Fault Location Of Single-Phase Earth For Cable In Distribution Network Based On Distributed Parameter Line Model

With the rapid development of national economy and the launching of the citydistribution network remaking work, a large of the power cables had been put intooperation, there had been a large number of single-cable power lines and overheadline-cable hybrid power lines. The fault of power cables occurs more frequently,especially cable single-phase ground fault, accounting for80%of the number of the allfaults, thus the rapid and accurate fault location of single-phase ground fault for powercable in the distribution network is important to ensure the safe and stable operation ofpower systems. At present, the system of distribution cable is the low current system,when happening the single-phase ground fault, the fault current is very low, thecharacteristic of fault steady state is not obvious, so the frequently-used of the faultlocation method based on fault steady state information is limited. There is a need toresearch on a new fault location method for the single-phase ground fault for powercable in the distribution network based on the fault transient state information.The time domain fault location method based on line model can use the faultsteady state and transient state information, suiting for the fault location of thesingle-phase ground fault in the distribution network. In view of the disadvantage of thecurrent line model of the fault location algorithm, the paper adopted a new linedistributed parameter model in which multi-order distance infinitesimal was taken intoaccount, the model suits for the requirements of the fault location of the single-phaseground fault in the distribution network.Based on the line distributed parameter model, the paper proposed a new timedomain two-ended fault location method. Utilize synchronous fault informationinvolved in voltages and currents measured at both terminals to locate the fault location,and adopt face-to-face search algorithm along the whole length of the cable line todecide the distance corresponding to the point where the error of zero-sequence voltageis the minimum, and this distance is the fault distance. The method is the time domainfault location method, can use the fault steady state and transient state information, andsuits for the fault location of the single-phase ground fault. Based on the algorithmic, goon the researching on two-ended fault location method for hybrid power lines in thedistribution network.The paper used MATLAB and EMTP to go on the simulation, the results showed that the proposed fault location method overcomes the disadvantage of the currentmethod that based on the fault steady state information, The method can use thetransient state information to go on the fault location to get a higher of accuracy, and theaccuracy is independent of neutral point operation mode, fault initial phase angle,transition resistance and fault position.In the end, the paper went on exploratory research on single-ended time domainfault location method based on the line model. The method is to estimate the offsidecurrent information flowing to the fault point, and go on fault location based on that thecorresponding positive、negative、zero sequence current instantaneous value of the faultpoint is the same. Based on the single-ended algorithmic, going on the researching onthe single-ended fault location method for hybrid power lines in the distributionnetwork. The simulation results showed that the method is accurate and suitable for thefault steady state information.