JP2001037299A - Static exciter for generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a high top voltage for exciting a generator in order to achieve transient stability of a transmission system required by a nuclear power plant or a high output generator constructed at a remote place. SOLUTION: The static exciter for generator comprises a generator 6, a main transformer 9 for transmitting power to a transmission system through a main transformer circuit breaker 22, a generator load switch 8 paralleled/ paralleled off with/from the transmission system at the time of operating/ stopping the generator, an exciting power supply transformer 10 connected between the main transformer and the generator load switch and stepping down the voltage of a shunt excitation branch circuit to an AC voltage corresponding to a DC voltage required for the field circuit, and a thyristor rectifier 11 for converting the secondary (low voltage side) output of an excitation power supply transformer into a DC voltage. If the primary (high voltage side) of the excitation power supply transformer is normal at the time of short circuit fault on the secondary (low voltage side) of the excitation power supply transformer or failure of the thyristor rectifier, the generator load switch opens the generator from the field circuit and the main transformer circuit breaker is opened at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a generator exciter for a nuclear power plant, and more particularly, to a nuclear power plant constructed in a remote place and a stationary generator exciter for a large output generator.

[0002]

2. Description of the Related Art Conventionally, a stationary excitation device of a generator is constituted by an excitation power supply transformer, a thyristor rectifier, an automatic voltage regulator, a field circuit breaker and an initial excitation device. FIG. 4 is a configuration diagram of a conventional stationary generator exciting device 15. The power generated by the generator 6 is low-voltage synchronized with the power transmission system by closing the generator load switch 8, the power is boosted by the main transformer 9, and the power is transmitted through the main transformer breaker 22. It transmits power to the grid and supplies power to the on-site loads. The exciting device 15 converts the generator output voltage branched from the power system to be supplied to the in-plant load by the exciting power supply transformer 10 in order to convert a part of the generator output to an AC voltage equivalent to the DC voltage required by the field circuit. Step down and convert the output on the secondary side (low voltage side) of the excitation power transformer 10 from AC to DC by the thyristor rectifier 11, while controlling the thyristor rectifier 11 by the automatic voltage regulator 12 to maintain the generated voltage Is supplied to the generator 6 via the field breaker 16. When the generator 6 is started, an initial excitation current is supplied to the generator 6 from the in-site DC power supply via the initial excitation device 13. Excitation power transformer overcurrent relay (51ET)
18 operates due to a short circuit accident on the secondary side (low voltage side) of the excitation power supply transformer 10. Also, the excitation power supply transformer ratio differential relay (87ET) 19 is used to connect the excitation power supply transformer 10 when an accident occurs on the primary side (high voltage side) of the excitation power supply transformer 10.
It operates with a difference current between primary and secondary currents. Here, the function of the field circuit breaker 16 is to turn on and off a field current to the generator 6 by opening and closing operations when the generator 6 is started / stopped, and furthermore, furthermore, to the secondary side of the excitation power supply transformer 10 ( In the event of an electrical accident due to a short circuit accident on the low voltage side) and an accident on the primary side (high voltage side) of the excitation power supply transformer 10, the short circuit current is reduced by opening the field breaker 16 to prevent the accident from spreading.
More shut off.

In order to disconnect the generator 6 from the short-circuit current and disconnect it from the power transmission system in the event of an electrical accident, it is necessary to open the main transformer circuit breaker 22 in addition to the opening operation of the field circuit breaker 16. It is. In the event of an electrical accident, the logic for disconnecting the generator 6 from the short-circuit current and disconnecting it from the power transmission system is shown in FIG.
Shown in Here, the generator closing relay (86G1) (main) 20 and the generator closing relay (86G2) (backup) 21 are used to operate the excitation power transformer overcurrent relay 18, the excitation power transformer ratio differential relay 19, and the like. Operate based on The occurrence of a short circuit accident on the secondary side (low voltage side) of the excitation power supply transformer 10 or the difference current between the primary / secondary current of the excitation power supply transformer 10 due to the accident on the primary side (high voltage side) of the excitation power supply transformer 10 Excitation power transformer overcurrent relay 18
Or, when the excitation power transformer ratio differential relay 19 operates, or when the generator load switch 8 is closed, that is, when the thyristor rectifier 11 fails during plant startup, the generator closing relay (main) 20, the generator closing relay (backup) 21 operates, and the field breaker 16
Is opened, the short-circuit current is cut off from the generator 6, the main transformer circuit breaker 22 is opened, and the generator 6 is disconnected from the power transmission system. When the thyristor rectifier 11 fails while the generator load switch 8 is open, the field breaker 16 is opened. Japanese Patent Application Laid-Open No. H10-42599 discloses a configuration in which a disconnector for maintenance and inspection work is added to a generator excitation device circuit. However, no consideration is given to the operation of the generator load switch, and there is no suggestion.

