JPS63177098A - Nuclear power plant - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a nuclear power plant in which at least one 100% bypass plant is installed among a plurality of nuclear power plants, and in particular, The present invention relates to a nuclear power plant that is equipped with a protection device that allows power to be supplied from a generator in a 100% bypass plant to other plants when external power is lost due to a ground fault or the like in an external power system.

(Conventional technology) Generally, a nuclear power plant consists of multiple nuclear power plants (
These plants include, for example, a 100% bypass plant in addition to a normal plant.

Here, a normal plant is a nuclear power plant that has a bypass capacity for bypassing, for example, several tens of percent of the flow rate of main steam generated in a nuclear reactor to a turbine condenser.

In addition, a 100% bypass plant is a nuclear power plant that has a bypass capacity to bypass almost 100% of the main steam flow rate generated in the reactor to the turbine condenser, and when there is a load shedding of the generator, Almost 100% of the main steam flow rate is bypassed to the turbine condenser through the bypass path, preventing reactor scram and allowing continued reactor operation.

Therefore, in a nuclear power plant with a 100% bypass plant, for example, in the event of an accident in the external power system, the 100% bypass plant can continue to operate even if the reactor scrams in the normal plant, reducing the availability rate. The decline can be prevented.

However, in a 100% bypass plant, almost 100% of the main steam flow is processed by its turbine condenser, so
The turbine condenser becomes larger and costs increase.

Therefore, in general nuclear power plants, 3 to 4
Each plant has one or 2M of 100% bypass plants.

The electrical system of a conventional nuclear power plant is configured as shown in Figure 6. For example, there are three normal plants 1°4.5, and two 100% bypass plants 2.3, the first and second. A total of five units are installed.

These plants 1 to 5 have substantially the same configuration except for having different bypass capacities, and have N generators 1A to 5A, respectively.

Each of the generators 1A to 5A is driven by a steam turbine that introduces main steam generated in a nuclear reactor (not shown) to rotate, and generates electricity. are connected to each.

For convenience of explanation, FIG. 6 shows the configuration of the internal power system of the plant indicated by reference numeral 1.2 in the figure, and the other plants 3 and 4.5 are not shown, but the configuration of the internal power system Since all plants 1 to 5 are almost the same, plant 1.2 will be described below, and the other plants 3°4.5 will be omitted.

Each plant 1.2 has a generator IA, 2A connected to an in-house transformer 7A.
, 7B to the normal busbars 8A and 8B, respectively,
Regular auxiliary equipment ID and 2D are connected to the normal buses 8A and 8B, while a starting transformer 11A is connected to the emergency buses 10A and 10B, which have emergency power supplies 9A and 9B consisting of diesel generators (D/G).

11B are connected to each other.

Emergency auxiliary equipment IE, 2E such as a residual heat removal system, for example, is connected to each emergency bus bar 10A, 10B, respectively.

When the generators 1A and 2A are in output operation, the power from these generators 1111A and 2A is transferred to the station transformers 7A and 7B, the normal buses 8A and 8B, and the emergency bus 1.
Regular use, emergency auxiliary equipment ID, 2D, through 0A, IOB,
Power is supplied to 1E and 2E, respectively.

In addition, if power cannot be supplied through the in-house transformers 7A and 7B, each auxiliary equipment 1D, 20.1E,
Powered to 2E.

Furthermore, in the event that an accident occurs in which power cannot be supplied from the external power supply through the starting transformers 11A and 11B, the emergency power supplies (D/G) 9A and 9B are started to generate electricity, and from this the emergency bus 10A is connected.

Power is supplied only to the emergency auxiliaries 1ff1E and 2E through 10B, thereby ensuring safe operation of the plant 1.2.

A nuclear power plant configured in this way has a bus circuit breaker 12.
The in-house switchyard busbar 6 on which A and 12B are interposed is connected via line breakers 13A and 13B to a pair of N transmission lines 14A and 14B by two circuits that are external power systems, respectively.

A first substation 15 or switchyard and a second substation 16 or switchyard are interposed in the middle of these power transmissions 15114A and 14B, and these first and second substations 15.1
Line breakers 17A are installed on the power transmission lines 14A and 14B in 6.
17B, 18A, and 18B are installed respectively.

In addition, in the middle of the power transmission lines 14A and 14B, there is a hydroelectric power station 19 and two
One pair of branch power lines 20A in line.

20B is connected.

Furthermore, the first and second 100% bypass plants 2.3
is equipped with the protection device shown in Fig. 5, and the other normal plants 1 and 4.5 are the same except that the "100% bypass failure signal" in Fig. 5 is replaced with the "partial bypass failure signal". Each configured protection device is installed.

