JPH09322575A - On-site power supply equipment for nuclear power plants - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To suppress a voltage drop of a power bus voltage when a large capacity induction motor of a nuclear power plant is started. SOLUTION: In the in-house power supply equipment configured to supply power to the large-capacity induction motor from the in-station high-voltage power bus that supplies power to the components of the nuclear power plant, the transformer ratio of the in-house transformer is set. The load voltage regulator to be changed, the first manual switch means 25, and the load voltage regulator is adjusted when the first manual switch means 25 is turned on to adjust the secondary side voltage of the station transformer to the station high voltage power bus. Control means 30, 3 for boosting to a predetermined high voltage higher than the rated voltage of
1, 34, the second manual switch means 24, and when the second manual switch means 24 is turned on, the power breaker is turned on (40) and the large capacity induction motor is connected to the in-house high voltage power supply busbar to generate large capacity induction. Second control means 36, 3 for starting the electric motor
8, 39, 40 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply facility for a nuclear power plant, and more particularly to a nuclear power supply suitable for alleviating a power supply voltage drop even when a large-capacity induction motor is directly inserted and started when the power plant is started. The present invention relates to a power supply facility in a power plant.

[0002]

2. Description of the Related Art In a power supply facility of a thermal power plant or a nuclear power plant, a load such as an induction motor or a low-voltage transformer for step-down to reduce the voltage on the downstream side of the power bus is connected to each power bus. Has been done. During normal operation of the plant, each of these receives a power source that is stepped down to the rated voltage of the power source bus by a transformer from an external power source. In addition, power is supplied from the power bus to the induction motor, which is a load, and a low-voltage transformer on the downstream side by a cable.

The induction motor, which is a load, is often a direct-insertion start in order to simplify the equipment required for starting it.
When the induction motor is directly inserted and started, a large starting current flows at the time of starting, and this current causes a large voltage drop in the transformer and the cable. For this reason, the impedance of the transformer is reduced to reduce the impedance voltage drop in the transformer, and the number and size of cables from the power source bus to the load are increased to improve the cable impedance. To reduce the voltage drop in the cable by reducing the voltage, and to reduce the starting current itself when the induction motor is directly inserted and started.

However, each of these countermeasures has the following restrictions and is naturally limited. That is, (1) When the impedance of the transformer is reduced, the short-circuit current that flows at the time of a short-circuit accident on the secondary side of the transformer increases, but the magnitude of the short-circuit current is less than or equal to the breaking current of the breaker provided on the power bus. Need to be kept to.

(2) Increasing the number and size of cables from the power source bus to the load increases the quantity of cables and the quantity of electrical work. Also, the work of connecting the cable to the power panel and the induction motor becomes difficult.

(3) When the starting current at the time of direct insertion of the induction motor is made smaller, the torque at the time of starting becomes smaller and the starting time becomes longer. Further, since it is necessary to increase the number of windings of the induction motor, the size of the induction motor becomes large.

Therefore, in a thermal power plant, when a load voltage regulator (hereinafter referred to as LTC) is provided in a transformer and the induction motor is directly inserted and started, as described in, for example, Japanese Patent Laid-Open No. 2-293912. In addition, a technique has been developed in which the LTC tap is switched to increase the power supply bus voltage and to reduce the voltage drop rate at the time of starting the induction motor.

As a conventional technique for boosting the power supply voltage by the LTC when the AC motor is started, there is, for example, JP-A-60-144147 in addition to the above.

[0009]

It is an effective technique to mount an LTC on a transformer and switch taps of the LTC at the time of starting the induction motor to boost the power supply bus voltage. However, JP-A-2-293912 and JP-A-60-1
In the conventional technique disclosed in Japanese Patent No. 44147, the tap is switched at the same time as the start command at the time of starting the electric motor to boost the power supply voltage, and thus the conventional technique cannot be directly applied to the in-house power supply facility of the nuclear power plant. The reason is that the capacity of an induction motor used in a thermal power plant is significantly different from that of an induction motor used in a nuclear power plant. For example, an induction motor that drives a circulating water pump of a nuclear power plant has a capacity of about 10,000 kW, and in order to start the induction motor for this circulating water pump, the tap of the LTC is switched at the same time as the induction motor start command. I can't get a smooth start.

An object of the present invention is to provide an on-site power supply facility of a nuclear power plant capable of smoothly starting a large-capacity induction motor installed in a nuclear power plant and suppressing the voltage drop rate of a power bus at the time of starting. To do.

