Fault Location Based On Single-end Transient Travelling Wave For Single-phase Ground Fault In Distribution Network

As the framework of the grid,transmission and distribution lines have a significant impact on the social economy.In order to ensure the safe and stable transportation of the power after fault,fault location should be confirmed quickly and accurately to make the power supply normal on time.Therefore,it is necessary to study the fault location of the single-phase grounding fault of the small current grounding system.The structure of the distribution network is complex and the branches are massed.Comparing with the double-end method,the single-ended fault location is more advantageous,so this paper's basic principle is the single-ended method.This paper analyzes the characteristics of transient traveling wave in single-phase ground fault and obtains the line-mode component and the zero-mode component by phase-mode transformation.The line-mode component is usually used as location for its stability,while the zero-mode component also contains fault information,making full use of its characteristics can improve the accuracy of fault location.By analyzing the transmission characteristics of zero-mode component,it is concluded that the high-frequency component has higher velocity but the larger attenuation,so the difference between initial velocity and reflection velocity vary in different bands.The wave velocity decreases with the increase of fault distance,thus the reflection wave velocity must be smaller than the initial wave velocity.These features can achieve the estimation of zero-mode wave velocity.In a frequency band,the wave velocity is stable,the initial wave velocity is closest to first reflection wave velocity,so the first reflection velocity can take the place of the initial velocity to achieve fault location.Due to the attenuation of wave velocity,the location method based on the modulus transmission time difference still remains error,so the fault location can be used as the initial result to achieve further ranging.Since the initial result is smaller than the actual fault distance,the search range of wave heads can be reduced.Then the fault point reflection wave head and the opposite bus wave head can be determined at the same time by using their relationship,bring the corresponding time of the two wave heads into the formula to obtain a more accurate distance.