[0004]

The prior art employs a field circuit breaker 16 in a field circuit of an excitation device, operates an excitation power transformer overcurrent relay 18, operates an excitation power transformer ratio differential relay 19, and the like. When the electrical accident occurs, the main transformer breaker 22 is opened by the operation of the generator closing relays 20 and 21, the generator 6 is disconnected from the power transmission system, and the field breaker 16 is opened. The exciter field circuit is disconnected from the generator 6. Here, the specifications of the field breaker 16 are determined by the voltage and current of the exciter, but in order to improve the transient stability of the power transmission system, it is necessary to increase the top voltage of the exciter (the generator is Even if the load (power consumption) suddenly changes, the output voltage is controlled to be constant by the automatic voltage regulator (AVR). However, if the peak point pressure of the exciter is small, the load suddenly changes, such as in a high-speed reclosing circuit. In large cases, excessive stability limits may be exceeded and generators may lose synchrony, especially in power plants where power consumption is far away and connected by long-distance transmission systems. Since the impedance is large and the impedance fluctuation of the transmission system due to high-speed reclosing becomes more remarkable, a high peak voltage is required.) For that purpose, it is necessary to increase the secondary voltage of the excitation power transformer 10. That. In addition, since the exciting power supply transformer capacity and the secondary-side rated current also increase, the short-circuit current at the time of a short-circuit accident on the secondary side (low-voltage side) of the exciting power supply transformer 10 also increases. Also, when the single-unit output of the generator 6 increases, the rated voltage and current of the exciter, which is the base of the generator, increase in the first place. If the above-described measures for improving the transient stability of the power transmission system are added to this, the rated current and the short-circuit current on the secondary side (low voltage side) of the exciting power supply transformer 10 will further increase. On the other hand, the field circuit breaker 16 is a circuit breaker that blocks direct current, and there is a problem in increasing its breaking capacity. For example, the maximum specifications of a circuit breaker that exists at present are a rated voltage of 750 V, a rated current of 7500 A, and a rated breaking current of 60 kA. From the rating of the field circuit breaker, the requirements of a 1350 MW class nuclear power plant to be currently constructed are almost limited. . In addition, the nuclear power plants currently under planning tend to construct high-power (1500MW class) power plants in remote areas from the power consuming area, and are increasingly connected to the power consuming areas with long-distance transmission lines. The demand for high transient stability of the transmission system and the reduction of the relative construction costs of power plants have led to the trend toward construction of power plants with higher single-unit generator output. In this case, there is a problem in that it is difficult to set the peak voltage of the exciter required for securing the transient stability of the power transmission system.

SUMMARY OF THE INVENTION It is an object of the present invention to increase the top voltage of an exciting device of a nuclear power plant and a high-power nuclear power plant to be constructed in a remote place, and to form a stationary generator suitable for forming a power system having a large transient stability. An exciting device is provided.

[0006]

In order to solve the above-mentioned problems, a generator load is set when a short circuit accident occurs on the secondary side (low voltage side) of an exciting power supply transformer of a stationary generator exciting device or when a thyristor rectifier fails. The generator is released from the field circuit by the switch. When the secondary side (low voltage side) of the excitation power supply transformer of the stationary generator excitation device is short-circuited or the thyristor rectifier fails, the primary side (high voltage side) of the excitation power supply transformer is normal. The generator is opened from the field circuit by the machine load switch and the main transformer circuit breaker is opened.

