 1, it shows that the main transformer circuit breaker which disconnects a power plant and a power transmission system by the operation | movement of the said accident detection signal of the protective device which detects the electrical accident in a power transmission system or a switch station, and the said protection device is open | released A generator voltage control system for a power plant having a configuration that switches to control for generating a no-load field voltage in a field winding of a generator according to an AND condition of a signal.   In claim 1, according to an AND condition of the accident detection signal of the protective device for detecting an electrical accident in a power transmission system or a switching station and a signal provided with a time-return timer for instantaneous operation on the closing signal of the main transformer circuit breaker, A generator voltage control system for a high-voltage synchronous power plant, characterized in that it has a configuration for switching to control for generating a no-load field voltage in a field winding of a generator.   In Claim 2, 3, the said accident detection signal of the protective device which detects the electrical accident in a power transmission system or a switch station, and the said signal (signal opened by the accident detection signal of the protective device) which show the switching state of the main transformer circuit breaker (In addition to the instantaneous signal for the closed signal, a signal with a timer for resetting the time), in addition to the signal indicating that the generator load switch is closed, an unloaded field voltage is generated in the generator field winding. A generator voltage control system for a low-voltage synchronous power plant, characterized by having a configuration for switching to control. A generator, a main transformer provided on the generator output side, a main transformer circuit breaker connected to the main transformer high-voltage side, and a power transmission system connected via a switch station, the switch station and the power transmission system A protective device for detecting electrical accidents,
Necessary for operation of a power plant connected via an in-house transformer connected to a circuit branched from the generator and the main transformer, and an in-house transformer power receiving breaker connected to the in-house transformer An on-site power system consisting of an in-house high-voltage bus that supplies power to the in-house load,
Furthermore, a thyristor for converting AC power supplied from an excitation power transformer connected to a circuit branched from the generator and the main transformer to DC power, and connected to the thyristor output side, is excited in the event of an accident. A field breaker that breaks the circuit;
Generator voltage control device for controlling a generator field current by controlling the thyristor, and generator voltage control of a power plant having an instrument transformer for transmitting the generator output voltage signal to the generator voltage control device In the system,
During normal operation of the generator, the generator output voltage is monitored by the instrument transformer provided on the generator output side, and the thyristor is controlled so that the output voltage of the generator becomes a predetermined voltage value. Monitoring power consumption of the on-site transformer circuit for supplying power to a load and the excitation power transformer circuit for supplying excitation power of the generator;
When an electrical accident occurs in a power transmission system or switching station, the generator voltage control device captures an accident detection signal of the protection device that detects the accident, and when the accident detection signal is input, it is applied to the field winding of the generator. A generator voltage control system for a power plant, characterized in that it has a configuration for switching to control that generates an appropriate field voltage while the measured power consumption is supplied by the generator.   In Claims 1-5, the generator voltage control device of the power plant after switching control due to an accident in the power transmission system monitors the output voltage of the generator, and the time when the voltage falls outside the set range is a set value. When it becomes above, it has the structure which monitors and changes to the state which controls a generator output voltage so that a generator voltage may be maintained at a setting value, The generator voltage control system of the power plant characterized by the above-mentioned.

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