JP2022158267A - Method for changing rated voltage - Google Patents

Abstract

To provide a method for changing the rated voltage of a measurement control system quickly.SOLUTION: A first-voltage direct-current power 21 is supplied to each control panel 15, and the supply of the first-voltage direct-current power 21 to at least one control panels 151 is stopped. After that, each first element component 11 is replaced with a second element component 12, and a second-voltage direct-current power 22 is supplied to a control panel 151(15). This operation is repeated on all the control panels 15 (151...15m...15M).SELECTED DRAWING: Figure 2

Description

An embodiment of the present invention relates to a method for changing the rated voltage of an instrumentation control system.

Facilities such as factories, buildings, and power plants are equipped with a large number of sensors and actuators to manage their operations. The instrumentation control system processes measurement data input from these sensors in a logic circuit and outputs operation signals for these actuators. Furthermore, the instrumentation control system also has a function of monitoring measured values from each sensor and manually operating each actuator. And, in the instrumentation control system designed in conformity with the foreign standard, the specification of the rated voltage may differ from the Japanese standard in accordance with the foreign standard.

JP-A-6-289189

In the inspections and inspections that are periodically performed at the facilities described above, the components of the instrumentation control system that have deteriorated over time are replaced during inspections. For this reason, it is necessary to procure such parts and equipment in a timely manner as necessary and to always secure an appropriate amount of inventory.

On the other hand, the number of operating nuclear power plants in Japan is declining, and the supplies of parts and equipment for facilities designed in accordance with the above-mentioned foreign standards are originally small due to special specifications that require strict quality. This makes it extremely difficult to secure. On the other hand, the parts and equipment conforming to Japanese standards cannot be substituted for the parts and equipment of the instrumentation control system of facilities designed in conformity with foreign standards, because the rated voltage is different.

The embodiments of the present invention have been made in consideration of such circumstances, and it is an object of the present invention to provide a method of changing the rated voltage of an instrumentation control system in a short period of time so that parts and instruments conform to standards.

In the method for changing the rated voltage according to the embodiment, a plurality of control panels equipped with a group of a plurality of types of first element parts that operate at a first rated voltage are arranged, and each of the control panels receives DC power of the first voltage. a step of stopping the supply of the DC power of the first voltage to at least one of the plurality of control panels, and a step of replacing each of the first element parts with a second element part operating at a second rated voltage; and applying a second voltage to the control panel after the replacement of the first element part with the second element part is completed. and applying power.

Embodiments of the present invention provide a method for rapidly changing the voltage rating of an instrumentation control system to bring components and fixtures into compliance.

1 is a schematic diagram of an instrumentation control system to which a rated voltage changing method according to an embodiment of the present invention is applied; FIG. (A) and (B) are explanatory diagrams of steps of a method for changing the rated voltage according to the first embodiment. (A), (B), and (C) are explanatory diagrams of steps of a method for changing the rated voltage according to the first embodiment. (A), (B), and (C) are explanatory diagrams of a temporary module applied in the method of changing the rated voltage according to the second embodiment. (A), (B), and (C) are explanatory diagrams of a switching terminal block applied in the method of changing the rated voltage according to the second embodiment. 4 is a flowchart for explaining a method of changing the rated voltage according to each embodiment;

(First embodiment)
An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic diagram of an instrumentation control system 10 to which a rated voltage changing method according to an embodiment of the present invention is applied. The control panel 15 arranged in the central control room 20 of the nuclear power plant includes a main panel 15 _x for normal operation, start-up, shutdown operation and monitoring, and operation and monitoring for plant safety in the event of an abnormality. Control panels 15 _m (m=1 to M) and 15 _n (n=1 to N) are arranged to exhibit various functions. Here, the relationship between the control panel 15 _m (m=1 to M) and the control panel 15 _n (n=1 to N) is such that even if one of the functions fails, the other functions to complement each other. This is an example of matching multiplexing (here, duplexing).

In this way, the arrangement of the control panels 15 is grouped by the same section, and the control panels 15 of the facilities in a multiplexing (redundancy) partner relationship are separated from each other. These control panels 15 receive process quantities measured by sensors installed on site as input signals 17 _m (m=1 to M) (FIG. 2). The control panel 15 processes the input signal 17m in the logic circuit 19, and outputs the drive signal for the actuators installed on site as the output signal _18m ( _m =1 to M) (FIG. 2). Also, the input signal 17 may be an operation signal for a switch or the like provided on the control panel 15 . The output signal 18 may also be a display signal such as a gauge or warning light provided on the control panel 15 .