In addition, all plants 1 to 5 include load cutoff detection relays (not shown) that detect the blockage of the rectangular tubes of the power generation TFIs 1A to 5A, and reverse power detection relays 1C to 5C that detect reverse power flowing back from the external power system, etc. , a blockage relay that stops the operation of the power generators 1fiIA to 5A, and a turbine overspeed detector (not shown) that detects the overspeed of the turbine (not shown) that drives each power generator tlIA to 5A, respectively. and each turbine overspeed detector sets its set value to the rated rotational speed of the turbine, that is, for example, about 1 of the rated frequency.
11%, and when it is detected that the rotation speed of the turbine exceeds this set value, the turbine overspeed signal S4 is activated.
(See Figure 5) is output and the reactor is scrammed.

By the way, as shown in Fig. 6, both the first and second substations 1
5. At point X and point Y between 16, power transmission for a pair of two lines #
If an external power system fault such as a ground fault occurs simultaneously in 14A and 14B, the line breakers 17A, 17B, 18A,
18B is shut off, and all protection devices of all plants 1 to 5 and the hydroelectric power plant 19 are respectively activated.

That is, if a ground fault or the like occurs simultaneously at points X and Y of power transmission lines 14A and 14B, line breakers 17A and 1
78. 18A and 18B are cut off and accident points X and Y
is removed from the external power system, and each plant 1~
The load current of the 8 IJIs 11A to 5A in FIG. Output.

When the load interruption detection relay operation signal $1 is applied to each of the protection devices, all the protection devices quickly open the turbine main steam control valve and the turbine bypass valve at almost the same time. When this fails and a 100% bypass failure signal S2 or a partial bypass failure signal is output, a total $1,611 rod rapid insertion signal S3 is output, which causes all control rods to be rapidly inserted into the reactor at once. All plants 1-5 are reactor scrammed.

Furthermore, if the turbine main steam control valve fails to close quickly, the steam turbine is accelerated, and a turbine overspeed signal S4 is output from a detector (not shown) that detects this.

When this turbine overspeed signal S4 is input to the protection device, the protection device receives the turbine main steam stop valve closing signal S4.
5 and also outputs the all control rod rapid insertion signal S3 to scram the reactor, and also outputs the blockage relay trip signal S6 to trip the blockage relay (not shown) and switch the generators 1A to 5A. Stop operation.

However, for the first and second 100% bypass plants 2.3, when 100% bypass is successful, hot air is bypassed to the turbine condenser without being introduced to the turbine, so turbine overspeed will not occur. First, the reactor is not scrammed, so reactor operation continues.

The blocking relay is also tripped when the protection device receives a reverse power detection relay operation signal S7, which is output when the reverse power detection relay detects reverse power and operates. Further, when the blockage relay trip signal S6 is output, the station transformer 7A.

7B is switched to the starting transformers 11A and 11B, and the generator parallel circuit breakers 1B to 5B are cut off.

Meanwhile, track breaker 17A was shut down due to a track accident.

178. When 18A and 18B are shut off, output adjustments such as constant frequency are performed at the nuclear power plant and the hydroelectric power plant 19. However, if this is malfunctioning, the hydroelectric power plant 19 Since power flows backwards from the source to the nuclear power plant, this reverse power is transferred to all plants
Reverse power detection relays 5 (not shown) each detect and operate, and a reverse power detection relay operation signal S7 is given to all protection devices.

For this purpose, the protection device is connected to the station transformer 7A as described above.
is switched to each starting transformer 11A, and all generator parallel circuit breakers 1B to 5B are cut off.

In addition, since the output adjustment at the hydroelectric power plant 19 has a slow response,
Line breakers 17A, 17B, 18A.

After 18B is cut off, that is, after the load is cut off, the frequency tends to increase for a certain period of time. This also synchronizes the nuclear power plant's generators 1Δ-5A, eventually causing turbine overspeed, and a turbine overspeed signal S4 is applied to all protection devices, tripping all turbines (not shown).

Then, the connections between all the power generators 11A to 5A of all plants 1 to 5 are cut off by the interruption of all generator parallel circuit breakers 1B to 5B, respectively, and the station switchyard bus 6 loses power, and the normal plant 1.4.5 All of the reactors in the reactor eventually scrammed, and the hydroelectric power plant 19 was also shut down due to tripping of reactors m119A and 19B.

As a result, the reactor scrammed in a conventional plant 1.4.
In step 5, start the emergency power supply 9A and turn on the emergency power supply 1i110.
Power is supplied only to emergency auxiliary equipment IE and 2E, such as the residual heat removal system, through A.

(Problem to be solved by the invention) However, with such conventional protection devices, in the event of an accident in the external power system, all units of the plant 1,4゜5 are normally scrammed, and the emergency power supply 9A is activated. Generate electricity and feed the emergency auxiliary equipment 1F from this 9A emergency power supply,
There is a problem in that restarting a nuclear power plant after an external power system accident is restored requires a great deal of effort, cost, and time, and reduces the operating rate of the nuclear power plant.

