JPH0373891A - Electromagnetic pump control device - Google Patents

Abstract

PURPOSE:To improve power factor and to obtain flow cost down characteristics by providing the electromagnetic pump control device with a synchronizing machine in parallel with an electromagnetic pump, and at the time of generating abnormality, supplying an excited current to be changed by a cause-sorted program. CONSTITUTION:At the normal operation, a variable voltage/variable frequency power supply device 9 receives a flow rate command signal 10 and applies an adjusting current to the electromagnetic pump 1 and the synchronizing machine 3. The machine 3 is overexcited based upon a function fn selected by an excited current controller 7 to compenstate the delay current of the pump 1. At the time of generating an accident such as a failure in the insertion of a control rod, an ATWS signal 16 is outputted and the controller 7 selects a function f2, so that an excited current with a slow change ratio is applied to the pump 1 and a slow flow cost down characteristic is applied to a cooling material circulation system. Consequently, the power factor of the electromag netic pump 1 is improved and the flow cost down characteristic optimum to the cause of the abnormality can be applied.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an electromagnetic pump control device used in a coolant circulation system of a fast breeder reactor, and in particular, to improve the power factor of an electromagnetic pump. The present invention also relates to an electromagnetic pump control device that can adjust the flow coast down characteristics of coolant in various ways.

(Prior Art) In fast breeder reactors that use conductive metallic sodium as a coolant, mechanical sodium pumps have conventionally been used to circulate the coolant. As with other general-purpose pumps, an induction motor is generally used as the drive source for this mechanical sodium pump, and its operation control method has been established.

Induction motors generally have a power factor of 0. Since it is extremely excellent at 8 to 0°9, efficient operation can be performed without installing a power factor correction device or the like.

Furthermore, the capacity and efficiency of the electric motor uniquely determine the capacity of its driving power source. Note that since the motor has an excellent power factor, its driving power supply capacity is also relatively small.

By the way, when an abnormality occurs in an operating fast breeder reactor, the control rods are rapidly inserted into the reactor core, causing a transient temperature difference in the coolant at the core entrance and exit.
It may cause a large thermal shock to the structural materials around the reactor core.

In order to alleviate such thermal transient phenomena and maintain the integrity of the structural materials, a so-called flow-coast-down feature, which allows coolant to flow for a while even after the sodium pump's driving power is cut off, is used. It is desirable to have

In conventional mechanical sodium pumps, flow coast down is achieved by rotating the pump impeller for a short period of time using the inertial force held by the rotor of the electric motor or the inertial force of the flywheel that is integrally attached to the rotating shaft of the electric motor. It has acquired characteristics.

Since the specifications of the rotor or flywheel are uniquely defined, only one type of flow coastdown characteristic can be maintained. In addition, the setting conditions for core structural materials and peripheral equipment are determined to correspond to specific flow coast down characteristics, and it is difficult to individually demonstrate flow coast down characteristics in response to various abnormal phenomena. there were.

On the other hand, in recent years, electromagnetic pumps have often been adopted in place of the conventional mechanical sodium pumps.

This electromagnetic pump utilizes the fact that liquid metal sodium is a good conductor of electricity, and is based on the principle that when a current-carrying conductor is placed in a magnetic field, it receives a force in the direction perpendicular to the magnetic field strength. It transports coolant. Compared to conventional mechanical sodium pumps, this electromagnetic pump can easily adjust the coolant flow rate linearly, has a completely sealed structure, and is small, so there are no restrictions on installation location. It has excellent features such as no moving parts, easy maintenance and management, and the ability to obtain high discharge pressure.

Conventionally, relatively small-capacity electromagnetic pumps placed in the sodium auxiliary system of fast breeder reactors are generally used under constant flow conditions, and there is little need for flow control.

(Problems to be Solved by the Invention) However, since the electromagnetic pump has an extremely high inductance load, the power factor is about 0.5, which is extremely small compared to a mechanical sodium pump. Therefore, when using an electromagnetic pump as a pump that requires a large capacity, such as a coolant circulation pump in a fast breeder reactor, some kind of power factor improvement means is required to compensate for the reactive power of the electromagnetic pump with a low power factor load. Otherwise, the drive power capacity would be enormous,
There are problems in that the layout of the power supply equipment becomes difficult, the design work becomes complicated, and the plant cost increases significantly.

