JP3396326B2 - Harmonic protection device for advanced capacitor equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention monitors a harmonic voltage 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 the damage to power equipment due to harmonics has increased.
Especially in phase-advancing capacitor equipment, an increase in the inflow of harmonic current into the phase-advancing capacitor circuit causes accidents such as overheating, burnout, or dielectric breakdown of the series reactor.

As one of the measures against the above, the current distortion rate or the harmonic current component of the phase advancing capacitor circuit is detected and monitored, and when the limit value is exceeded, an alarm is issued and the phase advancing capacitor facility is opened. Is being done.

[0004]

In the above-mentioned prior art, when the phase-advancing capacitor circuit is opened by the operation of the harmonic current alarm device, the subsequent current detection becomes impossible, and therefore, the re-starting and the re-operation are performed thereafter. There was a drawback that it was impossible to judge whether or not.

FIG. 2 shows an example in which a harmonic current alarm device is applied to a conventional phase-advancing capacitor circuit. In the phase-advancing capacitor equipment, a harmonic current is added to a circuit consisting of a phase-advancing capacitor, a series reactor and a switch. This device is equipped with an alarm device.This device detects the current of the phase advancing capacitor circuit with the current transformer for the instrument, and when the harmonic current amount increases and the phase advancing capacitor circuit is overloaded, it gives an alarm. The control signal is issued to open the switch.

In the above device, when the switch opens due to the operation of the harmonic current alarm device, the current in the phase-advancing capacitor circuit becomes zero, and it becomes impossible to monitor the harmonics thereafter, and it is judged whether or not the switch can be reclosed. There was a drawback that I could not.

Further, in general, a current transformer for an instrument is often not connected in a phase-advancing capacitor equipment, and when a harmonic current monitoring device is newly provided, it is necessary to install a current transformer for an instrument. was there.

In addition to the above-described current detection, a method of measuring only the voltage distortion rate of the power supply system and opening the switch to stop the phase advancing capacitor equipment when the voltage distortion rate exceeds the limit value is adopted. However, the number of harmonics included in the power supply system is not only a single one, but multiple harmonics are always combined, so the harmonics that flow into the phase-advancing capacitor equipment are also combined. In such a case, the loss of the capacitor and the series reactor varies greatly depending on each harmonic, and setting the single voltage distortion factor only or the method of setting only the combined voltage distortion factor protects the circuit. There was a need for a harmonic monitoring and control device that could not cooperate with each other and was capable of calculating the weighted average value of harmonic distortions of multiple orders and that had a more sophisticated calculation function.

[0009]

DISCLOSURE OF THE INVENTION The present invention is to solve the above problems, and measures the amount of higher harmonics contained in a power supply system so that protection cooperation can be performed against the higher harmonics. This is a phase-advancing capacitor equipment harmonic protection device. That is,

(1) Instrument transformer 1 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 protection device including a control unit 9 and a display unit 10, and the memory unit 3 of the protection device.
Converts the harmonic voltage contained in the power supply system 11 into a digital signal by the A / D converter 2 via the transformer for instrument 1 and stores the digital signal, and the arithmetic unit 5 stores the output signal of the memory unit in the fast Fourier transform. Analyze each harmonic voltage contained in the power supply system by analysis, convert this to the harmonic current amount, and calculate the harmonic current by the formula for calculating the harmonic order selected by the harmonic order selection unit 4. The weighted integrated value of the quantity is output, and the comparison unit 7
Is an upper limit value of the permissible harmonic current amount of the phase-advancing capacitor equipment connected to the power supply system set by the harmonic current permissible value setting unit 6, and when the value exceeds the value of the arithmetic unit output signal, the 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 the phase advance capacitor A phase-advancing capacitor configured to open the switch 12 of the facility 13 and reclose the circuit when the amount of harmonic current contained in the power supply system returns to a value equal to or lower than the set allowable value, and to repeat the series of operations. In the equipment harmonic protection device 14, a fast Fourier analysis is performed from the input value input from the memory unit 3 to the arithmetic unit 5 to calculate each harmonic voltage, and thereby the phase advance capacitor connected to this system. Each inflow to the facility The harmonic current is calculated, and from this, the equivalent fifth harmonic current value that controls the generated loss of the series reactor of the phase-advancing capacitor equipment is calculated. If this value exceeds the upper limit value set in the allowable value setting unit 6, switching is performed. A phase-advancing capacitor equipment harmonic protection device characterized in that a control signal for opening the device (12) is obtained, and when it is reduced to a certain value or less, it is closed again.

[0011]

(2) Further, instead of calculating the above-mentioned equivalent fifth harmonic current value, the sum of each harmonic voltage of the terminal voltage of the capacitor of the phase advancing capacitor equipment is calculated, and this is the allowable value setting section. When the upper limit value set in 6 is exceeded, a control signal for opening the switch is obtained, and when it is reduced below a certain value, the circuit is closed again. It is a wave protection device.

