Research On Fault Location Of 110kV Transmission Lines On PSCAD

High voltage transmission line is responsible for long-distance power transmission,and is closely related to industrial and agricultural production and people’s daily life.The accurate location of fault location device can help the line operators to find the fault points in time,and also find some hidden dangers that are difficult to detect.This paper compares the principles of various fault location algorithms,and tell about the merits and shortcomings of them.In order to improve the accuracy of fault location on 110kV transmission line with single ended quantity,two mainly aspects should be solved from the accuracy of the line parameters and the solution of the transition resistance.The comprehensive comparison of various algorithms,that the negative sequence current method with high accuracy for zero moment M side negative sequence current approximate fault zero sequence current,this algorithm can locate the fault according to the sampling value of line parameters and single terminal voltage,current,and it doesn’t need to know the parameters of the system on the side and the running state.This algorithm considers the distributed parameter model can also be used in EHV power transmission network.For llOkV transmission lines,it is less affected by the distribution parameters,the length of line often is not long,so the error is smaller with the algorithm.Simulation calculation for negative sequence current on M end approximating fault zero sequence current proves that the effect is good.However,due to the limited sampling frequency,the real zero crossing point can’t be picked up,and the gap between the sampling point and the zero value is larger with the increase of short-circuit current.To solve this problem,an improved negative sequence current method is proposed in this paper.Recording the moment of the second wave after fault which is the minimum value of the negative sequence current on M end,and calculate the sampling value with the momen and the previous moment.The error due to a positive and a negative sum,its value tends to zero,the error is smaller.The algorithm is still to reduce the error of wave impedance,.It is less influenced by the zero sequence parameters,mainly involved in the calculation of wave impedance is positive sequence impedance,reduce the influence of zero sequence impedance parameter error on measurement distance is not accurate.The PSCAD simulation is used to establish the line parameter model by using the measured parameters of a certain line with single-phase grounding fault and two phase grounding fault are carried out.The results show that this improved negative sequence current method can obtain higher accuracy,and is suitable for 110kV transmission line fault location.