Furthermore, because electromagnetic pumps do not have rotating members, they cannot conserve kinetic energy like conventional mechanical pumps when the drive power is cut off, such as during a reactor scram. , the coolant flow rate decreases rapidly. Therefore, in order to sufficiently withstand thermal transients during abnormal conditions, it is necessary to provide a large margin in the design standards for core structural materials, and it has been necessary to adopt excessive design standards. In addition, in order to impart flow coast down characteristics that alleviate the above-mentioned thermal transients, it was necessary to install some kind of energy storage means, but it was difficult to find an inexpensive and effective means.

In addition, the electromagnetic pump as a coolant circulation pump installed in a power generation fast breeder reactor plant maintains the steam condition supplied to the turbine constant, so that
Increase the sodium coolant flow rate from 100% of the rated flow rate to 30%
It is necessary to have a control system that can continuously change the temperature up to about %.

The present invention was made in order to solve the above problems, and it improves the low power factor of the electromagnetic pump and at the same time enables smooth flow control, and the power circuit of the electromagnetic pump is cut off during normal operation of the plant. An object of the present invention is to provide an electromagnetic pump control device that can compensate for flow coast down characteristics that alleviate thermal transients in a plant when an abnormality occurs.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, an electromagnetic pump control device according to the present invention is operated in parallel with an electromagnetic pump that circulates coolant etc. during normal operation of a plant, and the electromagnetic pump is powered by a power source. A synchronous machine that regenerates excitation current from rotational energy in the event of an abnormality such as a circuit being cut off, and sends the excitation current to the electromagnetic pump, and a plurality of synchronous machines in which the rate of change of the excitation current value is programmed according to the cause of the abnormality. Built-in function generator,
By switching to a specific function generator depending on the cause of the abnormality,
The present invention is characterized by comprising an excitation current controller that controls an excitation current that is supplied to the electromagnetic pump.

(Function) According to the electromagnetic pump control device having the above configuration, during normal operation of the plant, by overexciting the synchronous machine, the synchronous machine advances by taking current from the power source and flowing it to the electromagnetic pump to operate the phase adjuster. conduct. Therefore, the power factor of the electromagnetic pump is improved, and the attached power supply equipment can be significantly downsized.

In addition, if an abnormality occurs such as cutting off the power supply circuit connected to the electromagnetic pump, the rotational energy stored in the rotor of the synchronous machine is supplied to the electromagnetic pump as an excitation current, and the necessary flow coast down characteristic is generated. As a result, thermal transient phenomena are effectively suppressed. At this time, the excitation current controller supplies the optimum excitation current to the electromagnetic pump in accordance with the output signal of the function generator programmed in advance for each abnormality cause. Therefore, it is possible to provide optimal flow coast down characteristics for each cause of abnormality, and safety within the plant system can be effectively maintained.

(Example) Next, an example of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a system diagram showing an embodiment in which an electromagnetic pump control device according to the present invention is applied to a coolant circulation system of a fast breeder reactor.

That is, during normal operation of the nuclear reactor, the electromagnetic pump control device according to this embodiment is operated in parallel with the electromagnetic pump 1 that circulates metallic sodium as a coolant, and the main power circuit 2 of the electromagnetic pump 1 is cut off. A synchronous machine 3 that regenerates excitation current from rotational energy when such an abnormality occurs and sends the excitation current to the electromagnetic pump 1, and a plurality of function generators in which the rate of change of the excitation current value is programmed according to the cause of the abnormality. Vessel 4. 5. 6, and a specific function generator for each cause of abnormality 4. 5. 6, an excitation current controller 7 controls the excitation current supplied to the electromagnetic pump l.
It is composed of:

Further, the power supply main circuit 2 connects the high voltage bus 8 to the electromagnetic pump 1 and the synchronous machine 3. A variable voltage/variable frequency power supply (VVVF) 9 is disposed in the main power supply circuit 2, and the variable voltage/variable frequency power supply 9 receives a flow rate command signal 10 from a plant control system (not shown). , is configured to adjust the power supply voltage and frequency of the electromagnetic pump 1 to perform flow rate control operations.