[0011]

[Means for Solving the Problems] The above object is to provide a main transformer that transforms generated power of a main generator of a nuclear power plant and outputs the transformed power to an external power transmission system, and an in-house facility that supplies power to components of the nuclear power plant. In the on-site power supply facility of a nuclear power plant, which comprises a high-voltage power bus and an on-site transformer that extracts and transforms a part of the generated power of the main generator for in-house use, the on-site transformer A load voltage regulator for changing the transformation ratio of the power supply, a power supply circuit breaker for connecting / disconnecting the large-capacity induction motor and the local high-voltage power bus, a first manual switch means, and the first manual switch means First control means for adjusting the secondary voltage of the in-house transformer to a predetermined high voltage higher than the rated voltage of the in-house high-voltage power supply bus by adjusting the under-load voltage regulator, and a second manual switch. And a second control for starting the large-capacity induction motor by connecting the large-capacity induction motor to the local high-voltage power bus when the second manual switch means is closed. It is achieved by including means.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a single-line connection diagram showing on-site power supply equipment of a nuclear power plant according to an embodiment of the present invention. In FIG. 1, 1 is an external power transmission system, 2 is a main transformer, 3 is a generator load switch, 4 is a main generator, 5 is a station transformer, 6 is a station transformer load voltage regulator (LTC). , 7
Is a circuit breaker for receiving the high-voltage power supply bus on the secondary side of the transformer,
8 is a high-voltage power supply bus in the office, 9 is a circuit breaker for feeding a large capacity induction motor, 10 is a large capacity induction motor for driving a circulating water pump, 11 is another load, 12 is a voltage transformer (P
T), 13 is a high voltage power supply busbar voltage monitoring relay (59H)
1: high voltage on the high voltage side, 14 is a high voltage power bus bus monitoring relay in the station (59H2: high voltage side normal voltage), 15 is a high voltage power bus voltage monitoring relay in the station (27L1: low voltage high voltage),
Reference numeral 16 is an internal high voltage power bus voltage monitoring relay (27L2: low voltage side normal voltage).

FIG. 2 shows a vector diagram of the voltage drop in the on-site power supply facility shown in FIG. In FIG. 2, E1 is the primary side voltage of the station transformer 5, E2 is the secondary side voltage of the station transformer 5, I is the load current, and 20 is the impedance of the station transformer 5.
The dance voltage drop, θ is the phase delay angle (power factor = cos) of the load current I with respect to the secondary side voltage E2 in the in-house transformer 5.
θ), Ix is the reactance voltage drop in the in-house transformer 5,
Ir represents the resistance voltage drop in the in-house transformer 5.

During normal times other than the start of the large capacity induction motor 10, the load voltage regulator 6 (LTC) of the on-site transformer 5
Is a voltage drop due to the load current I of the other load 11 and the impedance of the in-house transformer 5 (≈Ir · cos θ + Ix ·
sin θ), that is, E2 is constant (≈E1)
Is controlled so that

FIG. 3 is a sequence diagram for controlling the on-site power supply equipment shown in FIG. The sequence part in the upper half of FIG. 3 is a known technique, and this part outputs the tap-up request signal and the tap-down request signal of the LTC 6 to output the power supply bus 8
Is controlled so that the voltage of is within a predetermined range. In the embodiment of the present invention, two types of "high voltage range" and "normal voltage range" are provided as the predetermined range, the "high voltage range" is selected when the large capacity induction motor is started, and the "normal voltage range" is selected during normal operation. I am trying to select. The "high voltage range" is selected by selecting the relays 13 and 15, and the "normal voltage range" is selected by selecting the relays 14 and 16.

That is, during normal operation, the voltage of the in-house high-voltage power supply bus bar 8 is the relay (59H2: high-voltage side normal voltage) 14
Set voltage and relay (27L2: low voltage side normal voltage) 1
The value is between 6 and the set voltage. During normal operation of the plant, the LT shown in FIG.
C6 switches the taps (T1 to T17) to change the transformation ratio of the in-house transformer 5 and adjusts the voltage of the in-house high-voltage power bus 8 so that both the relay 14 and the relay 16 are within the inoperative range. Control.

For example, when the voltage of the power bus 8 is higher than the set voltage of the relay 14, the relay 14 operates and the LTC
The tap-up request signal 26 is output. As a result, the taps (T1 to T17) are moved to the one with the larger number, the turns ratio between the primary side and the secondary side of the station transformer 5 becomes smaller, and the secondary side voltage of the station transformer 5 becomes smaller than before. Get lower.