In other words, although conventional protection devices pose no safety problems,
In a normal plant 1.4.5 where the nuclear reactor is in scram due to a power outage at the switchyard bus 6 in the nuclear power plant,
Emergency power supply 9A due to loss of in-house power supply and loss of external power supply
is started, and only the emergency auxiliary equipment 1E connected to the emergency bus 10A is powered and operated.

Therefore, in the event of an external power system fault, the station transformer 7△,
Although switching from 7B to starting transformers 11A and 11B,
Since the external power supply is lost, power cannot be supplied to the regular auxiliary machine 1D, and the regular auxiliary machine 1D is tripped.

For this reason, the reactor cannot be cooled by the turbine condenser, and only the auxiliary equipment connected to the emergency bus, such as the residual heat removal system, is operated, so normally the plant 1°4.5 is restarted. In this case, it is necessary to manually restore the power to many of the tripped regular auxiliary machines, which requires a great deal of effort, cost, and time to restart the nuclear power plant, leading to a decrease in operating efficiency.

Additionally, if a ground fault occurs in the external power system, nuclear power plants operating at base load will stop operating sooner than hydropower plants19, which is undesirable from the standpoint of stable power supply. There is a problem.

In other words, when a ground fault or the like occurs in the external power system, load shedding occurs in the generators 19A and 19B of the hydroelectric power plant 19, and the output is adjusted to keep the frequency constant, but the frequency rapidly increases. Go.

The setting value of the frequency increase detection relay (not shown) of the hydroelectric power plant that detects this frequency increase is, for example, approximately 1 of the rated frequency.
This setting value is set to 20%, and this setting value is a high value, whereas the setting value of the turbine overspeed detector that detects turbine overspeed in a nuclear power plant is, for example, approximately 111% of the rated rotation speed (rated frequency). It becomes.

Accordingly, the accusation of hydropower plant 19 [119A.

Due to the increase in the frequency of the output of 19B, the frequency of the power generation g11A to 5A in the nuclear power plant is also increased synchronously, that is, the turbine speed increases, and the rated rotation speed (rated frequency), for example, 110
% overspeed, a turbine overspeed detector detects this turbine overspeed and trips the turbine.

Therefore, the generator 19A of the hydroelectric power plant 19.

Before 19B is tripped by the detection operation of the frequency rise detection relay (OFR), the turbine of the nuclear power plant is tripped quickly by the detection operation of the turbine overspeed detector, and for this reason, all of the power generation units 111A to 5A are tripped. , the nuclear power plant shuts down much earlier than the hydroelectric power plant 19.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a nuclear power plant that can supply power to regular and emergency auxiliary equipment of a normal plant in which a nuclear reactor has been scrammed, without starting the emergency power supply of the nuclear power plant.

[Structure of the invention]

(Means for Solving the Problems) The present invention was made with a focus on a 100% bypass plant that allows nuclear reactor operation to continue without being scrammed even in the event of an accident in an external power system. The feature is that the generator of this 100% bypass plant is configured as a power source for the regular and emergency auxiliary equipment of other plants whose reactors are scrammed due to an accident in the external power system, as follows. configured.

Each generator in multiple nuclear power plants is connected to the on-site switchyard bus through a generator parallel circuit breaker, and this on-site switchyard bus is connected to the external power system via an on-site line breaker. The power generation plant includes a reverse power detection relay that detects reverse power from the external power system, a load shedding detector that detects load shedding of the generator, and a turbine that trips the turbine when turbine overspeed is detected. A 100% bypass plant having an overspeed detector, and at least one of these nuclear power plants having a bypass feature that bypasses approximately 100% of the main steam flow rate generated in the reactor to the turbine condenser. a frequency rise detector that has a set value set at a lower frequency than the set value of the turbine overspeed detector and detects a frequency rise of electric power applied to the above-mentioned switchyard bus; , the generator parallel circuit breaker in the 100% bypass plant is turned on, the reverse power detection relay detects reverse power, and the load shedding detection relay detects load shedding of the generator and operates. Moreover, when this 100% bypass plant detects that the reactor is not scrammed at almost the same time, or when the frequency rise detector detects a frequency rise exceeding a set value, the station line breaker On the other hand,
A protection device was provided to close the generator parallel circuit breaker of at least one 100% bypass plant.

(Function) When a power failure occurs in the external power system, for example, the load shedding detection relays of all plants at the nuclear power plant detect load shedding of the generators and operate, and the reverse power detection relays operate at the hydropower plant. It operates by detecting reverse power flowing back to the nuclear power plant from other sources.

Furthermore, as a result of this ground fault accident, each generator in the nuclear power plant undergoes load shedding, which causes each turbine in the nuclear power plant to overspeed, increasing the frequency of the power applied to the plant's switchyard bus.

When this frequency rise exceeds the set value of each frequency rise detector in the nuclear power plant, the frequency rise detector detects and operates earlier than the turbine overspeed detector, and a frequency rise detector operation signal is output.

