JP2535938B2 - Automatic power factor adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention detects a reactive power in order to adjust a power factor of an electric circuit, and controls a power factor adjusting capacitor based on the detected value. The present invention relates to a power factor automatic adjustment device that performs the following.

[Prior Art] FIG. 3 shows a conventional automatic power factor adjusting device described in Japanese Patent Publication No. 60-47823. An electric transformer 1 is connected to an instrument transformer 2 and an instrument current transformer 3, and the output thereof is connected to the reactive power detection device 4 of the automatic power factor adjustment device 30. The detected reactive power is supplied to the comparison circuits 6 and 8 via the amplification circuit 5. The other input of the comparison circuit 6 is connected to the output of the closing point setting resistor 7. The comparison circuit 6 outputs an output signal if the amplified reactive power exceeds the set input point. A breaking point setting resistor 9 is connected to the other input of the comparison circuit 8. The comparator circuit 8 outputs an output signal when the amplified reactive power exceeds the set cutoff point. The timer circuit 20 is provided to prevent the hunting operation. The timer circuit 20 releases the reset state upon input from the OR gate 19, generates an output after the time set by the timer setting resistor 21 has elapsed, and thereafter returns to the reset state again.

The first sequential circuit 23 is energized by the output of the first gate circuit 17, that is, the output of the comparison circuit 6 and the output of the timer circuit 20, and selects the capacitors 62a, 62b, 62c connected to the electric circuit 1. The second sequential circuit 24 is energized by the output of the second gate circuit 18 to disconnect it from the electric circuit 1.
Select 62a, 62b, 62c. The relay circuit 25 energizes the relay corresponding to the capacitor selected in the first sequential circuit 23 and deactivates the relay corresponding to the capacitor selected in the second sequential circuit 24. The relay contacts 26a to 26n correspond to the first to nth capacitors 62a to 62n and are energized or deenergized by the relay circuit 25.

[Problems to be Solved by the Invention] The conventional automatic power factor adjusting apparatus cannot set a plurality of closing point setting values and a plurality of closing point setting values. Therefore, it is necessary to make the capacity of each adjustment capacitor equal. That is, control using capacitors having different capacities could not be performed.

Further, in order to determine the setting value of the closing point or the setting value of the breaking point, the calculation has to be performed based on the capacity of the adjusting capacitor, the current transformer ratio, and the transformer transformation ratio. For this reason, there has been a problem that the change of the set value is complicated and an error easily occurs.

The present invention has been made in order to solve the above-described problems, and has as its object to provide an automatic power factor adjustment device that can be easily set and can be controlled using capacitors having different capacities. I do.

[Means for Solving Problems] An automatic power factor adjusting device according to the present invention is a reactive power detecting means for measuring reactive power of an electric circuit based on outputs of a transformer and a current transformer, and the above-mentioned transformer. Setting means for setting the transformation ratio, the current ratio of the current transformer, and the capacities of a plurality of capacitors for adjusting the power factor, calculating means for calculating the closing level and the cutoff level based on the installation value of the setting means, reactive power detection If the reactive power measured by the means exceeds the input level, output a control signal to connect a capacitor for power factor adjustment,
If the reactive power exceeds the cutoff level, a control signal output means for outputting a control signal for disconnecting the power factor adjusting capacitor, and the control signal for the control signal output means according to the state of the signal given from the outside. Prohibition signal input means that enables relay operation control from external equipment by prohibiting or canceling prohibition of the output of, the closing end signal when all the adjustment capacitors are turned on, and the cutting end signal when all are turned off, An end signal output means for outputting to the outside as a control end signal of the device is provided.

[Operation] The calculating means calculates the closing level and the cutoff level based on the transformation ratio, the current ratio and the capacitance of each capacitor set by the setting means. The control signal output means outputs a closing control signal if the reactive power exceeds the closing level,
If the reactive power exceeds the cutoff level, a cutoff control signal is output. The prohibition signal input from the prohibition signal input means prohibits the control signal from being output. The end signal output means outputs a closing end signal when all the capacitors are turned on, and outputs a cutting end signal when all the capacitors are turned off.

[Embodiment] Fig. 1 shows a system configuration diagram of an embodiment of an automatic power factor adjusting apparatus according to the present invention. An electric transformer 1 and an electric current transformer 3 are connected to the electric circuit 1, and the output thereof is connected to the reactive power detecting unit 101 of the automatic power factor adjusting device 100. The output of the reactive power detection unit 101 is given to the CPU 102.

