Pump motor control device

Abstract

To reduce a material quantity while maintaining the reliability of a fast reactor.SOLUTION: A pump motor control device 100 comprises: an inverter 101 that converts a voltage and a frequency of AC power supplied from a power supply P; bypass lines 102A, 102B, and 102C for directly supplying AC power supplied from the power supply P to a pump motor 7; and a switching control unit 108 that switches between outputting converted power that is the AC power after being converted by the inverter 101 to the pump motor 7 and outputting bypass-line power that is the AC power supplied from the power supply P via the bypass lines 102A, 102B, and 102C to the pump motor 7.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pump motor control device for controlling the rotation speed of a pump motor. [Background technology]

[0002] Tank-type nuclear reactors are known in which primary system equipment such as an intermediate heat exchanger, a pump, and primary coolant is housed in a main vessel (see, for example, Patent Document 1). In a nuclear reactor, a pump motor drives a primary system pump to supply primary coolant to the reactor core and raise its temperature, and an intermediate heat exchanger exchanges heat between the heated primary coolant and the secondary coolant, thereby transferring thermal energy to the secondary coolant. The heat transferred to the secondary coolant passes through a steam generator and is converted into power in a turbine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-88947 Summary of the Invention [Problem to be solved by the invention]

[0004] In fast reactors, the flow rate of coolant is controlled by continuously controlling the rotation speed of the pump motor using an inverter in accordance with the reactor power. The pump motors used in fast reactors are large, so a large inverter is required to drive them. However, from the standpoint of reliability, fast reactors have a complete standby redundant configuration in which large inverters with the same performance are duplicated, which results in an increase in the amount of equipment required.

[0005] The present invention has been made in consideration of these points, and aims to reduce the amount of material while maintaining the reliability of fast reactors. [Means for solving the problem]

[0006] A pump motor control device according to a first aspect of the present invention is a pump motor control device that controls the rotational speed of a pump motor that drives a primary or secondary pump installed in a fast reactor, and includes: a conversion unit that converts the voltage and frequency of AC power supplied from a power source; a bypass line for directly supplying the AC power supplied from the power source to the pump motor; and a switching control unit that switches between outputting converted power, which is the AC power converted by the conversion unit, to the pump motor, or outputting bypass line power, which is the AC power supplied from the power source via the bypass line, to the pump motor.

[0007] The pump motor control device may further have a synchronization unit that synchronizes the phase of the AC power supplied from the power source with the phase of the converted power, and when switching the power output to the pump motor from the bypass line power to the converted power, the switching control unit may perform the switching after the phase of the AC power and the phase of the converted power have been synchronized by the synchronization unit. [Effects of the Invention]

[0008] The present invention has the effect of reducing the amount of material while maintaining the reliability of the fast reactor. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a schematic configuration of a tank-type reactor. [Figure 2] FIG. 2 is a diagram illustrating a configuration of a pump motor control device. [Figure 3] FIG. 10 is a diagram showing the relationship between the change in the electrical output ratio during daily load following operation of a fast reactor having a control device according to the present embodiment and the switching between converted power and bypass line power. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Structure of Tank-Type Reactor 1] A pump motor control device 100 according to this embodiment is a device that is installed in a fast reactor and controls the rotation speed of a pump motor that circulates sodium as a coolant inside the fast reactor. In explaining the pump motor control device 100, the structure of a tank-type reactor 1, which is a type of fast reactor, will be described with reference to the drawings. In the following explanation, the pump motor control device 100 will also be simply referred to as the control device 100. FIG. 1 is a diagram showing the schematic configuration of the tank-type reactor 1. In FIG. 1, the flow of sodium as a coolant is indicated by arrows.

[0011] As shown in Fig. 1, a reactor core 3, an intermediate heat exchanger 4, a primary system pump 5, and in-core piping 6 are provided inside a main vessel 2 of a tank-type nuclear reactor 1. Sodium, which is a liquid metal, is contained inside the main vessel 2 as a primary coolant. A pump motor 7 is connected to the primary system pump 5, and a control device 100 that controls the rotation speed of the pump motor 7 is connected to the pump motor 7.

