KR100441942B1 - Apparatus and Method for the Risk Assessment on Free Conducting Particle in Gas-insulated Switchgear - Google Patents

Abstract

The present invention relates to a device and a method for measuring the risk of breakdown and the like of a gas insulated high voltage device. If free conductive particles bounce from the GIS enclosure electrode across the gas space to the center conductor under the influence of an electric field, the likelihood of dielectric breakdown is very high. Therefore, the rising height of particles is an important data for evaluating the risk of breakdown. In the present invention, the risk of equipment is predicted by measuring the period of partial discharge and the time the particles stay in the space and indirectly calculating the rising height of the particles.

Description

Apparatus and Method for the Risk Assessment on Free Conducting Particle in Gas-insulated Switchgear}

The present invention relates to a method and apparatus for determining a risk of a gas insulated high voltage device such as gas-insulated switchgear / lines (GIS / GIL), and more specifically, to separately detect and detect a signal of a partial discharge generated by fine particles in a GIS. The present invention relates to a method and apparatus for determining the risk of gas insulated high voltage equipment that analyzes the risk and measures the relative risk.

Partial discharge occurs when there are floating electrodes, conductive particles, or sharp parts inside a gas insulator such as a gas insulated switchgear (GIS) or a gas insulated transmission line (GIL) used in a substation, power plant or switchboard. Therefore, the insulation breakdown of the gas insulated switchgear may be induced, causing equipment failure. Insulation breakdown, which accounts for most of the failure of the GIS facility, is caused by various types of internal defects such as inflow of particles, poor contact between conductors, damage to the conductor surface, and defects in spacers. Insulation breakdown by particles. If conductive particles are present inside the GIS, if the voltage applied to the center conductor exceeds a certain value, the particles placed on the bottom of the enclosure electrode stand up and repeat the action of bouncing in the insulation space or approach the center conductor across the space. This acts as a direct cause of dielectric breakdown. When conductive particles continue to bounce in the GIS, it is now possible to detect these defects from outside, with recent developments such as ultra high frequency (UHF) partial discharge detection technology.

Therefore, thanks to this technique, a signal generated during partial discharge can be detected by vibration, ultrasonic wave, high frequency, and ultra high frequency sensor, and the abnormal signal caused by discharge is separated from the detected signal to analyze the fault that can occur in gas-insulated high voltage equipment. Efforts have been made to prevent this.

The prior art resulting from this effort is a simple partial discharge pulse counter that amplifies the partial discharge signal detected by the sensor and displays the number of discharges, amplifies the partial discharge signal detected by the sensor and displays the frequency with respect to the applied voltage phase. How to do it. As another conventional technique, there is a technique of removing noise using a neural network, and a method of extracting only a specific frequency component and displaying the phase and time of an applied voltage.

In this prior art, the signal detected by the sensor is appropriately amplified and filtered to display the number and magnitude of partial discharges with respect to the phase of the applied voltage. However, such a method does not provide useful information for the measurer to determine the risk from the partial discharge signal generated by the irregularly moving particles, but only confirms that the signal is irregular. That is, in the case of partial discharge by particles, the amount and frequency of discharges by the partial discharge are quite random, so that the risk of measuring the partial discharge signal as a comparison of magnitude and frequency with respect to the applied voltage phase of the prior art is measured. impossible. In addition, in the prior art, only the specific processing of the partial discharge signal detected by a specific sensor is possible, and it is impossible to process the signal detected by another type of sensor in the same manner.

When particle defects are detected in the GIS, it is very important for the equipment operator to make a judgment as to whether the GIS will lead to an insulation breakdown and predict when the breakdown will occur. This insulation breakdown risk measurement technology is a difficult part in the field of preventive diagnosis technology of power equipment, and despite the intensive R & D efforts in this field as in the prior art, it is not reliable enough to be applied to the field until now. I can't. Accordingly, the present invention provides a reliable risk measurement method for the occurrence of insulation breakdown when the conductive particles that make up the largest portion of GIS internal defects are bouncing in the GIS. The purpose is to prevent accidents in advance.

1 is an overall system diagram of an apparatus for measuring a partial discharge signal from a signal detected by a sensor and measuring a risk;

2 is an example of a distribution diagram in which the measured partial discharge signal displayed on the display unit is drawn with respect to an applied voltage phase;

3 is an example of a distribution diagram of measured partial discharge signal cycles (time intervals between respective partial discharge signals) displayed on the display unit;

4 is a simulation diagram simulating the rising height of the particles with respect to the discharge cycle when the particles are moving in the device and partial discharge;

5 is a graph showing a motion trajectory of a particle with respect to time using a high speed camera photographing 1000 times per second, and

Fig. 6 is a histogram showing a distribution chart of discharge cycles when several particles discharge simultaneously.

