Study On Single-phase-to-ground Fault Location Method And Device Of Compensated Power Distribution System

Along with the investment and construction of China’s smart grid,composition and function of smart distribution network increasingly perfect day by day.A basic requirement to smart distribution network is fault self-healing,also the important functional feature of smart distribution network.Nowadays,compensated power distribution network is the main form in China,in order to increase the power supply reliability,meanwhile single-phase-to-ground fault is the most common. Study on single-phase-to-ground fault location method and device of compensated network can increase the efficiency of fault location,decrease time of fault exclusion,promote the realization of grid self-healing.Therefore, single-phase-to-ground fault location method and device of compensated network is studied in-depth in this paper.The paper starts from a zero-sequence full-waveform equivalent circuit that describes the voltage and current characteristics of compensated network with single-phase-to-ground fault,establishing equation of time-domain voltage and current relationship,in turn obtaining an least-square objective function that includes three unkown fault parameters fault distance,fault resistance and capacitance to earth.In order to obtain optimal parameters,the least-square parameter estimation method is used to get the distance from fault position to substation.In addition, considering branches likely existed in the distribution lines, deductive logics are constructed as the complement for the basic fault location method to improving the applicability of the method.As to the device,its modular function and electronic circuit are designed to fetch up its hardware shortage. The new distance measuring device includes two smart module named busbar board and general board,as well as five peripheral module named source board,anolog-input board,digital output board,back board and man-machine board. The smart module manage exchange of data and information,along with the calculation of location algorithm. The peripheral module manage operating power supply,data collection,result output and man-machine communication. The device provides a good hardware platform for the realization of location algorithm.A series of simulations and experiments indicates that the location method has high accuracy and strong practicability.The method has certain directive function to the faultlocation of the branch line. The design of location device hardware function is reasonable and complete.