The protection device detects the operation of the load shedding detection relay and the reverse power detection relay, and also detects the state in which the 100% bypass plant continues to operate the reactor without reactor scram, and the power generation i parallel 'a disconnector. When the closed state is detected almost simultaneously, or when the operation of the frequency rise detector is detected, the station line breaker is shut off before the turbine is tripped by the turbine overspeed detector, The nuclear power plant is disconnected from the external power system, and the generator parallel circuit breaker of at least one 100% bypass plant is kept closed without being shut off.

For this reason, at least one generator of the 100% bypass plant, in which turbine tripping of the nuclear power plant is avoided and reactor operation continues, is connected to the plant switchyard bus line via the generator parallel circuit breaker in the closed state. remains connected to.

Therefore, the in-station switchyard busbar has one
Power is supplied from the generator of the 00% bypass plant,
Power outages are avoided.

As a result, the plant's regular and emergency auxiliary equipment during the reactor scram is powered through the on-site switchyard busbar.
There is no need to start up the plant's emergency power supply during a reactor scram, which reduces the effort required to restart the nuclear power plant when the emergency power supply is activated, allowing for rapid reactor restart. Since startup is possible, it is possible to improve the operating rate of nuclear power plants.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4. Note that in FIGS. 3 and 4, parts common to those in FIG. 6 are given the same reference numerals.

FIG. 3 shows the overall configuration of an embodiment of the present invention, and this embodiment includes a pair of frequency rise detectors 50A and 50B shown in FIG. 3 in a nuclear power plant, and a protection device 20 shown in FIG. ．．
The feature is that 30 are provided respectively.

Frequency rise detectors 50A and 50B are installed in a nuclear power plant. In a switchyard facility (not shown) having J6, a pair of station line breakers 13Δ.

13B and a pair of power transmission lines 14A, 14B, and when it is detected that the frequency rise of the power supplied to these station switchyard busbars 6 exceeds a set value, a pair of station line breakers 13A, 13B respectively.

Moreover, these frequency rise detectors 50A and 50B are
f# Operates when the frequency top of the power of the confined space bus 6 exceeds a set frequency or exceeds a predetermined frequency rise rate corresponding to it, and outputs a frequency rise detector operation signal 85.
0 (see Figure 1), and its set value is set to, for example, about 108% of the rated frequency, and the set value of the turbine overspeed detector (not shown) in a nuclear power plant is set to, for example, 111%. %, it is set slightly lower.

This is a frequency rise detector 50A at a nuclear power plant.

50B detects a frequency increase that exceeds the set value, and before the pair of in-house line breakers 13A and 13B are shut off, each turbine overspeed detector in the nuclear power plant operates and each turbine is tripped. This is to prevent

Therefore, even after the in-house line breakers 13A and 13B are shut off, each turbine in the nuclear power plant continues to operate until the turbine overspeed detector performs a detection operation, and during that time, the generators 1A to 5A connected to each turbine receive the necessary power. power is output, and power outage of the station switchyard bus 6 is avoided.

On the other hand, the protection devices 20.30 shown in FIG. 1 are installed in each of the 100% bypass plants 2.3 and 1, 4. As for '5, the protection device shown in FIG. 5 is incorporated as is, and the explanation of this protection device will be omitted.

The protection device 20 of this embodiment provided in the first 100% bypass plant 2, one of the 21, is configured as shown in FIG.
A, reverse power detection relay operation signal 511A, load cutoff detection relay operation signal 512A, and reactor scram signal 5
13A as an input.

The generator parallel circuit breaker close signal 510A is output when a detector (not shown) detects that the generator parallel circuit breaker 2B of the first 100% bypass plant 2 shown in FIG. 3 is in the closed state. The reverse power detection relay operation signal S11A is a signal output when the reverse power detection relay 2G of the first 100% bypass plant 2 detects a reverse power horn from the power transmission lines 14A, 148, etc. and operates. The set time T1 is delayed by the first timer 1A.

In addition, the load cutoff detection relay operation signal 512A is
This is a signal that is output when a load shedding detection relay (not shown) of the 00% bypass plant 2 detects a load shedding of the output Rm2A, and the output is held for a second set time by the second timer TA.

Furthermore, the reactor scram signal 513A is the first 100%
This is a signal output from the reactor protection system (not shown) when the bypass plant 2 performs a reactor scram, and when the output of this reactor scram signal is stopped, it is inverted by the Not circuit 22 and becomes a logic signal "1". is applied to the first AND circuit 21.

First AND output signal 521 from first AND circuit 21
A is timer T. Set time T by A.

The signal is delayed and given to the generator parallel circuit breaker 2B of the first 100% bypass plant 2 as the generator parallel circuit breaker interrupt signal 814A to shut it off.

