| SF6 Gas Insualate Switchgear(GIS)with the construction of smart grid,It is widely used in power systems.The safe operation of GIS is directly related to the safety of power systems.Therefore,effective and reliable detection and diagnosis of GIS partial discharge is implemented,so that GIS defects are eliminated in the bud,and serious accidents are avoided.The online detection system is urgently needed at present,and it is of great significance to ensure the stable operation of the power system.This article studies the partial discharge phenomenon existing in GIS and compares the existing detection methods.The UHF detection method is superior to other detection methods in anti-interference ability and monitoring sensitivity.Fundamentally research and analyze the mechanism of partial discharge signal,and analyze the characteristic parameters of partial discharge,the propagation path of electromagnetic wave in GIS and based on partial discharge positioning principle.This paper systematically studies the application of electromagnetic wave equation in GIS coaxial waveguide.The qualitative analysis of the electromagnetic wave attenuation law inside GIS has laid a foundation for anti-interference research.Based on the shortcomings of traditional monitoring system,we are committed to improving the existing inadequate distributed detection system.The acquisition and noise reduction of local processing signals are converted into digital signals,and then the digital signals are directly uploaded to the upper monitoring center to realize fault type judgment and fault location.Then,aiming at the problem of mixed Gaussian white noise interference in UHF on-line PD monitoring.According to the shortcomings of real wavelet in the existing denoising,a new algorithm of double tree complex wavelet transform under the improved threshold is proposed to suppress the white noise interference,and the performance of the improved algorithm is mainly evaluated from the denoising effect.It is determined that under the improved threshold is the practicability of double tree complex wavelet transform in the GIS partial discharge signal denoising. |
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