Further, an AC control center (C/C) 11 serving as an excitation power source for starting the synchronous machine 3 is connected to the excitation current controller 7 via a circuit breaker 12 .

On the other hand, the power supply main circuit 2 is connected to the exciting current controller 7 via the circuit breaker 13 . In addition, the power supply main circuit 2 includes a circuit breaker 14.
is provided, and this circuit breaker 14 receives the reactor trip signal 1
5, it is configured to open.

Further, the function generator 4 of the excitation current controller 7 has a function f programmed in advance so as to cause current to flow through the electromagnetic pump 1 as an excitation current to the synchronous machine 3 during normal operation. Output. In response to the reactor trip signal 15, the function generator 5 outputs a preprogrammed function fl to rapidly decrease the excitation current. Similarly, the function generator 6 generates a preprogrammed function f2 to slowly decrease the excitation current in response to the control rod insertion failure (ATWS) signal 16.
Output. The functions f, ft, and f2 are configured to be switched depending on the cause of the abnormality, such as during normal operation, when the reactor trip signal 15 is output, and when the ATWS signal 16 is output.

Next, the action will be explained.

During normal operation of the nuclear reactor, the variable voltage/variable frequency power supply device 9 receives a flow rate command signal 10 from the plant control system.
In response to this, a current adjusted to the required voltage and frequency is applied to the electromagnetic pump 1 and the synchronous machine 3 to control the flow rate of the coolant. Further, the synchronous machine 3 connected in parallel to the electromagnetic pump 1 as a coolant circulation pump is overexcited in accordance with a function f selected by the excitation current controller 7. Synchronous machine 3
By overexciting the pump, a current flows through the synchronous machine 3, a phase changer operation is performed, and the delayed current flowing through the electromagnetic pump 1 is compensated for. As a result, the apparent load power factor of the electromagnetic pump 1 is improved, and the power capacity of the electromagnetic pump 1 can be significantly reduced.

That is, a variable voltage/variable frequency power supply device 9 is generally used as a power supply device to facilitate flow control, but this power supply device 9 is intended for the electromagnetic pump 1 with a large flow rate and a low power factor load. Therefore, it is necessary to compensate for the reactive power as well, and as a result, the physical capacity becomes significantly larger than that of a conventional mechanical sodium pump.

However, due to the phase modifier operation of the synchronous machine 3, it is theoretically possible to make the power factor almost 1 as a load, and as a result, the installed capacity of the variable voltage/variable frequency power supply device 9 can be made extremely small. becomes possible.

On the other hand, during reactor scram, the reactor trip signal 15 causes the circuit breaker 15 of the main power circuit 2 to open, and the excitation current controller 7 automatically switches from the function f during normal operation to the function fl. will be done. At this time, the synchronous machine 3, which was operated in parallel with the electromagnetic pump 1 and operated as a phase adjuster, continues to rotate due to its own inertia force. The synchronous machine 3 converts the rotational energy into electrical energy, regenerates an exciting current according to the function fl, and supplies it to the electromagnetic pump 1. As a result, the electromagnetic pump 1 can continue to flow the required flow rate of coolant and exhibit flow coast down characteristics.

Here, the flow coast down characteristic of the coolant flow rate can be achieved by changing the excitation current of the synchronous machine 3, but the rate of change of this excitation current can be controlled by the excitation current controller 7.
executed by That is, during a reactor scram, the excitation current controller 7 selects the function fl based on the reactor trip signal 15, so that the flow coast down characteristic of the coolant flow rate having a relatively steep rate of change is controlled by the coolant flow rate. Provided to the circulatory system.

In addition, in the event of an accident such as control rod insertion failure, the ATWS signal 16
is output, the excitation current controller 7 selects the function f2, so that the electromagnetic pump 1 receives an excitation current having a relatively slow rate of change, and changes the slow coolant flow coast down characteristic to the coolant flow rate. Gives to the circulatory system.

In FIG. 1, excitation power at the time of starting the synchronous machine 3 is supplied from an AC control center (C/C) 11, and after the synchronous machine 3 enters synchronous operation, the circuit breaker 12 is opened. The circuit breaker 13 is closed and switched to self-excitation operation.

