JPH08223721A - Fault detection device for gas-insulated apparatus - Google Patents

Abstract

PURPOSE: To obtain a fault detection device which detects a fault correctly by a method wherein a pressure rise in terms of a direct current due to the fault is detected even when an arc fault is generated inside a gas-insulated electric apparatus in such a way that a pressure vibration component and an electric noise component are contained in a pressure sensor which detects the pressure rise due to the arc fault. CONSTITUTION: A pressure sensor 2 which detects a gas pressure is installed in a gas section 1 for a gas-insulated switchgear, and a moving average processing part 3 which detects the moving average value of its output signal is installed. A pressure rise detection part 4 which detects a pressure rise from the output of the moving average processing part 3 is installed, and a judgment part 5 which judges the gas section 1 to be a fault when the output exceeds a preset monitoring value is installed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-insulated electric device, such as a gas-insulated switchgear or a gas-insulated transformer, which detects a fault when a ground fault or a short-circuit fault occurs inside the gas-insulated electrical device. The present invention relates to a failure detection device.

[0002]

2. Description of the Related Art Generally, a gas-insulated switchgear is formed by accommodating a device such as a circuit breaker or a disconnector in a metal container and encapsulating an insulating gas such as sulfur hexafluoride gas having a certain enclosing pressure value. It is compact, highly reliable and safe. However, if a ground fault or a short-circuit fault occurs inside the gas-insulated switchgear, the gas-insulated switchgear has a closed structure, so it is not possible to visually confirm from the outside that the fault has occurred. Have difficulty.
Therefore, when a ground fault or a short-circuit fault occurs, the gas pressure of the insulating gas rises due to the fault arc energy. Therefore, a failure of the gas insulated switchgear may be detected by detecting this pressure rise. Conventionally, this failure detection device is provided with a pressure sensor in the gas-insulated switchgear, and the pressure sensor measures the pressure value of the insulating gas. Then, at a certain sampling cycle, the pressure increase value is obtained from the difference between the instantaneous pressure value that is the output of the pressure sensor and the enclosed pressure value, and when this pressure increase value exceeds the preset monitoring value, it is determined that there is a failure. Is configured to.

Further, in the gas-insulated switchgear, the inside thereof is usually divided into a plurality of gas compartments such as a circuit breaker gas compartment and a disconnector gas compartment, and a failure has occurred from the viewpoint of stable power supply. It is necessary to shorten the power outage time by recovering the sound gas section other than the gas section that is healthy and has no trouble even when voltage is applied, in an early stage. Therefore, in order to detect the faulty section, a faulty section detecting device may be used, and the output of the faulty detecting apparatus is also used as one input of the faulty section detecting device.

[0004]

The above-mentioned conventional failure detection device has the following problems. The pressure waveform of the insulating gas when a failure occurs includes not only a direct pressure increase but also a pressure oscillation component due to the pressure wave being reflected by the inner wall of the gas-insulated electrical equipment. Therefore, the pressure oscillation component is also included in the output signal of the pressure sensor. In particular, when this pressure oscillation component is larger than the direct pressure increase, it oscillates positively and negatively based on the enclosed pressure value. Therefore, if the pressure rise is calculated by simply subtracting the enclosed pressure value from the instantaneous pressure value of the output of the pressure sensor, if the pressure rise becomes negative, it is falsely detected that there is no pressure rise, and a failure occurs. However, the failure may not be detected. In addition, the output of the pressure sensor is AC
Electrical noise such as induction noise may be superimposed,
The noise may be erroneously detected as an increase in pressure, and may be erroneously detected as a failure even though no failure has occurred.

Therefore, an object of the present invention is to eliminate a pressure vibration component due to reflection on the inner wall of a gas-insulated electric device and an electrical noise signal superimposed on a pressure sensor to detect a direct pressure increase due to a failure, An object of the present invention is to provide a failure detection device for gas-insulated electrical equipment that can correctly detect a failure.

