Study On The Technology Of Fault Location In High Voltage Measurement To Distribution Network

The small current grounding system has got a wide range of applications in distribution network of China. Single-phase earth fault is a major failure of small current grounding system. For years, the problems of fault location are not gained a very good sulution, which needs new methods and equipments to improve the reliability of fault location.This paper describes the development trend of the distribution network. The technolgy of singnal sampling, processing and communication for the optical current transducer are researched in order to satisfy the demand of current measurement and information network in modern distribution network. According to the characteristics of small current grounding system, optical current transducer is used to transform traveling wave signals, and Hilbert-Huang Transform is used to process signals in this paper, which enhances the reliablitity of fault line selection and fault location and comes into being a integrated fault location method.Firstly, the basic theory of Hilbert-Huang Transform using in electric system is introduced in this paper. The scarcity of the analyzing principle based on steady signals is fetched up with Hilbert-Huang Transform. It doesn't need to choose the primary function, and it has a good self-adaptability which can reveal the inherent characteristics of the signals, so it is more reliable.Secondly, taking the characteristics intrinsic mode energy as criterions, the new line selection analysis based on characteristics intrinsic mode energy is conducted. Fault location is based on fault line selection. The signals are analyzed by empirical mode decomposition. Hilbert transform is used for the instrinsic mode functions to extract instantaneous frequency and detect the head of traveling wave, which improves the accuracy of fault location.At last, by ATP, a simulation model of low current grounding system is established in this paper. A large number of simulation experiments are processed by MATLAB. The theoretical analysis and experimental results prove that the method proposed in this paper is effective.