CN102116824A - Distributed local discharge on-line monitoring method and device for high voltage cable system - Google Patents

Abstract

The invention provides a method and device for on-line monitoring of distributed partial discharge in a high-voltage cable system. A high-frequency broadband electromagnetic coupling sensor is installed at each attachment of the entire cable line, and the sensor is socketed on the ground wire or cross interconnection wire of the cable attachment to couple partial discharge. signal, the 50Hz current sensor is socketed on the cable body to couple the power frequency current signal, the lower computer performs conditioning, high-speed acquisition and preprocessing of the sensor signal, and transmits the digital signal to the upper computer monitoring software through the optical fiber transmission network to realize high-voltage cable equipment. On-line monitoring of distributed partial discharge. The invention has the advantage of being able to realize partial discharge on-line monitoring through distributed synchronous high-speed sampling of high-voltage cable three-phase accessories according to site needs.

Description

Method and device for distributed partial discharge on-line monitoring of high voltage cable system

technical field

The invention relates to a cable equipment detection device, in particular to a distributed partial discharge online monitoring method and device for a high-voltage cable system.

Background technique

With the development and application of high-voltage and extra-high-voltage power cables, cross-linked polyethylene (XLPE) power cables are widely used in China for their reasonable technology and structure, excellent electrical performance, simple installation and laying, less operation and maintenance work, and safety and reliability. It has been widely used in power system. As an important part of urban power supply and main grid, high-voltage and extra-high-voltage cable system has occupied a very important position in my country's urban power grid. How to realize the status detection of these cable equipment and ensure the safe and reliable operation of the cable equipment is a hot research topic at home and abroad. On-line detection of partial discharge in the cable system can detect potential faults in time, predict and evaluate insulation degradation in advance, and actively and effectively prevent sudden operating faults in the cable system. It is an essential technical means to achieve condition-based maintenance of cable equipment.

Cable accessories such as intermediate joints are manually manufactured and installed under on-site conditions, and their insulation quality is often lower than that of the cable body, which is the weak link in the insulation of the cable system. Various construction defects caused by poor construction technology of the intermediate joint make the electric field distribution in the joint uneven, resulting in partial discharge. Under power frequency voltage, partial discharge will cause the generation and expansion of electric tree in the cable insulation, and accelerate the deterioration of insulation, eventually leading to insulation breakdown.

At present, the on-site measurement results of many high-voltage cable partial discharge online monitoring systems are not ideal. The main reasons are: (1) There are many sources of external strong electromagnetic field interference. The anti-interference method has certain requirements for the measurement settings; (2) the collected partial discharge signal is weak, the amplitude is small, and it is easily submerged by the background noise; (3) the narrow-band filter and the high multiple amplifier make the collected signal (4) The cable partial discharge signal identification technology is not mature enough, lacking the identification and judgment technology of the partial discharge pulse signal waveform, frequency and amplitude measured on site; (5) The lack of XLPE cable insulation degradation Evaluate the accumulation of practical operating experience such as research on basic theories and operating status criteria.

The existence of the above-mentioned various factors greatly reduces the sensitivity, accuracy and reliability of on-line detection of partial discharge of high-voltage cables. Therefore, how to use the existing advanced technology to suppress interference to the greatest extent, accurately extract partial discharge signals, and provide information for subsequent insulation diagnosis more reliably and sensitively has become an important direction in the on-line partial discharge detection of high-voltage cable equipment.

Contents of the invention

The technical problem to be solved by the present invention is: Aiming at the above-mentioned problems of online detection of current cable equipment, the present invention proposes a distributed partial discharge online monitoring method and device for a high-voltage cable system, which can monitor each accessory of the entire cable line in a distributed manner And the partial discharge signal of the body within a certain range of accessories.

The technical scheme adopted in the present invention is: a method for on-line monitoring of distributed partial discharge in a high-voltage cable system. A high-frequency broadband electromagnetic coupling sensor is installed at each attachment of the entire cable line, and the sensor is socketed on the ground wire or cross interconnection wire of the cable attachment. The partial discharge signal is coupled up, and the 50Hz current sensor is socketed on the cable body to couple the power frequency current signal. The lower computer performs conditioning, high-speed acquisition and preprocessing of the sensor signal, and transmits the digital signal to the upper computer monitoring software through the optical fiber transmission network. Realize the on-line monitoring of the distributed partial discharge of high-voltage cable equipment, which is characterized in that it includes the following steps:

(1) A high-frequency broadband electromagnetic coupling sensor is socketed on each cable accessory ground wire or cross interconnection wire of the entire cable line, and connected to the channel of the high-speed data acquisition card after signal conditioning to perform three-phase synchronous trigger high-speed sampling, And after being processed by the FPGA circuit, the digital signal is stored in the ROM of the lower computer;

(2) A 50Hz power frequency current sensor is socketed on the cable body, and after signal conditioning, it is also connected to the channel of the high-speed data acquisition card for sampling, which is used to trigger the partial discharge signal acquisition channel to determine the power frequency of the partial discharge signal voltage phase;

(3) The lower computer includes a signal conditioning module, a high-speed data acquisition card, and an I/O card, which are used to complete preliminary interference suppression, trigger acquisition, and data storage of partial discharge signals;

(4) The optical fiber transmission network connects each lower computer monitoring unit to the upper computer monitoring unit;

(5) The upper computer monitoring unit completes the hardware control of the lower computer, the reception of collected data, the display of the apparent discharge amount, and the display of the discharge spectrogram of the discharge amount-discharge phase;

(6) Through the continuous monitoring of the discharge capacity of each accessory, a discharge trend database is formed, so as to grasp the insulation operation status of the entire cable line.