By disconnecting this generator parallel circuit breaker 2B, the first 100
% bypass plant 2's generator 2A from the station switchyard bus 6 l/JIIIL, power transfer between this generator 2A and u=i3A of the second 100% bypass plant 3, that is, stop the cross flow. Can be done.

The generator parallel circuit breaker closing signal 5IOA and the reverse power detection relay operation signal 311A delayed by the set time T3 by the third timer T3A are connected to the second AND circuit 23.
The output side of the second AND circuit 23 outputs a blocking relay trip signal 515A.

The blockage relay trip signal 515A is given to a blockage relay (not shown) of the first 100% bypass plant 2,
This is blocked, the operation of the generator 2A of the plant 2 is stopped, and backup is provided in case the generator parallel circuit breaker 2B fails to shut off. That is, first, when the generator parallel circuit breaker cutoff signal 514A is output and the generator parallel circuit breaker 2B is shut off, the output of the generator parallel circuit breaker closing signal 510A is stopped. The AND condition of the AND circuit 23 is not satisfied, and the blocking relay trip signal 515A is not output.

Therefore, this blocking relay trip signal 515A is outputted only when the generator parallel circuit breaker 2B fails to shut off, and serves as a backup.

Each of the above timers T1A, T2A, 3rd Δ, and King.

Each setting time of A is T < T 1T, < 72, T
<The third setting is respectively set, so after the generator parallel breaker cutoff signal 514A is output, the blockage relay trip signal 515A is output, and after the generator parallel breaker 2B is cut off, the power generation starts. The operation of machine 2A is stopped by the blocking relay.

In addition, the second 100% bypass plant 3 of the two
The protection device 30 installed at
t circuit 32, each timer T B, second B, third B,
T and B, and when these timers are set, IT, bottom and third degree T are also T < T, T < T 1T
<T.

That is, the third AND circuit 31 outputs the generator parallel circuit breaker cutoff signal 5 in the second 100% bypass plant 3.
IOB, the reverse power detection relay operation signal 311B, the load cutoff detection relay operation signal 8128, and the inverted signal of the reactor scram signal 313B are input, and the fourth AND circuit 33 receives the generator parallel circuit breaker closing signal 810B. and reverse power detection relay operation signal 311B are input.

Moreover, the generator parallel interrupter 11i cutoff signal 314B is sent from the output side hs+ of the third AND circuit 31, and the blocking relay trip signal 8 is sent from the output side of the fourth AND circuit 33.
15B are output, and after the generator parallel circuit breaker 3B of the second 100% bypass plant 3 is shut off,
If the interruption fails, the operation of the generator 71in3A is stopped by tripping a blocking relay (not shown) as a backup.

And the first and third AN of both protection devices 20.30
The output side of the D circuit 21.31 is connected to the input side of the first OR circuit 34. Third AND circuit 21.3
When the output from 1 satisfies the OR condition of the first OR circuit 34, the station line breaker xi low signal 16 is output.

The first OR circuit 34 also includes a frequency rise detector 50A,
The frequency rise detector operating signal 850 from 50B (see FIG. 3) is input.

Therefore, when either the output signal from the first AND circuit 21 and the third AND circuit 31 or the frequency rise detector operation signal S50 is given to the first OR circuit 34, the OR condition is When established, an in-station line breaker cutoff signal 516 is given to the in-station line breakers i, 13A and 13B, respectively, and causes them to be cut off.

Moreover, since the station line cutoff Vs'ij1 cutoff signal S16 is not delayed by a timer or the like, the timer TDA.

It is output earlier than the generator parallel interrupter interrupt signals 514A and 514B, which are delayed by T and B.

When the in-house line circuit breaker cut-off signal S16 is applied to the in-house line lji disconnectors 13A and 13B of the nuclear power plant shown in FIG. 3, these are cut off, disconnecting the nuclear power plant from the external power system.

In addition, both timers ToA of the above-mentioned protection devices 20.30,
Power generation parallel circuit breaker interrupting signal @514A via T and B,
The reason for outputting 814B is as follows.

That is, as described above, the station line breakers 13A, 13
B is shut off and the nuclear power plant is disconnected from the external power system, the first and second 100% bypass plants 2.
3 reverse power detection relay 2C.

This is because 3C is reset. However, in reality,
Power generation 8m2A, 3 due to factors such as differences in manufacturers
Because there are differences in characteristics between A and the turbine that drives it,
Even at the same rotation speed, there will be some difference in the generated power. Due to this difference, power is transferred between generators 2A and 3A, that is,
Galvanization occurs, and the reverse power detection relay 20 of the power generation Ml (assumed to be the generator 2A here) into which the output flows continues to operate even when the external power system is disconnected. However, since the generator 3A is sending out electric power, the operation of the reverse power detection relay 30 is reset.