[0006]

A gas-insulated electric device in which an insulating gas is sealed is provided with a pressure sensor for detecting the gas pressure. A moving average processing unit is provided that calculates an average value of a predetermined average period from the instantaneous pressure value detected by this pressure sensor, sequentially calculating the pressure average at each time by sequentially moving the predetermined average period over time. . A pressure rise detection unit for detecting a pressure rise from the output of the moving average processing unit is provided. A determination unit is provided that compares the output from the pressure increase detection unit with a preset monitoring value and determines a failure if the output exceeds the monitoring value.

[0007]

According to the present invention, with the above-mentioned configuration, the moving average value of the pressure values measured by the pressure sensor is obtained, and the pressure vibration component due to the inner wall reflection of the gas-insulated electrical equipment and the electrical component superimposed on the pressure sensor. The static noise signal,
It is possible to correctly detect the failure by detecting the DC pressure increase due to the failure.

[0008]

FIG. 1 shows an embodiment of the present invention. In addition, this embodiment shows a case of applying to a gas-insulated switchgear, and the gas-insulated switchgear is usually divided into a plurality of gas compartments. An example for one gas compartment will be described.
In FIG. 1, a gas compartment 1 of the gas insulated switchgear is formed by accommodating a device such as a circuit breaker (not shown) in a metal container 1a and enclosing an insulating gas 1b such as sulfur hexafluoride. . The gas compartment 1 is provided with a pressure sensor 2 for detecting the gas pressure of the insulating gas 1b. From the instantaneous pressure value detected on the output side by the pressure sensor 2, an average value of a predetermined average period is sequentially obtained by time-shifting the predetermined average period,
A moving average processing unit 3 for detecting the pressure average value at each time, that is, the pressure moving average value is provided. Moving average processing unit 3
Is provided with a pressure increase detection unit 4 for detecting a pressure increase value from the output of the gas section 1 and compares the pressure increase value with a preset monitoring value, and when the pressure increase value exceeds the monitoring value, the gas compartment 1
Is provided as a failure, and a determination unit 5 that outputs the determination result is provided.

Next, the operation of the present invention will be described. Gas compartment 1
When a failure occurs in the insulating gas 1b, the pressure of the insulating gas 1b rises, but the waveform of the pressure rise includes a direct pressure increase and a pressure oscillation component due to reflection on the inner wall of the gas section 1. Since this is detected by the pressure sensor 2, the output of the pressure sensor 2 naturally has a similar pressure rise waveform. Further, even during normal times when no failure has occurred, electrical noise such as AC induction noise may be superimposed on the output of the pressure sensor 2, and the noise signal may be output.

The moving average processing unit 3 detects the pressure moving average value from the output of the pressure sensor 2 which becomes such a signal. That is, in the moving average processing unit 3, for example, the instantaneous pressure value detected by the pressure sensor 2 is sampled at a certain sampling period Ts, and the pressure moving average value is obtained from the sampled pressure sample value as follows. The average value of the instantaneous pressure values detected by the pressure sensor 2 in the predetermined averaging period T can be calculated by adding all the pressure sample values for the N averaging parameters and dividing the sum by the averaging parameter N. However, the averaging parameter N is a value obtained by dividing the predetermined averaging period T by the sampling period Ts. The calculation of this average value is performed in the sampling cycle T
By moving each time by s and performing each movement, the pressure average value at each time, that is, the pressure moving average value is obtained. Naturally, the pressure sample value for which the average value is to be calculated is sequentially updated because the sampling cycle Ts moves by time.