[0012] The main vessel 2 is a vessel with a diameter of approximately 15 to 20 meters. The reactor core 3 is supported horizontally inside the main vessel 2. The reactor core 3 is provided with core fuel containing fissionable material and control rods for controlling the core reactivity. The control rods are driven by a control rod drive mechanism. The control rod drive mechanism controls the amount of insertion of the control rods into the core fuel. This controls the nuclear fission of the core fuel and the thermal output in the reactor core 3. The reactor core 3 heats up sodium, which serves as the primary coolant. In the following explanation, sodium before it is heated is referred to as low-temperature sodium, and sodium that has been heated to a high temperature is referred to as high-temperature sodium.

[0013] The intermediate heat exchanger 4 has an inlet window through which high-temperature sodium flows in and an outlet window through which low-temperature sodium flows out after heat exchange. The intermediate heat exchanger 4 exchanges heat between the high-temperature sodium that flows in through the inlet window and the sodium that functions as the secondary coolant. Specifically, the high-temperature sodium, whose temperature has risen to approximately 550°C in the reactor core 3, flows into the inlet of the intermediate heat exchanger 4 by the action of the primary system pump 5. The high-temperature sodium that flows in exchanges heat with the secondary system sodium that functions as the secondary coolant, thereby becoming low-temperature sodium whose temperature has dropped to approximately 400°C. The low-temperature sodium flows out through the outlet window to the bottom of the main vessel 2. The secondary system sodium flows into the steam generator 8, where it heats water and generates steam to drive a turbine.

[0014] There are multiple primary system pumps 5, and although not shown, they are provided on the circumference on which multiple intermediate heat exchangers 4 are installed. The primary system pumps 5 are driven by pump motors 7 controlled by current supplied from a control device 100. The primary system pumps 5 pump the low-temperature sodium that has flowed out of the intermediate heat exchangers 4 into the in-core piping 6. The in-core piping 6 guides the low-temperature sodium pumped by the primary system pumps 5 to the reactor core 3.

[0015] In a fast reactor, the flow rate of coolant is controlled by continuously controlling the rotation speed of a pump motor using an inverter in accordance with the reactor power, in order to vary the power output in response to load fluctuations over a predetermined period (e.g., one day). Since the pump motors used in fast reactors are large, a large inverter is required to drive these pump motors. However, in conventional fast reactors, from the standpoint of reliability, large inverters with the same performance are duplicated to provide a complete standby redundant configuration, which poses a problem of increasing the amount of equipment required.

[0016] In contrast, the control device 100 according to the present invention has an inverter and a bypass line for directly supplying AC power supplied from a power source without passing through the inverter to the pump motor 7. The control device 100 switches between outputting AC power converted by the inverter to the pump motor 7 and outputting AC power supplied from the power source via the bypass line to the pump motor 7. This allows the control device 100 to reduce the operating rate of the inverter, thereby lengthening the mean time between failures and improving reliability compared to when power is supplied using only the inverter. This allows the control device 100 to reduce the amount of material while maintaining the reliability of the fast reactor. The configuration of the control device 100 will be described below.

[0017] 2 is a diagram showing the configuration of the pump motor control device 100. The pump motor control device 100 has an inverter 101 as a conversion unit, bypass lines 102A, 102B, and 102C, a phase synchronization processing circuit 103 as a synchronization unit, a first input side circuit breaker 104, a first output side circuit breaker 105, a second input side circuit breaker 106, a second output side circuit breaker 107, and a switching control unit 108.

[0018] The inverter 101 is, for example, a VVVF (Variable Voltage Variable Frequency) inverter, and is provided between a first input side circuit breaker 104 and a first output side circuit breaker 105. The inverter 101 converts the voltage and frequency of AC power supplied from a power source P, which is a three-phase AC power source.

[0019] In a fast reactor, the flow rate of sodium as a coolant is set to increase in accordance with the reactor thermal power when operating at partial load or rated power. Therefore, when the fast reactor is operating at partial load, when switching from partial load operation to rated power operation, or when switching from rated power operation to partial load operation, the inverter 101 performs VVVF control of the AC power supplied from the power source P so that the flow rate of sodium pumped by the pump motor 7 increases in accordance with the reactor thermal power.

[0020] For example, when the fast reactor is operating at partial load, when the operation switches from partial load to rated power operation, and when the operation switches from rated power to partial load, the inverter 101 performs VVVF control of the AC power supplied from the power source P based on the output command value in the fast reactor. Also, when the fast reactor is operating at rated power, the inverter 101 stops operation.