For this reason, the power generation parallel circuit breaker 2B of the first 100% bypass plant 2 is quickly shut off by the same shutoff signal 814A, and the generator 3A of the other plant 3 is connected to the in-plant IFi.
lr11 becomes the power supply side for the bus 6, and input of the reverse power detection relay operation signal 811B and the load cutoff detection relay operation signal 812B to the protection device 30 of the plant 3 is stopped.

As a result, each output from the protection device 30 is subsequently stopped.

Next, the operation of this embodiment will be described.

First, the power transmission FJ14A, 1 of the external power system shown in Fig.
A case where, for example, a ground fault occurs at point X and point Y between the first substation 15 and second substation 16 will be described.

In this case, first, the line disconnectors 17A, 17B, 18A, and 18B of the first and second substations 15 and 16 are cut off, respectively, and the transmission lines 14A and 18B on the downstream side of the second substation 16 are
It is separated from 14B.

For this reason, the nuclear power plant and the hydroelectric power plant 19 have no supply destination, so both power plants perform governor-free operation, and output adjustment is performed to maintain the frequency at the rated value.

However, there is a difference in response between a hydroelectric power plant 19 whose output is adjusted using normal frequency control and a nuclear power plant whose output is reduced by urgently shutting off the steam introduced into the turbine. As the power increases, power flows back toward the nuclear power plant.

In addition, due to the delay in the output adjustment of the hydroelectric power plant 19, the frequency of the output of the generators 19A and 19B increases, and in synchronization with this frequency increase, the generator 1 of all plans I of the nuclear power plant
The frequency of A to 5A also increases.

For this reason, when the frequency rise of the power of the station switchyard bus 6 exceeds the setting value of the pair of frequency rise detectors 50A and 50B, for example, about 108% of the rated frequency, this frequency rise causes the frequency rise of the pair of frequency rise detectors 50A and 50B. , 50B, and the frequency rise detector operation signal S50 is applied to the first OR circuit 34 of the protection device shown in FIG. , 3B, respectively, to shut them off and disconnect the nuclear power plant from the power transmission lines 14A and 14B.

However, if the frequency rise of the power of the station switchyard bus n6 when the pair of station circuit breakers 13A and 13B are disconnected does not exceed the set value of each turbine overspeed detector (for example, about 111%), Since no turbine overspeed signal is output from each turbine overspeed detector, the turbines of all plants 1 to 5 continue to operate without being tripped, and the generators 1A to 5A are driven to output electric power.

On the other hand, the reverse power flowing back in a nuclear power plant is
5, the load shedding detection relays detect and operate the load shedding, and the reverse power detection relay operation signals S7.811A, 511B and load shedding detection relay operation signals 81, 812Δ, 512B are activated. , the first and second 100% bypass plants 2.3 are given to each protection device 20.30 shown in FIG. 1, and the normal plant 1.4.5 is shown in FIG. 5 as in the conventional example. The protection device is given as a reverse power detection relay operation signal S7 and a load cutoff detection relay operation signal S1, respectively.

Therefore, in the normal plant 1.4.5, in addition to the reactor scramming as described above, the station transformer 7A is switched to the startup transformer 11A, and the generator parallel circuit breaker 18.
4B and 5B are cut off, and each generator IA, 4A, and 5A is
It is separated from the station switchyard busbar 6.

However, since the regular and emergency auxiliary equipment of the normal plant 1.4.5 are supplied with power from the 100% bypass plant 3 as illustrated, there is no external power loss, and each emergency
[9A etc. are not activated.

On the other hand, in the first and second 100% bypass plants 2.3, these protection devices 20.30 (see Figure 1) output reverse power detection relay operation signals 511A, 511B and load shedding detection relay operation signals 512A, 312B. , 100%
At the same time, the generator parallel M disconnection closing signals 510A and 510B of the bypass plant 2.3 are received almost simultaneously, and the 10
0% bypass plant 2.3 without reactor scram,
When the output of the reactor scram signals 513A and 813B is stopped, the AND conditions of the first and third AND circuits 21.31 of both protection devices 20.30 are satisfied, and the first OR circuit 34 is satisfied. Since it satisfies the OR condition of
An on-site line breaker cutoff signal 816 is output from the OR circuit 34 of the station, which shuts off the on-site line breakers 13A and 13B, disconnects the nuclear power plant from the external power system, and cuts off the reverse power flowing back from the hydroelectric power station 19, etc. At the same time, the blocking relay is prevented from tripping due to overspeeding of the turbine of the nuclear power plant due to an increase in the frequency of the output from the generators 19A and 19B of the hydroelectric power plant 19.

Next, as described above, after being disconnected from the external power system, power is exchanged between the generator 2A and the power generator 13A (here, it is assumed that power flows from the generator 3A to the power generator 12A).

), the generator parallel circuit breaker closing signal 514A is output from the protection device 20, the generator parallel circuit breaker 2B of the first 100% bypass plant 2 is shut off, and the generator 2△ is disconnected from the station switchyard bus 6. be separated.

