KR20000033819A - Current zero predicting device and method thereof - Google Patents

Abstract

PURPOSE: A current zero predicting device and method thereof are provided to predict a current zero crossing point of the current flowed through a high pressure breaker by a current sinewave applied from a current source in a capacity test, especially a composition test of the high pressure breaker, and to accurately control a driving timing of the current source applying high pressure according to a specific setting time by a user. CONSTITUTION: A current zero predicting device comprises the parts of: a rectifier(10) rectifying an internal current sinewave through a high pressure breaker flowed by a fault current applied from a current source; a differentiators(11) differentiating the above rectified current; a clipper(12) clipping the above differentiated current more than a specific volume; an amplifier(13) amplifying outputs of the above clipper; a comparator(14) comparing output signals of the above amplifier with a reference volume; a peak detector(PD) reversing the output signals of the above current zero detector to logic elements; a counter(16) counting the above current zero detecting signals and peak detecting signals corresponding to the reference CLK; a digit comparator(17) predicting the above current zero according to the above count value and controlling the driving timing of the current source according to a setting time specified by a user; and a multi vibrator(18) generating output signals in a pulse width suitable for outputs of the above digit comparator.

Description

Current zero prediction device and method

The present invention relates to an apparatus and method for predicting current zero point required for a performance test of a high voltage circuit breaker. More particularly, the present invention relates to a current zero current predicting device and a method of performing a high voltage circuit breaker. The present invention relates to a current zero prediction device and method for predicting zero crossing time and automatically controlling driving timing of a voltage source applying a recovery voltage according to a time set by a user.

In general, the high-voltage circuit breaker detects a failure occurring in a transmission / distribution system of a power facility, and automatically performs a blocking operation when a failure occurs. The blocking operation includes a current converted by a current transformer. A blocking operation is automatically performed at the time of zero, and when the blocking operation is performed as described above, a very large high pressure is applied to the anode of the high voltage circuit breaker.

Therefore, the high pressure circuit breaker should be verified and manufactured through a performance test to determine whether it can withstand the high pressure applied during the breaking operation. In the performance test of the high-voltage circuit breaker, a direct test or a synthetic test is usually used, and the direct test is performed using a single energy source in the same manner as in the actual situation. There is an advantage that does not need to separately detect the instant (Zero), but there is an inadequate disadvantage to apply to a high-voltage circuit breaker with a large breaking capacity. In the synthesis test, a current source and a voltage source are respectively used to generate a zero current detected when a failure occurs, and a high pressure applied by a breaking operation when detecting the zero current, and supply it to a high voltage circuit breaker to test performance. It can be applied to high pressure circuit breaker with large breaking capacity. However, the timing for applying the high voltage must match the point at which the current becomes zero. Therefore, in the synthesis test, in addition to the current source and the voltage source, it is necessary to use a current zero predictor for predicting the time when the current becomes zero.

However, the current zero predictor is an expensive instrument using a complicated circuit configuration and an algorithm, and is currently used depending on the total amount of income.

Therefore, the present invention was created to solve the above problems, and in the performance test of the high voltage circuit breaker, in particular, the synthesis test, the zero crossing point of the current flowing in the high voltage circuit breaker by the sine wave current applied from the current source. The present invention provides a zero point predicting apparatus and a method for accurately controlling the driving timing of a voltage source to which a high voltage is applied according to an arbitrary setting time set by a user.

Figure 1 shows an embodiment in which the current zero prediction apparatus according to the present invention is used,

Figure 2 shows the overall configuration of the current zero prediction device according to the present invention,

3A and 3B show waveform diagrams of each part of the current zero predictor according to the present invention;

4 is a flowchart illustrating an operation of the current zero prediction method according to the present invention.

