JP2008051805A - Feed-water controller, nuclear power plant, and method for controlling feed-water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the possibility of scram of a nuclear reactor when one of feed-water pumps trips. <P>SOLUTION: The feed-water controller 7 of a nuclear power plant having three or more feed-water pumps 4a, 4b and 4c supplying water to the reactor vessel 1, electric motors 5a, 5b and 5c driving the feed-water pumps 4a, 4b and 4c and electric power converters 6a, 6b and 6c connected to the electric motors 5a, 5b and 5c is equipped with a water level controller, a flow rate controller, and a trip compensation means. The water level controller calculates a feed-water flow rate to the reactor vessel 1 based on the detected amount indicating the state of the nuclear power plant and a preset value of the water level of the reactor vessel 1, and outputs it as a feed-water flow rate command signal. The flow rate controller generates a rotation speed command signal for the electric motors based on the flow rate command signal. If one of the feed-water pumps 4a, 4b and 4c trips, the trip compensation means increases the rotation speed of the electric motors for driving the feed-water pumps that do not trip. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a water supply control device, a nuclear power plant using the same, and a water supply control method.

  As control methods of the feed water flow rate to the nuclear reactor, there are known rotation speed control of a turbine driven nuclear reactor water pump and feed water control valve control of an electric motor driven nuclear reactor water pump.

On the other hand, the water supply apparatus which drives a water supply pump with the electric motor of the rotation speed variable using a power converter is examined (for example, refer patent document 1). In this water supply device, when one of the motor-driven nuclear reactor water pumps cannot supply water due to any cause (trip), the backup electric motor-driven nuclear reactor water pump quickly rises due to the interlock and starts backup. It is like that.
Japanese Patent Publication No. 61-59479

  When the motor is started up rapidly, a large current is required as compared with normal operation. On the other hand, there is a limit to the current that can be passed through the power converter, and the motor can only supply a current within the limit range. Therefore, it takes time for the electric motor to complete startup. On the other hand, when installing a power supply device that can supply the current necessary to start up the motor rapidly, it is unavoidable to install a power supply device that exceeds the capacity required for normal operation. Absent.

  For this reason, if a large-capacity power supply device is not installed, even if a backup activation signal is input, it takes about 10 seconds for the auxiliary water supply pump and the driving motor to reach the minimum number of rotations from the stopped state. In addition, it usually takes about 15 seconds to reach the rated rotational speed.

  In addition, the water supply flow rate rapidly decreases due to a trip of one water supply pump. On the other hand, since the start-up characteristics of the backup water pump that started up as a backup are slow and it takes a long time to reach the rated flow rate, the reactor water level also drops even though the backup water pump is installed and started. There is a risk that the reactor will scram.

  Thus, in a water supply apparatus that drives a water supply pump with an electric motor with a variable rotation speed using a power converter, it is difficult to quickly start up the electric motor that drives the spare water supply pump. For this reason, when one of the water pumps in operation trips, there is a problem that the water supply flow rate to the reactor is temporarily reduced.

  Conventionally, among the trip factors of the feed water pump, the failure of the power converter is detected by the self-diagnosis of the power converter itself. Therefore, depending on the failure state of the power converter, the self-diagnosis may not operate normally and the failure may not be detected. In this case, the backup motor-driven reactor water supply pump is not backed up and the feed water flow rate decreases, so that the reactor water level may continue to decrease and the reactor may scram.

  Therefore, an object of the present invention is to reduce the possibility that the reactor will scram when the feedwater pump trips.

  In order to achieve the above-mentioned object, the present invention includes three or more water supply pumps for supplying water to a nuclear steam supply system that generates steam by heat generated in a nuclear reactor, an electric motor that drives the water supply pump, In a water supply control device for a nuclear power plant provided with a power converter connected to an electric motor, based on the detected amount of the state of the nuclear power plant and the set value of the water level of the nuclear steam supply system, A water level controller that calculates a feed water flow rate to the nuclear steam supply system and outputs it as a feed water flow rate command signal, a flow rate controller that generates a rotation speed command signal of the electric motor based on the feed water flow rate command signal, and When one of the water supply pumps trips, the number of rotations of the electric motor that drives at least one of the water supply pumps that have not tripped is set. And trip compensating means for pressurizing, characterized in that it has a.