When this generator parallel circuit breaker 2B is disconnected, the output of the generator parallel circuit breaker closing signal 5IOA is stopped, so the AND condition of the second AND circuit 23 is not satisfied, and the mu
Relay trip signal 515A is not output. but,
When the generator parallel circuit breaker 2B fails to shut off, a blockage relay trip signal 515A is output, a blockage relay (not shown) trips, and the operation of the generator ff1tfi2A is stopped.

For this purpose, a second 100% bypass plant 3 is
1 unit 3A is the generator parallel circuit breaker 3B which is still in the closed state.
It is connected to the station switchyard bus 6 via
Since reactor operation continues in the 100% bypass plant 3, the plant switchyard 1'nFi! 6.

In this way, in the second 100% bypass plant 3, the moment the nuclear power plant is disconnected from the external power system, the output of the reverse power detection relay operation signal 311B is stopped.
A of the third and fourth AND circuits 31 and 33 of the protection device 30
The ND condition is not satisfied.

Therefore, the generator parallel circuit breaker cutoff signal 814B and the blocking relay trip signal 815B are not output from the protection device 30, and the generator parallel circuit breaker 3B of the second 100% bypass plant 3 is not shut off and is in the closed state. is held in
The generator 3A continues to operate.

Is it for this purpose? The power generated by 1ti3A is supplied to the station switchyard bus 6 through the generator parallel circuit breaker 3B which is in the on state, and the power outage is avoided.

As a result, a normal plant with reactor scram 1.4
．． The regular and emergency auxiliary equipment of No. 5 is supplied with 100% power via the starting transformer 11A connected to the station switchyard bus 6 which is currently being powered.
Electricity can be supplied from the power generation m3A of bypass plant 3, and the emergency power supply of 9A, etc. of normal plants 1, 4.5 is not started because the in-house power supply is secured, and after the ground fault in the external power system is restored. nuclear power plants can be restarted quickly and easily, and the operating rate of nuclear power plants can be improved.

FIG. 2 shows a protection device M40 according to another embodiment of the present invention, and FIG. 3 shows a power transmission line 14A of an external power system.

An example is shown in which the hydroelectric power plant 19 is not connected to 14B.

That is, in this embodiment, if an accident such as a ground fault occurs in the external power system, reverse power will be generated from the hydroelectric power plant 19 to the nuclear power plant, as in the embodiment shown in FIG. 1 above. Since this is impossible, the protection device 40 is configured not to output the station line breaker cutoff signal 816 shown in FIG.

In addition, in this embodiment, when there are two 100% bypass plants 2.3 as in the nuclear power plant shown in FIG. In addition to preventing power transfer (cross current) between 2.3 and the generator parallel circuit breaker 2B or 3B
generator 2A or 3A in case of failure to shut off.
It is sufficient to stop the operation and back up the protection device 4o shown in Fig. 2 by 100% bypass plant 2.3.
It is enough to set each of them.

The protection device 40 receives the power generation i parallel circuit breaker closing signals S10 and C.
1 Reverse power detection relay operation signal 5iic, load cutoff detection relay operation signal 812C and reactor scram signal 813
A first AND circuit 41 which receives C as an input, a second AND circuit 42 which receives a generator parallel circuit breaker closing signal 510C and a reverse power detection relay operating signal 811C, and timers T1C, T C, and T2O. , and a NOt circuit 43 that inverts the reactor scram signal S13C.

The reverse power detection relay signal 811G is transmitted to two 100% bypass plants 2.
This is a signal detected by the reverse power detection relay when power is exchanged between generators 2A and 3A in Figure 3. Other signals are the same as the signals with the same name shown in Figure 1. Therefore, its explanation will be omitted.

Also, each set time T, T2 . of each timer T1C1T2C1T3C. T3 is set to T1<T, T2<T3, and the AND of the first and second AND circuits 41 and 42
When the conditions are met, first, the generator parallel circuit breaker cutoff signal 514C is output, and then, when the generator parallel circuit breaker 2B or 3B fails to shut off, the blockage relay trip signal 815G is output. By tripping this blocking relay, the operation of either the generator 2A or 3A is forcibly stopped.

For this purpose, cross current between the two generators 2A and 3A is prevented, and one of the generators fife! 12A or 3A can be used to supply power to the on-site switchyard bus 6, and via this on-site switchyard bus 6 power can be supplied to normal or emergency auxiliary equipment of the reactor scrammed normal plant 1.4.5. Because it can supply power and there is no need to drive an emergency power supply of 9A,
For the same reason as the embodiment shown in FIG. 1, it is possible to improve the operating rate of the nuclear power plant.

In each of the above embodiments, a case has been described in which two 100% bypass plants are installed in a nuclear power plant, but the present invention is not limited to this, and may be one or three or more. % When one bypass plant is installed, the generator parallel circuit breaker cutoff signal 514 shown in FIG.
The timers TA and ToB that output A and 814B may be omitted.