※ Explanation of code for main part of drawing

10: rectifier 11: differential

12: Clipper 13: Signal Amplifier

14: comparator 15: negative logic element

16: Counter 17: Digit Comparator

18: Multi Vibrator

The current zero predicting apparatus according to the present invention for achieving the above object, the zero detection means for detecting the zero of the current being energized; Peak detection means for detecting a peak of the current; Counting means for counting a detection time between the zero point and the peak point; And control means for applying a control signal to the outside in a specific phase of the current, based on the counted detection time. The current zero prediction method according to the present invention is further characterized in that Detecting a zero point and counting time; Detecting a peak point of the current; Estimating the time counted until the peak point detection as the time required until the next zero point detection; And four steps of outputting a predetermined control signal before completion of the predicted required time.

The current zero predicting apparatus and method according to the present invention, which is configured as described above, detects a zero point and a peak point of a sine wave current applied from a current source, and detects the zero point and the peak point. While calculating the detection time Tzp between the peaks, paying attention to the fact that the detection time Tpz between the detected peak and zero points is the same as the detection time Tzp between the zero point and the peak point. In addition, it is possible to accurately predict the continuous zero detection time, and to automatically and accurately control the driving timing of the voltage source according to an arbitrary time set by the user.

Hereinafter, a preferred embodiment of the current zero prediction apparatus and method according to the present invention will be described in detail with reference to the accompanying drawings.

1 shows an embodiment of a synthesis test in which a current zero predicting apparatus according to the present invention is used, a current source 1 for applying a fault current to a high-voltage circuit breaker 3 that is a performance test object; A voltage source (2) for applying a high voltage recovery voltage to the high voltage circuit breaker (3); When the fault current is applied, the current zero predictor 4 which detects and predicts the current zero energized in the high voltage circuit breaker 3 and controls the driving timing of the voltage source 2 is shown. same.

First, when the current generated from the current source 1, that is, the fault current that the high voltage circuit breaker detects as a fault in an actual situation, is applied to the high voltage circuit breaker 2, the current zero predictor 4 energizes inside the high voltage circuit breaker. The zero point and the peak point of the sinusoidal current to be detected are detected, and the time required from the zero point detection to the peak point calculation is calculated. Based on the calculated required time, a current zero time time to be detected is predicted, and a control signal for controlling the driving timing of the voltage source 2 is output to the voltage source 2 according to an arbitrary time set by the user. . Accordingly, the voltage source 2 is a synthetic test that is a performance test of the high voltage circuit breaker by applying a high voltage recovery voltage to the high voltage circuit breaker 3.

2 is an overall configuration diagram of a current zero predicting apparatus according to the present invention, the rectifier 10 for full-wave rectifying the internal sine wave current of the high-voltage circuit breaker 3 is energized by the fault current applied from the current source (1) ; A differentiator (11) for differentiating the full-wave rectified current; A clipper 12 that clips the output of the differentiator to a set voltage or more; An amplifier 13 for amplifying the output of the clipper 12; A zero detector ZD including a comparator 14 for comparing the output signal of the amplifier 13 with a reference voltage Vref, and an output signal of the zero detector of the zero detector; 15) a peak detection unit PD for inverting and outputting the counter, a counter 16 for counting the zero detection and peak detection signals corresponding to the reference clock CLK, and a current zero according to the count value. A digital comparator 17 for controlling the driving timing of the voltage source 2 according to a user-set setting time, and an appropriate pulse width based on the output of the digital comparator. And a multi vibrator 18 for generating an output signal of the multi-vibrator.

Operation of the current zero predicting apparatus according to the present invention configured as described above will be described below in detail with reference to the accompanying drawings.

First, FIGS. 3A and 3B show a waveform diagram of each part of the current zero predicting apparatus according to the present invention, and FIG. 4 shows an operation flowchart of the current zero predicting method according to the present invention. Referring to the operation of the current zero prediction method according to the present invention, first, a current that is energized inside the high voltage circuit breaker 3 by a fault current applied from the current source 1, that is, a sine wave current as shown in FIG. When the rectifier 10 is input to the zero detector ZD of the predictor 4, the rectifier 10 performs full-wave rectification of the input sinusoidal current as shown in FIG. 3A, and outputs the result to the differentiator 11. The radio wave rectified output of FIG. 3A is further differentiated as shown in FIG. 3A and output to the clipper 12. The clipper 12 clips the differential waveform of (c) of FIG. 3A to a predetermined voltage or more and outputs an output signal as shown in (d) of FIG. 3A to the signal amplifier 13.

