An anti-interference method for on-line partial discharge monitoring of large generators

Abstract

The invention relates to an anti-interference method for on-line partial discharge monitoring of a large generator, comprising the steps of: 1) installing a VHF capacitive sensor at the three-phase outlet bus of the generator, installing a high-frequency current sensor on the neutral point grounding line, and installing a VHF capacitive sensor Both the sensor and the high-frequency current sensor are connected to the partial discharge monitoring device through a high-frequency coaxial cable; 2) Use the analog partial discharge pulse generator to connect the discharge pulse at different positions, start the monitoring host, and send commands to the partial discharge monitoring The device collects all sensor signals synchronously, finds the corresponding pulse of the high-frequency current sensor channel at the same time according to the pulse of the VHF capacitive sensor channel, and determines the position of the pulse discharge source through the pulse polarity of the two signals. The beneficial effect of the invention is that it can effectively filter out various pulse interferences from the direction of the ground wire and the direction of the high-voltage bus, especially various random pulse interferences which are most difficult to filter out.

Description

technical field [0001] The invention belongs to the technical field of insulation monitoring of large generators, in particular to an anti-interference method for on-line partial discharge monitoring of on-line generators. Background technique [0002] There are mainly the following methods for large-scale generator insulation monitoring: Ultrasonic sensor detection method. Ultrasonic sensors are pasted on the surface of the generator with a frequency range of 10kHz to 10MHz. The purpose of generator insulation monitoring; radio frequency sensor monitoring method, a microstrip radio frequency antenna is built near the stator slot inside the generator as a sensing device to couple electromagnetic wave signals in the partial discharge space, and its frequency range is 10MHz to 1GHz. It must be installed when the generator is produced; the high-frequency current sensor method is to clamp the high-frequency current sensor on the neutral point grounding line of the generator to c...

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Problems solved by technology

The advantage of the ultrasonic method is that it is easy to install, and the discharge point can be located through multiple measuring points. The disadvantage is that the generator itself has a large vibration noise, and the ultrasonic interference is relatively serious, resulting in a high rate of misjudgment. The advantage of the radio frequency sensor monitoring method is that the detection frequency band High, high signal-to-noise ratio, suitable for on-line monitoring, the disadvantage is that it needs to be built in in advance, and it has a certain impact on the insulation performance of the generator itself, and it cannot be detected for the generator that has been running; the advantage of the high-frequency current sensor method is that it is easy to install and does not Changing the wiring of the generator, no electrical connection with the generator, does not affect the normal operation of the generator at all, the low frequency band is convenient for signal acquisition and system integration, and is suitable for online monitoring. The disadvantage is that the pulse interference is relatively large, especially corona interference and grid fluctuations The various interferences caused can basically not be effectively filtered out; the advantage of the very high frequency (VHF) capacitive sensor coupling method is that the coupling efficiency of the partial discharge signal of the generator is high, and multiple sensors can be combined with each other to form a variety of algorithm strengthening systems Anti-interference ability, the disadvantage is that the sensor is connected in parallel on the bus, the stability of the sensor has a certain impact on the generator, and it is difficult to filter out corona interference and random pulse interference, especially the transmission of pulse interference from the ground direction, which can directly cause system errors. sentence

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