Study On Insulation Aging Failure Mechanism Of Impulse Capacitor Based On Partial Discharge

The insulation capability of impulse capacitors, which is the kernel elements of impulse power system, determines the security of the entire system. After a long period of recharging under DC , impulse capacitor will discharge instantly. It is necessary for the internal dielectric of capacitor being durable to extremely high field strength during the process of high-current releasing. Capacitors are usually broken-down during working period; however, the research of effective method for insulation condition detection and dielectric failure mechanism was not available now. Study on the method of insulation detection and dielectric failure mechanism of impulse capacitors in working condition can provide theoretical supports for the capacitor insulation detection. The research result can also be used to lead the design of insulation construction of impulse capacitor. Therefore, the working stability of impulse power system can be improved.In this thesis, the latest achievements of existing capacitor insulation detection methods were introduced firstly in detail. The advantage and feasibility of direct current partial discharge detection technology, which was one of the impulse capacitor detection methods, were emphatically analyzed. Then, the causes of impulse capacitor insulation defects were thoroughly discussed; the polypropylene dielectric insulation defects and the partial discharge performance were emphatically analyzed. Based on the direct current partial discharge test and scanning electron microscopy test, the breakdown process of polypropylene insulation and impulse capacitor were discussed in detail and breakdown mechanism of impulse capacitor was analyzed. Finally, the suggestions to the construction design of impulse capacitor were put forward.The result of this thesis, which is meaning to improve the fabrication and detection process of capacitor, can be referenced during the process of impulse capacitors' insulation construction design. Meanwhile, this thesis was an attempt to research the insulation failure mechanism of impulse capacitors, which may promote the research in this field.