The Research For Fault Detection And Identification Of Distribution Network With Distributed Generator Supply

With the global energy crisis increasing,Distributed Generator(DG) came into being.DG changes the radiation structure of a single power supply network with more and more distributed power supply access to the distribution network, although the distributed power ease the global energy shortage situation.The topology and operation of the distribution network will change,this will cause the distribution network fault detection and identification process becomes more complex,the existing fault detection and identification program will be affected,some are no longer applicable.Therefore,in the context of building intelligent distribution network, it is necessary to carry out research on fault detection and identification of distribution network with DG .Specific work is as follows:(1)This paper first analyzes the influence of access DG on distribution network,especially on the short circuit fault detection and identification of distribution network.Aiming at the influence on fault detection, the fault detection and recognition based on wavelet singular entropy(WSE) theory and fuzzy logic are studied and made a judgment for several types of fault in distribution network using the output of fuzzy logic,which provides the theoretical basis for the subsequent relay protection and island detection.(2)After the fault type is determined, for the single-phase ground fault which has high occurrence,then carry out the fault line selection work.Firstly, the fault simulation model with DG is built. Secondly, the zero sequence current of each line is S-transformed, preprocessing the data, extracting the fault feature, finding the characteristic frequency band and judging the fault line time.Finally, the transient energy calculation of each line is carried out in the characteristic spectra.In order to solve the limitation of the application for selecting fault line in the distribution network with DG,an adaptive fault line selection method with transient energy ratio is proposed.The experimental results show that the wavelet singular entropy theory and fuzzy logic method can quickly detect the fault and can classify the fault accurately,the adaptive line selection algorithm with transient energy ratio can be adapted to the distribution network with DG, also can accurately identify the fault line,having good adaptability and can improve the protection margin.