-Explanation of symbols for the main parts of the drawings-

110: partial discharge sensor 113: band select filter

114: envelope detector 115: signal buffer

116: AD converter 119: period detector

120: simulation data 121: data storage / controller

122: display unit

In order to achieve the above object, the present invention provides a method and apparatus for extracting information irrespective of phase or magnitude of applied voltage from partial discharge signals generated by particles and the like in a gas insulated high voltage device to predict the risk of the device. do. That is, after amplifying the partial discharge signal that occurs intermittently, the signal is measured continuously for a long time through simple signal processing, and the time interval (or period) between each discharge is continuously extracted to determine the distribution of the time interval between the discharge and the discharge. Write. By extracting the frequency and longest interval of each time interval from the plot, the average and maximum rise and maximum rise of the particles are obtained from the time-height function diagram, from which the operator can immediately measure the risk of the machine. Provide a method.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is an overall system diagram of an apparatus for measuring a partial discharge signal from a signal detected by a sensor and measuring a risk.

Partial discharge generated in a gas insulator such as a GIS is detected by an ultrasonic wave, VHF, or UHF partial discharge sensor 110, and one or several sensors are selectively selected or selected by the signal selector 111. The signal is synthesized and amplified in the broadband low noise amplifier 112. The amplified signal extracts only the partial discharge signal from the band select filter 113 according to the characteristics of the ultrasonic wave, the microwave, and the microwave sensor.

The extracted partial discharge signal extracts only the contour of the waveform from the envelope detector 114, which is a kind of low-pass filter, and extracts the data of the analog-digital convertor 116. Through the peak-hold signal buffer 115 slightly faster than the speed, only the highest value of each partial discharge signal is extracted and the phase detector 118 based on the voltage signal 117 applied to the measurement target. ), The phase distribution of the partial discharge signal is extracted, and the periodic distribution of the partial discharge signal is extracted by the period detector 119, and the extracted data are accumulated in the data accumulation / controller 121. The band filter 113 and the signal buffer 115, which can adjust the bandwidth according to the condition input by the measurer, are adjusted by the data accumulation / controller 121. The data accumulation / controller 121 displays the simulated data 120 and the measurement data accumulated in the data accumulation / controller 121 according to the basic specifications of the device inputted by the data inputter 123, and stores the measurement data. In consideration of the basic specifications and the operating voltage of the risk of the partial discharge and the degree is displayed on the display unit 122.

2 is an example of a distribution diagram in which the measured partial discharge signal displayed on the display unit 122 is drawn with respect to an applied voltage phase. This distribution plots the partial discharge signal generated by metallic particles with respect to the applied voltage phase when the voltage of 120, 140, 160, 180 kHz is applied to a 362 kW gas insulated transmission path. . As can be seen in Figure 2, the change due to the voltage change in the distribution of the phase of the applied voltage is not known.

3 is an example of a distribution diagram of the measured partial discharge signal periods (time intervals between respective partial discharge signals) displayed on the display unit 122. This distribution plots the time interval distribution of discharges extracted from partial discharge signals generated by metallic particles when voltages of 120 (301), 140 (302) and 180 (303) are applied to the gas insulated transmission path for 362 ㎸. It is drawn using the apparatus of FIG. As can be seen in FIG. 3, as the applied voltage increases, the time interval (period) between the partial discharge and the partial discharge increases. In other words, it can be seen that the longer the applied voltage is, the longer the particle stays in the space. Therefore, it is possible to detect the longest time interval (period) in Fig. 3 (position 304, the same position as 501 in Fig. 5).

Figure 4 is a simulation of the rise height of the particle with respect to the discharge cycle when the particle is moving in the device and the partial discharge. The time interval (period) of the occurrence of the partial discharge signal and the rising height of the particles are correlated with the increase in height as the time interval for the particle to perform the single upward movement increases. In order to investigate such correlations, the positional equations of particles are simulated by a computer, and the correlation between the time interval at which particles collide with the bottom of the gas insulator and the maximum rise height of the particles is indicated by reference numeral 401 of FIG. 4. In Fig. 4, when y (m) is the maximum rising height and the time required for one up-down stroke is t (s), it can be seen that there is a relationship of y = (gt ² ) / 8 + h ₀ . . Where g is 9.8 ㎨. In the above equation, (gt ² ) / 8 represents the relationship between the distance (height) of the highest point and the time required when the object moves vertically in the gravitational field. In FIG. 4, h ₀ is the rising height 402 of the particle changing by the electric field after starting the bottom, and it can be seen from FIG. 4 that the relative time decreases as compared with (gt ² ) / 8 (403). have. All objects present in the gravitational field are governed by (gt ² ) / 8 (403), and considering that the value of h ₀ is a relatively small value, most of the particles that may be present inside the gas insulated high voltage equipment are removed from the bottom of the enclosure. In the case of the upward movement toward the center conductor, an approximation of the elevation height can be calculated from the equation y = (gt ² ) / 8 (403) regardless of the particle shape, material, applied voltage, or elastic modulus.

This simulation result can be obtained even when the rising trajectory is captured by a high-speed digital camera (1,000 frames / second) when the particle moves up in the GIS chamber, and the trajectory of time is drawn.

