JPH05260617A - Ventilation-control method for switch board - Google Patents

Abstract

PURPOSE:To drive a ventilator under fuzzy control in an optimal way with advantages in lifetime, energy saving and noises for use in a switch board having a transformer in a process-control apparatus. CONSTITUTION:A set of phenomenal control data items comprise an output signal generated from a mean-value calculation unit 8 for calculating a load current of a transformer 4 to indicate load conditions, an output signal generated from an operational time integrating unit 9 for integrating an operational time of a ventilator 5, and a signal generated from a temperature sensor 7 outside the control board. The fuzzy inference unit 10 calculates an operational probability for each cause factor of the ventilator 5. The operational probability is compared with a ceiling operational probability value (A) and a bottom operational probability value (B), which are previously set, so that the ventilation 5 is controlled at its starting and stopping time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to ventilation control of a switchboard that houses a transformer by a control device such as a process controller, and more particularly to a switchboard ventilation control system for performing optimum control using fuzzy inference.

[0002]

2. Description of the Related Art In power distribution facilities of water treatment facilities, step-down power transformers are installed in order to supply low-voltage loads such as various mechanical facilities and on-site lighting facilities.

Generally, the operating condition of a water treatment facility resembles a social life pattern, and the load condition of a power transformer is almost the same. That is, the high load state of the power transformer is about 6 to 8 hours per day.

This power transformer is housed in a unit-closed type switchboard to improve safety and maintainability, and is provided with a ventilation fan for discharging the heat generated inside the panel due to the loss of the transformer to the outside of the panel. .

[0005]

However, in general, the control of the ventilation fan is interlocked with the on / off state of the transformer primary side circuit breaker, and in normal states other than accident interruption,
The ventilation fan operates continuously, but has the following problems.

(1) High cost of maintenance and reduction of transformer operating rate due to shortened life of the ventilation fan.

(2) Higher cost of operating electric power for the ventilation fan.

(3) The maintenance environment deteriorates due to noise from the ventilation fan.

The present invention has been made in view of the above problems, and introduces fuzzy inference to control the start and stop of the ventilation fan to reduce the operating time of the ventilation fan and prolong the life of the ventilation fan.
It is an object of the present invention to provide a switchboard ventilation control method that saves energy and improves the maintenance environment by reducing the noise generation time.

[0010]

Means for solving the above-mentioned problems in the present invention is, in the ventilation control of a switchboard in which a transformer is built in, and the heat generated by the transformer is discharged to the outside of the board by a ventilation fan,
The moving average value of the transformer load current indicating the load state, the winding temperature of the transformer, the cumulative operating time of the ventilation fan and the temperature outside the panel are the phenomenon items, and the operating probability of the ventilation fan of the causal item is calculated by fuzzy inference. It is characterized in that the operation control for starting or stopping the ventilation fan is performed by comparing with the preset upper and lower limits of the operating probability.

[0011]

The transformer load current is taken into the moving average value calculating unit via CT and the moving average value for about 10 minutes is calculated and used as the load state signal. Further, the operating signal of the ventilation fan is sent to the operating time integrating section to obtain the integrated value of the operating time. Simultaneously with the load state signal and the integrated operation time signal, four inputs of the transformer winding temperature and the outside temperature obtained from each temperature sensor are input to the fuzzy inference section as phenomenon items. In the fuzzy inference unit, the membership function and IF-
After the membership value (the degree of establishment) of the driving probability for each rule is calculated based on the THEN-type control rule, the center of gravity of the combined values thereof is further calculated as the inference value of the driving probability. This operation probability is guided to the comparison unit and compared with preset operation probability upper and lower limits. If the upper limit or higher, the ventilation fan is activated, and if it is lower than the lower limit, the operation is stopped.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the system configuration diagram of FIG. In the figure, 1 is a circuit breaker and 2 is a current transformer, which takes in a transformer load current. Reference numeral 3 is a transformer panel, which incorporates a transformer 4, a ventilation fan 5, and a temperature sensor 6 for detecting the winding temperature of the transformer 4. Reference numeral 7 is a temperature sensor for detecting the temperature outside the panel. Reference numeral 8 denotes a load current moving average value calculation unit, which calculates the load state. Reference numeral 9 denotes an operating time integrating unit, which calculates an integrated operating time of the ventilation fan 5. Reference numeral 10 is a fuzzy inference unit, which uses the moving average value of the load current that represents a steady load state, the transformer winding temperature, the cumulative operating time of the ventilation fan, and the outside temperature as the phenomenon items and the operating probability as the cause. To do. Reference numeral 11 denotes a comparison unit, which compares the driving probability inference value X with preset operating probability upper limit values A and lower limit values B, and sends a start command or a stop command to the ventilation fan 5 based on the result.