  Further, the present invention provides a nuclear steam supply system that generates steam by heat generated in a nuclear reactor in a nuclear power plant, a power generation turbine that is driven by steam supplied from the nuclear steam supply system, and the power generation turbine. A condenser for condensing the driven steam, a plurality of feed pumps for supplying water generated by condensation in the condenser to the nuclear steam supply system, and a quantity indicating the detected state of the nuclear power plant And a water level controller that calculates a feed water flow rate to the nuclear steam supply system based on a set value of the water level of the nuclear steam supply system and outputs it as a feed water flow command signal, and based on the feed water flow command signal When one of the flow rate controller that generates the rotation speed command signal of the motor and the water supply pump trips, a trip is detected. It characterized by having a a trip compensating means for increasing the rotational speed of the electric motor for driving at least one of the water supply pump which is not.

  The present invention also provides three or more water supply pumps that supply water to a nuclear steam supply system that generates steam by heat generated in a nuclear reactor, an electric motor that drives the water supply pump, and electric power connected to the electric motor. In the method for controlling water supply of a nuclear power plant comprising a converter, based on the detected amount indicating the state of the nuclear power plant and a set value of the water level of the nuclear steam supply system, the nuclear steam supply system Of the water supply flow rate, and outputting as a water supply flow rate command signal, generating the motor rotation speed command signal based on the water supply flow rate command signal, and one of the water supply pumps tripped. A step of increasing the number of revolutions of the electric motor that drives at least one of the water pumps that are not tripped. And butterflies.

  According to the present invention, the possibility that the reactor will scram when the feedwater pump trips is reduced.

  An embodiment of a water supply control device according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar structure, and the overlapping description is abbreviate | omitted.

[First Embodiment]
FIG. 1 is a system diagram of a nuclear power plant according to a first embodiment of the present invention.

  The nuclear power plant has a reactor vessel 1 and a power generation turbine 2 that contain a core. A condenser 3 is connected to the power generation turbine 2. The reactor vessel 1 and the power generation turbine 2 are connected by a main steam pipe 40. A water supply pipe 41 connects between the condenser 3 and the reactor vessel 1. The water supply pipe 41 is branched into three parallel pipes along the way, and water supply pumps 4a, 4b, 4c driven by electric motors 5a, 5b, 5c with variable rotation speeds are inserted into the parallel pipes. ing.

  The three water supply pumps 4a, 4b, and 4c each have a capacity of 50% or more of the total water supply amount to the reactor vessel 1. During start-up, stop, and normal operation, two of these three water supply pumps 4a, 4b, and 4c are used as regular water supply pumps, and the remaining one is a spare water supply pump. In addition, an induction motor, a synchronous motor, etc. are used as the electric motors 5a, 5b, 5c for driving the water supply pumps 4a, 4b, 4c.

  In the following description, reference numerals 4a and 4b indicate normal water pumps, and reference numeral 4c indicates a spare water pump. Note that any two of the three water supply pumps 4a, 4b, and 4c may be used as ordinary water supply pumps.

  Steam generated by heat generated in the nuclear reactor is sent from the reactor vessel 1 to the power generation turbine 2 via the main steam pipe 40 to drive the power generation turbine 2. The steam that has driven the power generation turbine 2 is condensed in the condenser 3 and returned to the water, and is supplied again to the reactor vessel 1 through the water supply pipe 41.

  Although a nuclear power plant using a boiling water reactor (BWR) is described here as an example, a nuclear reactor having a nuclear steam supply system that is supplied with water by a feed water pump, for example, a pressurized water reactor The present embodiment can also be applied to (PWR) and the like.

  The water supply control device 7 includes a trip determination circuit 22, a flow rate regulator 25, and a control switch 24. The water supply control device 7 receives signals such as motor rotation speed signals 26a, 26b, and 26c from the electric motors 5a, 5b, and 5c that drive the water supply pumps 4a, 4b, and 4c, and backs up the power converters 6a, 6b, and 6c. Signals such as rotation speed command signals 8a, 8b, and 8c are transmitted via the start circuits 23a, 23b, and 23c.

  FIG. 2 is a block diagram of a part of the water supply control device 7 according to the first embodiment.

  The water supply control device 7 has a water level controller 15 and a water level setter 16. In addition, flow rate controllers 19a, 19b, and 19c that transmit rotation speed command signals 8a, 8b, and 8c to the three power converters 6a, 6b, and 6c are provided. Moreover, it has the flow volume setting device 20a, 20b, 20c corresponding to each flow volume controller 19a, 19b, 19c.

