JP3137172B2 - Power factor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power factor control device for improving a power factor of a power system, and more particularly to a power factor control device including a capacitor and a reactor.

[0002]

2. Description of the Related Art Conventionally, as a power factor control device of this kind, FIG.
There were the following. 3A, 3B, and 3C.
Shows a connection state diagram and an equivalent circuit diagram of a conventional device.

FIG. 1A shows a conventional power factor control device 3.
00 is connected in parallel to a load 200 connected to the power system 100, and is formed by a series circuit of a capacitor 11C (or 12C) and a reactor 11L (or 12L);
The capacitor 11C (or 12C) compensates for the phase delay caused by the load 200, and the reactor 11L
(Or 12L) to suppress the effect of inrush current. In addition, when the capacitor 11C (or 12C) and the reactor 11L (or 12L) are regarded as a series resonance circuit, the power factor control device 300 absorbs a harmonic current generated in the load 200 by the series resonance circuit. Thereby, the harmonic current flowing out to the power system 100 can be suppressed.

The power factor control device 30 shown in FIG.
0 is a capacitor 11C, a reactor 11L and a resistor 11L.
Formed by connecting in series with R to act as a tuning filter. That is, the values of the capacitor 11C and the reactor 11L are constant so that 2πfn = 1 / square root (LC) with respect to the harmonic frequency fn to be absorbed so as to resonate at a single harmonic and obtain a low impedance. Is the configuration to be selected.

The power factor control device 300 shown in FIG. 3 (C) has a secondary type high-power circuit by connecting a reactor 12L and a resistor 12R in parallel, and connecting a capacitor 12C in series with this parallel circuit. Act as a next filter.
Since the resonance circuit as the secondary high-order filter has low impedance even in the lowest frequency band at the resonance frequency, it can absorb the harmonic current in a wide frequency range.

[0006] Each of the reactors 11L and 12L acts to control the flow of an excessive current to the capacitors 11C and 12C by a current generated by a back electromotive force. FIG. 4 is a schematic configuration diagram of another conventional power factor control device.

Referring to FIG. 1, a conventional power factor control device applies a switch S1 (S2, S3), a capacitor C1 (C2, C3) and a reactor L1 (L2, L3) to a load 200 connected to a power system 100. Are connected in parallel with each other, and based on the load current IL from the current transformer CT5 and the load voltage VL from the voltage transformer PT5, the switch control circuit 30 switches the switches S1, S2, S3, Is configured to be selected and input.

The switch control circuit 30 calculates the reactive power QL flowing into the load 200 from the detected load current IL and the load voltage VL, and calculates one of the series circuits F1, F2 corresponding to the reactive power QL. , F3, and operates to turn on the switch S1 (or S2, S3) of any of the selected series circuits F1 (or F2, F3).
By turning on the switch S1 (or S2, S3), one of the series circuits F1 (or F2, F3) is connected in parallel to the load 200, and the power factor on the power system 100 side can be improved.

[0009]

Since the conventional power factor control device is constructed as described above, polyvinyl chloride (PCB) is used as an insulating oil for a capacitor constituting the device.
When a capacitor is used, when an excessive current flows due to a resonance phenomenon in the capacitor, the capacitor is overheated to cause deterioration of characteristics, and there is a problem that an explosion may occur.

A capacitor using this PCB is shown in FIG.
Production banned in 1975 and banned in 1977,
Existing equipment is still used because it is allowed to be used continuously. If the explosion occurs in a capacitor using a PCB that is operating as an existing facility as described above, the toxicity of the PCB has a serious effect on the human body and has a risk of environmental pollution. Further, the reactor also has a problem that it is overheated by the application of an excessive current due to the resonance phenomenon and causes deterioration of characteristics, which may cause an explosion.

As described above, automatic power factor control is performed even when an overcurrent is flowing due to a resonance phenomenon caused by harmonics. If the capacitor is switched on and off in this state, the life of the switch is significantly shortened. Or the condenser or the reactor itself may explode.

In order to prevent an overheating and an explosion accident due to a resonance phenomenon of a capacitor and a reactor forming the power factor control device, there are conceivable methods such as surface temperature measurement of equipment and monitoring of abnormal sound. There was a problem that monitoring could not be performed, and it was necessary to approach the device to confirm it, which was dangerous.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to propose a power factor control device capable of preventing deterioration and explosion of a capacitor and a reactor used for power factor improvement. I do.

[0014]

FIG. 1 is a diagram illustrating the principle of the present invention. In the power factor controller according to the present invention the figure, is connected in parallel to the load connected to the electric power system, the power factor controller which is formed by serially connecting a capacitor and a reactor, specific caused by the load High harmonics
Capacitor and reactor tuned to wave current
A harmonic filter comprising a series resonant circuit formed by:
The load, the harmonics detection means for detecting a harmonic of the predetermined value occurring in equipment that affects the power system or the power system, a harmonic issued before dangerous is the specific harmonic field <br Separation means for separating the capacitor or the reactor from the power system, and a notification means for outputting an alarm as an occurrence of an abnormality when the harmonic is detected, thereby affecting the load, the power system or the power system. This protects the capacitor or the reactor from harmonics generated by devices that provide the following.