Such sensors include flowmeters, pressure gauges, liquid level gauges, thermometers, and analyzers for measuring density, specific gravity, viscosity, humidity, and the like. Actuators include valves, pumps, motors, hydraulic equipment, and the like.

DC power 21 of a first voltage is supplied to these control panels 15 from a first power supply 31 (31a, 31b) via opening/closing switches 16m ( _m =1 to M) and 16n ( _n =1 to N). It is The first power supply 31 includes a rectifier 35 that rectifies the AC power 36 into the DC power 21 of the first voltage, and a storage battery 28 that outputs the DC power 21 of the first voltage. By configuring the first power supply 31 in this manner, the control panel 15 is supplied with power by commercial AC power 36 in normal times. The storage battery 28 is composed of a lead-acid battery, is installed outside the central control room 20, and is charged by AC power 36 during normal times. When the AC power 36 fails, the storage battery 28 supplies power to the control panel 15 .

The control panel 15 (FIG. 2) is provided with a logic circuit 19 on the inner surface of the housing while securing a working space for the operator 25 in the internal space of the housing. In this logic circuit 19, a plurality of types of first element parts 11, wiring for transmitting input signals 17 and output signals 18, and terminal blocks connecting these wirings are arranged. Examples of the first element component 11 include a PLC (Programmable Logic Controller), a relay, and the like.

Based on FIGS. 2A, 2B and 3A, 3B, and 3C, steps of the method for changing the rated voltage according to the first embodiment will be described. As shown in FIG. 2(A), a plurality of control _panels 15 (15 ₁ . . . 15 _m . DC power 21 of a first voltage is supplied to the control panel 15 of the .

Next, as shown in FIG. 2B, the supply of the DC power 21 of the first voltage to at least one control panel 15 ₁ (15) among the plurality of arranged ones is stopped. Furthermore, each of the first element parts 11 mounted on the control panel 15 ₁ (15) to which the power supply has been stopped is replaced with a second element part 12 that operates at the second rated voltage. Then, as shown in FIG. 3A, the DC power 22 of the second voltage is supplied to the control panel 15 ₁ (15) in which the replacement of the first component 11 with the second component 12 has been completed.

Subsequently, as shown in FIG. 3B, the supply of the DC power 21 of the first voltage to the control panel 15 _m (15) is stopped. Then, the first element part 11 of the control panel _15m (15) is replaced with the second element part 12, and the DC power 22 of the second voltage is supplied. Similarly, as shown in FIG. 3(C), all the control _panels 15 (15 ₁ . . . 15 _m . is supplied to complete the work.

By the way, in the method of changing the rated voltage in the first embodiment, the control panel 15 in which the first element part 11 is replaced with the second element part 12 cannot transmit and receive the input signal 17 and the output signal 18. there is Therefore, in order to change the rated voltage of the instrumentation control system 10 so as not to stop the operation of the nuclear power plant, the control panels 15 _m and 15 _n that are partners in the redundant configuration are connected from the first element part 11 to the second The replacement with the component parts 12 is carried out at different times.

By the way, the work of replacing the first element part 11 with the second element part 12 in the control panel 15 requires promptness because the number of replacement objects (especially relays) is enormous. Therefore, it is desirable to check the operation of each relay separately before and after the relay is newly installed as the second element component 12 .

Therefore, the second power supply 32 that supplies the DC power 22 of the second voltage to the control panel 15 has the same configuration as the above-described second power supply 32 except that the output voltage is the second voltage. there is As a result, the replacement time can be reduced by checking the operation before the replacement using a test control panel (not shown) different from the control panel 15 . In addition, by adopting a lithium-ion battery for the storage battery attached to the second power supply 32, the overall configuration can be made smaller, and it can be arranged in the control room of the control panel 15 or in a nearby area in the same building. . As a result, the length of the cable that connects the storage battery and the control panel 15 can be shortened, and power transmission loss can be reduced.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. FIGS. 4A, 4B, and 4C are explanatory diagrams of the temporary module 26 applied in the method of changing the rated voltage according to the second embodiment. In FIG. 4, parts having configurations or functions common to those in FIG. 1 are denoted by the same reference numerals, and overlapping descriptions are omitted.

The method of changing the rated voltage in the second embodiment enables transmission and reception of the input signal 17 and the output signal 18 while the power supply to the control panel 15 is stopped. Here, the temporary module 26 outputs an output signal 18 common to the corresponding control panel 15 in response to the input signal 17 .