  The water level controller 15 is configured to set the water level from the reactor water level detector 9 to the reactor water level signal 12, from the main steam flow rate detector 10 to the main steam flow rate signal 13, and from the feed water flow rate detector 11 to the reactor feed water flow rate signal 14. A reactor water level setting signal 17 is transmitted from the vessel 16. The water level controller 15 performs a calculation based on the reactor water level signal 12, the main steam flow signal 13, and the reactor feed water flow signal 14, and compares the calculation result with the reactor water level setting signal 17, thereby A water supply flow rate command signal 18 that matches the water level setting signal 17 is output.

  The flow rate controllers 19a, 19b, and 19c are rotated to the power converters 6a, 6b, and 6c by the feed water flow rate command signal 18 or the flow rate setting signals 21a, 21b, and 21c transmitted from the flow rate setting units 20a, 20b, and 20c. Number command signals 8a, 8b and 8c are transmitted. In this way, by adjusting the frequency of the power converters 6a, 6b, 6c to control the speed of the electric motors 5a, 5b, 5c, that is, the speed of the feed water pumps 4a, 4b, 4c, the reactor feed water flow rate is reduced. Control.

  The water supply control device 7 has trip determination circuits 22a, 22b, and 22c corresponding to the electric motors 5a, 5b, and 5c that drive the three water supply pumps 4a, 4b, and 4c. Trip determination circuits 22a, 22b and 22c determine trips of water supply pumps 4a, 4b and 4c based on rotation speed command signals 8a, 8b and 8c and motor rotation speed signals 26a, 26b and 26c of electric motors 5a, 5b and 5c. To do.

  FIG. 3 is a block diagram of the trip determination circuit 22 according to the first embodiment. The water supply control device 7 has three trip determination circuits 22a, 22b, and 22c corresponding to the three water supply pumps 4a, 4b, and 4c. FIG. 3 shows only one of them. ing. The symbols “a”, “b”, and “c” indicate devices, circuits, and the like that correspond to the three water supply pumps, respectively. In FIG. 3, the symbols “a”, “b”, and “c” The description of “c” is omitted.

  The trip determination circuit 22 includes a subtractor 27, a threshold determination circuit 28, and a timer 29. The trip determination circuit 22 receives the rotation speed command signal 8 and the motor rotation speed signal 26, and the subtractor 27 takes these deviations. The threshold determination circuit 28 determines whether or not the deviation is an allowable value. If the value is not acceptable, a signal is output to the timer 29. The timer 29 outputs a pump trip signal 30 when this signal continues for a predetermined time or more. In order to prevent unnecessary trip determination, the time until the timer 29 outputs the pump trip signal 30 is set longer than the time that the power converter 6c can be recovered by restarting.

  In the present embodiment, the trip determination circuit 22 is installed corresponding to all the feed pumps 4a, 4b, 4c, but is installed corresponding to only the regular feed pumps 4a, 4b. Also good.

  Thus, in the water supply control device 7 of the present embodiment, the rotation speed command signal 8 and the motor rotation speed signal 26 are compared, and when a large deviation continues, it is determined that the pump trip occurs, and the pump trip signal 30 Is output. For this reason, it becomes possible to detect the inability to supply water when the power converters 6a and 6b fail without depending on the self-diagnosis function of the power converters 6a and 6b, and the backup water supply pump 4c can be activated. It becomes possible. As a result, the possibility of reaching the scram due to the low reactor water level can be reduced. Further, by providing the timer 29, the water supply pump is not tripped unnecessarily until the power converter 6c can be restored by restarting.

  FIG. 4 is a block diagram of the periphery of the backup activation circuit 23 and the control switch 24 according to the first embodiment. The water supply control device 7 has three backup activation circuits 23a, 23b, 23c and control switchers 24a, 24b, 24c corresponding to the three water supply pumps 4a, 4b, 4c, but in FIG. , One of them is shown. The symbols “a”, “b”, and “c” indicate devices, circuits, and the like that correspond to the three water supply pumps, respectively. In FIG. 4, the symbols “a”, “b”, and “c” The description of “c” is omitted.

  The backup activation circuit 23 includes a power converter 6, a power converter control switch 31, and a backup activation switch 32. A power source 33 having a frequency of about 50 Hz or about 60 Hz supplied from the transformer bus of the power plant is connected to the backup activation circuit 23.

  When a certain water supply pump is operated as a regular water supply pump 4a, 4b, the power converter control switch 31 of the backup activation circuit 23 is turned on, the backup activation switch 32 is turned off, and the electric motor 5 that drives the water supply pump is The rotational speed is controlled by the power converter 6.

