Extreme climate impact on periodicity of fault

In reliability analysis of power system, component failures are usually supposed to be independent from each other. Consequently, the number of component failure in given time interval should have exponential distribution and there should not be periodicity in the time series of component failure. In our previous work, it has been observed that component failure in distribution system follow power law distribution and have long term autocorrelation, i.e., it behave self organized criticality and there are phenomena like periodicity in time series of fault. The impact of extreme climate on power law distribution of fault has been identified, while the influence on periodicity of fault has not been reported. In the article, Hurst exponent, which denotes long term autocorrelation of a time series of data, is utilized to represent periodicity of power system fault. Fault data of Changsha distribution system in China is analyzed. It is found that the investigated system has long term autocorrelation. In order to investigate influence of extreme climate on periodicity in fault, the days with largest number of fault are removed and the Hurst exponent is calculated. Based on in-depth analysis of cause of removed fault data and variation of Hurst exponent, the factors contribute to periodicity of fault are identified.