As shown in FIG. 4A, a temporary module 26 corresponding to the control panel 15 to replace the first element part 11 is prepared. This temporary module 26 is activated by power supplied from an arbitrary power source. As shown in FIG. 4B, the cable of the input signal 17 is switched from the input terminal 37a of the control panel 15 to the input terminal 37b of the temporary module 26. Then, as shown in FIG. Similarly, the cable for the output signal 18 is changed from the output terminal 38 a of the control panel 15 to the output terminal 38 b of the temporary module 26 . Thus, transmission and reception of the input signal 17 and the output signal 18 are continued in the temporary module 26 . Subsequently, the open/close switch 16 is switched from the closed state to the open state, power supply to the control panel 15 is stopped, and the replacement work for the second element part 12 is performed.

As shown in FIG. 4(C), when the replacement work for the second element part 12 is completed, the cable for the input signal 17 is connected back from the input terminal 37b of the temporary module 26 to the input terminal 37a of the control panel 15. . Similarly, the cable of the output signal 18 is connected back from the output terminal 3b of the temporary module 26 to the output terminal 38a of the control panel 15. FIG. In this way, even when the period of replacement work for the second element part 12 is entered, it is possible to continuously transmit and receive the input signal 17 and the output signal 18 .

Next, a modification of the second embodiment of the present invention will be described with reference to FIG. FIGS. 5A, 5B, and 5C are explanatory diagrams of the switching terminal block 27 (27a, 27b) applied in the method of changing the rated voltage according to the modified example of the second embodiment. In FIG. 5, parts having configurations or functions common to those in FIG. 4 are denoted by the same reference numerals, and overlapping descriptions are omitted.

In the method of changing the rated voltage in the modified example of the second embodiment, connection switching of the cables for the input signal 17 and the output signal 18 between the control panel 15 and the temporary module 26 is instantaneously performed. In the case of FIG. 4, transmission and reception of the input signal 17 and the output signal 18 become impossible during the period required for connection switching of many cables. Therefore, in FIG. 5, the period required for switching the connection of the cable is instantaneous, and the transmission and reception of the input signal 17 and the output signal 18 are seamless.

As shown in FIG. 5A, the switching terminal block 27a of the input signal 17 is connected to the input terminal 37a of the control panel 15 and the input terminal 37b of the temporary module 26. As shown in FIG. Similarly, the switching terminal block 27b of the output signal 18 is connected to the output terminal 38a of the control panel 15 and the output terminal 38b of the temporary module 26. FIG. The switching terminal block 27a (27) for the input signal 17 and the switching terminal block 27b (27) for the output signal 18 have the same structure.

As shown in FIGS. 5A and 5B, the switching terminal block 27a (27) inputs the input signal 17 to either the control panel 15 or the temporary module 26 by switching. Then, the switching terminal block 27b (27) outputs the output signal 18 from either the control panel 15 or the temporary module 26 by switching. This allows instant switching of input signals 17 and output signals 18 between the control panel 15 and the temporary module 26 .

A method of changing the rated voltage according to each embodiment will be described with reference to the flowchart of FIG. 6 (see FIG. 1 as needed). Open/close switches 16 _m (m = 1 to M), 16 _n (n = 1 to N) are all set to the closed state, control panel 15 _m (m = 1 to M), 15 _n (n = 1 to N) are supplied with the DC power 21 of the first voltage (S11). Then, the open/close switch 16 ₁ (m=1 or n=1) among them is switched from the closed state to the open state, and the DC power 21 of the first voltage is supplied to the control panel 15 ₁ (m=1 or n=1). is stopped (S12, S13).

Then, each of the first element parts 11 mounted on the control panel 15 ₁ to which the power supply has been stopped is replaced with the second element part 12 (S14). Then, the open/close switch 16 ₁ is switched from the open state to the closed state to supply the DC power 22 of the second voltage to the control panel 15 ₁ that has been replaced (S15). Then, for all the control panels 15 _m (m=1 to M) and 15 _n (n=1 to N) (S16 No), replacement with the second element parts 12 is carried out (S13, S14), The two-voltage DC power 22 is supplied (S15), and the work is completed (S16 Yes, END).

The method of changing the rated voltage according to the embodiment described above has been applied to an instrumentation control system arranged in the central control room of a nuclear power plant. However, the method for changing the rated voltage according to the present invention can also be applied to, for example, an instrumentation control system installed in facilities such as factories and buildings, and there is no limitation to the target of application.