Further, the power factor control device according to the present invention includes a detection setting value unit for setting a frequency value of a harmonic detected by the harmonic detection unit to an arbitrary value as necessary .

[0016]

[0017]

According to the present invention, the load is detected by the harmonic detection means.
Emitted from the power system or equipment that affects the power system
The generated harmonics are detected, and the detected
Characteristic harmonics caused by the load connected in parallel with the wave filter
If it is a current, another force connected to the same power system
Output of specific harmonics to the rate control device.
In addition, when a harmonic other than this specific harmonic current is detected,
In the normal case, disconnect the harmonic filter by separating means.
In addition, an alarm is output by the notification means, so that the load,
Power system or equipment that affects the power system
The resulting harmonics form a capacitor and a capacitor that form a harmonic filter.
Flow into the reactor and the reactor.
Can prevent the reactor from deteriorating and exploding. Further
Other than the load connected in parallel with the harmonic filter,
Power system or equipment that affects the power system
When the generated harmonics are not detected,
Harmonics generated from the load can be absorbed, and
The output of the harmonics is blocked.

Further, in the present invention, by setting the detection level of harmonics arbitrarily by the detection value setting means,
The constant for the harmonic frequency of the capacitor and the reactor can be adjusted, and the power factor on the load side can be adjusted by setting the optimum detection state for each device.

[0019]

[0020]

[0021]

An embodiment of the present invention will be described below with reference to FIG. FIG. 2 shows a block diagram of the apparatus of this embodiment. In the figure, the power factor control device according to the present embodiment has three phases and three phases.
The load current IL of the power supply line 10 is connected to the current transformers CT1, C
At T2, the load voltage VL of the power supply line 10 is detected.
Is detected by the voltage transformer PT1, the control calculation unit 1 calculates a reactive power component based on the detected load current, IL and load voltage VL, outputs a control command signal S3, and outputs a control command signal S3 from the timer 4. An on / off command signal S4 is output based on the time-over signal S2, and a capacitor switch connected to the power supply line 10 via the control circuit unit 21 based on the control command signal S3 or the on / off command signal S4. In this configuration, the closing / opening of the capacitor switch 11 of the series resonance circuit of the reactor 11, the reactor 12, and the capacitor 13 is controlled.

Current transformers CT 3 and CT 4 are connected to the lead-in line to the series resonance circuit, and detect the current IC and output it to the harmonic detector 3. This harmonic detector 3
Extracts harmonic components such as third, fifth, and seventh harmonics based on the detected harmonics of the current IC, and sets the harmonics set and input in advance by the harmonic level setting unit 6. And outputs a detection signal S1 of "H" or "L" to the timer 4 and the alarm output unit 5.

When a detection signal S1 (hereinafter, "H" detection signal) indicating that a higher harmonic than the set harmonic has been extracted is input, the timer 4 outputs the "H" detection signal S1.
When the integrated value is equal to or greater than a preset value, a time-over signal S2 is output to the control operation unit 1.

When the "H" detection signal is input, the alarm output unit 5 outputs an alarm indicating that a current including a harmonic component has flowed into the series resonance circuit to the outside. The control circuit unit 21 receives the control command signal S3 and the ON / OFF command signal S4 from the control operation unit 1 by turning on / off the capacitor switch 11.
It is converted to a signal to control opening.

Next, the operation of the apparatus of this embodiment based on the above configuration will be described. First, the upper limit value and the lower limit value of the reactive power are set in advance by the reactive power value setting unit 7. Usually, the load current IL and the load voltage VL are controlled by the current transformers CT1, CT2 and the voltage transformer PT1. Enter 1
The control arithmetic unit 1 measures the reactive power and outputs a control command signal S3 when the reactive power exceeds the upper limit value, thereby outputting a cutoff signal to the capacitor switch 11 via the control circuit unit 21 and the reactor 12 , The capacitor 13 and the power line 10
Disconnect from When the calculated reactive power falls below the lower limit value, the control unit 21 outputs a control command signal S3 to output an input signal to the capacitor switch 11 via the control circuit unit 21. To adjust the power factor.

In parallel with the power factor adjustment, the current transformer CT
3. The current IC is constantly detected by CT4, and the harmonics of the detected current IC are extracted by the harmonic detector 3, and the higher harmonic than the value set in advance by the harmonic level setting unit 6 is extracted. When the extraction time continues for a time longer than the time set by the timer 4, a signal is output to the control operation unit 1. Upon receiving this signal, the control operation unit 1 stops the automatic power factor control, and at the time of this stop, the capacitor switch 1
If 1 is turned on, a shutoff signal is output immediately to turn off the capacitor switch 11, and the reactor 12, the capacitor 13
Is disconnected, and an alarm signal is output by the alarm circuit unit 5 to notify the abnormality.

