JPH08275378A - Phase-advancing capacitor facility higher harmonic current protector - Google Patents

Abstract

PURPOSE: To enable protection and cooperation to plural degrees of higher harmonics by detecting plural degrees of higher harmonic currents flowing into a phase-advancing capacitor, and finding out the quantity of higher harmonic currents geared to the degree of higher harmonics, and opening a switch if this gets over the value of the tolerable higher harmonic currents of the phase-advancing capacitor facility. CONSTITUTION: For a higher harmonic current protector 14, an instrument current transformer 1 for a meter is connected to the input end of a phase-advancing capacitor facility, and further a higher harmonic current signal is inputted into an A/D converter 2, and it is outputted to a computer 5 through a memory 3. The computer 5 computes the quantity of higher harmonic currents of the degree of higher harmonics of each degree contained in a power system. A comparator compares the upper limit value of the quantity of the tolerable current of a phase-advancing capacitor facility with the output signal from the computer 5, and opens the switch of the phase-advancing capacitor facility when it gets over the upper limit value. Hereby, the overheating, burning, or dielectric breakdown of a series reactor or the phase-advancing capacitor can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention monitors harmonic currents superimposed on a power supply system and protects a phase advancing capacitor equipment from harmonic interference.

[0002]

2. Description of the Related Art Recently, with the spread of harmonic generating loads such as inverters, the voltage distortion of the power supply system has increased, and many cases of failures in power equipment due to harmonics have been reported. In the failure example, particularly in phase-advancing capacitor equipment, an increase in inflow of harmonic current into the phase-advancing capacitor circuit causes an accident such as overheating, burnout, or dielectric breakdown of the series reactor.

As one of the measures against the above, it is possible to detect and monitor the current distortion rate or the harmonic current component of the phase advancing capacitor circuit, and when the limit value is exceeded, an alarm is issued and the phase advancing capacitor facility is opened. Has been done.

[0004]

Conventionally, as described above,
There were many examples of applying a harmonic current alarm device to a phase-advancing capacitor circuit, but the method of setting the harmonic current monitoring device for a phase-advancing capacitor circuit is to set each harmonic current distortion factor or single harmonic The harmonic current that normally flows into the phase-advancing capacitor circuit is a combination of multiple harmonic currents.Therefore, in particular, the series reactor used in series with the phase-advancing capacitor circuit is used. In contrast, the higher the harmonic order, the larger the loss, and the conventional method described above cannot provide protection coordination. Therefore, there has been a need for a harmonic current protection device capable of coping with comprehensive multiple harmonic loss.

[0005]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems, and it is possible to measure the harmonic current amount of a plurality of harmonics flowing into a phase-advancing capacitor and perform protection cooperation for the harmonics of a plurality of harmonics. This is a phase-advancing capacitor equipment harmonic current protection device. That is,

(1) Current transformer 1 for instrument and A / D converter 2
, Memory unit 3, harmonic order selection unit 4, and operation unit 5
An allowable value setting unit 6, a comparison unit 7, and a response time setting unit 8
A phase-advancing capacitor equipment harmonic current protection device comprising a control section 9, a control section 9 and a display section 10, wherein the memory section 3 measures the harmonic current flowing into the phase-advancing capacitor equipment with the current transformer 1 for an instrument.
Is converted into a digital signal by the A / D converter 2 via the A / D converter and stored, and the arithmetic unit 5 performs a fast Fourier analysis on the output signal of the memory unit to calculate the amount of harmonics contained in each harmonic. Then, when an arithmetic expression for obtaining the amount of harmonic current according to the harmonic order is input in the harmonic order selection unit 4, the Fourier-analyzed harmonic amount of each order is weighted and integrated to obtain a signal converted into a current value. Is output to the comparison unit 7. In the comparison unit 7, the upper limit value of the allowable harmonic current that flows into the phase-advancing capacitor equipment connected to the power system is set by the harmonic current allowable value setting unit 6, and the value is exceeded by the value of the arithmetic unit output signal. Output an operation signal. The control unit 9 receives the operation signal output from the comparison unit, corrects the control time width to the operation time width preset by the response time setting unit 8 and outputs the operation signal, and opens / closes the phase advance capacitor equipment 13. It is a phase-advancing capacitor equipment harmonic current protection device configured to open the circuit 12.