[0021] One end of each of the bypass lines 102A, 102B, and 102C is connected to a second input-side circuit breaker 106, and the other end is connected to a second output-side circuit breaker 107. The bypass lines 102A, 102B, and 102C are provided to directly supply AC power supplied from a power source P to the pump motor during rated output operation.

[0022] The phase synchronization processing circuit 103 is connected in parallel with the inverter 101 and is provided between the first input side circuit breaker 104 and the first output side circuit breaker 105. The phase synchronization processing circuit 103 changes the phase of the AC power converted by the inverter 101, thereby synchronizing the phase of the AC power supplied from the power source P with the phase of the converted power.

[0023] The first input side circuit breaker 104 has one end connected to the power source P and the other end connected to the inverter 101 and the phase synchronization processing circuit 103. The first output side circuit breaker 105 has one end connected to the inverter 101 and the phase synchronization processing circuit 103 and the other end connected to the pump motor 7. The first input side circuit breaker 104 and the first output side circuit breaker 105 are high-speed circuit breakers that can be switched, for example, in several tens of milliseconds, and switch between electrically connecting and disconnecting the inverter 101 and the pump motor 7 under the control of the switching control unit 108.

[0024] The second input-side circuit breaker 106 has one end connected to the power source P and the other end connected to the bypass lines 102A, 102B, and 102C. The second output-side circuit breaker 107 has one end connected to the bypass lines 102A, 102B, and 102C and the other end connected to the pump motor 7. The second input-side circuit breaker 106 and the second output-side circuit breaker 107 are high-speed circuit breakers that can be switched, for example, in several tens of milliseconds, and are controlled by the switching control unit 108 to switch between electrically connecting and disconnecting the bypass lines 102A, 102B, and 102C from the pump motor 7.

[0025] The switching control unit 108 is, for example, a CPU (Central Processing Unit), and switches between supplying converted power, which is AC power converted by the inverter 101, to the pump motor 7, and outputting bypass line power, which is AC power supplied from the power source P via bypass lines 102A, 102B, and 102C, to the pump motor 7. The switching control unit 108 controls the first input side circuit breaker 104, the first output side circuit breaker 105, the second input side circuit breaker 106, and the second output side circuit breaker 107, thereby switching between outputting the converted power to the pump motor 7 and outputting the bypass line power to the pump motor 7.

[0026] Specifically, when the fast reactor is operating at rated power, the switching control unit 108 controls the first input side circuit breaker 104 and the first output side circuit breaker 105 to cut off the supply of converted power from the inverter 101 to the pump motor 7, and controls the second input side circuit breaker 106 and the second output side circuit breaker 107 to supply bypass line power to the pump motor 7.

[0027] In addition, when the fast reactor is in partial load operation, when switching from partial load operation to rated output operation, or when switching from rated output operation to partial load operation, the switching control unit 108 controls the first input side circuit breaker 104 and the first output side circuit breaker 105 to supply the converted power output from the inverter 101 to the pump motor 7, and controls the second input side circuit breaker 106 and the second output side circuit breaker 107 to cut off the supply of bypass line power from the bypass lines 102A, 102B, and 102C to the pump motor 7.

[0028] Here, when switching the power output to the pump motor 7 from bypass line power to converted power, the switching control unit 108 switches the power output to the pump motor 7 after the phase of the AC power and the phase of the converted power are synchronized by the phase synchronization processing circuit 103.

[0029] For example, when switching the power output to the pump motor 7 from the bypass line power to the converted power, the switching control unit 108 controls the first input-side circuit breaker 104 to supply power from the power source P to the inverter 101 and the phase synchronization processing circuit 103, and causes the phase synchronization processing circuit 103 to synchronize the phase of the AC power with the phase of the converted power. Thereafter, the switching control unit 108 controls the first output-side circuit breaker 105 to output the converted power to the pump motor 7, and controls the second input-side circuit breaker 106 and the second output-side circuit breaker 107 to cut off the supply of bypass line power from the bypass lines 102A, 102B, and 102C to the pump motor 7. In this manner, it is possible to prevent the pump motor 7 from becoming unstable due to a difference in phase between the power before and after the power output to the pump motor 7 is switched.