According to the method for changing the rated voltage of at least one embodiment described above, the rated voltage of the instrumentation control system is changed for a short period of time by stopping the power supply to the control panel and replacing the mounted element parts. It is possible to change parts and equipment in accordance with the standard.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

Next, an example for confirming the effect of the present embodiment will be described.
The voltage of the DC power supply that supplies power to the monitoring control panel, which is equipped with instruments that monitor process variables for operating the nuclear reactor, turbine, and generator, is DC 125V, which applies the US standard, where the technology was introduced. Yes, and the AC power supply is AC 120V. The same applies to the voltage of the DC power supply and the AC power supply supplied to the monitoring control panel installed with instruments for monitoring the safety function process variables in order to settle the accident in the event of a nuclear reactor accident or the like.

Therefore, work will be carried out to change the rated voltage of this DC power supply from the US standard of DC 125V to the Japanese standard of DC 110V, and similarly from the US standard of AC 120V to the Japanese standard of AC 105V. During this construction period, it is necessary to continue the operation of at least the system for maintaining the habitability for plant operators to operate and operate the facility, the instrumentation air system for driving the instrumentation system, etc. Furthermore, it is necessary to shorten the construction period as much as possible to reduce the probability (risk) of power outages and other incidents during periods when the nuclear fuel monitoring and instrumentation functions are not in operation.

A nuclear power plant is provided with a safety function process to settle an accident when it occurs. The process quantity of each process is monitored on the main panel of the central control room by means of instruments installed on-site and indicators for signals transmitted from the site. This main panel receives AC and DC power from an external power source, and starts and stops valves and pumps by means of an interlock using a control signal that detects a change in an indicator or its indicated value. In this way, the power generation equipment of the plant is operated, and the equipment for resolving the accident that has occurred is put into operation.

Logic circuits and relays are installed in control panels that control auxiliary equipment systems and power supply systems in nuclear power plants. Power of DC 125V and AC 120V is supplied from a power supply facility installed in another room. For important instruments, a backup power supply such as a lead-acid battery is provided so that monitoring can continue even if the external commercial AC power supply fails.

In each control panel, the received AC 120V and DC 125V are supplied to the internal element parts as they are, or the voltages converted according to the respective specifications are supplied. The element parts installed in the control panel include a logic circuit that combines relay contacts, a controller that logically calculates input signals with a CPU, and switches for operators to manually start, stop, and switch modes. There are various types such as

These element parts conform to the American standard rated voltage that can withstand insulation of DC 125V or AC 120V. In this way, there is a fact that supply makers are limited for these element parts conforming to the rated voltage different from the Japanese standard.

In a control panel that monitors process variables in a nuclear power plant, element parts that deteriorate over time are replaced during regular inspections. Therefore, it is necessary to procure the necessary parts and equipment before the periodic inspection. The parts to be procured must have sound insulation and operation at a voltage of 125 V DC and 120 V AC, which is different from the Japanese standard, with a fluctuation range of ±10% (one example). When procuring such parts and equipment, it is necessary to confirm that they meet the specifications of foreign standards and conformity to other quality requirements, and it is necessary to store the test data at that time. was a very heavy burden.

Furthermore, after the Great East Japan Earthquake that occurred on March 11, 2011, it has become even more difficult to procure equipment that conforms to the DC125V and AC120V rated voltage standards and that satisfies the quality requirements of nuclear power plants.

One reason for this is the stringent quality requirements of the nuclear industry and the reduced demand associated with fewer nuclear plants in operation. Furthermore, although it is relatively easy to procure component parts that comply with the rated voltage specified by Japanese Industrial Standards (JIS, etc.), the required specifications differ from those of US standard component parts used in nuclear power plants. , cannot be applied as is.

Therefore, we plan to change the rated voltage of the power supply of the instrumentation control system to the Japanese standard of 100V AC and 100V DC. Furthermore, along with this, the control panel will be updated, and the element parts mounted on each control panel will be changed to the Japanese standard AC100V and DC100V specifications. At that time, in order to shorten the period during which the monitoring function of the nuclear power plant, etc., will substantially stop functioning due to this renewal work, the renewal work of a plurality of control panels will be carried out partially in order. Although there is a period during which the control panel loses its functions during the implementation of this renewal work, the functions of the control panel are maintained before and after the implementation.

In addition, the power supply equipment for the instrumentation control system of the nuclear power plant was designed to be able to supply power for 8 hours even if the external AC power supply was cut off at the time of the nuclear reactor accident. Learning from the severe accident caused by the earthquake, it was decided to install a storage battery that can supply power 24 hours a day.

