Research The Fault Location Of Power Systems With Traveling Wave Based On Hilbert-Huang Transform

The power systems with low current grounding have got a wide range of applications in low voltage distribution network of China. If this kind of systems generates a single-phase grounding fault, the obscuration of fault feature will brought some difficulties to the fault line selection and the fault location. Single-phase grounding fault is a major failure of the systems with low current grounding. For years, the automation of distribution network has got a tremendous improvement, but the problems of fault location have not gained a very good solution. How to improve the accuracy and reliability of fault location with new methods is necessary.This paper briefly describes the traits of low current grounding systems, and than analyzes the transient characteristics of these systems with the single-phase grounding fault. A new method of traveling wave fault location based on three-terminal measurement data, which can effectively improve the accuracy and reliability of distance measurement, has been brought. This method uses Hilbert-Huang transform to detect the head of traveling wave. Combined with the fault line selection, it comes into being a integrated fault location method.The uncertainty of traveling wave velocity, as well as the power lines distortion caused by sag is two important factors affecting the measure accuracy of fault location. This paper uses a new method of traveling wave fault location. This method uses three terminals. Compared with the traditional method which uses single-terminal or double-terminal, it eliminates the effect of traveling wave velocity and line's sag distortion, and then the accuracy of fault location is increased.Hilbert-Huang Transform is a new method of signal analysis. It has no use to choose the primary function. Compared with the wavelet, it has an obvious predominance in dealing with the break transient signal and the weak signal. HHT method has a good self-adaptability, which helps to improve the accuracy of signal analysis, therefore it can be used to detect the transient traveling wave and determine the time when the head of wave arrives.This article uses the PSB toolbox of Matlab in to establish a simulation model of low current grounding system. Based on the model, a large number of experiments which simulate the single-phase grounding fault are processed. Theoretical analysis and experimental results prove that the method proposed in this paper is effective.