Research on the self-healing failure characteristics and its protection methods of high-voltage self-healing capacitors

There are no reliable measures for identifying self-healing failures in capacitors. Therefore, the high-voltage self-healing capacitor have not been widely adopted in power systems yet. It is urgent to study new scheme to protect the self-healing failure of high-voltage capacitors. Simulations tests and experiments were conducted to further assess self-healing of capacitors. The broken-down capacitor samples were connected into the test circuit with a vacuum contactor, and recorded the experimental phenomena and current wave-forms. The impedance changes were measured before and after the test, and calculated the active power dissipated by the sample. The test results showed that the insulation of self-healing failure sample temporarily restores or deteriorates rapidly. No visual defects are observed in the case of temporarily restored insulation, and the capacitor can continue to operate. However, if the insulation was deteriorated, unwanted gas generation, consisting of 85% H(2), potentially lead to smoke and fire. Our study showed no obvious correlation between impedance change and occurring self-healing phenomena. It is found that the process consumes a lot of active power in case of deterioration. Therefore, a method of capacitor self-healing failure protection based on active power variation was proposed