CN104808123A - Switchgear partial discharge detecting system - Google Patents

Abstract

A switch cabinet partial discharge detection system, used to realize accurate detection and positioning of switch cabinet partial discharge, the technical solution is that the system includes a tablet computer, a data acquisition card, a TEV sensor, an ultra-high frequency sensor and four ultrasonic sensors, The TEV sensor, the ultra-high frequency sensor and the four ultrasonic sensors are respectively installed on different parts of the switchgear surface, and their signal output terminals are connected to different input terminals of the data acquisition card, and the signal output terminals of the data acquisition card are connected to the tablet computer , the tablet computer is connected to the host computer through a wireless network. The invention uses three kinds of sensors with complementary advantages to jointly monitor the partial discharge of the switchgear, which can not only effectively avoid the interference caused by the complex environment on site, improve the detection accuracy, but also realize the accurate positioning of the partial discharge source and the accurate identification of the discharge mode , greatly improving the detection level of switchgear partial discharge.

Description

A switch cabinet partial discharge detection system

technical field

The invention relates to a device capable of accurately detecting the position and type of partial discharge in a high-voltage switch cabinet, and belongs to the technical field of switches.

Background technique

High-voltage switchgear is a very important electrical equipment in the power system, and its operation reliability directly affects the safety and stability of the entire system. Due to the manufacturing process and other reasons, the insulation of the high-voltage switchgear will gradually age during operation, resulting in partial discharge. The continuous spread and development of this discharge will in turn accelerate the deterioration of the insulation and cause serious power supply accidents. Therefore It is of great significance to study the partial discharge detection technology of switchgear to improve the reliability of power supply.

At present, the widely used partial discharge detection methods of switchgear include ultra-high frequency method (UHF), ultrasonic method (AE), transient earth wave method (TEV), etc., and the above three methods can realize continuous power detection. The ultra-high frequency method uses the sensor to receive the ultra-high frequency (300MHz-3GHz) electromagnetic signal generated by the partial discharge, and detects the partial discharge according to the ultra-high frequency electromagnetic signal. Since the frequency of the usual interference signal is below 300MHz, this method It has relatively excellent anti-interference performance, but due to the complex on-site environment and the lack of corresponding standards, this method cannot quantify the magnitude of partial discharge. The ultrasonic method detects partial discharges based on the ultrasonic waves generated by the violent collision of molecules in the partial discharge area (the center frequency is generally 40KHz). The biggest advantage of this method is that it is free from electrical interference and has relatively accurate positioning capabilities. Due to the complex structure of the switchgear, the ultrasonic waves will be attenuated and refracted during the propagation process, which may easily cause missed or misjudgment. The TEV method detects partial discharge by inducing the transient ground voltage generated by the electromagnetic wave generated by the discharge pulse on the metal cabinet surface of the switch cabinet during the partial discharge. This method can quantify the partial discharge, but it cannot avoid a large number of on-site Electromagnetic interference has certain limitations.

The "acoustic-acoustic" method is generally used for the localization of switchgear partial discharge. Due to the complex internal insulation structure of the switchgear and the attenuation of ultrasonic waves, this method often causes large positioning errors.

In view of the advantages and disadvantages of the above methods, it is necessary to develop a joint detection and positioning device to make up for the shortcomings of existing methods and realize accurate detection and positioning of partial discharge in switchgear.

Contents of the invention

The object of the present invention is to provide a partial discharge detection system of a switchgear to realize accurate detection and positioning of the partial discharge of the switchgear aiming at the drawbacks of the prior art.

Problem described in the present invention is solved with following technical scheme:

A partial discharge detection system for a switchgear, comprising a tablet computer, a data acquisition card, a TEV sensor, an ultra-high frequency sensor, and four ultrasonic sensors, the TEV sensor, an ultra-high frequency sensor, and four ultrasonic sensors are respectively installed on a switchgear Different parts of the cabinet surface, their signal output terminals are connected to different input terminals of the data acquisition card, the signal output terminals of the data acquisition card are connected to a tablet computer, and the tablet computer is connected to the host computer through a wireless network.

The above switchgear partial discharge detection system also includes a TEV signal detection amplifier, and the ultra-high frequency signal output by the TEV sensor is sent to the data acquisition card through the TEV signal detection amplifier.