  On the other hand, when a certain water supply pump is used as the spare water supply pump 4c, the power converter control switch 31 is turned off and the backup start switch 32 is turned on, and the electric motor 5 that drives the water supply pump is connected to the power converter 6 It is directly driven by the power source 33 without going through.

  That is, in the water supply control device 7 of the present embodiment, when it is determined that the operating water supply pump is a trip, the number of rotations of the electric motor 5c that drives the non-tripped auxiliary water supply pump 4c is increased to supply water by the trip. Compensates for the decrease in flow rate. Specifically, the backup water supply pump 4 c is rapidly activated by the backup activation circuit 23 using the power supply 33 directly, and is operated at the voltage and frequency of the power supply 33. That is, it is possible to start the spare water supply pump rapidly without installing a large-capacity power converter. As described above, since rapid activation is possible without being restricted by the output current limitation of the power converter 6, it is possible to select a power converter 6 having an optimum capacity, which is economical.

  The control switching unit 24 outputs a rated flow rate setting signal 35 corresponding to the number of revolutions when the power source 33 is operated to the flow rate setting unit 20 that controls the power converter 6c corresponding to the backup water pump 4c that has been backed up. To do. The flow rate setting device 20 of the feed water pump is set to output a flow rate setting signal corresponding to the number of revolutions when operated by the power source 33 to the flow rate controller 19.

  Further, the control switch 24 outputs a switch command signal 34, turns off the backup start switch 32, and then turns on the power converter control switch 31 to turn on the drive power source of the spare water pump. To the power converter 6. The number of revolutions of the electric motor 5 temporarily decreases by switching. Then, according to the rotation speed command signal corresponding to the rotation speed when operating with the power supply 33 transmitted from the flow rate controller 19 of the feed water pump, the rotation speed before switching is restored.

  In this embodiment, the backup activation circuit 23 and the control switch 24 are installed corresponding to all the water supply pumps 4a, 4b, 4c, but are installed only corresponding to the spare water supply pump 4c. You may keep it.

  FIG. 5 is a block diagram of the periphery of the flow rate regulator 25 according to the first embodiment.

  Here, the case where the feed water pump indicated by reference numeral 4b trips and the backup pump indicated by reference numeral 4c starts backup will be described.

  The flow rate regulator 25 outputs a decrease signal 36 for decreasing the flow rate request signal to the flow rate controller 19c that controls the power converter 6c corresponding to the backup activated feed water pump 4c at a constant rate, and is positive and negative with the decrease signal 36. A reverse correction signal 37 is output to the water level controller 15. Further, the flow rate regulator 25 takes the deviation between the feed water flow rate command signal 18 from the water level controller 15 and the flow rate setting signal 21c. When this deviation is within the allowable range, the flow rate regulator 25 stops the output of the decrease signal 36 and the correction signal 37 and changes the input to the flow rate controller 19c from the flow rate setting signal 21c to the feed water flow rate command signal 18. . Control is performed to increase the flow rates of the other feed water pumps while decreasing the flow rate of the backup feed water pump 4c that has been started up.

  The spare feed water pump 4c automatically shifts from the operation at the rated rotation speed to the control operation by the power converter 6c and is automatically controlled at the rotation speed in accordance with the feed water flow command signal 18, so that the reactor water supply A flow rate can be stably supplied. In addition, the operation burden on the operator is small.

  Thus, according to the water supply control device of the present embodiment, the backup water pump can be activated by detecting the inability to supply water when the power converter has failed regardless of the self-diagnosis function of the power converter. it can. For this reason, the possibility of scram due to low reactor water level can be reduced. In addition, the backup water pump can be quickly backed up as compared with the power converter, and the possibility of scram due to low reactor water level can be reduced. In addition, since rapid start-up is possible without being restricted by the output current limit of the power converter, it is possible to select a power supply device having an optimum capacity, which is economical.

[Second Embodiment]
FIG. 6 is a system diagram of the nuclear power plant according to the second embodiment of the present invention.

  The water supply control device according to the present embodiment is obtained by omitting the trip determination circuit from the water supply control device according to the first embodiment.

