JPH0652759A - Non-effectively earthed system opening phase control device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a non-effective grounding system opening phase control device capable of performing non-effective grounding system shunt reactor interruption without causing re-arcing. [Configuration] Power supply system 1 with non-effective grounding system shunt reactor 4
The opening phase of the circuit breaker 2 that opens and closes is controlled. The phase detecting means 7 detects the voltage phase of the power system 1.
Based on the detected voltage phase, the time calculating means 8
The time during which the circuit breaker 2 can be interrupted without re-ignition is calculated. In accordance with the calculated breakable time, the break command means 9 and 10 send a break command 13 to the breaker 2 to cause the breaker 2 to break during the breakable time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an opening phase control device for preventing a high frequency re-arc surge that occurs when a non-effective earthing system shunt reactor connected to a power system via a circuit breaker is disconnected. .

[0002]

2. Description of the Related Art Generally, a shunt reactor and a power system are connected to each other via a circuit breaker and a power cable. However, when the shunt reactor circuit is disconnected from the system, the inductance of the shunt reactor and the capacitance of the power cable, etc. A high-frequency re-ignition phenomenon may occur between the circuit breaker poles due to the electric circuit composed of the minute parts.

FIG. 4 is a voltage / current waveform diagram showing a high frequency re-arcing phenomenon when the circuit breaker for a shunt reactor is opened. In this case, (a) shows a voltage waveform and (b) shows a current waveform. Since most of the shunt reactor circuit is an inductance component, the current phase has a waveform delayed by 90 ° with respect to the voltage phase. Normally, the circuit breaker interrupts the current at the time when the current becomes zero (referred to as the current zero point). At this current zero point, the voltage waveform in which the phase leads the current by 90 ° becomes the maximum value.

By the way, in the normal shunt reactor load current interruption, since the interruption ability of the circuit breaker is high with respect to the current value, as shown in FIG. 4, immediately before the current zero point (time t ₀ ).
The phenomenon of cutting off the current occurs. Along with this breaking phenomenon, a breaking surge 31 of about several kHz occurs in the voltage waveform as shown in FIG. The frequency of this breaking surge is determined by the natural vibration frequency of an electric circuit composed of L and C components existing in the shunt reactor and the power cable. When the oscillating voltage determined in this way is applied between the circuit breaker poles for the shunt reactor, the voltage difference between the circuit breaker poles remains almost at the maximum commercial voltage at the power supply side end. Occur. Then, when the circuit breaker pole transient recovery voltage cannot withstand the circuit breaker pole insulation recovery characteristic, reignition occurs between the circuit breaker poles. 3 of FIG.
Reference numerals 2 and 33 respectively indicate a voltage surge and a current surge associated with such re-arcing.

[0005]

As described above, when a shunt reactor load current is interrupted and a re-ignition occurs between the circuit breaker poles, the surge associated with this re-ignition is as shown in FIG. The voltage level is not so high, but the frequency is as high as several hundreds to several kHz. And while such surges are less of a problem in the short term,
Since it is repeatedly applied many times in the long term, the insulation characteristics of the shunt reactor, the power cable, the circuit breaker, etc. are deteriorated, which is a problem.

In this case, there is no problem if the occurrence of the re-arcing itself can be prevented, but it is stochastically difficult to prevent the re-arcing. That is, the case where the circuit breaker pole insulation recovery characteristics cannot withstand the above-mentioned circuit breaker pole transient recovery voltage is
This is the case where the circuit breaker is opened and the electrodes are not opened sufficiently, and the current is cut off when the insulation distance between the electrodes is insufficient. It is difficult to reliably prevent the occurrence of arcing, and therefore, recurrence arcs will always occur with probability.

As described above, in the conventional non-effective grounding system shunt reactor interruption, a recurrence arc always occurs stochastically due to the gap distance of the interruption command and the current phase of the grid, and the recurrence arc cannot be prevented. For this reason, in the long term, the surge associated with the re-ignition is repeatedly applied, which deteriorates the insulation characteristics of the shunt reactor, the power cable, the circuit breaker, and the like, which is a problem.