The above switchgear partial discharge detection system also includes a UHF signal detection amplifier, and the UHF signal output by the UHF sensor is sent to the data acquisition card through the UHF signal detection amplifier.

The above switchgear partial discharge detection system also includes a filter amplifier. The ultrasonic signals output by the four ultrasonic sensors are processed by the filter amplifier and then sent to different input terminals of the data acquisition card.

In the above switch cabinet partial discharge detection system, four ultrasonic sensors are respectively installed at the four corners of the switch cabinet.

The invention adopts three kinds of sensors with complementary advantages to jointly monitor the partial discharge of the switchgear, which can not only effectively avoid the interference caused by the complex environment on site, improve the detection accuracy, but also realize the accurate positioning of the partial discharge source and the accurate identification of the discharge mode , greatly improving the detection level of switchgear partial discharge. Generally speaking, there are a large number of electromagnetic wave interference signals and acoustic wave interference signals at the site where the switchgear operates. Therefore, the monitoring method based on these two physical quantities can eliminate misjudgments caused by background noise. In terms of positioning, because the traditional " The "acoustic" method is not as accurate as the "acoustic" method for determining the occurrence time of partial discharge, and the processing of these signals is more complicated, which is difficult to use in positioning detection.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing.

Fig. 1 is a structural representation of the present invention;

Figure 2 is a schematic diagram of the installation of four ultrasonic sensors.

The labels in the figure are: PD, partial discharge point, S1 ~ S4, the first ultrasonic sensor to the fourth ultrasonic sensor, U1, data acquisition card, U2, tablet computer, U3, host computer, LF, filter amplifier, JF1, TEV Signal detection amplifier, JF2, UHF signal detection amplifier, TEV, TEV sensor, GP, UHF sensor.

Detailed ways

Referring to Fig. 1, the present invention includes four ultrasonic sensors (i.e., the first ultrasonic sensor S1 to the fourth ultrasonic sensor S4), an ultra-high frequency sensor GP, a TEV sensor, a filter amplifier LF, a TEV signal detection amplifier JF1, and an ultra-high frequency signal detection amplifier. Amplifier JF2, data acquisition card U1, tablet computer U2 and power supply module U3.

Four ultrasonic sensors are respectively arranged in the four corners of the switch cabinet and connected with the filter amplifier LF (see Figure 2); the UHF sensor GP is arranged in the front window of the switch cabinet and connected with the UHF signal detection amplifier JF2; TEV The sensor is installed on the surface of the switch cabinet and connected with the TEV signal detection amplifier JF1. The filter amplifier LF is used to receive the signals of four ultrasonic sensors, filter out the interference signals, and then amplify the filtered signal and send it to the data acquisition card U1; TEV signal detection amplifier JF1 and UHF signal detection amplifier JF2 It is used to realize the detection and processing of TEV and ultra-high frequency signals. Because the frequency of TEV signals and ultra-high frequency signals is too high, it is not conducive to the processing of data acquisition card U1, so two detection amplifiers are required for frequency reduction and amplification before sending Data acquisition card U1.

The data acquisition card U1 is a multi-channel, high-speed synchronous acquisition card, and any one of the channels can be selected as the ultrasonic signal receiving channel, the TEV signal receiving channel or the UHF receiving channel.

The data collected by the data acquisition card U1 is connected to the tablet computer U2 through a USB cable, and the tablet computer U2 processes the received signals. Before the test, calculate the maximum value t _max and the minimum value t _min of the sound wave propagation time in the switch cabinet, and use the output signal of the ultra-high frequency sensor GP or TEV sensor as the trigger signal to calculate the propagation time t of the ultrasonic signal, if t _{If min} <t<t _max , it is judged as the internal discharge of the switchgear, and then the partial discharge is located, and combined with the discharge amount measured by the TEV sensor, the discharge type is pattern recognized. The t _max can be determined according to the size of the switchgear and the sound velocity.

The power module of this system uses a rechargeable battery, and the power module supplies power to the tablet computer U2 and the data acquisition card U1, which can ensure that the system has a long use time.

Tablet PC U2 has the function of alarm and wireless data transmission, which can send out alarm bells with different loudness according to the severity of the discharge, and at the same time, use the wireless module to transmit the measurement data to the host computer U3 for storage, recording and printing.