[0007] The present invention is limited to a low-voltage synchronization system in which a generator having an in-house power supply configuration is synchronized at a low voltage by a generator load switch that is paralleled and disconnected from the power transmission system. According to the present invention,
Since the function of the conventional field breaker (field blocking function) has been added to the original function of the generator load switch in the generator low-voltage synchronous system, the field breaker becomes unnecessary and can be deleted. In addition, it is possible to increase the peak voltage of the exciter, which has been conventionally restricted by the specifications of the field circuit breaker, and to contribute to the transient stability of the power transmission system.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. FIG. 3 is an overall schematic system diagram in the case where the present invention is applied to a nuclear power plant. FIG.
In the above, the steam generated in the core of the reactor 1 is guided to the high-pressure turbine 4 and the low-pressure turbine 5 via the steam regulating valve 2 and the main steam pipe 3, and drives the generator 6 connected thereto to generate power. Do. The power generated by the generator 6 is low-voltage synchronized with the power transmission system by closing the generator load switch 7 having the function of blocking the field, the power is boosted by the main transformer 9, and the power transmission system And power to the on-site load. The shunt type excitation device 14 between the generator load switch 7 and the main transformer 9 includes an excitation power supply transformer 10, a thyristor rectifier 11, an automatic voltage regulator 12,
It is composed of the initial excitation device 13, and in order to make a part of the generator output an AC voltage equivalent to the DC voltage required by the field circuit,
The generator output voltage branched from the power system to be supplied to the in-plant load is stepped down by the excitation power supply transformer 10, and the output of the secondary side (low voltage side) of the excitation power supply transformer 10 is converted to a thyristor rectifier
, The thyristor rectifier 11 is controlled by the automatic voltage regulator 12, and the field current necessary for maintaining the generator voltage is supplied to the generator 6 via the field breaker 16. . When the generator 6 is started,
An initial excitation current is supplied to the generator 6 from an in-house DC power supply via the initial excitation device 13.

FIG. 1 is a configuration diagram of a stationary generator exciting device 14 according to an embodiment of the present invention. 1, the same reference numerals as those in FIG. 4 denote the same objects. The difference between the exciter 14 of the present embodiment and the conventional exciter 15 is that the generator load switch 7 of the present embodiment includes a generator 6 connected to a power transmission system when the generator 6 which is an original function is operated / stopped. The function of the field circuit breaker 16 of the conventional excitation device 15 is added to the function of parallel / disconnecting, so that the excitation device 1 of the present embodiment is
In No. 4, the field breaker 16 of the conventional exciter 15 becomes unnecessary and is eliminated. Here, the function added to the generator load switch 7 of the present embodiment is the excitation power transformer 1
In other words, the generator load switch 7 is opened only at the time of a short circuit accident on the secondary side (low voltage side) 0, and the short circuit current is cut off from the generator 6. This is because the generator load switch 7 does not have an interrupting capability for a short-circuit current flowing due to an accident on the primary side (high voltage side) of the excitation power supply transformer 10.

FIG. 2 shows an excitation power supply transformer 10 according to this embodiment.
Shows a logic for cutting off the short-circuit current from the generator 6 only at the time of a short-circuit accident on the secondary side (low-voltage side). In this logic, the operation of the excitation power supply transformer overcurrent relay 18 or the failure of the thyristor rectifier 11 that is activated when a short-circuit accident on the secondary side (low voltage side) of the excitation power supply When the AND condition that the primary / secondary current difference current is normal and the operation excitation power supply transformer ratio differential relay 19 is inactive is satisfied, the generator load switch 7 is opened, and Excitation power transformer Overcurrent relay 18
Or the failure of the thyristor rectifier 11 and the establishment of the AND condition of the opening of the generator load switch 7, the generator closing relays 20, 21 are operated, and the main transformer circuit breaker 22 is opened. In this logic, the main transformer circuit breaker 22 is opened, the generator 6 is disconnected from the power transmission system, and the generator load switch 7 is opened, whereby the short-circuit current is cut off from the generator 6. When an abnormality occurs in the difference between the primary and secondary currents of the excitation power supply transformer 10, the operation excitation power supply transformer ratio differential relay 19 operates, and this operation and the operation of the excitation power supply transformer overcurrent relay 18 Or thyristor rectifier 11
When the AND condition with the failure is satisfied, the generator closing relays 20 and 21 are operated, and the main transformer circuit breaker 22 is opened. In this logic, since the primary side (high voltage side) of the excitation power transformer 10 is in an accident, the main transformer circuit breaker 22 is opened and the generator 6 is disconnected from the power transmission system to reduce the short-circuit current. More shut off. As described above, in this embodiment, since the generator load switch 7 has the operation of the conventional field breaker 16, the conventional field breaker 16 becomes unnecessary and can be deleted.