  Also in this embodiment, when it is determined that the water pump being operated is tripped by, for example, self-diagnosis of the power converter itself, the backup water pump is rapidly activated by the power source 33 (FIG. 4) by the backup activation circuit. It is operated at a voltage and frequency of 33 (FIG. 4). For this reason, when one regular feedwater pump trips, it is possible to start up a backup feedwater pump more quickly than when a power converter is started. The possibility can be reduced. In addition, since rapid start-up is possible without being restricted by the output current limit of the power converter, it is possible to select a power supply device having an optimum capacity, which is economical.

  Moreover, after the rotation speed of the electric motor 5 is once reduced by switching, the rotation speed request corresponding to the rotation speed when the motor 5 is operated by the power supply 33 (FIG. 4) transmitted from the flow rate controller 19 (FIG. 4) of the feed water pump. According to the signal, it returns to the rotation speed before switching. The activated backup water pump automatically shifts from the operation at the rated speed to the control operation by the power converter and is automatically controlled at the speed according to the feed water control signal. It can continue to be supplied stably.

  In addition, control is performed to increase the flow rate of the other pumps while decreasing the flow rate of the backup water supply pump. Further, by increasing the feed water flow command of the pump on the operation side in advance at a rate corresponding to the decrease on the backup side, the total feed water flow rate does not fluctuate and fluctuations in the reactor water level can be suppressed.

[Third Embodiment]
FIG. 7 is a system diagram of a nuclear power plant according to the third embodiment of the present invention.

  The water supply control device 7 according to the present embodiment is obtained by omitting the backup activation circuit, the control switching device, and the flow rate regulator from the first embodiment.

  Also in this embodiment, the rotational speed command signals 8a, 8b, and 8c are compared with the rotational speeds of the electric motors 5a, 5b, and 5c, and when a large deviation continues, it is determined that the pump trip occurs and the pump trip signal 30 is output. To do. For this reason, it is possible to detect the inability to supply water when the power converters 6a, 6b, 6c fail, regardless of the self-diagnosis function of the power converters 6a, 6b, 6c, and start the backup water pump 4c. can do. Therefore, the possibility of scram due to low reactor water level can be reduced. Further, by providing the timer 29, the water supply pump is not tripped unnecessarily when it can be recovered by self-diagnosis of the power converter.

[Fourth Embodiment]
FIG. 8 is a system diagram of a nuclear power plant according to the fourth embodiment of the present invention.

  In the nuclear power plant according to the present embodiment, all three water supply pumps 4a, 4b, 4c each having a capacity of 50% or more of the total water supply amount are operated as regular water supply pumps. That is, during normal operation, each of the water supply pumps 4a, 4b, and 4c supplies one third of the total water supply capacity.

  Further, the water supply control device 7 of the present embodiment includes a trip determination circuit 22, a restart flow rate adjuster 54, and a trip time controller 51. The water supply control device 7 receives signals such as motor rotation speed signals 26a, 26b, and 26c from the electric motors 5a, 5b, and 5c that drive the water supply pumps 4a, 4b, and 4c, and backs up the power converters 6a, 6b, and 6c. Signals such as rotation speed command signals 8a, 8b, and 8c are transmitted via the start circuits 23a, 23b, and 23c.

  FIG. 9 is a block diagram of a part of the water supply control device of the present embodiment.

  The water supply control device 7 includes a water level controller 15, a water level setter 16, and a trip time controller 51. In addition, flow rate controllers 19a, 19b, and 19c that transmit rotation speed command signals 8a, 8b, and 8c to the three power converters 6a, 6b, and 6c are provided. Moreover, it has the flow volume setting device 20a, 20b, 20c corresponding to each flow volume controller 19a, 19b, 19c. The water supply control device 7 has trip determination circuits 22a, 22b, and 22c corresponding to the electric motors 5a, 5b, and 5c that drive the three water supply pumps 4a, 4b, and 4c, as in the first embodiment. (See FIG. 3).

  The water level controller 15 is configured to set the water level from the reactor water level detector 9 to the reactor water level signal 12, from the main steam flow rate detector 10 to the main steam flow rate signal 13, and from the feed water flow rate detector 11 to the reactor feed water flow rate signal 14. A reactor water level setting signal 17 is transmitted from the vessel 16. The trip time controller 51 detects when one of the water supply pumps 4 a, 4 b, 4 c trips for some reason, and outputs a trip time control signal 52 to the water level controller 15.

  The water level controller 15 performs a calculation based on the reactor water level signal 12, the main steam flow signal 13, and the reactor feed water flow signal 14, and compares the calculation result with the reactor water level setting signal 17, thereby A water supply flow rate command signal 18 that matches the water level setting signal 17 is output.