If an attempt is made to construct this storage battery by integrating lead-acid batteries having a general single-cell capacity, a large installation space is required in order to achieve a capacity that allows operation at DC 100V and several thousand Ah for 24 hours. In addition, lead-acid batteries are installed in a separate room away from the control panel because hydrogen can be produced from the sulfuric acid used in the electrolyte when discharged. On the other hand, if the storage battery is constructed with a lithium-ion battery, it can be installed in a narrower installation space than the lead-acid battery.

During the renovation work, it is necessary to minimize the downtime of one control panel. For that purpose, a temporary test board having the same circuit as the relay logic circuit is installed, and the function of the relay to be replaced is checked in advance using this temporary test board. And if only the work to replace the relay is carried out on the control panel, and the confirmation test of the logic circuit is limited to confirming whether the output signal of the control panel is the same as before replacement, it contributes to shortening the construction time.

Also, for the verification of the replaced element part, the operation of the sensor or actuator related to this element part can be checked by checking the operation before replacement with a test control panel (not shown) different from the control panel 15 concerned. Since it is enough to check only, it contributes to shortening the construction time. Furthermore, regarding the operation check of the instrument, conventionally, it was confirmed whether the five points indicated correctly over the indication range, but now it is possible to check the operation with only one indication of the instrument.

In addition, the operation of the motor drive circuit, which has been replaced with relays, devices and parts in the logic circuit, has been confirmed by checking the rotation direction and no-load current of the motor itself, and then starting it by the logic of the control panel. I was checking to see if I could stop it. By using a temporary test board (not shown) to check the start/stop logic of the motor after the relays, devices and parts in the logic circuit are replaced, the cables connecting the replaced control board and the motor control center are checked correctly. To confirm the connection, it is sufficient to confirm the output signal to the motor control center (MCC) of the control unit without disconnecting the cable at the end of the motor as a confirmation test of the motor circuit.

Furthermore, by connecting a temporary module that can replace the function of the control panel in parallel with the corresponding control panel, even when replacing the element parts of the control panel, the temporary module can replace the function of the control panel, reducing downtime. can be shortened. The temporary modules are equipped with alarms, pump and valve operation switches, and instruments that monitor parameters to confirm the operational status of the auxiliary equipment system and power supply system, similar to those installed in the corresponding control panel. ing.

10... instrumentation control system, 11... first element part, 12... second element part, 15, 15 _m (m = 1 to M), 15 _n (n = 1 to N), ... control panel, 15 _x ... Control panel (main panel) 16 Open/close switch 17 Input signal 18 Output signal 19 Logic circuit 20 Central control room 21 First DC power 22 Second DC power 25 Work Member 26 Temporary module 27 (27a, 27b) Switching terminal block 28 Storage battery 31 First power supply 32 Second power supply 35 Rectifier 36 AC power 37 Input terminal 37a Input terminal of control panel 37b Input terminal of temporary module 38 Output terminal 38a Output terminal of control panel 38b Output terminal of temporary module.

Claims (6)

A step of supplying DC power of a first voltage to each of a plurality of control panels mounted with a group of a plurality of types of first element parts operating at a first rated voltage, and supplying DC power of a first voltage to each of the control panels;
stopping the supply of DC power of the first voltage to at least one of the plurality of control panels;
a step of replacing each of the first element parts mounted in the control panel to which the power supply has been stopped with a second element part that operates at a second rated voltage;
and supplying DC power of a second voltage to the control panel in which the replacement of the first element part with the second element part is completed. In the method for changing the rated voltage according to claim 1,
A method of changing a rated voltage, wherein the control panels that are partners in a redundant configuration perform replacement of the first element parts with the second element parts by staggering each other in terms of time. In the method for changing the rated voltage according to claim 1 or claim 2,
A rated voltage changing method, wherein the mounted first element part includes a relay, and the operation of the corresponding second element part is checked before and after replacement. In the rated voltage changing method according to any one of claims 1 to 3,
The DC power of the second voltage is a rated voltage changing method in which a lithium-ion battery arranged in a common building with the plurality of control panels is adopted as a storage battery. In the rated voltage changing method according to any one of claims 1 to 4,
During the period in which the power supply to the control panel is stopped,
A rated voltage changing method for inputting at least part of an input signal to the control panel and activating a temporary module outputting an output signal common to the control panel. In the method for changing the rated voltage according to claim 5,
inputting the input signal to either one of the control panel and the temporary module;
Alternatively, a rated voltage changing method using a switching terminal block for outputting the output signal from either the control panel or the temporary module.

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