Study On Continuous And Intermittent High-impedance Earthing-fault Detection Algorithm For Grounded Distribution System

With the rapid development of the distribution network,and its grounding from traditional non-effectively grounded into effective grounding.Based on the characteristics of grounded high resistance,the paper establish a high-impedance ground fault model;nonlinear harmonic characteristics and other characteristics of the intermittent characteristics of high impedance fault current with a ground fault,a new detection algorithms and a high-impedance ground fault detection scheme.The paper mainly completed the work in the following four areas:1.Based on the existing literature on the high impedance ground fault detection,the paper summed up the characteristics of high impedance fault earth fault,on the basis of a detailed analysis of the persistent high impedance and intermittent high resistance of two types of high-impedance ground fault feature.The high-impedance ground fault of the apparent failure characteristics of nonlinear harmonic characteristics and intermittent characteristics are analyzed.2.For the accumulation of the original fault data,the actual high-impedance ground fault through physical simulation system are simulated.Physical simulation system includes fault resistance and arc typical setup and test systems.EMTP digital simulation tools use high-impedance ground fault simulation,broader access to information about different types of faults.3.For the sustained high-impedance ground fault in the process of harmonic characteristics proposed harmonic detection algorithm based on harmonic characteristics.The algorithm can be realized only by the current persistent high impedance ground fault detection,through the fault component current harmonic analysis,extraction of third harmonic and fundamental amplitude and phase of the third harmonic and fundamental compare retardation.This paper describes the principles,and process algorithm was validated,simulation results show the effectiveness of the algorithm.4.For intermittent high resistance earth fault during intermittent characteristics,calculated for intermittent transient conduction intermittent and transient detection algorithm direction.The algorithm to identify the fault line based on transient power Hilbert transform direction,by intermittent detection to detect intermittent failures.Effective use of transient fault information,the application is not limited to the field of high-impedance ground fault detection.EMTP simulation results demonstrate the effectiveness of the algorithm.From the physical simulation systems and EMTP simulation,the high-impedance ground fault detection algorithm is verified.Theoretical and experimental results show that the proposed fault detection scheme is correct and effective.