FIG. 5 is a graph showing a motion trajectory of a particle with respect to time using a high speed camera photographing 1000 times per second. In this figure, the time intervals and peaks in one rising-falling cycle are extracted and shown in FIG.

Fig. 6 is a histogram showing a distribution chart of discharge cycles when several particles discharge simultaneously. Even when several particles move and discharge at the same time, as shown in FIG. 4, the maximum value 501 of the period can be obtained to calculate an approximation of the rising height of the internal particles.

The maximum rise height can be obtained from the above equation from the maximum time interval by statistically extracting the time interval (period) of the partial discharges obtained from the above. In general, when particles are present, the dielectric breakdown field of the gas insulator drops sharply, and when the particles are close to the central conductor, there is a high possibility of generating flashover. In order to evaluate the risk (insulation breakdown) at this time, input basic specifications such as the applied voltage of GIS or GIL, size of internal electrode and enclosure, type and pressure of insulation gas, and simulate the phenomenon. The dielectric breakdown field can be calculated for the height. The probability distribution of the probability of dielectric breakdown of the GIS or GIL to be measured can be predicted from the rise height distribution of the particles and the measured maximum rise height, so that the driver of the device should immediately determine the risk in consideration of the relative importance of the device and the driving situation. It is possible.

In summary, the UHF signal is generated by a particle in a state where a voltage is applied to a 362 kW experimental GIS having a distance of 188 mm from the center electrode (120 mm in diameter) to the enclosure electrode (496 mm in diameter). If the maximum time interval was measured to be 267㎳ for a certain time, it can be seen that the minimum value of the particle rise height at this time is 87 mm from the equation y = (gt ² ) / 8. This corresponds to the case where it rises to about 50% height of the central conductor height of 188mm of the experimental GIS. Therefore, it is very likely to cause insulation breakdown, so it can be judged as dangerous. As you can see, there is a need to perform particle removal quickly.

According to the apparatus and method for measuring the risk of gas insulated high voltage equipment according to the above description, the statistics of the discharge phenomenon are accumulated in the partial discharge phenomenon regardless of the phase of the applied voltage, and the rising height of the particles from the discharge period from the accumulated data. By calculating the approximate value, the operator or operator can immediately know the risk of the device, such as insulation breakdown, so that the device can be prevented in advance.

While the invention has been shown and described with respect to certain preferred embodiments thereof, the invention is not limited to these embodiments, and has been claimed by those of ordinary skill in the art to which the invention pertains. It includes all variants of various forms that can be implemented without departing from the technical idea.

Claims (6)

(Correction) In the method of measuring the risk of gas-insulated high voltage equipment for predicting the occurrence of insulation breakdown due to internal defects such as particles, A partial discharge signal generated when a particle or the like collides with the bottom of an enclosure of a gas insulated high voltage device using a wideband low noise amplifier, and a partial discharge signal for extracting a predetermined discharge signal using a band selection filter Detecting; An envelope detector is used to extract the contour of the partial discharge signal, a peak-hold signal buffer is used to extract the maximum value of the partial discharge signal contour, and a period detector is used to statistically extract the period of the maximum value. Extracting; And The period the formula ^{y = (gt 2) / 8} + h 0 ( where, y (m) is the maximum rising height of the particles, t (s) is the time, g is the gravitational acceleration 9.8 ㎨ spent on upstroke once, H ₀ is substituted for the rising height of the particle after the particle leaves the floor and calculates the rising height of the particle.The basic specifications of the object to be measured are electrode size, distance between electrodes, type and pressure of insulating gas, and insulation. A risk measurement method for a gas insulated high voltage device comprising the step of determining the risk in consideration of the strength and the operating voltage. (delete) (delete) In the device for measuring the risk of gas-insulated high voltage equipment which predicts the possibility of occurrence of insulation breakdown due to internal defects such as particles, A partial discharge signal detector for detecting a partial discharge signal generated by internal defects such as particles; A broadband low noise amplifier for wideband low noise amplification of the partial discharge signal is provided, and a bandwidth-adjustable band selection filter for extracting the selective discharge signal from the wideband low noise amplified partial discharge signal is provided. Band selection filter means for extracting a selective discharge signal of the signal; And An envelope detector for extracting the contour of the selective discharge signal is provided, and a peak-hold signal buffer is provided for maintaining the highest value of the contour signal to generate the highest value signal. A period detector for detecting is provided, including period detecting means for detecting a period of the selective discharge signal, The period the formula ^{y = (gt 2) / 8} + h 0 ( where, y (m) is the maximum rising height, t (s) of a particle is raised - the time it takes to fall administration once, g is the gravitational acceleration 9.8 H, and h ₀ is a risk measurement of the gas-insulated high voltage device, which is determined by considering the operating voltage by calculating the rise height of the particle by substituting the rise height of the particle after the particle leaves the floor. Device. (delete) (delete)