The present invention has been proposed in order to solve the problems of the prior art as described above, and an object thereof is to perform ineffective grounding system shunt reactor interruption without causing re-arcing. It is an object of the present invention to provide a non-effective grounding system opening phase control device capable of performing the above.

[0009]

A non-effective grounding system opening phase control apparatus according to the present invention is a non-effective grounding system for controlling the opening phase of a circuit breaker for opening and closing a non-effective grounding system shunt reactor with respect to a power system. In the system opening phase control device, the phase detection means for detecting the voltage phase of the power system, and the time calculation means for obtaining the time during which the circuit breaker can be interrupted without re-ignition based on the detected voltage phase, calculated. And a disconnection command means for transmitting a disconnection command to the circuit breaker in accordance with a circuit breakable time and causing the circuit breaker to perform a circuit break during the circuit breakable time.

[0010]

The operation of the present invention having the above-described structure will be described with reference to the voltage / current waveform diagram showing the high frequency recurrence phenomenon at the time of opening the shunt reactor circuit breaker shown in FIG. In the subsequent current interruption region, if the circuit breaker poles open up to a position where the circuit breaker pole insulation recovery characteristics are superior to the circuit breaker pole transient recovery voltage, the circuit breaker can be broken without re-ignition. In order to simplify the explanation, the circuit breaker poles will be moved to a position where the circuit breaker pole insulation recovery characteristics are superior to the circuit breaker pole transient recovery voltage in the current interruption region after the circuit breaker is opened. The time interval is called the shortest arc time.

That is, from the voltage phase of the system obtained by the phase detection means, the time calculation means calculates the time obtained by adding the shortest arc time to the opening time, and the interruption command means calculates the current zero point after the calculated time. If a break command is sent to the circuit breaker when it comes, it will be possible to break the circuit without re-ignition. FIG. 5 is a current phase diagram showing a current phase when the circuit breaker for a non-effective grounding system shunt reactor is opened. As shown in FIG. 5, after the first phase is cut off at time t ₁ , the second phase and the third phase become a single-phase circuit and the phase changes, and the second phase and the third phase are delayed by 90 ° from the first phase. Both reach the current zero point (time t ₂ ). Therefore, the second phase and the third phase can be interrupted without re-ignition by sending an interrupt command to the circuit breaker at a timing delayed by 90 ° from the first phase.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG.
It will be described with reference to FIGS. In this case, FIG. 1 is a block diagram showing an embodiment of a non-effective grounding system opening phase control device according to the present invention, and FIG. 2 shows technical points of the non-effective grounding system opening phase control device of FIG. The principle diagram and FIG. 3 are operation timing charts showing the operation timing of the present embodiment for the voltage / current waveform of the shunt reactor for one phase. That is,
First, as shown in FIG. 1, one end of a circuit breaker 2 is connected to a three-phase power system 1, and a shunt reactor 4 is connected to the other end of the circuit breaker 2 via a power cable 3. It is connected. The voltage transformer 5 for voltage detection is also connected to the power system 1, and the voltage phase of the power system 1 is detected by this voltage transformer 5 and the non-effective grounding system opening phase control device 6 is detected. It is supposed to be entered.

The non-effective grounding system opening phase control device 6 is
As shown in FIGS. 1 and 2, a phase detection circuit 7, a control circuit 8, a timer 9, and a thyristor 10 are provided. Here, the phase detection circuit 7 is a secondary output 1 of the instrument transformer 5.
It is a phase detection means for inputting 1 and detecting the voltage phase of the power system 1. Further, the control circuit 8 obtains the time during which the circuit breaker 2 can be interrupted without re-ignition based on the voltage phase obtained by the phase detection circuit 7 when the cut command 12 is input from the outside of the circuit breaker. After a predetermined time, each phase of thyristor 10
Is a means for operating the timer 9 so as to sequentially send the disconnection command (interruption command) 13 to the corresponding breaker, and corresponds to the time calculation means of the present invention. Further, the timer 9 and the thyristor 10 correspond to the shutoff command means of the present invention.

