Monitoring Method for GIS Electrical Contact State Based on VMD-Hilbert Marginal Spectrum Energy Entropy

To diagnose the electrical contact state of gas-insulated switchgear (GIS), the monitoring method based on variational mode decomposition (VMD) and Hilbert marginal spectrum energy entropy is proposed. The multi-physical field coupling model of GIS is established, and vibration signals under various states and operating currents are simulated. The GIS prototype and laboratory test platform are developed, and vibration tests are conducted under four different electrical contact states. Experimental results indicate that at the same contact state, with the current increases, the vibration amplitude of the GIS contact shows an increasing trend; under the same current, with the deterioration of the contact state, the vibration amplitude of the GIS contact shows an increasing trend. Further, the method of GIS contact state diagnosis based on VMD-Hilbert spectrum energy entropy is proposed. The online monitoring experiment is carried out in the substation. The results indicate that, aiming at the abnormal contact state of GIS, the energy entropy of the intrinsic mode function 6(IMF6) is 0.704, below 0.7368, while that of IMF7 is 0.2176, exceeding 0.187, which indicates a mechanical fault state. The conclusions show that the monitoring method can accurately identify the electrical contact state of GIS.