[0013]

[Function] Detects and stores the voltage components of multiple harmonics that are superimposed on the power supply system, outputs this to the calculation unit at regular time intervals, and performs Fourier analysis to determine the amount of harmonics contained in each harmonic. On the other hand, when the calculation of the harmonic current amount according to the harmonic order is selected and input in the harmonic order selection unit, the harmonics of each order obtained by the Fourier analysis are calculated. The waves are weighted and integrated into a signal converted into a current value and output to the comparison unit. Next, when the upper limit of the allowable harmonic current value of the phase-advancing capacitor equipment connected to the power supply system is set in the allowable value setting unit and input to the comparison unit, this value is the value of the output signal of the arithmetic unit. When is exceeded, the operation signal is output from the comparison unit to the control unit. Further, in the control unit, the control response time is set in advance by the response time setting unit to delay the response speed, the switch of the phase advancing capacitor equipment is opened, and the amount of harmonic current in the power supply system is reduced. At this time, the switch of the advanced capacitor equipment is closed again, and the above operation is repeated as a series of operations.

[0014]

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 protection device 14 is such that the instrument transformer 1 is connected to the power supply system 11 and a harmonic voltage signal is input to the A / D converter 2 and the A / D converter is This is converted into a digital signal and input to the memory unit 3, and the memory unit 3 stores this and outputs it to the arithmetic unit 5 at regular intervals. The calculation unit 5 performs fast Fourier analysis on the memory output signal to calculate the amount of harmonics (%) of each harmonic order contained in the power supply system, while the harmonic order selection unit 4 uses a single or multiple harmonic order. Is input to the arithmetic unit, and the arithmetic unit receives the above and calculates the above harmonic amount by the weighted integrated value of the current values of the selected harmonic orders (equivalent fifth harmonic current value). ) And output to the comparison unit 7. The comparing unit 7 determines the upper limit value of the permissible current amount of the phase advancing capacitor equipment connected to the power supply system as the permissible value setting unit 6
The input signal is input to the comparison unit 7 and is compared with the output signal output from the calculation unit. When the output signal of the calculation unit exceeds the set value, the operation signal is output to the control unit. 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, and the switch of the phase advancing capacitor facility is opened.

When the harmonics of the power supply system are reduced to a certain value or less, the output signal of the arithmetic unit is input to the control unit to reclose the switch 12, and by repeating this, overheating and burnout of the phase-advancing capacitor equipment are performed. Alternatively, dielectric breakdown can be prevented.

Generally, from the amount (%) of the harmonic voltage distortion rate of the power supply system, the formula for calculating the nth harmonic current Icn flowing into the phase advancing capacitor equipment connected to the power supply system is

[0017]

[Equation 1]

Therefore, for example, the inflowing nth harmonic current Icn when the compensation ratio of the series reactor of the phase advancing capacitor equipment to the phase advancing capacitor is 6%,

[0019]

[Equation 2]

The n-th harmonic current content (In%) can be calculated by

[0021]

[Equation 3]

From the harmonic voltage distortion rate (%),
It is possible to calculate the harmonic content rate (%) flowing into the phase-advancing capacitor equipment.

Next, when the compensation rate of the series reactor is 6%, the equivalent fifth harmonic content rate of the total harmonic current in the inflow of the combined harmonic currents of the plurality of orders is:

[0024]

[Equation 4]

For example, when a plurality of harmonics are converted into the fifth harmonic current content rate (%) and calculated, the series reactor allowable harmonic current content rate is 35% for the fifth harmonic according to the JIS standard. By setting 35% as the set value, it is possible to protect against multiple harmonics.

As described above, the phase-advancing capacitor equipment harmonic protection device for detecting and protecting the harmonic voltage of the present invention comprises:
When the compensation rate of the series reactor is 6%, the harmonic order setting unit 4 selects the value of Formula 4, the harmonic voltage is measured, and the calculation unit 5 uses the preset formula to set the phase-advancing capacitor equipment. The inflowing harmonic current is calculated, and if it exceeds a preset limit value preset by the tolerance setting unit 6, a control signal is output to protect the phase-advancing capacitor equipment.

When the compensation ratio of the series reactor of the phase advancing capacitor equipment is 8% or 13%, the amount of the inflowing harmonic current due to the harmonic voltage distortion ratio is different from the above 6%. The equivalent fifth harmonic current content rate (%) when the inflow harmonic is a total harmonic when the compensation output is calculated and output by a suitable calculation formula, for example, when the compensation rate is 8%,

[0028]

[Equation 5]

As in the case of the compensation rate of 6% for the series reactor, it is possible to convert the synthesized harmonics of a plurality of orders into the fifth harmonics. Further, the 8% series reactor allowable harmonic current content rate is 35% for the fifth harmonic according to the JIS standard, and setting 35% as the set value can protect against multiple harmonics.