  Further, when one of the feed water pumps 4 a, 4 b, 4 c trips, the water level controller 15 outputs a feed water flow rate command signal 18 based on the trip time control signal 52. As a result, the feed water flow command signal 18 increases, and the rotational speed of the electric motor that drives the other feed water pumps that have not tripped is increased to compensate for the drop in the feed water flow due to the trip. Specifically, the setting of the flow controller 19 of the feed water pump that is not tripped is increased. In the following description, the case where the feed water pump 4c trips will be described, but the same applies to the case where the other feed water pumps 4a and 4b trip.

  FIG. 10 is a block diagram of the restart flow rate regulator of the present embodiment.

  The restart flow rate adjuster 54 outputs an increase signal 53 that increases the flow rate request signal to the flow rate controller 19c that controls the power converter 6c corresponding to the water supply pump 4c restarted after the trip at a constant rate. Further, the increase signal 53 and the positive / negative correction signal 37 are output to the water level controller 15. Further, the deviation between the water supply flow rate command signal 18 and the flow rate setting signal 21c from the water level controller 15 is taken, and when the deviation is within the allowable value, the output of the increase signal 53 and the correction signal 37 is stopped. Further, the input to the flow rate controller 19c is changed from the flow rate setting signal 21b to the feed water flow rate command signal 18.

  In such a water supply control device 7, the rotational speed command signal and the motor rotational speed are compared, and when the state where the deviation is large continues, it is determined that the pump is tripped, and the pump trip signal 30 is output. Moreover, when it determines with the water pump in driving | operation being a trip, the water supply command signal of the remaining two water pumps which are not determined to be a trip is increased. Furthermore, it controls to decrease the flow rate of the other pumps while increasing the flow rate of the feed water pump restarted after the trip.

  Therefore, it becomes possible to detect the inability to supply water regardless of the self-diagnosis function of the power converter. For this reason, the scram caused by the low reactor water level can be avoided more reliably. Further, by providing the timer 29, when the power converter can be restored by restarting, the water supply pump is not tripped.

  Further, when one of the feed water pumps 4a, 4b, 4c trips, a scram caused by a low reactor water level when the feed water pump trips can be avoided by increasing the feed water flow rate command of the feed water pump that has not tripped.

  Moreover, in the nuclear power plant of this Embodiment, since all the feed water pumps 4a, 4b, and 4c are regular feed water pumps, when one of them trips, the feed water is in a state where the rotation is stopped. There is no need to start the pump quickly. For this reason, it becomes possible to select a power supply device having an optimum capacity without being restricted by the output current limit of the power converter, which is economical.

  Moreover, since the restarted feed water pump is automatically controlled to the rotation speed according to a feed water control signal, it can continue supplying the reactor feed water flow volume stably. Furthermore, by reducing the feed water flow command of the pump on the operation side at a rate corresponding to the increase of the feed water pump that has been restarted after a trip, the total feed water flow does not fluctuate and fluctuations in the reactor water level can be suppressed. .

  Even when one of the water supply pumps needs to be inspected during operation, the rated water supply flow rate can be maintained by operating the remaining two water supply pumps. Moreover, the normal state can be quickly restored by the function of the flow rate adjustment circuit, and the maintainability is also high.

[Fifth Embodiment]
FIG. 11 is a system diagram of a nuclear power plant according to the fifth embodiment of the present invention.

  The water supply control device 7 of the present embodiment is obtained by deleting the trip determination circuit and the trip time controller 51 from the water supply control device 7 of the fourth embodiment. Even with such a water supply control device 7, as with the water supply control device 7 of the fourth embodiment, the flow rates of the other water supply pumps 4a and 4b are increased while increasing the flow rate of the water supply pump 4c restarted after the trip. It is controlled to decrease.

  Even when such a water supply control device 7 is used, the water supply pump 4c restarted after the trip automatically shifts from the operation at the minimum rotational speed to the control operation by the power converter 6c. Furthermore, since the rotation speed is automatically controlled according to the feed water flow command signal 18, an appropriate feed water flow can be stably supplied.

  Further, by reducing the feed water flow rate command signal 18 of the feed water pumps 4a and 4b during operation at a rate corresponding to the increase in the pump 4c restarted after the trip, the total feed water flow rate does not fluctuate and the reactor water level Variation can be suppressed. Even when one of the water supply pumps 4a, 4b, and 4c needs to be inspected during operation, the rated water supply flow rate can be maintained by operating the remaining two water supply pumps. Further, the normal state can be quickly restored by the function of the flow rate regulator 54 at the time of restart, and the maintainability is high.