The signal amplifier 13 amplifies the output signal of the clipper 12 input as shown in (d) of FIG. 3a, and outputs a zero crossing signal (ZC) of the square wave as shown in (f) of FIG. The cross signal is inverted and output as a peak detection signal PD of a square wave as shown in FIG.

On the other hand, as shown in FIG. 3B, the zero crossing signal f and the peak detection signal g of the square wave output by inversion with the comparator 14 determine the operation mode of the counter 16. When a signal corresponding to a reference clock CLK such as (h) of FIG. 3B, for example, a high frequency clock corresponding to 100 KHz is input, the counter 16 is up / down depending on the operation type. By counting, the counter CT result as shown in FIG. 3B (i) is output to the digital comparator 17. FIG.

Accordingly, the digital comparator 17 receives the count output CT as shown in (i) of FIG. 3B from the counter 16 (S10), and the point of time at which the count output CT becomes zero. The maximum time point is recognized as the current zero point (C) and the peak point (PD), respectively, and the detection time (Tzp = ZC-PD) required from the zero point to the peak point is calculated (S11).

Thereafter, the controller determines a time set by the user (S12), calculates a difference (Cts = Tzp-Tst) between the detection time Tzp and the set time Tst (S13), and then receives a count output. (S14), when the received count output CT corresponds to the difference Cts between the detection time and the set time (S15), a control signal CTL for controlling the driving timing of the voltage source 2 is applied. The output S16 to the voltage source 2 allows the recovery voltage of the voltage source 2 to be applied to the high voltage circuit breaker 1.

For reference, the set time (Tst) is a control signal that is set by the user in consideration of the characteristics of the facility, so that the high voltage applied from the voltage source 2, that is, the recovery voltage exactly matches the current zero point detection time. For example, the current zero predictor allows the user to output the output timing of the control signal CTL 500 μsec before the zero point of detection in consideration of characteristics of the voltage source 2 and the like. When set to (4), the digital comparator 17 calculates the difference between the time Tst set by the user and the time Tzp = Tpz at which zero detection is expected, and is 500 µsec from the time point at which the zero detection is predicted. The control signal CTL for driving the voltage source 2 is output at a previous time.

As described above, the configuration of the current zero predictor according to the present invention corresponds to the embodiment, and the design can be changed as necessary.

The current zero predicting apparatus and method according to the present invention, which is configured as described above, greatly improves the accuracy of the current zero predictor required for the performance test of the high-voltage circuit breaker, and also recovers the recovery voltage according to a time set by the user. It is a very useful invention to precisely and automatically control the driving timing of an applied voltage source.

Claims (7)

Zero point detection means for detecting a zero point of energized current; Peak detection means for detecting a peak of the current; Counting means for counting a detection time between the zero point and the peak point; And And control means for applying a control signal to the outside in a specific phase of the current based on the counted detection time. The method of claim 1, And the control means compares an arbitrary set time with the counted detection time and applies a control signal to the outside according to the result. The method of claim 1, And the counting means increases the number of counts from zero detection to peak detection and decreases the number of counts from peak detection to zero detection. The method of claim 1, And the counting means decreases the number of counts from zero detection to peak detection and increases the number of counts from peak detection to zero detection. The method according to any one of claims 1 to 4, And the control signal is a signal for adjusting a driving timing of a voltage source applying high voltage to the high voltage circuit breaker. Counting time by detecting a zero point of the energized current; Detecting a peak point of the current; Estimating the time counted until the peak point detection as the time required until the next zero point detection; And And a four step of outputting a predetermined control signal before completion of the estimated time required. The method of claim 6, In the fourth step, the predetermined zero point prediction time is determined by comparing the elapsed time with a predetermined set time while setting the estimated required time.