As described above, in the device of the present invention, when the compensation rate of the series reactor is 8%, the formula 5 is selected in the harmonic order setting unit 4, and the harmonic voltage is measured to calculate the arithmetic unit 5. The harmonic current that flows into the phase-advancing capacitor equipment is calculated by the formula set in step 2.When the preset limit value set by the upper limit setting unit is exceeded, a control signal is output to protect the phase-advancing capacitor equipment. is there.

Further, the terminal voltage of the phase-advancing capacitor in this case becomes an overvoltage because each harmonic voltage is superposed on the fundamental wave voltage due to the inflow of the harmonic current, so that this terminal voltage is changed.

[0032]

[Equation 6]

When the result is calculated by the above, and the result exceeds the preset limit value set in advance in the upper limit value setting section, a control signal can be output to protect the phase advancing capacitor.

[0034]

According to the present invention, it is possible to re-operate the switch 12 after the open circuit, as compared with the conventional monitoring apparatus for only the harmonic current, and to compare with the monitoring for only the harmonic voltage distortion rate. The harmonic current content rate flowing into the phase advancing capacitor equipment can be calculated by the calculation formula set by the calculator 5 according to the compensation ratio of the series reactor, and if the preset limit value preset by the upper limit setting unit 6 is exceeded, the phase advance is advanced. If the capacitor equipment can be opened reliably and the harmonic current flowing into the phase advancing capacitor equipment is reduced below the allowable value, the switch can be reclosed, and harmonic interference of the phase advancing capacitor equipment can be restored. Can be reliably prevented, and there are some industrially and practically valuable things.

[Brief description of drawings]

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

FIG. 2 is a circuit example of a conventional harmonic current alarm device.

[Explanation of symbols]

1 Instrument transformer 2 A / D converter 3 memory section 4 Harmonic order selection section 5 computing section 6 Allowable value setting section 7 comparison section 8 Response time setting section 9 control unit 10 Display 11 power supply system 12 switches 13 Phase-advancing capacitor equipment 14 Phase-advancing capacitor equipment harmonic protection device 20 Current transformers for instruments 21 Harmonic current monitor

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Toshifumi Tachibana Toshifumi Tachibana 4th floor, Uehara Building, 4th floor, 191 Nakabori-cho, Nichicon Co., Ltd. (72) Inventor Hirotaka Sawamura Kyoto Prefecture Kyoto Prefecture 4 Uehara Bldg., 3rd floor, 191, Nakabori-cho, Oike Dori, Karasuma Higashiiri, Nakagyo-ku, Nichicon Co., Ltd. (56) Reference JP-A-6-165368 (JP, A) JP-A-5-199652 (JP, A) JP-A-5-207640 (JP, A) JP-A-7-23527 (JP, A) JP-A-8-43459 (JP, A) JP-A-6-153380 (JP, A) JP-A-4-312322 (JP, A) JP-A-4-261329 (JP, A) Actual development 5-43726 (JP, U) Actual development 6-17333 (JP, U) (58) Fields investigated (Int.Cl. ⁷⁾ , DB name) H02H 3/52 H02H 7/16 G05F 1/70

Claims (2)

(57) [Claims] 1. An instrument 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 protection device, and the memory unit (3) of the protection device includes a power supply system (11) via an A / D converter (2) and an instrument transformer (1). ), The arithmetic unit (5) is connected to the output end of the memory unit (3) and the input end to the harmonic order selection unit (4), and the display unit (10) and the comparison unit (7). ) Is connected to the output terminal, and the comparison section (7) is connected to the calculation 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 unit (7) and the input end of the response time setting unit (8) are connected, and the control output end is connected to the switch (12) of the phase advancing capacitor facility (13), Fast Fourier analysis is performed from the input value input from the memory unit (3) in the operation unit (5) to calculate each harmonic voltage, and Each harmonic current that flows into the phase-advancing capacitor equipment connected to this system is calculated, and from this, the equivalent fifth harmonic current value that controls the generated loss of the series reactor of the phase-advancing capacitor equipment is calculated, A control signal for opening the switch (12) is obtained when this exceeds an upper limit value set in the allowable value setting section (6), and reclosing is performed when the switch signal is reduced below a certain value. Harmonic protection device for phase-advancing capacitor equipment. 2. Instead of calculating the equivalent fifth harmonic current value, the scalar sum of each harmonic voltage of the terminal voltage of the capacitor of the phase advancing capacitor equipment is calculated, and this is the allowable value setting section (6). The control signal for opening the switch (12) is obtained when the upper limit value set in the above is exceeded, and the control signal is closed again when it is reduced to a certain value or less.
Harmonic protection device for advanced phase condenser equipment.