On the contrary, when the voltage of the power bus 8 is lower than the set voltage of the relay 16, the relay 16 operates and the LTC
The tap down request signal 27 is output. As a result, the taps (T1 to T17) are moved to the smaller numbers, the turns ratio between the primary side and the secondary side of the station transformer 5 is increased, and the secondary side voltage of the station transformer 5 is higher than before. Get higher

By repeating the above operation, the voltage of the power supply bus 8 is balanced with a voltage at which both the relay 14 and the relay 16 do not operate.

At this time, the relay 14 is set higher than the rated voltage of the power bus 8 by a value considering the control error, and the relay 1
If 6 is set lower than the rated voltage of the power bus 8 by a value that takes control error into consideration, the voltage of the power bus 8 can be maintained at approximately the rated voltage.

When starting the nuclear power plant, the circulating water pump must be started. In this case, a large-capacity induction motor for driving the circulating water pump is directly inserted and started by manual operation. At this time, the "high voltage range" is selected and the voltage of the power source bus bar 8 is boosted to be higher than usual. .
This step-up voltage is replaced with the relay 1 instead of selecting the relays 14 and 16.
This is done by selecting 3,15. In this case, the LTC6 of the in-house transformer 5 changes the transformation ratio of the in-house transformer 5 by switching the taps (T1 to T17) to change the voltage of the power bus 8 to
In-station high-voltage power supply bus voltage monitoring relay (59H1: high-voltage side high voltage) 13 set to a voltage higher than the set voltage of the relay 14, and in-station high-voltage power supply bus set to a voltage higher than the set voltage of the relay 16 Voltage monitoring relay (27
(L1: low-voltage side high voltage) 15 are controlled so as to be within a range in which both do not operate.

That is, when the voltage of the power bus 8 is higher than the set voltage of the relay 13, the relay 13 operates and the LTC
The tap-up request signal 26 is output. As a result, the taps (T1 to T17) move to the larger number, the turns ratio between the primary side and the secondary side of the in-house transformer 5 decreases, and the secondary voltage of the in-house transformer 5 does not become too high. To

On the contrary, when the voltage of the power bus 8 is lower than the set voltage of the relay 15, the relay 15 operates and the LTC
The tap down request signal 27 is output. As a result, the taps (T1 to T17) are moved to the smaller numbers, the turns ratio of the primary side and the secondary side of the station transformer 5 increases, and the secondary voltage of the station transformer 5 becomes higher than before. To do.

By repeating the above operation, the voltage of the power supply bus 8 is balanced with a high voltage at which both the relay 13 and the relay 15 do not operate.

Each set voltage of the relay 13 and the relay 15 is
As described above, the relay 1 used during normal plant operation
4 and the relay 16 are set higher than each set voltage so that the voltage drop rate can be suppressed even when the large capacity induction motor 10 is started. As described above, the voltage of the power bus 8 is preliminarily boosted for starting the induction motor before starting the large-capacity induction motor 10, because the induction motor that starts when starting the nuclear power plant has an extremely large capacity. Since it is unparalleled in the technical field of LTC6, it takes time to switch the taps of LTC6 (in order to increase the number of taps), and it takes about several minutes to perform the boost operation and boost the voltage to the target voltage. This is because of this.

When boosting the voltage of the power source bus 8 for starting the large capacity induction motor 10, in the vector diagram shown in FIG. 2, when the load current I reaches the starting current Is of the large capacity induction motor 10, If the voltage of the bus bar 8 is set higher than the rated voltage by an amount corresponding to the voltage drop due to the impedance of the transformer 5 (≈Isrcos θ + Isx sin θ), the voltage drop at the start of the large capacity induction motor 10 can be compensated.

Next, the sequence logic at the time of starting the large capacity induction motor described in the lower half of FIG. 3 will be described. In this sequence logic, two manual switches 24 and 25 are provided. The switch 25 is a pre-start condition switch that is turned on before starting the large-capacity induction motor 10. When the "pre-start" side is selected, an ON signal is output to one input terminal of the OR logic 30, and the "start-up" is started. The neutral signal is output from the selected position "n" except at the time of selection. The neutral signal n is adapted to enter the selecting step 32 of the relays 14 and 16 for selecting the "normal voltage range" via the wipeout function 31. The output of the OR logic 30 is returned to the other input terminal of the OR logic 30 via the wipeout function 33, whereby the “before start” selection signal is transmitted to the OR logic 3
It is self-holding at 0. The output signal of the OR logic 30 is the relay 1 for selecting the "high voltage range".
It also serves as an input condition signal for the wipeout function 31 while entering the selection step 34 of 3 and 15.