In the above, the embodiment in which the reactive power is detected has been described. However, the present invention can also be applied to a power factor control device that switches on and off a capacitor and a reactor by power factor control, current control, time control, and the like. In the case of detecting a harmonic, not only the current transformers CT3 and CT4 but also a method using the current transformers CT1 and CT2 can be applied.

In the figure, the current transformers CT3 and CT4 are set above the capacitor switch 11, but a current transformer can be installed inside the capacitor switch 11. In the above-described embodiment, the timer 4 outputs the time-over signal based on a preset reference time. However, the timer 4 may include a reference time setting unit that sets the reference time to an arbitrary value. Can also. Since the reference time can be set arbitrarily in this manner, the optimum time corresponding to each harmonic filter can be selected.

In the above embodiment, the capacitor 13 of the power factor control device is used for leading the phase and the reactor 12
Acts so as to suppress the effect of the inrush current. However, the reactor 12 and the capacitor 13 are tuned to a specific harmonic current generated in the load 2 connected in parallel with the reactor 12 and the capacitor 13. , And maintains the closed state without opening the capacitor switch 11 even when the harmonic detector 3 detects a harmonic corresponding to the specific harmonic current. It can also be configured as follows.

Even if a specific harmonic is generated from the load 2 connected in parallel to the reactor 12 and the capacitor 13 as described above, the specific harmonic is transmitted to another power factor control device connected to the same power supply line 10. Output can be prevented. Further, when a harmonic current other than the specific harmonic is generated and output from another load connected to the same power supply line 10, the detection by the harmonic detection unit 3 is performed in the same manner as in the embodiment. The control circuit 21 controls the capacitor switch 11 to open based on the above, and the reactor 12 and the capacitor 13 can be separated from the power supply line 10 to prevent deterioration and explosion.

[0031]

As described above, in the present invention, the harmonic
The detection means may affect the load, the power system, or the power system.
Harmonics generated by devices that detect
Harmonics are generated by the load connected in parallel to the harmonic filter.
If the harmonic current is unique,
Unique harmonic output to other connected power factor controllers
Harmonics other than this unique harmonic current
Separation means for harmonic filter in case of abnormality detected
And output an alarm by the notification means.
Impact on the load, the power system or the power system concerned.
Harmonics generated by such devices form a harmonic filter.
To the condenser and reactor
To prevent deterioration or explosion of capacitors or reactors.
This has the effect that it can be stopped . In addition, harmonic filters
Other than the load connected in parallel to the
Harmonics generated by devices that affect the power system are detected
Harmonics arising from loads connected in parallel during normal operation
Waves can be absorbed, preventing the output of harmonics to the outside.
This has the effect of stopping. In the present invention,
Arbitrarily set the detection level of harmonics using the detection value setting means.
The harmonic frequency of the capacitor and reactor
Can be adjusted for each device.
The detection state has an effect that the power factor on the load side can be adjusted .

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of a power factor control device according to the present invention.

FIG. 2 is a block diagram of a power factor control device according to one embodiment of the present invention.

FIG. 3 is a connection mode diagram and an equivalent circuit diagram of a conventional power factor control device.

FIG. 4 is a schematic configuration diagram of another conventional power factor control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control calculation part 2, 200 load 3 Harmonic detection part 4 Timer 5 Alarm output part 6 Harmonic level setting part 7 Reactive power value setting part 10 Power supply line 11 Capacitor switch 12 Reactor 13 Capacitor 21 Control circuit part 100 Power system 300 Power factor control device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-153380 (JP, A) JP-A-4-312322 (JP, A) JP-A-6-165368 (JP, A) 17333 (JP, U) JP 6-48018 (JP, U) JP 2 125546 (JP, U) JP 2 2723 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G05F 1/70

Claims (2)

(57) [Claims] 1. A power factor control device, which is connected in parallel to a load connected to a power system and is formed by connecting a capacitor and a reactor in series, tunes to a specific harmonic current generated in the load. Before
Series resonance circuit formed by the capacitor and the reactor
A harmonic filter consisting of the load, the harmonics detection means for detecting a harmonic of the predetermined value occurring in equipment that affects the power system or the power system, the harmonics unique said issued before dangerous comprising separating means for separating the capacitor or reactor when it is harmonic from the electric power system, and a notification unit for outputting a warning an abnormality occurs when the is harmonics detection, the load, the power system or the power system A power factor control device characterized in that a capacitor or a reactor is protected from harmonics generated by devices or the like that affect the power factor. 2. The power factor control apparatus according to claim 1, further comprising a detection value setting unit that sets a frequency value of a harmonic detected by the harmonic detection unit to an arbitrary value. Rate control device.