Further, the present invention provides a pair of second frequency upper limit detection systems 2S in the in-house switchyard of a hydroelectric power plant 19, as shown in FIG.
51A and 51B as a pair of station line interrupters 190
．． 19D and a pair of branch power transmission lines 20A.

20B, respectively, while the nuclear power plant has a pair of frequency rise detectors 50A shown in FIG.

50B is deleted, and when these second frequency rise detectors 5IA and 51B detect that the frequency rise of the electric power supplied to the unillustrated switchyard bus of the hydroelectric power plant exceeds the set value, the pair of frequency rise detectors 5IA and 51B Station line '11 disconnector 19C, 19D
Each i! It may be configured so that it is cut off once.

The second frequency rise detectors 51Δ, 51B are a pair of frequency rise detectors 2!85OA, 50 of the embodiment shown in FIG.
The configuration is almost the same as B, and the set value is set to, for example, about 108% of the rated frequency, or to a predetermined frequency increase rate corresponding thereto.

That is, in the embodiment of the third cause, all atomic couplants 1 to 5 are
However, in the embodiment shown in FIG. 4, one hydroelectric power plant is tripped by a pair of second frequency rise detectors 51A and 51B, so this inconvenience can be eliminated. Power supply can be stabilized.

〔Effect of the invention〕

As explained above, the present invention enables the auxiliary equipment of a normal nuclear power plant that has undergone reactor scram to be added to the auxiliary equipment of a normal nuclear power plant that has not undergone reactor scram when an accident such as a ground fault occurs in the external power system.
Since the power generated by the 00% bypass plant can be supplied with more power, there is no need to start up the emergency power source of the nuclear power plant in which the reactor has been scrammed, which has the effect of improving the operating rate of the nuclear power plant.

Further, since unnecessary activation of the emergency power source (D/G) can be prevented, safety can be improved.

[Brief explanation of the drawing]

FIG. 1 is an interlock circuit diagram of a protection device of one embodiment of a nuclear power plant according to the present invention, FIG. 2 is an interlock circuit diagram of a protection device of another embodiment of the present invention, and FIG. 3 is a diagram of an interlock circuit diagram of a protection device of another embodiment of the present invention. FIG. 4 is a system diagram showing the overall configuration of one embodiment together with a part of the external power system, FIG. 4 is a system diagram of another embodiment of the present invention, FIG. 5 is an interlock circuit diagram of a conventional protection device, and FIG. The figure is a system diagram showing a part of a conventional nuclear power plant and an external power system. 1 to 5... Nuclear power plant, 1A to 5A... Ti generator, 1B to 5B... Generator parallel circuit breaker, 6...
・In-house switchyard busbar, 9A, 9B...Emergency power supply, 13
A, 13B... Station line breaker, 19... Hydroelectric power plant, 20.30.40... Protective device, 21... First
AND circuit, 23...Second AND circuit, 31...
・Third AND circuit, 33...Fourth AND circuit, 3
4... First OR circuit, 50A, 50B... Frequency rise detector, 51A, 51B... Second frequency rise detector, 5IOA, 810B, 510C... Generator parallel circuit breaker closing Signal, 5IIA, 5IIB, 5IIC...
- Reverse power detection relay operation signal, 312A, Sl 2B. 512C...Load detection relay operation signal, S13A. 8138.813C...Reactor scram signal, 514
A, 314B, 814C... Generator parallel breaker cutoff signal, 515A, 515B, 515C... Blockage relay trip signal, 816... Station line M breaker cutoff signal,
$50...Frequency rise detector operation signal.

Claims (1)

[Claims] Each generator in multiple nuclear power plants is connected to the on-site switchyard bus through a generator parallel circuit breaker, and this on-site switchyard bus is connected to the external power system via an on-site line breaker. The power generation plant includes a reverse power detection relay that detects reverse power from the external power system, a load shedding detector that detects load shedding of the generator, and a turbine that trips the turbine when turbine overspeed is detected. an overspeed detector, and convert at least one of these nuclear power plants into a 100% bypass plant having a bypass capacity that allows approximately 100% of the main steam flow rate generated in the reactor to be bypassed to the turbine condenser. In the nuclear power plant, a frequency increase detector has a set value set to a lower frequency than the set value of the turbine overspeed detector and detects a frequency increase of electric power applied to the in-station switchyard bus; The generator parallel circuit breaker in the 100% bypass plant is turned on, the reverse power detection relay detects reverse power, and the load shedding detection relay detects load shedding of the generator and operates; Moreover, when the 100% bypass plant detects almost simultaneously that the reactor is not scrammed, or the frequency rise detector detects a frequency rise exceeding a set value, the above-mentioned power generation of at least one 100% bypass plant A nuclear power plant characterized by being equipped with a protection device that closes a machine parallel circuit breaker.