As described above, the electromagnetic pump control device according to the present embodiment is provided with the synchronous machine 3 that has two functions: the power factor improvement function of the electromagnetic pump 1 and the coolant flow rate flow coast down characteristic compensation function. In addition to being able to downsize the power supply capacity of the electromagnetic pump 1, it is also possible to give the electromagnetic pump 1 the function of accumulating an apparent inertial force, thereby significantly alleviating thermal transients in the reactor. I can do it.

In addition, by configuring the program of the function generators 4, 5, 6 in the excitation current controller 7 to be switched as appropriate, the excitation current changes depending on the cause of abnormality, such as during reactor scram or control rod insertion failure (ATWS). It becomes possible to set the rate arbitrarily, and it is possible to provide the optimum coolant flow rate flow coast down characteristic for each cause of abnormality.

In other words, in the event of control rod insertion failure (ATWS), the flow coast down characteristic of the electromagnetic pump 1 becomes relatively slow in proportion to the programmed function f2, and the reactor core becomes subcritical due to thermal expansion of the reactor core. .

On the other hand, during a reactor scram, a flow coast down characteristic is obtained with a relatively steep rate of change, and as a result of compensating for transient changes in the core structural materials, the integrity of the core structure can be maintained.

In this way, an electromagnetic pump control device that can provide a flow coast down characteristic to the electromagnetic pump in addition to the function of adjusting the coolant flow rate can be obtained, making it possible to provide a sodium-cooled fast breeder reactor with excellent safety and economic efficiency. It becomes possible.

In the above embodiments, an example is shown in which the device is applied to an electromagnetic pump that circulates coolant in a sodium-cooled fast breeder reactor, but the device of the present invention is not limited to the above-mentioned applications, and is, for example, used for transferring pig iron in a steel manufacturing plant. It can also be applied to electromagnetic pumps used in plants that require mitigation of thermal shock during transient times, such as electromagnetic pumps.

〔Effect of the invention〕

As explained above, according to the electromagnetic pump control device according to the present invention, during normal operation of the plant, by overexciting the synchronous machine, the synchronous machine advances by taking current from the power source and flowing it to the electromagnetic pump to operate the phase adjuster. I do. Therefore, the power factor of the electromagnetic pump is improved, and the attached power supply equipment can be significantly downsized.

In addition, if an abnormality occurs such as the power circuit connected to the electromagnetic pump being cut off, the synchronous machine supplies the rotational energy stored in the rotor to the electromagnetic pump as excitation current.
Since it provides the necessary flow coast down characteristics, thermal transient phenomena etc. are effectively suppressed. At this time, the excitation current controller supplies the optimum excitation current to the electromagnetic pump in accordance with the output signal of the function generator programmed in advance for each abnormality cause. Therefore, it is possible to provide optimal flow coast down characteristics for each cause of abnormality, and safety within the plant system can be effectively maintained.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an example in which an embodiment of the electromagnetic pump control device according to the present invention is applied to a coolant circulation system of a fast breeder reactor. 1... Electromagnetic pump, 2... Main power circuit, 3... Synchronous machine, 4. 5. 6...Function generator, 7...Exciting current controller, 8...High voltage bus, 9...Variable voltage/variable frequency power supply (VVVF), 10...Flow rate command signal, 11...・AC control center (C/C)
, 12, 13. 14... Circuit breaker, 15... Reactor trip signal, 16... ATWS signal.

Claims (1)

[Claims] During normal operation of the plant, it is operated in parallel with the electromagnetic pump that circulates coolant, etc., and when an abnormality occurs such as the power circuit of the electromagnetic pump being cut off, the excitation current is regenerated from the rotational energy, and the excitation current is used as described above. It has a built-in synchronous machine that feeds the electromagnetic pump, and multiple function generators that program the rate of change of the excitation current value for each abnormality cause.By switching to a specific function generator for each abnormality cause, the rate of change of the excitation current value is sent to the electromagnetic pump. An electromagnetic pump control device comprising: an excitation current controller that controls a supplied excitation current.