Next, referring to FIG. 3, the operation of the present embodiment having the above-mentioned structure will be described. That is,
As shown in FIG. 3, and inputs the switching instruction from the outside (time t _a), the control circuit 8, the voltage phase of the first phase flowing in the shunt reactor 4 was confirmed by phase detecting circuit 7 (phase confirmed Time T ₁ ), the time when the shortest arc time T ₃ is added to the circuit breaker opening time T ₂ is calculated, and the current zero point (time t _c ) comes after the time (T ₂ + T ₃ ) from the disconnection command of the thyristor 10. Then, the timer 9 is controlled so that a disconnection command is sent from the thyristor 10 to the first-phase circuit breaker 2 (time t _b ). As a result, the timer 9 operates after a predetermined time, the thyristor 10 sends a disconnection command to the first-phase circuit breaker 2 at time t _b , and the time t _c after the time (T ₂ + T ₃ ) is reached. One phase shutoff is performed.

After the current flowing through the shunt reactor 4 of the first phase is cut off as described above, the second and third phases become a single phase, and the current flowing through the shunt reactor of the first phase. The current reaches the zero point 90 ° after the cutoff. Therefore,
By controlling the timer 9 so that the disconnection command is sent to the second-phase and third-phase circuit breakers 2 at a timing 90 ° behind the disconnection command for the first-phase circuit breaker 2, the timer 9 is controlled. 9 operates after a predetermined time, and a disconnection command is sent from the thyristor 10 of each phase to the circuit breakers 2 of the second and third phases at a timing 90 ° behind the disconnection command of the circuit breaker 2 of the first phase. The second phase and the third phase are shut off after a lapse of time (T ₂ + T ₃ ) from the off command.

As described above, in the present embodiment, the secondary output 11 of the instrument transformer 5 conventionally provided in the electric power system is utilized, and the phase detection circuit 7, The relatively simple configuration of connecting the control circuit 8, the timer 9 and the thyristor 10 makes it possible to interrupt the circuit breaker for the ineffective grounding system shunt reactor without harmful re-ignition. Therefore, unlike the conventional case, the surge associated with the re-ignition is not repeatedly applied, so that the insulation characteristics of the shunt reactor, the power cable, the circuit breaker, etc. can be maintained for a long period of time.

The present invention is not limited to the above-mentioned embodiment, and the specific constitution of each part of the non-effective grounding system opening phase control device can be freely selected.

[0018]

As described above, in the non-effective grounding system opening phase control device of the present invention, the time during which the circuit breaker can be interrupted without re-ignition is obtained based on the voltage phase of the power system.
By sending a break command to the breaker in accordance with the calculated breakable time and making the breaker perform the break during the breakable time, the non-effective grounding system shunt reactor breaks,
It can be performed without causing a recurrent arc, which has been a problem in the past.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a non-effective grounding system opening phase control device according to the present invention.

FIG. 2 is a principle diagram showing technical points of the non-effective grounding system opening phase control device of FIG.

FIG. 3 is an operation timing chart showing the operation timing of the present embodiment for the voltage / current waveform of the shunt reactor for one phase.

FIG. 4 is a voltage waveform diagram (a) and a current waveform diagram (b) showing a high frequency re-arcing phenomenon when the shunt reactor circuit breaker is opened.

FIG. 5 is a current phase diagram showing a current phase when the non-effective grounding system shunt reactor circuit breaker is opened.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electric power system 2 ... Circuit breaker 3 ... Electric power cable 4 ... Shunt reactor 5 ... Instrument transformer 6 ... Non-effective grounding system open phase control device 7 ... Phase detection circuit 8 ... Control circuit 9 ... Timer 10 ... Thyristor 11 … Secondary output of transformer for instrument 12… Off command from outside circuit breaker 13… Off command from thyristor

Claims (1)

[Claims] 1. A non-effective earthing system opening phase control device for controlling an opening phase of a circuit breaker for opening and closing a non-effective earthing system shunt reactor with respect to a power system, the phase detecting a voltage phase of the power system. Detecting means, time calculating means for obtaining the time during which the circuit breaker can be interrupted without re-arcing based on the detected voltage phase, and the circuit breaker can be interrupted by sending an interrupting command to the circuit breaker in accordance with the calculated interruptable time A non-effective grounding system opening phase control device, comprising: a shutoff command means for causing the breaker to shut off at time.