[0011]

As described above, according to the present invention,
In a nuclear power plant, the field breaker of the conventional stationary generator exciter is no longer necessary, and the function of the conventional field breaker (field blocking function) is replaced with the original function of the generator load switch. By adding this, it is possible to excite the generator with a high peak voltage, improve the transient stability of the power transmission system when connected to the power consuming area by a long distance transmission line, and increase the power output of the generator Thus, the stability of the transmission system can be improved. Further, by eliminating the conventional field breaker, it is possible to rationalize the stationary generator exciter.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a stationary generator excitation device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an operation logic of the present invention.

FIG. 3 is an overall schematic system diagram of a nuclear power plant to which the present invention is applied.

FIG. 4 shows a conventional static generator excitation device.

FIG. 5 is a diagram showing an operation logic of a conventional example.

[Explanation of symbols]

6 generator, 7 generator load switch with field blocking function, 8 generator load switch, 9 main transformer, 10 excitation power transformer, 11 thyristor rectifier, 14 of the present invention Stationary generator exciter, 15 ... Conventional stationary generator exciter, 16 ... Field circuit breaker, 18 ... Exciting power transformer Overcurrent relay (51ET), 19 ... Exciting power transformer ratio differential relay (87ET) ), 22 ... Main transformer breaker

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masashi Sugiyama 3-1-1, Sachimachi, Hitachi-City, Ibaraki Pref. Hitachi, Ltd. Hitachi Plant (72) Inventor Toshiya Morita 3-1-1 Sachimachi, Hitachi-City, Ibaraki No. 1 Inside Hitachi, Ltd. Hitachi Plant (72) Inventor Koji Nishi 3-2-1 Komachi, Hitachi, Ibaraki F-term within Hitachi Engineering Co., Ltd. 5G044 AC01 BA02 BA08 5H590 AA10 AA11 AA30 AB02 AB03 AB10 AB20 BB11 CA05 CC01 CD01 CE01 DD24 DD64 HA02 HA04 HB02 HB03

Claims (2)

[Claims] 1. A generator, a generator load switch that is paralleled and disconnected from the power transmission system when the generator is operating and stopped, and a generator transformer and a main transformer that boosts the generator voltage. An excitation power transformer for reducing the voltage of the branch circuit for shunt excitation to an AC voltage equivalent to the DC voltage required by the field circuit, and the output of the secondary side (low voltage side) of the excitation power transformer A static generator exciter having a thyristor rectifier for converting to a thyristor, the generator load switch including the thyristor rectifier, when a short circuit accident occurs on the secondary side (low voltage side) of the exciting power supply transformer or when the thyristor rectifier fails. Is released from the field circuit. 2. A generator, a main transformer for boosting the generator voltage and transmitting the power to a power transmission system via a main transformer circuit breaker, and a power generator parallel and disconnected from the power transmission system when the generator is operated or stopped. Machine load switch, and an exciting power transformer for reducing the voltage of a branch circuit for shunt winding between the main transformer and the generator load switch to an AC voltage equivalent to a DC voltage required by a field circuit. When,
In a stationary generator exciter having a thyristor rectifier for converting an output on a secondary side (low voltage side) of the excitation power supply transformer into a direct current, a short circuit accident on the secondary side (low voltage side) of the excitation power supply transformer or When the thyristor rectifier fails, when the primary side (high voltage side) of the excitation power transformer is normal,
A static generator exciting device characterized in that the generator is opened from the field circuit by the generator load switch and the main transformer circuit breaker is opened at the same time.