Study on separation algorithm of convolutive mixing model and separation of mixing signals of multiple partial discharges

To identify individual partial discharges(PD)signals produced by multiple insulation defects in gas insolated switchgear (GIS),this paper analyses the mechanism of propagation and mixing of multiple PD electromagnetic wave signals in GIS cylinder and proposes the convolutive mixing model to describe it for a separation algorithm to acquire individual PD signals. With the non-stationary property,mixing PD signals are changed at time domain into a set consisting of short-time stationary PD signals and then the Molgedey-Schuster decorrelation approach is employed to separate these stationary PD signals at frequency domain. The correlation of the envelope of separated PD signals in this set is used to reconstruct PD signals to realize the separation of non-stationary UHF PD mixtures. The effective separation of actual UHF PD mixing signals validates the assumption of convolutive mixing process in GIS and also offers a new approach to the identification of mixing PD signals by external ultra-high frequency detection scheme from multiple insulation defects in GIS.     

Study on the testing device for simulating the partial discharges of different defects in gas insulated switchgear

To overcome the shortage of existing experimental device for partial discharges in gas insulated switchgear(GIS),an installation for testing PD in GIS with multi-structures is designed, which can simulate T-type,L-type and line-type configurations of GIS expediently. The physical dimension and material parameter are given by calculating the characteristic of the propagation of ultra-high frequency electromagnetic waves and the stress of materials. The experiments under single defect and multiple insulation defects are carried on by using the designed 4 physical models of typical insulated defects for GIS. The results show that the built device can simulate the PD,TE mode and TM mode waves with different wave bands in GIS. The system makes a foundation for the further investigation of the electromagnetic waves propagation,the conditions of generating electromagnetic waves,testing method and pattern recognition of the PD in GIS.