This will be described in detail with reference to FIG. Figure 2
Shows the output of the pressure sensor 2, the pressure sample value P (i) obtained by sampling the pressure sensor 2 at the sampling period Ts, and the pressure moving average value PM (i) obtained from the pressure sample value P (i). However, i = ........., -3, -2, -1, 0, 1,
2, 3, ......... In FIG. 2, the pressure moving average value PM (0) at time t (0) is the pressure sample value P (-N + 1) at time t (-N + 1) in the past from the pressure sample value P (0) at time t (0). ) Is added to all the pressure sample values for N averaged parameters and divided by the averaged parameter N. Next, the pressure moving average value PM at time t (1) after the sampling period Ts from t (0)
(1) is the pressure sample value P at time t (-N + 2) in the past from the pressure sample value P (1) at time t (1).
All the pressure sample values for N averaged parameters up to (−N + 2) are added, and the values are divided by the averaged parameter N to obtain the value. Similarly, the pressure moving average value PM (i) at each time is obtained by moving the sampling period Ts by time. That is, the pressure moving average value PM at each time t (i)
(I) is PM (i) = (1 / N) · {P (i) + P
(I-1) + P (i-2) + ......... + P (i-N +
1)}.

In this way, the pressure moving average value PM (i)
As a result, the positive and negative signals of the AC component, which is a pressure oscillation component due to the reflection of the inner wall of the gas section 1 and the like, are canceled and attenuated, but the DC pressure rise is not canceled and is not attenuated. Will be output. That is, the moving average processing unit 3 plays a role of a low-pass filter, whereby the AC noise included in the output of the pressure sensor 2 is removed and the DC pressure rise is extracted.
The frequency component to be removed is determined by a predetermined averaging period T for calculating the average value, that is, the averaging parameter N. Therefore, by setting this to an appropriate value, the pressure oscillation component and noise due to AC induction are removed. it can. This will be described below.

The frequency of a certain alternating current is f0, and the period T0 (= 1 / f0) of the alternating current is multiplied by a natural number n.
Xn), the instantaneous value of the alternating current is integrated for T period, and the integrated value is divided by the period T, that is, the average value of the average period T is the integral value of the positive half cycle and the negative half cycle. The integral value cancels out and becomes zero. Therefore, a certain alternating current cycle T0
When a natural number n times is equal to the average period T, that is, T = T0 × n, the average value of the average period T of the alternating current becomes zero. Here, when T = T0 × n is transformed, (1 / T0) = n (1 / T), and f0 = 1
From / T0, f0 = n. (1 / T). from now on,
In the case of an alternating current having a frequency obtained by multiplying the frequency (1 / T) obtained from the reciprocal of the average period T by a natural number n, the average value of the average period T of the alternating current becomes zero and is eliminated.

Further, the frequency determined by the averaging period T (1 /
The average value of the average period T of the alternating current of the frequency f ′ equal to or higher than T) and not a natural number n times the frequency (1 / T) is as follows. That is, during the averaging period T, the integral value of the positive half-cycle and the integral value of the negative half-cycle that are not cancelled and are divided by the averaging period T. For the period TA in which the integrated value is not canceled, the period T'is multiplied by an integer obtained by dividing the average period T by the AC period T '(= 1 / f') and rounding down the decimal point. The average period T is subtracted. Therefore, the average value of the average period T is a value obtained by integrating the instantaneous value of the alternating current in the period TA and dividing the integrated value by the average period T. Here, the frequency at which the integral value that is not canceled is the maximum is the frequency at which the period TA where the integral value is not canceled and the half period of the cycle T ′ match. This is, for example, a frequency that is 1.5 times, 2.5 times, or 3.5 times the (1 / T) frequency. The average value of the average period T of the alternating current having such a frequency is obtained by integrating the instantaneous value of the alternating current of the frequency for a half cycle (T ′ / 2) of the alternating current and dividing the integrated value by the average period T. It becomes a value.

On the other hand, the magnitude of the alternating current of the frequency before obtaining the average value of the average period T is the half cycle of the alternating current (T '/
It is an average value obtained by integrating the instantaneous value in the period 2) and dividing the integrated value by the period of a half cycle (T '/ 2). here,
Since f '> (1 / T) and f' = (1 / T '),
T '<T, and the average value of the former average period T becomes smaller than the average value of the alternating current before obtaining the average value of the latter average period T, and is attenuated.