The CPU 102 performs processing according to a program stored in the ROM 103. FIG. 2 shows this program as a flowchart. In step S1, the CPU 102
Reads the measured reactive power value detected by the reactive power detection unit 101. Based on this, the reactive power value is calculated (step S2). Next, it is determined whether the reactive power value is advanced or delayed (step S3). If it is advanced, the process proceeds to step S4, and it is determined whether the reactive power value has exceeded the cutoff point set value. If the reactive power value exceeds the cutoff point set value, a cutoff signal is output via the relay control unit 107 (step S5). If not exceeded, the process returns to step S1. The control signal from the relay control unit 107 is given to the capacitor control unit 50. Upon receiving the cutoff control signal, the capacitor control unit 50 cuts off the corresponding capacitors 62a, 62b, 63c.

In step S3, when the reactive power value is delayed, the process proceeds to step S6, and it is determined whether the reactive power value has exceeded the input point set value. If the reactive power value has exceeded the closing point set value, a closing signal is output via the relay control unit 107 (step S7). If not, step S1
Return to Upon receiving the input signal, the capacitor control unit 50 inputs the corresponding capacitors 62a, 62b, 62c.

When no signal is input to the closing prohibition / cutoff prohibition signal input unit 109, the operation is performed as described above. Then, when all the capacitors are turned on or cut off, a closing end signal or a closing end signal is output from the closing end / cutting end signal output unit 108.

On the other hand, when the closing prohibition signal or the breaking prohibition signal is input, the closing signal is not output and the control state is maintained as it is.

Which of the capacitors 62a, 62b, 62c is to be turned on or off is determined by a signal from the relay control unit 107.

If the capacitor capacities set in the setting unit 105 are all equal, the CPU 102 performs cyclic control to make the number of times of opening and closing uniform. When the capacitors have different capacities, priority control is performed to control the capacitors having smaller capacities. As a result, it is possible to prevent an extreme leading power factor or lagging power factor when the load is light.

[Advantages of the Invention] The automatic power factor adjusting device according to the present invention has the following advantages.

According to the present invention, there is provided a calculating means for calculating the closing level and the cutoff level based on the set value of the setting means. Therefore, it is only necessary to set the transformation ratio, the current transformation ratio, and the capacitance of the capacitor, and there is no need to perform cumbersome calculations as in the conventional case. Since the capacity of each capacitor can be individually set by the setting means, capacitors having different capacities can be used. In addition, depending on the state of the signal given from the outside, the prohibition signal input means that prohibits or releases the prohibition of the control signal output to the control signal output means, and if all the adjustment capacitors are turned on or off, the closing or closing Since the end signal output means for outputting the end signal to the outside as the control end signal of the device is provided, the power factor adjustment by turning on / off the capacitor connected to the device based on the relay operation control from the external device. Can be started, and the end of control can be transmitted to another external device.

[Brief description of drawings]

FIG. 1 is a diagram showing a system of an automatic power factor adjusting device according to an embodiment of the present invention, FIG. 2 is a diagram showing its operation as a flowchart, and FIG. 3 is a configuration of a conventional automatic power factor adjusting device. It is a figure. 2 is an instrument transformer, 3 is an instrument current transformer, 101 is a reactive power detection unit, 102 is a CPU, 105 is a setting unit, 107 is a relay control unit,
Reference numeral 108 is a closing end / cutoff end signal output section, and 109 is a closing prohibition / cutoff prohibition signal input section. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A reactive power detection means for measuring the reactive power of an electric circuit based on the output of a transformer or a current transformer, a transformer conversion ratio, a current transformer ratio of the current transformer, and a power factor adjustment. Setting means for setting the capacities of a plurality of capacitors, a calculating means for calculating the making level and the cutoff level based on the set values of the setting means, and if the reactive power measured by the reactive power detecting means exceeds the making level. A control signal output means for outputting a control signal for connecting a capacitor for adjusting the power factor and outputting a control signal for disconnecting the capacitor for adjusting the power factor when the reactive power exceeds the cutoff level. Inhibition signal input means that enables relay operation control from an external device by inhibiting or releasing the output of the control signal to the control signal output means according to the state, and an adjustment coil Poured completion signal when all charged capacitors,
An automatic power factor adjusting device comprising: an end signal output means for outputting a cutoff end signal to the outside as a control end signal of the device if all of them are cut off.