Pattern Analysis of Discharge Characteristics for Condition Evaluation of Polymer Insulators in Fog-Haze Environment

With the frequent appearance of fog-haze weather in China, outdoor insulators are exposed to the new contamination problem, which is characterized as the long-term heavy humidity and severe fine polluted particles, which can enhance the probability of the surface discharges, even flashover. An artificial fog-haze system was established to simulate typical fog-haze conditions of outdoor insulators in the operation. The salt fog and fine particles were simultaneously injected into the artificial climate chamber. The fog was generated by an ultrasonic vibration salt fog generator filled with saline water solution. The fine particles were prepared by both conductive and nonconductive particles at different components. When the experimental condition was sustained for different duration, the transition of surface discharges until the flashover was recorded by using an analog to digital (A/D) converter, with the sampling frequency of 10kHz. Then, pattern identification of discharge currents was carried out based on non-linear analysis method to reflect the process and underlying mechanism of surface flashover in fog-haze environments. The obtained results show that with the duration of fog-haze conditions, the flashover voltage show the rapid decreasing tendency, especially with the increase in the conductive components of fine-particles and fog conductivity. The nonlinear analysis of discharge currents can reveal the prominent increase of peak value with the experimental duration, and with the increase in the conductive components of fine-particles and fog conductivity, which is well in accordance with the transition of surface discharges to the flashover. The investigation is beneficial to reflect the discharge characteristics and flashover mechanism of outdoor insulators in fog-haze environments, which is helpful to enhance the operating reliability of outdoor insulator in power system.