From the above, by obtaining the average value of the average period T of a certain signal, the frequency component of the natural number times the frequency (1 / T) which is the reciprocal of the average period T included in the signal becomes zero, and , Other frequency components will also be attenuated. For example, if the lowest frequency of the pressure vibration component due to the inner wall reflection of the gas compartment 1 is 10 Hz and the AC induction noise superimposed on the pressure sensor 2 is 50 Hz or 60 Hz, the frequency component to be removed is 10 Hz or more. Therefore,
If the predetermined average period T for calculating the average value is 100 ms,
Attenuate the reciprocal frequency component of 10Hz or more,
Also, the frequency component that is a natural multiple of 10 Hz becomes zero, and 50
AC induced noise components of Hz and 60 Hz are removed. Therefore, the predetermined average period T for calculating the average value may be set to 100 ms. Further, the averaging parameter N is calculated by dividing the average period T by the sampling period Ts when the sampling period Ts is 1 ms, which is 100.

Therefore, when a failure occurs in the gas compartment 1, the pressure rise detection unit 4 uses the output from the moving average processing unit 3 from which the pressure vibration component and the electrical noise superimposed on the pressure sensor 2 are removed. Since the pressure change is detected, the pressure rise does not become negative, and only the DC pressure rise due to the failure is correctly detected. When the pressure rise value exceeds a preset monitoring value, the determination unit 5 determines that the gas compartment 1
Is determined to be a failure, and the result is output. Therefore, the failure can be correctly detected without falsely detecting the failure due to the pressure vibration component or the electrical noise.

During normal times when no failure occurs, the pressure in the gas compartment 1 does not rise, so the output of the pressure sensor 2 becomes the enclosed pressure value, and the moving average processing unit 3 produces a DC pressure value, that is, a pressure that does not change. It only extracts the value. Therefore, the pressure increase detection unit 4 does not detect the pressure increase, and the determination unit 5 does not determine that the gas section 1 is in failure because the pressure increase value is less than or equal to the monitoring value. Further, even when electrical noise is superimposed on the output of the pressure sensor 2 in normal times, since the moving average processing unit 3 removes the noise, the pressure rise detection unit 4 does not detect the pressure rise due to the noise. Therefore, the determination unit 5 does not erroneously determine the gas section 1 as a failure.

Although the above embodiment has been described with respect to one gas compartment of the gas insulated switchgear, it can be similarly applied to other gas compartments. Further, the invention is not limited to the gas-insulated switchgear, and can be applied to gas-insulated electrical equipment such as a gas-insulated transformer.

[0020]

As described above, according to the present invention, the pressure oscillation component due to the reflection of the inner wall of the gas-insulated electric equipment and the noise such as the electric noise signal superimposed on the pressure sensor are removed, and the DC pressure increase due to the failure is removed. Only the failure can be detected, and the failure can be correctly detected by detecting only the failure without erroneous detection or erroneous detection due to the pressure vibration component or electrical noise.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the present invention.

[Explanation of symbols]

 1 Gas Section 2 Pressure Sensor 3 Moving Average Processing Section 4 Pressure Rise Detection Section 5 Judgment Section

Claims (1)

[Claims] 1. A pressure sensor which is provided in a gas-insulated electric device in which an insulating gas is sealed and which detects the gas pressure, and an average value of a predetermined average period from instantaneous pressure values detected by the pressure sensor. A moving average processing unit that sequentially obtains a predetermined moving average for a predetermined average period and calculates a pressure moving average value at each time, and a pressure increase detection unit that detects a pressure increase from the output of the moving average processing unit. A gas-insulated electrical device, comprising: a determination unit that compares the output from the pressure increase detection unit with a preset monitoring value, and determines a failure if the output exceeds the monitoring value. Equipment failure detection device.