The present invention also provides a distributed partial discharge on-line monitoring device for a high-voltage cable system, which includes a high-frequency broadband electromagnetic sensor, an optical fiber transmission network, and a host computer. , is characterized in that it also includes a lower computer data preprocessing acquisition unit, the upper computer is connected with the lower computer through an optical fiber transmission network, and the lower computer data preprocessing acquisition unit further includes a signal preconditioning unit, an I/O control unit, and a high-speed data acquisition unit. card, the signal pre-conditioning unit conditions the signal coupled by the high-frequency broadband electromagnetic sensor, the high-speed data acquisition card collects the conditioned signal, the I/O control unit completes the control of the collection, and transmits the collected data through the optical fiber transmission network to the host computer.

The beneficial effect of the present invention is: the advantage of the present invention is that it can realize partial discharge on-line monitoring by performing distributed synchronous high-speed sampling on high-voltage cable three-phase accessories according to site needs. The wide-band high-speed acquisition method of this device can obtain a complete partial discharge signal waveform, and can display the apparent discharge amount and various discharge spectra in real time. The continuous monitoring of the discharge can realize the monitoring of the insulation status of the cable system, and provide strong technical support for the condition maintenance of the cable equipment.

Description of drawings

Fig. 1 is a schematic flowchart of a method for on-line distributed partial discharge monitoring of a high-voltage cable system according to an embodiment of the present invention.

Fig. 2 is a functional block diagram of a distributed partial discharge on-line monitoring device for a high-voltage cable system according to an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

Referring to FIG. 1 and FIG. 2 , they are principle and functional block diagrams of the distributed partial discharge on-line monitoring method and device for a high-voltage cable system provided by an embodiment of the present invention.

The distributed partial discharge on-line monitoring device of the high-voltage cable system of the present invention includes a high-frequency broadband electromagnetic sensor, an optical fiber transmission network and a host computer. That is, it also includes a lower computer data preprocessing acquisition unit, the upper computer is connected with the lower computer through an optical fiber transmission network, and the lower computer data preprocessing acquisition unit further includes a signal pre-conditioning unit, an I/O control unit, a high-speed data acquisition card, and a signal The pre-conditioning unit regulates the signal coupled by the high-frequency broadband electromagnetic sensor, the high-speed data acquisition card collects the conditioned signal, the I/O control unit completes the control of the collection, and transmits the collected data to the host computer through the optical fiber transmission network .

The high-frequency broadband electromagnetic sensor is installed on the grounding wire of the cable accessory or the cross interconnection line to couple the partial discharge signal, and the 50Hz power frequency voltage sensor is installed on the body near the accessory to couple the power frequency current signal; the partial discharge signal pre-conditioning unit completes the grounding line Preprocessing of mixed signals, conditioning the signal to the input range of the high-speed data acquisition card for high-speed data acquisition, and storing the collected data in a large-capacity ROM; the optical fiber transmission network is used to transmit the data collected by the lower computer to the upper computer for monitoring at high speed Software; the host computer controls the signal conditioning and acquisition unit, and performs software anti-interference processing after receiving the collected data, and displays the discharge amount of the TV and the discharge spectrum such as q-φ.

The main components of the device are described one by one below:

(1) High-frequency broadband electromagnetic coupling sensor

The high-frequency broadband signal sensor adopts nickel-zinc ferrite, and the frequency range is 20kHz-20MHz. When measuring, it is connected to the three-phase accessory ground wire or cross interconnection wire to form a sensor pair. The coupled signals include partial discharge signals, interference, and background noise. .

The 50Hz power frequency signal sensor is used to couple the power frequency current signal of the cable body to trigger acquisition and determine the power frequency phase of the discharge signal.

(2) Lower computer data preprocessing acquisition unit

The lower computer unit is installed near the sensor, and performs hardware filtering on the signal output by the sensor to partially interfere, so that the subsequent amplifying unit can amplify the partial discharge signal to improve the detection sensitivity.

The program-controlled signal amplification unit has 1, 5, 10, 20, 50, 100 times of amplification, and adjusts the signal to the best input range of the data acquisition card.

The highest sampling rate of the data acquisition card used is 60MS/s, the analog bandwidth is 30MHz, the A/D resolution is 12 bits, and the high-speed collected signals are stored in ROM.

The I/O control card is used to send and receive control commands between the upper and lower computers.

(3) Optical fiber transmission network

Use strip steel Kay sleeve optical fiber, one of which is used as a spare. Each fiber has 16 cores, and the fiber is cut and fused in the fiber hub of each node, and a fiber is led out to connect to a lower computer unit.