[0007]

[Action]

(2) The calculation unit 5 performs fast Fourier analysis from the input values input from the memory unit 3 to calculate each harmonic current,
From this, the equivalent fifth harmonic current of the harmonic current weighted integrated value that governs the heat generation amount of the series reactor of the phase-advancing capacitor equipment is calculated, and if this exceeds the upper limit value set by the allowable value setting unit 6, the control signal (1) is a phase-advancing capacitor equipment harmonic current protection device.

(3) The operation unit 5 performs fast Fourier analysis from the input value input from the memory unit 3 to calculate each harmonic current, and from this, each harmonic of the terminal voltage of the phase-advancing capacitor equipment. The phase-advancing capacitor equipment harmonic current protection device of (1) above, which calculates a scalar sum of voltages and obtains a control signal when it exceeds the upper limit value set by the allowable value setting unit 6.

[0009]

[Function] Detects and stores multiple harmonic currents flowing into the phase-advancing capacitor equipment, outputs them to the calculation unit at regular intervals and performs Fourier analysis to determine the amount of harmonic current contained in each harmonic. On the other hand, when the calculation formula (Formula 1 or 2) for calculating the harmonic current amount according to the harmonic order is selected and input in the harmonic order selection unit, The wave amount is weighted and integrated to be converted into a current value, which is output to the comparison unit. Next, set the allowable harmonic current value of the phase-advancing capacitor equipment connected to the power supply system in the allowable value setting section and input it to the comparison section, and this value is exceeded by the output signal value of the above calculation section. Then, the operation signal is output from the comparison unit to the control unit. In the control unit, the control response time is set in advance by the response time setting unit to delay the response speed, and the switch of the phase advancing capacitor equipment is opened.

[0010]

Embodiment 1 FIG. 1 shows an embodiment of the present invention. The phase-advancing capacitor facility 13 is connected to the power supply system 11 via the switch 12. In the above circuit, the phase-advancing capacitor equipment harmonic current protection device 14 is configured such that the instrument current transformer 1 is connected to the input end of the phase-advancing capacitor equipment, and a harmonic current signal is input to the A / D converter 2. The A / D converter converts this into a digital signal and inputs it to the memory unit 3, which stores it and outputs it to the arithmetic unit 5 at regular intervals. The calculation unit 5 performs fast Fourier analysis on the memory output signal,
The harmonic current amount (%) of each harmonic order contained in the power supply system is calculated, while the harmonic order selection unit 4 sets an arithmetic expression in which a single or a plurality of harmonic orders to be converted is set. When input to the arithmetic unit, the arithmetic unit receives this and converts the harmonic current amount into the equivalent fifth harmonic current obtained by weighted integration of the current values of the selected harmonic orders, and outputs the equivalent fifth harmonic current. The comparison unit 7 sets the upper limit value of the permissible current amount of the phase advancing capacitor equipment connected to the power supply system by the permissible value setting unit 6, inputs the upper limit value to the comparison unit 7, and outputs the output signal from the calculation unit. In comparison, the operation signal is output to the control unit when the output signal of the calculation unit exceeds the set value. In the control unit 9, the response time of the switch 12 is set in advance by the response time setting unit 8, the control response time is delayed to an appropriate value, the switch of the phase advancing capacitor equipment is opened, and the series reactor and the phase advancing capacitor are opened. Prevent overheating, burnout or dielectric breakdown.

The content rate of the equivalent fifth harmonic current, which is converted into the loss of the series reactor in the harmonic currents of a plurality of orders flowing into the phase-advancing capacitor equipment, is

[0012]

[Equation 1]

The multiple harmonics are converted into the content ratio of the fifth harmonic current by the method. The allowable harmonic current content rate of the series reactor of the fifth harmonic is defined as 35% in the JIS standard, and setting this value allows protection against multiple harmonics. Is used to protect the series reactor and protect the phase-advancing capacitor equipment from harmonic current disturbance.