[Sixth Embodiment]
FIG. 12 is a system diagram of a nuclear power plant according to the sixth embodiment of the present invention.

  In the nuclear power plant of the present embodiment, a feed water pump 4d, an electric motor 5d that drives the water pump, a power converter 6d, a flow rate controller 19, and a trip determination circuit 22 are added to the nuclear power plant of the fourth embodiment. It is a thing. This water supply pump 4d is provided in parallel with the other water supply pumps 4a, 4b, 4c. Each of the four water supply pumps 4a, 4b, 4c, and 4d has a capacity of one third or more of the total water supply amount to the reactor vessel 1. During normal operation, the four water supply pumps 4a, 4b, 4c, and 4d are all operated as regular water supply pumps, and supply one quarter of the total amount of water supplied to the reactor vessel 1 per one water supply pump.

  If there are three regular feed pumps, and one of the feed pumps trips, the feed rate of the other feed pumps must be increased from 1/3 to 1/2 of the total feed rate. However, in the nuclear power plant of this embodiment, when one of the feed water pumps 4a, 4b, 4c, 4d trips, the feed water flow rate of the other feed water pumps is reduced from 1/4 to 1/3 of the total feed water flow rate. It only has to be increased.

  For this reason, the water supply flow rate at the time of trip of the water supply pump quickly returns to the rated flow rate. Further, when one of the water supply pumps 4a, 4b, 4c, 4d trips, the load on the electric motors 5a, 5b, 5c, 5d and the power converters 6a, 6b, 6c, 6d is also reduced. For this reason, it becomes possible to select a power supply device having an optimum capacity without being restricted by the output current limit of the power converter, which is economical.

[Other embodiments]
The above description is merely an example, and the present invention is not limited to the above-described embodiments, and can be implemented in various forms. For example, although the above-described embodiment has been described by taking a boiling water nuclear power plant as an example, it can also be applied to other types of nuclear power plants. Moreover, it can also implement combining the characteristic of each embodiment.

1 is a system diagram of a nuclear power plant according to a first embodiment of the present invention. It is a partial block diagram of the water supply control apparatus of 1st Embodiment which concerns on this invention. 1 is a block diagram of a trip determination circuit according to a first embodiment of the present invention. It is a block diagram of the periphery of the backup start-up circuit and the control switch of the first embodiment according to the present invention. It is a block diagram of the circumference | surroundings of the flow regulator of 1st Embodiment which concerns on this invention. It is a systematic diagram of the nuclear power plant of 2nd Embodiment which concerns on this invention. It is a systematic diagram of the nuclear power plant of 3rd Embodiment which concerns on this invention. It is a systematic diagram of the nuclear power plant of 4th Embodiment which concerns on this invention. It is a partial block diagram of the water supply control apparatus of 4th Embodiment which concerns on this invention. It is a block diagram of the flow regulator at the time of restart of 4th Embodiment concerning this invention. It is a systematic diagram of the nuclear power plant of 5th Embodiment which concerns on this invention. It is a systematic diagram of the nuclear power plant of 6th Embodiment which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Reactor vessel, 2 ... Power generation turbine, 3 ... Condenser, 4, 4a, 4b, 4c, 4d ... Feed water pump, 5, 5a, 5b, 5c, 5d ... Electric motor, 6, 6a, 6b, 6c, 6 ... Power converter, 7 ... Feed water control device, 8, 8a, 8b, 8c, 8d ... Revolution command signal, 9 ... Reactor water level detector, 10 ... Main steam flow detector, 11 ... Feed water flow detector, DESCRIPTION OF SYMBOLS 12 ... Reactor water level signal, 13 ... Main steam flow signal, 14 ... Reactor feed water flow signal, 15 ... Water level controller, 16 ... Water level setter, 17 ... Reactor water level set signal, 18 ... Feed water flow command signal, 19 , 19a, 19b, 19c ... Flow rate controller, 20, 20a, 20b, 20c ... Flow rate setter, 21, 21a, 21b, 21c ... Flow rate setting signal, 22, 22a, 22b, 22c ... Trip determination circuit, 23, 23a , 23b, 23c, 23d ... Up start circuit, 24 ... control switch, 25 ... flow rate regulator, 26, 26a, 26b, 26c, 26d ... motor speed signal, 27 ... subtractor, 28 ... threshold judgment circuit, 29 ... timer, 30 ... pump trip Signal 31, power converter control switch 32, backup start switch 33, power source 34, switching command signal 35, rated flow rate setting signal 36, decrease signal 37, correction signal 40, main steam pipe 41 ... Water supply piping, 51 ... Trip controller, 52 ... Trip control signal, 53 ... Increase signal, 54 ... Restart flow rate adjuster