[0030] 3 is a diagram showing the relationship between the change in the electric output ratio during daily load following operation of a fast reactor having the control device 100 according to this embodiment and the switching between the converted power and the bypass line power. In the example shown in Fig. 3, the horizontal axis indicates the elapsed time from the reference time, and the vertical axis indicates the electric output ratio when the electric output during rated power operation of the fast reactor is set to 100%.

[0031] As shown in Figure 3, when the electrical output ratio is 100%, that is, when the fast reactor is operating at rated power, it can be seen that bypass line power is output to the pump motor 7. Figure 3 also shows that when the fast reactor switches from rated power operation to partial load operation, during partial load operation, and when switching from partial load operation to rated power operation, the converted power is output to the pump motor 7. Figure 3 also shows that rated power operation is performed for approximately half of the time period each day. Therefore, the availability factor of the inverter 101 is approximately 50%, which makes it possible to approximately double the mean time between failures compared to when power is supplied to the pump motor 7 using only the inverter. During rated power operation, maintenance such as part replacement of the inverter 101 can also be performed.

[0032] [Effects of this embodiment] As described above, the control device 100 according to this embodiment switches between outputting converted power, which is AC power converted by the inverter 101, to the pump motor 7, or outputting bypass line power, which is AC power supplied from the power source P via the bypass lines 102A, 102B, and 102C, to the pump motor 7. In this way, the control device 100 can reduce the amount of material while maintaining the reliability of the fast reactor.

[0033] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist. For example, in the above embodiments, the control device 100 has been described as controlling the rotation speed of the pump motor 7 that drives the primary pump 5, but this is not limiting.

[0034] The control device 100 may control the rotation speed of a secondary pump motor that drives the secondary pump. In this case, the control device 100 may include an inverter that converts the voltage and frequency of AC power supplied from a power source, and a bypass line that supplies the AC power supplied from the power source directly to the secondary pump motor.

[0035] The control device 100 may have a switching control unit that switches between outputting converted power, which is AC power converted by the inverter, to the secondary pump motor, or outputting bypass line power, which is AC power supplied from a power source via a bypass line, to the secondary pump motor. In this way, the control device 100 can reduce the amount of material in the secondary system while maintaining the reliability of the fast reactor.

[0036] Furthermore, although the control device 100 has been described as having the first input-side circuit breaker 104, the first output-side circuit breaker 105, the second input-side circuit breaker 106, and the second output-side circuit breaker 107, the present invention is not limited to this. The control device 100 does not have to have the first input-side circuit breaker 104 and the second input-side circuit breaker 106. In this case, the switching control unit 108 may switch between outputting the bypass line power to the pump motor 7 and outputting the converted power to the pump motor 7 by controlling the first output-side circuit breaker 105 and the second output-side circuit breaker 107.

[0037] Furthermore, all or part of the device can be configured in any unit, functionally or physically, distributed or integrated. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments. [Explanation of symbols]

[0038] 1. Tank-type reactor 2 Main vessel 3. Reactor core 4 Intermediate heat exchanger 5 Primary pump 6 Furnace piping 7. Pump motor 8 Steam Generator 100 Pump motor control device 101 Inverter 102A, 102B, 102C bypass lines 103 Phase Synchronization Processing Circuit 104 First input circuit breaker 105 First output circuit breaker 106 Second input side circuit breaker 107 Second output circuit breaker 108 Switching control unit

Claims

1. A pump motor control device that controls the rotation speed of a pump motor that drives a primary or secondary pump installed in a fast reactor, a conversion unit that converts the voltage and frequency of AC power supplied from a power source; a bypass line for directly supplying the AC power supplied from the power source to the pump motor; a switching control unit that switches between outputting converted power, which is the AC power converted by the conversion unit, to the pump motor, or outputting bypass line power, which is the AC power supplied from the power source via the bypass line, to the pump motor; A pump motor control device having the same.

2. a synchronization unit that synchronizes a phase of the AC power supplied from the power source with a phase of the converted power, When switching the power output to the pump motor from the bypass line power to the converted power, the switching control unit performs the switching after the phase of the AC power and the phase of the converted power are synchronized by the synchronization unit.

2. The pump motor control device according to claim 1.

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