(4) PC monitoring software

The upper computer software is used to control the data acquisition of the lower computer, set the program-controlled signal conditioning unit, and control the reception of the collected data stored in the ROM of the lower computer.

After the comprehensive anti-interference processing is carried out on the synchronous signals of each phase, the upper computer software extracts the partial discharge signal, displays the discharge amount of the partial discharge TV, and the discharge spectrum such as q-φ.

In the distributed partial discharge on-line monitoring method of the high-voltage cable system of the present invention, a high-frequency broadband electromagnetic coupling sensor is installed at each attachment of the entire cable line, and the sensor is sleeved on the cable attachment ground wire or cross interconnection wire to couple the partial discharge signal, and the 50Hz current The sensor is socketed on the cable body to couple the power frequency current signal; the lower computer performs conditioning, high-speed acquisition and preprocessing of the sensor signal, and transmits the digital signal to the upper computer monitoring software through the optical fiber transmission network to realize distributed partial discharge of high-voltage cable equipment online monitoring. Include the following steps:

(1) A high-frequency broadband electromagnetic coupling sensor is socketed on each cable accessory ground wire or cross interconnection wire of the entire cable line, and connected to the channel of the high-speed data acquisition card after signal conditioning to perform three-phase synchronous trigger high-speed sampling, And after being processed by the FPGA (Field Programmable Gate Array) circuit, the digital signal is stored in the ROM (memory) of the lower computer.

(2) A 50Hz power frequency current sensor is socketed on the cable body, and after signal conditioning, it is also connected to the channel of the high-speed data acquisition card for sampling, which is used to trigger the partial discharge signal acquisition channel to determine the power frequency of the partial discharge signal voltage phase.

(3) The lower computer includes a signal conditioning module, a high-speed data acquisition card, and an I/O card, which are used to complete preliminary interference suppression, trigger acquisition, and data storage of partial discharge signals.

(4) The optical fiber transmission network connects each monitoring unit of the lower computer to the monitoring unit of the upper computer.

(5) The monitoring unit of the upper computer completes the hardware control of the lower computer, the reception of collected data, the display of the apparent discharge amount, and the display of discharge spectrograms such as q-φ (discharge amount-discharge phase).

(6) Through the continuous monitoring of the discharge capacity of each accessory, a discharge trend database is formed, so as to grasp the insulation operation status of the entire cable line.

The distributed partial discharge on-line monitoring of the entire cable line can carry out early prediction and evaluation of insulation degradation, and actively and effectively prevent sudden operation failures of the cable system.

Claims (2)

1. An on-line monitoring method for distributed partial discharge in a high-voltage cable system. A high-frequency broadband electromagnetic coupling sensor is installed at each attachment of the entire cable line, and the sensor is socketed on the ground wire of the cable attachment or a crossover interconnection wire to couple the partial discharge signal, 50Hz The current sensor is socketed on the cable body to couple the power frequency current signal. The lower computer performs conditioning, high-speed acquisition and preprocessing of the sensor signal, and transmits the digital signal to the upper computer monitoring software through the optical fiber transmission network to realize the distributed localization of high-voltage cable equipment. The online monitoring of discharge is characterized in that it comprises the following steps: (1) A high-frequency broadband electromagnetic coupling sensor is socketed on each cable accessory ground wire or cross interconnection wire of the entire cable line, and connected to the channel of the high-speed data acquisition card after signal conditioning to perform three-phase synchronous trigger high-speed sampling, And after being processed by the FPGA circuit, the digital signal is stored in the ROM of the lower computer; (2) A 50Hz power frequency current sensor is socketed on the cable body, and after signal conditioning, it is also connected to the channel of the high-speed data acquisition card for sampling, which is used to trigger the partial discharge signal acquisition channel to determine the power frequency of the partial discharge signal voltage phase; (3) The lower computer includes a signal conditioning module, a high-speed data acquisition card, and an I/O card, which are used to complete preliminary interference suppression, trigger acquisition, and data storage of partial discharge signals; (4) The optical fiber transmission network connects each lower computer monitoring unit to the upper computer monitoring unit; (5) The upper computer monitoring unit completes the hardware control of the lower computer, the reception of collected data, the display of the apparent discharge amount, and the display of the discharge spectrogram of the discharge amount-discharge phase; (6) Through the continuous monitoring of the discharge capacity of each accessory, a discharge trend database is formed, so as to grasp the insulation operation status of the entire cable line. 2. A distributed partial discharge on-line monitoring device for a high-voltage cable system, including a high-frequency broadband electromagnetic sensor, an optical fiber transmission network and a host computer. It is characterized in that it also includes a lower computer data preprocessing acquisition unit, the upper computer is connected to the lower computer through an optical fiber transmission network, and the lower computer data preprocessing acquisition unit further includes a signal preconditioning unit, an I/O control unit, and a high-speed data acquisition card. The pre-signal conditioning unit conditions the signal coupled by the high-frequency broadband electromagnetic sensor, the high-speed data acquisition card collects the conditioned signal, the I/O control unit completes the control of the collection, and transmits the collected data to the upper position through the optical fiber transmission network machine.

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