Research On Fault Location Based On Distribution Phasor Measurement Unit In Distribution Network

With the continuous development of China’s social economy and the ever-increasing growth of people’s good life,higher standards are set for the reliability of power supply of the power grid.The distribution network is widely distributed,with harsh operating environment and frequent random failures.The safe and reliable operation of the distribution network will directly affect the users’ s satisfaction of the safety and reliability of power supply.Therefore,reliable automatic fault location technology for distribution network,which can speed up fault recovery and reduce blackout time,has always been a key concern and technical problem to be solved at home and abroad.The automatic fault location technology of distribution network is divided into three levels according to its function and implementation difficulty: fault line selection,section location and fault location.Among them,fault location is limited by the wide-area measurement level of distribution network for a long time and only stays at the theoretical research stage.With the continuous increase of distribution network construction and investment in recent years,the application of distribution phasor measurement unit(D-PMU)and its wide-area measurement system in distribution network has become a development trend and has been incorporated into the national key research and development plan,providing strong support for solving the practical engineering problems of distribution network fault location technology.This paper focuses on the fault location method based on D-PMU in distribution network.Based on DPMU and its multi-source measurement information,aiming at different types of D-PMU and their corresponding measurement point layout in engineering application,the fault location method based on time domain and traveling wave measurement information is studied to solve the problem of fault location and engineering implementation in distribution network under various complex scenarios.The existing D-PMU mainly includes conventional D-PMU and new D-PMU.Based on the conventional D-PMU and its transient digital signals which are widely used at the present stage,considering the complete layout of measuring points,aiming at the problem of fault location under the condition of line parameter distortion,a fault location method based on DPMU time domain information for distribution network is proposed.This method is based on the R-L parameter model,which uses the characteristic loop KVL time domain voltage equation with coupling parameters,the multi-time operation information and fault history information before the fault to identify the line parameters.Genetic algorithm and three-phase fault transient process recording data are used to calculate the percentage of each corresponding fault distance,construct the corresponding weight coefficient,and determine the fault location through fusion processing.This method improves the accuracy of fault location through automatic parameter identification,and the simulation accuracy is less than 100 m.At present,the new D-PMU has traveling wave measurement function.Considering that the traveling wave fault location method is not affected by distributed power supply and fault conditions,and the location accuracy is improved,a fault location method based on traveling wave information of D-PMU is studied and proposed on the basis of optimal arrangement of measuring points(measuring points are only placed at the end of the network)by using new DPMU and its traveling wave measurement signals.The method uses the arrival time of the initial traveling wave of the fault at the measuring point at the end of the network to define the calculated fault time independent of the wave speed,and determines the location of the fault point by comparing the calculated fault time of each reference point in the network.By using quartile method,abnormal data is eliminated,which improves the fault tolerance and fault location accuracy of traveling wave arrival time error.On this basis,overhead-cable hybrid lines are converted into equivalent overhead lines through wave velocity conversion,thus improving the adaptability of the positioning method in the hybrid line distribution network.The method does not need to identify the fault section,solves the problem that the fault section is difficult to accurately identify in the D-PMU optimal configuration scenario,has the traveling wave arrival time error tolerance capability,and the fault location accuracy is not affected by the distributed power source,the traveling wave speed,and the simulation location error is less than 30 m.Aiming at the engineering implementation problems of the above distribution network fault location methods,relying on the domestic autonomous master station platform,through the joint call of Linux and MATLAB,we developed a distribution network fault location system based on wide area synchronous measurement to meet system compatibility requirements.Through the on-site manual short circuit test,the fault location system and its traveling wave fault location method are verified.This theis concludes with a summary of the main research innovations and makes a prospect of the future research work.