In addition, in the phase advancing capacitor equipment composed of the series reactor and the capacitor, the terminal voltage of the phase advancing capacitor due to the inflowing multiple harmonic currents is

[0015]

[Equation 2]

It can be calculated by When the overvoltage allowable value of the phase advancing capacitor is 120%, for example, set the limit value to 12
By setting it to 0% and selecting the equation 2, it is possible to protect mainly the phase-advancing capacitor.

[0017]

According to the present invention, it is possible to detect the harmonic content rate of the harmonic current flowing into the phase advancing capacitor equipment and protect the series reactor by the above Equation 1, and by setting the Equation 2. Since the phase-advancing capacitor can be protected and the phase-advancing capacitor equipment can be surely protected from the harmonic interference, it is industrially and practically valuable.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a phase-advancing capacitor equipment harmonic current protection device of the present invention, which is an embodiment used for a phase-advancing capacitor equipment connected to a power supply system through a switch.

[Explanation of symbols]

 1 Current transformer for instrument 2 A / D converter 3 Memory part 4 Harmonic order selection part 5 Calculation part 6 Allowable value setting part 7 Comparison part 8 Response time setting part 9 Control part 10 Display part 11 Power system 12 Switch 13 Advanced capacitor equipment 14 Advanced capacitor equipment Harmonic current protection device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Toshifumi Tachibana Inventor Toshifumi Tachibana 1st floor of Oike Dori Karasuma Higashiiri, Nakagyo-ku, Kyoto Prefecture Uehara Building, 3rd floor, 191, Nakaboricho Nichicon Corporation (72) Inventor Hirotaka Sawamura Kyoto Prefecture 4th Uehara Building, 3rd floor, Uehara Building, 191, Nakabori-cho, Oike Dori, Karasuma Higashiiri, Nakagyo-ku, Kyoto

Claims (3)

[Claims] 1. An instrument current transformer (1), an analog / digital converter [hereinafter referred to as an A / D converter] (2), a memory section (3), and a harmonic order selection section (4). A calculation unit (5), an allowable value setting unit (6), a comparison unit (7), a response time setting unit (8), a control unit (9), and a display unit (1).
0) and a phase-advancing capacitor equipment harmonic current protection device, wherein the memory section (3) includes a power supply system (11) via an A / D converter (2) and a current transformer (1) for a meter. The calculation unit (5) has an output end of the memory unit (3) and an input end connected to the harmonic order selection unit (4), and the display unit (10) and the comparison unit (7). The output terminal is connected to and, the comparison section (7) is connected to the memory section (5) and the allowable value setting section (6) at the input terminal, and is output to the control section (9). In 9), the output end of the comparison part (7) and the input end of the response time setting part (8) are connected, and the control output end is connected to the switch (12) of the phase advancing capacitor equipment (13). Harmonic current protection device for advanced capacitor equipment. 2. The calculation unit (5) calculates the respective harmonic currents by performing a fast Fourier analysis from the input value input from the memory unit (3), and from this, heat generation of the series reactor of the phase-advancing capacitor equipment. The equivalent fifth harmonic current of the harmonic current weighted integrated value that controls the quantity is calculated, and this is calculated as the allowable value setting unit (6).
2. The advanced phase capacitor equipment harmonic current protection device according to claim 1, wherein a control signal is obtained when the upper limit value set by the above is exceeded. 3. A computing unit (5) performs fast Fourier analysis from the input value input from the memory unit (3) to compute each harmonic current, and from this, each terminal voltage of the phase-advancing capacitor equipment. The phase-advancing capacitor equipment harmonic current protection device according to claim 1, wherein the scalar sum of the subharmonic voltage is calculated, and a control signal is obtained if the sum exceeds a maximum value set by the allowable value setting unit (6). .