Research On Fault Location Of Power System Transmission Lines Based On Distributed Parameter Model

With the increasing complexity and diversification of transmission line faults,the difficulty in locating their precise faults has also greatly increased.This paper studied the fault location methods of transmission lines,aiming to improve the accuracy of fault location,which is of great significance for reducing the workload of maintenance personnel patrolling the line,reducing the loss of power users during power outages,and ensuring the safe,reliable and economic operation of the power system.The study work of this article is divided into the following aspects:(1)Aiming at the problems of traditional single-ended impedance method,such as low accuracy,fault location model is inaccurate and is greatly affected by fault impedance,Chapter 3 proposed an improved single-ended method based on distributed parameter model.An accurate distributed parameter model was adopted for transmission lines.Considering the increasingly close grid connections in major regions,a two-port Thevenin equivalent network model that fully considers its internal connection characteristics was adopted for power systems.The fault location method proposed in this chapter can perform high-precision fault location on various faults when the size of the fault resistance is within the normal range,which effectively improves the accuracy and location of the fault location without increasing the distance measuring device and cost accuracy.(2)The impedance method is greatly affected by the transitional impedance.The traveling wave method relies on the wave head detection and the fault transient data after the wave head can not be used for fault location.The frequency domain method requires filtering and phasor extraction and the conversion between the time domain and the frequency domain.In order tofurther improve the accuracy of fault location and further optimize the above problems,Chapter 4 proposed a two-terminal time-domain fault location method based on distributed parameter model.The line model is in the time domain,which is a new method that combines traditional phasor methods with traveling wave technology.The method directly uses the sampled values without filtering and phasor extraction,eliminating the time and frequency domain conversion process,and is not affected by factors such as transient resistance and grid frequency fluctuations.This method calculated the absolute difference of the fault voltage at both ends of the transmission line,thus ensuring a lower fault impedance and the influence of its electrical parameters.Compared with the Bergeron model,the two-terminal time-domain distributed parameter model algorithm proposed in this chapter is easier to execute and the relative error rate of fault location is reduced by about 75%.And even under the adverse conditions of fast self-extinguishing short circuit,low signal-to-noise ratio signal,inaccurate transformer and other adverse conditions,satisfactory results can be obtained.(3)Use MATLAB/Simulink for simulation to verified the fault location method proposed in this paper.The simulation results showed that the two methods proposed in this paper have good fault location accuracy and reduce the time to remove the fault.