On-line detection method and device for power capacitor

Abstract

The invention discloses an on-line detection method and device for a power capacitor. A current sensor is used for collecting a noise-contained local electric discharge signal of a capacitor; after the signal is processed, a complex signal is decomposed into limited intrinsic mode function components by empirical mode decomposition; the intrinsic mode function components are subjected to mathematical morphology alternate mixing filter by a flat structure element; a threshold value and a hard thresholding rule are determined by a 3sigma gross error standard to carry out threshold value discrimination to a new intrinsic mode function component; the intrinsic mode function component processed by the threshold value is reconfigured to obtain a de-noised power capacitor local discharge signal; and the signal is sent into the computer to obtain the on-line working condition of the capacitor. The on-line detection method has a clear physical meaning on processing non-linear and non-stable signals and has a good localized characteristic in a frequency domain and a time domain, the original morphological characteristics of the signal can be kept to the maximum degree, local signal dynamic behaviors and characteristics can be analyzed, and the on-line detection target of the power capacitor can be better realized.

Description

technical field [0001] The invention belongs to the field of power systems, and in particular relates to an online detection method and device for a power capacitor. Background technique [0002] With the development of social economy, the social electricity consumption is increasing rapidly, the scale and transmission capacity of the power system are also increasing rapidly, and the requirements for the reliable operation of the power system are getting higher and higher. The role of power capacitors in the power system is mainly to compensate the reactive power of the inductive load of the power system, improve the power factor, improve the voltage quality, and reduce line losses. The reliability of its operation is directly related to the safe and stable operation of the power system. However, due to the influence of overvoltage, overcurrent, temperature, harmonics, etc. during operation, the strength of the insulating medium will gradually decrease, which is obviously ma...

AI Technical Summary

Problems solved by technology

Although these methods can suppress the interference signal to a certain extent, the energy loss of the original partial discharge signal is relatively large, and when new interference occurs or the center frequency of the interference changes, the original parameter settings will become invalid.

Although the wavelet transform can extract the partial discharge signal better, this method will cause the signal to lose part of the energy after denoising, which will cause the signal to be distorted

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