Claims (9)

  Three or more water supply pumps that supply water to a nuclear steam supply system that generates steam by heat generated in the nuclear reactor, an electric motor that drives the water supply pump, and a power converter connected to the electric motor In a water supply control device for a nuclear power plant, a feed water flow rate to the nuclear steam supply system is calculated based on the detected amount indicating the state of the nuclear power plant and a set value of the water level of the nuclear steam supply system. A water level controller that outputs a feed water flow command signal, a flow controller that generates a rotation speed command signal of the electric motor based on the feed water flow command signal, and one of the feed pumps trips. And trip compensation means for increasing the number of revolutions of the electric motor that drives at least one of the water supply pumps that have not tripped. Water supply control apparatus, characterized in that.   The trip compensation means determines that the water supply pump is tripped when a predetermined time has elapsed when a deviation between the rotation speed indicated by the rotation speed command signal and the rotation speed of the electric motor exceeds a predetermined difference. The water supply control device according to claim 1, further comprising a trip determination circuit.   At least one of the water supply pumps is a standby water supply pump that stands by without being operated in a normal state, and the trip compensation means turns the spare water supply pump on when one of the water supply pumps trips. The water supply control device according to claim 1, further comprising a backup activation circuit that activates the electric motor to be driven by being directly connected to a power source having a constant voltage and frequency.   The trip compensation means includes a control switch that disconnects an electric motor that drives the auxiliary water supply pump from the power source and connects the electric power converter after a predetermined time has elapsed since the auxiliary water supply pump is activated. The water supply control device according to claim 3, wherein:   The trip compensation means includes a flow rate regulator that changes the rotational speed of an electric motor that drives the preliminary feed water pump so that the rotational speed of the preliminary feed pump decreases with time, and the water level controller includes: 5. The water supply control device according to claim 4, wherein a command for changing the rotation speed of the feed water pump is output so as to compensate for a change amount of the feed water flow rate accompanying a decrease in the rotation speed of the preliminary feed water pump. .   All the water supply pumps are service water pumps operated at normal times, and the trip compensation means increases the water supply flow rate indicated by the water supply flow rate command signal when one of the water supply pumps trips. The water supply control device according to claim 1, further comprising a trip time controller that transmits a trip time control signal to the water level controller.   When the tripped feedwater pump is restarted, the feedwater flow command signal increasing at a predetermined rate per unit time is transmitted to the flow rate controller corresponding to the feedwater pump, and the feedwater flow rate is supplied to the water level controller. The water supply control device according to claim 6, further comprising a restart-time flow rate regulator that transmits a correction signal that decreases at the predetermined rate per unit time.   A nuclear steam supply system that generates steam by heat generated in a nuclear reactor, a power generation turbine that is driven by steam supplied from the nuclear steam supply system, a condenser that condenses the steam that has driven the power generation turbine, and A plurality of feed pumps for supplying water generated by condensation in the condenser to the nuclear steam supply system; an amount indicating the detected state of the nuclear power plant; and a water level of the nuclear steam supply system. A feed water flow rate to the nuclear steam supply system is calculated based on a set value, and a water level controller that outputs the feed water flow rate command signal and a rotation speed command signal for the electric motor are generated based on the feed water flow rate command signal. If one of the flow controller and one of the feed pumps trips, at least one of the feed pumps that have not tripped Nuclear power plant characterized by having an a trip compensating means for increasing the rotational speed of the electric motor that drives.   Three or more water supply pumps that supply water to a nuclear steam supply system that generates steam by heat generated in the nuclear reactor, an electric motor that drives the water supply pump, and a power converter connected to the electric motor In the water supply control method for a nuclear power plant, the flow rate of the water supply to the nuclear steam supply system is calculated based on the detected amount indicating the state of the nuclear power plant and the set value of the water level of the nuclear steam supply system. A step of outputting as a feed water flow command signal, a step of generating a rotation speed command signal of the electric motor based on the feed water flow command signal, and a trip when one of the feed pumps trips. And increasing the number of rotations of the electric motor that drives at least one of the non-feeding water pumps. Method.

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