Working process of the present invention is as follows:

The data acquisition card U1 collects the detected and amplified UHF signal and the filtered and amplified ultrasonic signal, and transmits them to the tablet computer U2. Since the propagation speed of electromagnetic waves in space is close to the speed of light, it can be considered that the moment when the UHF signal is received is the moment when partial discharge occurs. The tablet computer U2 selects the UHF signal as the timing reference signal, and calculates the time difference between the time when the fourth ultrasonic sensor receives the signal and the time when the UHF sensor GP receives the UHF signal and the equivalent sound velocity v, and calculates the four ultrasonic sensors The distance to the partial discharge source, and then solve the coordinates of the partial discharge source.

The position of the UHF sensor GP should be placed at the gap between the cabinet door and the cabinet body. According to the test, since the switch cabinet is a metal cabinet, it has a shielding effect on electromagnetic waves, so the UHF sensor is placed between the cabinet door and the cabinet body. The connection gap will not hinder the reception of the signal, but also avoid the interference of other signals.

The signal collected by the TEV sensor is sent to the data acquisition card U1 after being detected and amplified; the data acquisition card U1 sends the collected TEV signal to the tablet computer U2; the tablet computer U2 extracts the characteristic quantity of the signal, and then identifies the Show the type of partial discharge.

Since each signal has some background noise to some extent, the three types of sensors in the present invention collect different types of signals, and each has its own advantages, so it can learn from each other. Specifically, both TEV sensors and UHF sensors have high sensitivity, and can detect even weak discharges, but at the same time, there are sometimes some electromagnetic interference noises on site, which cannot be achieved only by TEV sensors and UHF sensors. To determine whether partial discharge has occurred, it is possible to use an ultrasonic sensor for secondary confirmation. In addition, the TEV signal and the UHF signal are signals of different frequencies. The monitoring frequency of the TEV signal is relatively low, and the monitoring frequency of the UHF signal is relatively high. For a single discharge, the two discharge signals may not necessarily be generated. , so using these two methods can monitor the discharge more accurately. At the same time, ultrasound has certain advantages over TEV and UHF in terms of positioning, but because the speed of sound is significantly lower than the wave velocity of electromagnetic waves, the first signal detected by TEV or UHF signals can be used as the initial moment of discharge to carry out Location of partial discharge points.

In a word, the present invention can realize the detection, location and identification of the partial discharge of the switchgear. Experiments show that the present invention has a high recognition rate for the partial discharge, and the positioning is accurate, which effectively reduces the occurrence of missed judgments and misjudgments, and improves the Productivity of electrical equipment maintenance.

Claims (5)

1. A switchgear partial discharge detection system is characterized in that it includes a tablet computer (U2), a data acquisition card (U1), a TEV sensor, an ultra-high frequency sensor (GP) and four ultrasonic sensors, and the TEV sensor , UHF sensor (GP) and four ultrasonic sensors are respectively installed on different parts of the surface of the switchgear, and their signal output terminals are connected to different input terminals of the data acquisition card (U1), and the signal of the data acquisition card (U1) The output terminal is connected to a tablet computer (U2), and the tablet computer (U2) is connected to a host computer (U3) through a wireless network. 2. A switchgear partial discharge detection system according to claim 1, characterized in that the composition also includes a TEV signal detection amplifier (JF1), and the UHF signal output by the TEV sensor passes through the TEV signal detection amplifier (JF1) into the data acquisition card (U1). 3. A switchgear partial discharge detection system according to claim 1 or 2, characterized in that the composition also includes an ultra-high frequency signal detection amplifier (JF2), and the ultra-high frequency signal output by the ultra-high frequency sensor (GP) The signal is sent to the data acquisition card (U1) through the UHF signal detection amplifier (JF2). 4. A switchgear partial discharge detection system according to claim 3, characterized in that the composition also includes a filter amplifier (LF), and the ultrasonic signals output by the four ultrasonic sensors are processed by the filter amplifier (LF) and sent to the Different inputs of the data acquisition card (U1). 5. A switchgear partial discharge detection system according to claim 4, characterized in that four ultrasonic sensors are respectively installed at the four corners of the switchgear.