Therefore, even if the switch 25 is once put in "before starting" and the switch 25 returns to the neutral n position, the "before starting" selection state is held in the OR logic 30. As a result, the condition signal of the wipeout function 31 is input, the input of the ON signal output from the neutral n position to the “normal voltage range” selection step 32 is blocked, and the “high voltage range” selection step 34 is performed. To be selected. As a result, the voltage of the power bus 8 rises to the "high voltage range" as described above.

The output of the OR logic 30 is input to one input terminal of the AND logic 36 via the time delay means 35, and the start of the large capacity induction motor (the circulating water pump driving pump CWP in the illustrated example) is started. Lamp 37 indicating yes
Is also entered. When the delay time of the time delay means 35 is set to, for example, about 10 minutes, the lamp 37 lights up after a sufficient time has elapsed for boosting the bus voltage from the “normal voltage range” to the “high voltage range”. As seen, the operator turns on the switch 24 for starting the induction motor in the "start" position.

The ON signal output by selecting the "start" position of the switch 24 is input to one input terminal of the OR logic 38, and the output of the OR logic 38 is the wipeout function 3
The signal is returned to the other input terminal of the logic 38 via 9 and the wipeout function 39 uses the neutral n position selection signal of the switch 24 as a condition input signal. That is, when the switch 24 is set to the "starting" position, the "starting position" selection signal is output to the AND logic 36 via the OR logic 38, and the neutral n position is selected (as a matter of course, "starting").
The position selection signal is turned off. ) And wipeout function 3
A condition signal (neutral signal) is input to 9 and the self-holding of the OR logic 38 is released.

The AND logic 36 has, in addition to the output of the time delay means 35 and the output of the OR logic 38,
The "other conditions" signal is input. Switch 25
When the lamp 37 is turned on after a sufficient time has elapsed since the selection of "before starting" in step 1 and other conditions for starting the large capacity induction motor 10 are satisfied, the operator uses the switch 24 to "start". When the position is selected, an ON signal is output from the AND logic 36, and the power breaker 9 closing switch 40 of the large capacity induction motor 10 of FIG. 1 is closed. As a result, power is supplied to the large capacity induction motor 10 from the power source bus 8 boosted to the “high voltage range”, and the large capacity induction motor 10 is started.

The closing signal of the power breaker 9 is input as a condition signal to the aforementioned wipeout function 33 via the time delay means 41. That is, the self-holding of the OR logic 30 is released after the set time of the time delay means 41 has elapsed from the start of the start of the large capacity induction motor 10 (this set time is the time until the start is completed). This allows
When the selection in the relay selecting step 34 for selecting the “high voltage range” is completed, the condition signal input to the wipeout function 31 is turned off, and the ON signal output from the neutral n position of the switch 25 causes The relay selecting step 32 for selecting "normal voltage range" is selected.
Therefore, when the start of the large capacity induction motor 10 is completed,
The voltage of the power bus 8 is automatically returned to the normal voltage range, that is, the rated voltage.

As described above, according to this embodiment, since the voltage of the in-house high-voltage power supply bus 8 can be increased to a high voltage when the large capacity induction motor 10 is started, the voltage drop rate when the large capacity induction motor 10 is started is increased. It becomes possible to suppress. Further, since the voltage of the power bus 8 can be boosted up to the target voltage in advance when the large capacity induction motor 10 is started, it can be confirmed by the lamp.
No matter how large the capacity of the induction motor is, it can be started smoothly. Furthermore, since the voltage of the power bus is automatically returned to the rated value after the completion of start-up, there is no problem in normal plant operation.

[0034]

According to the present invention, the voltage drop rate when starting a large capacity induction motor of a nuclear power plant can be reduced.

[Brief description of drawings]

FIG. 1 is an internal single-line connection diagram according to an embodiment of the present invention.

FIG. 2 is a vector diagram of a voltage drop in the in-house transformer shown in FIG.

FIG. 3 is a voltage regulator (LT) under load for a transformer shown in FIG.
It is a sequence logic circuit diagram which controls C).

FIG. 4 is a voltage regulator (LT) under load for the transformer shown in FIG.
It is a detailed view of C).