Next, the operation will be described. When the circuit breaker 1 is in the closed state, the primary side load current flowing into the power transformer 4 in the transformer panel 3 is taken into the moving average value calculating unit 8 via the current transformer 2 and the current is calculated for about 10 minutes. The load current moving average value is calculated and sent to the fuzzy inference unit 10 as the load state. On the other hand, the winding temperature of the transformer 4 in the transformer board 3 is sent from the temperature sensor 6 to the fuzzy inference unit 10. At the same time, the operating signal of the ventilation fan 5 is sent to the operating time integrating section to obtain the integrated value of the operating time and send it to the fuzzy inference section 10. Furthermore, the temperature outside the transformer panel 3 is detected by the temperature sensor 7.
It is sent to the fuzzy inference unit 10.

In the fuzzy inference unit 10, the four inputs, that is, the load state signal, the winding temperature signal, the outside temperature signal, and the integrated operation time signal are used as the phenomenon items, and each rule is based on the IF-THEN type control rule. The degree of driving probability is calculated, the logical sum (maximum value) of the results obtained from each rule is calculated, the center of gravity is calculated, and the driving probability that is the causal item is inferred and output to the comparison unit 11.

The comparison unit 11 compares preset driving probability upper and lower values with the driving probability inference value,
If the operation probability inference value is larger than the upper limit value, a start command is sent to the ventilation fan 5, and if it is smaller than the lower limit value, a stop command is sent to the ventilation fan 5 to start / stop the ventilation fan 5.

Fuzzy inference will be described below.

First, the variables used for this fuzzy inference are defined as follows.

Phenomenon item; IA: load state, TA: winding temperature, TB: outside temperature, SA: operating time cause item; BT: operating probability Further, the variables of the cause item rather than the phenomenon item are shown in FIGS. We define a three-step membership function as shown in
The fuzzy labels are L, M, and S, and their meanings are as follows.

IA: load condition, SA: operating time, TA, TB: winding temperature, outside temperature L: high L: long L: high M: medium M: medium M: medium S: small S: Short S: Low BT: Driving probability L: High M: Medium S: Low Furthermore, the rule matrix is shown in Table 1.

[0020]

[Table 1]

Therefore, as the control rules, the following rules (1) to (n) are configured.

(1) IF IA is L AND TA is M AND TB is M THEN BT is L (2) IF IA is M AND TA is L AND TB is L THEN BT is S (3) IF IA is M AND TA is S AND TB is S AND SA is M THEN BT is M (4) IF IA is M AND TA is S AND TB is S AND SA is S THEN BT is L ：: ： (n) IF IA is S AND TA is M AND TB is M THEN BT is M The IF part of these rules is the condition part and the THEN part is the conclusion part.

As an inference method using these rule groups, for example, the MINIMAX method is applied.

That is, inference proceeds as follows. First, with respect to the input values of the variables IA, TA, TB, and SA of the phenomenon item, the membership value (degree of establishment) of each fuzzy set is obtained. Furthermore, for each rule, find a value with a low degree of success,
The degree to which the rule is satisfied. Next, the fuzzy set of the conclusion part is cut using the degree of success. Finally, the logical sum of the results from the respective rules is calculated, and the position of the center of gravity is set as the output value BT.

[0025]

As is apparent from the above description, according to the present invention, the ventilation fan is based on the operating probability and the operating probability upper and lower limit set values obtained by fuzzy inference based on the load state, the winding temperature, the operating time, and the temperature outside the panel. By controlling start / stop, the operating time can be reduced, the operating power can be saved and the service life can be extended, the transformer operating rate can be improved, and the maintenance
Cost is also reduced. Furthermore, since the noise generation time of the ventilation fan is reduced, it has an excellent effect of preventing deterioration of the maintenance environment.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 IA: Loaded membership function.

FIG. 3 TA: Membership function of winding temperature.

FIG. 4 TB: Membership function of outside temperature.

FIG. 5: SA: Membership function of cumulative operating time.

FIG. 6 BT: Driving probability membership function.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Circuit breaker 2 ... Current transformer 3 ... Transformer panel 4 ... Transformer 5 ... Ventilation fan 6 ... Transformer winding temperature sensor 7 ... Outside temperature sensor 8 ... Moving average value calculation unit 9 ... Operating time integration unit 10 ... Fuzzy reasoning section 11 ... Comparison section

Claims (1)

[Claims] 1. A moving average value of a load current of the transformer, which indicates a load state, and a winding temperature of the transformer, in ventilation control of a switchboard in which a transformer is built in and heat generated by the transformer is discharged to the outside of the panel by a ventilation fan. And the fan operating probability of the causal item calculated by fuzzy inference with the cumulative operating time of the fan and the outside temperature of the panel as the phenomenon items, is compared with preset operating probability upper and lower limits and the operation of starting and stopping the fan is performed. A switchboard ventilation control method characterized by performing control.