Research On Fault Feeder Selection Methods For Non-Effectively Earthed Networks Based On Fault Measure Of Travelling Wave

As a single-phase ground fault occurs in a distribution network, the current mutation amount of the fault feeder could be very weak. Therefore, the study of sensitive, rapid and reliable importance of small current grounding fault line selection method is more significant. This paper briefly describes the general concept of fault measure. Previously, the concept of fault measures applies to the fault feeder selection methods based on the transient and steady electrical quantities. However, in this paper, the concept of fault measures is combined with the fault feeder selection method based on the initial travelling waves.This paper take advantage of the fault transient information and propose the new feeder selection methods based on the initial travelling wave. The main work of this paper are as follows:(1) Based on the Sagami transform theory, the paper studies initial travelling waves of single-phase ground faults more accurately. Through a series of formula derivation, This paper derived the formulae of the zero mode failut initial voltage travelling waves and the zero mode failut initial current travelling waves. A comprehensive and detailed analysis of the propagation of fault initial travelling waves in the neutral point ungrounded and resonant grounding system.Through the analysis of the zero-mode faults initial current travelling waves, the article reveals the characteristics of the initial travelling waves about non-effective grounding grid single-phase ground faults.(2) Based on characteristics of fault initial travelling waves and wavelet transform modulus maxima, this paper defines amplitude fault measures about travelling waves. The amplitude fault measure of the fault feeder is 1.But, amplitude fault measures of the fault feeder are much smaller than 1. According to this rule, this paper proposes a new algorithm about the detection of single-phase ground faults neutral point non-effectively grounded grids:fault feeder selection algorithm based on amplitude fault measures.(3) Based on characteristics of fault initial travelling waves and wavelet transform modulus maxima, this paper defines polarity fault measures about travelling waves. The polarity fault measure of the fault feeder is 1.But, polarity fault measures of the fault feeder are much smaller than 1. According to this rule, this paper proposes a new algorithm about the detection of single-phase ground faults neutral point non-effectively grounded grids:fault feeder selection algorithm based on polarity fault measures.(4) When the bus occurs a single-phase ground fault,for the polarity of wavelet transform modulus maxim about zero-mode initial current travelling waves, all feeders are the same. According to this rule, this paper proposes an algorithm about the bus fault detection based on the initial travelling wave.(5) This paper established the effective grounding grid ATP simulation models. In non-ground neutral networks and resonant grounding networks,there are three main influencing factors:the fault point location, transition resistance and fault initial phase angle. With three main influencing factors changed, This paper simulate the single-phase grounding fault,so as to verify the correctness of algorithms proposed by this paper.The theoretical analysis and simulation show:the detection methods of single-phase ground faults neutral point non-effectively grounded grids presented in this paper is correct.This paper proposes a fault feeder selection method based on amplitude fault measures, a fault feeder selection method based on polarity fault measures and a method about the bus fault detection based on the initial travelling wave. With a broad scope of application, the algorithms is simple, effective, and have good sensitivity. The methods can be applied to the neutral point ungrounded grids and the neutral point arc suppression coil grounding grids.