[Explanation of symbols]

1 ... External power transmission system, 2 ... Main transformer, 3 ... Generator load switch, 4 ... Main generator, 5 ... In-house transformer, 6 ... In-house transformer load-time voltage switching (LTC), 7 ... In-house transformer Internal high-voltage power busbar power receiving circuit breaker on the secondary side, 8 ... In-station high-voltage power bus,
9 ... Circuit breaker for supplying power to load, 10 ... Large-capacity induction motor to start, 11 ... Other load, 12 ... Voltage transformer (P
T), 13 ... Internal high voltage power bus voltage monitoring relay (59H
1: High voltage on high voltage side, 14 ... High voltage power bus bus monitoring relay in station (59H2: High voltage side normal voltage), 15 ... High voltage power bus voltage monitoring relay in station (59L1: Low voltage high voltage),
16 ... In-house high-voltage power bus voltage monitoring relay (59L2: low-voltage side normal voltage), 20 ... Impedance voltage drop in in-house transformer, 24 ... Large-capacity induction motor 10 operation switch (CS), 25 ... Large-capacity Induction motor 10 Pre-start condition operation switch (CS), 26 ... LTC tap up request signal, 27 ... LTC tap down request signal, E1 ... Station transformer 5 primary voltage (PU), E2 ... Station transformer 2 Secondary voltage (P.U.), I ... Load current, θ ... Phase delay angle of load current I with respect to the secondary voltage E2 of the transformer (power factor = co
sθ), Ix ... Reactance voltage drop in the in-house transformer 5, Ir ... Resistance voltage drop in the in-house transformer, Is ... Large-capacity induction motor 10 starting current, Es2 ... Large-capacity induction motor 10 in-house transformer 5 Secondary voltage.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiya Morita 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Hirofumi Goya 3-chome, Hitachi-shi, Ibaraki 2-1 In Hitachi Engineering Co., Ltd. (72) Inventor Hiroaki Ota 3-2-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Engineering Co., Ltd.

Claims (6)

[Claims] 1. A main transformer that transforms the generated power of a main generator of a nuclear power plant and outputs it to an external power transmission system, a high-voltage power supply busbar that supplies power to components of the nuclear power plant, and the main power generation. At a load that changes the transformation ratio of the in-house transformer in the in-house power supply facility of a nuclear power plant equipped with an in-house transformer that takes out a part of the generated power of the machine for in-house use and transforms it to the in-house high-voltage power bus A voltage regulator, a power supply circuit breaker for connecting / disconnecting a large-capacity induction motor and the in-house high-voltage power bus, a first manual switch means, and the load voltage adjustment when the first manual switch means is turned on And a second control means for adjusting the secondary voltage of the in-house transformer to a predetermined high voltage higher than the rated voltage of the in-house high voltage power bus, a second manual switch means, and the second manual switch. Second, when the switch means is turned on, the power breaker is turned on to connect the large-capacity induction motor to the local high-voltage power supply busbar to start the large-capacity induction motor.
An on-site power supply facility for a nuclear power plant, comprising a control means. 2. The on-site power supply facility for a nuclear power plant according to claim 1, further comprising means for notifying that the voltage of the in-house high-voltage power supply bus has been boosted to the predetermined high voltage. 3. The nuclear power plant according to claim 2, wherein the notifying means measures a predetermined time from the time when the first manual switch means is turned on and notifies the end of the measurement. On-site power supply equipment. 4. The step-down means according to claim 1, which automatically adjusts the voltage regulator during load when the start of the large-capacity induction motor is completed to step down the voltage of the local high-voltage power bus to the rated voltage. An on-site power supply facility for a nuclear power plant, comprising: 5. The on-site power supply facility for a nuclear power plant according to claim 4, wherein the step-down means measures a predetermined time from the time when the power supply circuit breaker is turned on and after the measurement is completed. . 6. A main transformer that transforms the generated power of a main generator of a nuclear power plant and outputs it to an external power transmission system, a local high voltage power supply bus that supplies power to components of the nuclear power plant, and the main power generation. At a load that changes the transformation ratio of the in-house transformer in the in-house power supply facility of a nuclear power plant equipped with an in-house transformer that takes out a part of the generated power of the machine for in-house use and transforms it to the in-house high-voltage power bus A voltage regulator, a power supply circuit breaker for connecting / disconnecting the large-capacity induction motor and the local high-voltage power bus, a first switch means, and the load voltage regulator when the first switch means is turned on. First control means for adjusting and increasing the secondary side voltage of the in-house transformer to a predetermined high voltage higher than the rated voltage of the in-house high-voltage power bus, and the voltage of the in-house high-voltage power bus to the predetermined high voltage The second switch means that is turned on when the voltage is boosted, and the power breaker that is turned on when the second switch means is turned on to connect the large capacity induction motor to the local high voltage power supply busbar An on-site power supply facility for a nuclear power plant, comprising: second control means for starting the electric motor; and means for stepping down the voltage of the in-house high-voltage power supply bus to the rated voltage after the start of the large-capacity induction motor is completed.