Single Terminal Traveling Wave Based Fault Location Of Transmission Lines Using Mathematical Morphology

Traveling wave based fault locators for transmission lines have achieved commercial operation for many years.But there are still some aspects waiting to be further improved, such as the reliability,accuracy and so on.In particular,the various single terminal principles of fault location based on traveling wave are unable to be used alone in practice, because of those principles’ reliability is insufficient.As one of the single terminal principle,the traveling-wave correlation method has a unique advantage in the range of reliability,but not yet reaches a practical level.So,several aspect of research work has been done in this paper as follows:(1) In this paper,through the analysis of traveling wave based fault location principles and the fact waveform,two key questions which impact traveling-wave correlation method are discussed:the criterion of correlation function maxima is unreliable;the length of time window is difficult to pre-determine.(2) The reason that causes the "high frequency oscillation" in the traveling-wave waveform is analyzed,and its infection to the reliability of the criterion of correlation function maxima is pointed out.At the same time,a single terminal traveling wave fault location project based on mathematical morphological filtering and correlation function is proposed,which is line in accordance with the traveling-wave waveform’s characteristics and morphologic filter’s characteristics.First,the project treat the traveling wave on the fault transmission line with the appropriate mathematical morphological filter,which is designed as pre-morphological filter,through the design of pre-morphological filter,then, traveling wave correlation method is used to achieve the single terminal fault location on transmission line.(3) The algorithm of multi-resolution morphological gradient-correlation function which used for fault location is proposed.Based on separating transient surges reliably, using multi-resolution morphological gradient,that algorithm uses multi-resolution traveling-wave correlation method to find the fault location.The algorithm solves the problem of the difference width of transient surges which is separated by the high-pass filter,and the unreliable problem of the traveling-wave correlation method under the fixed time window.Theoretical analysis and traveling-wave waveform analysis indicate that the project can effectively control "high-frequency oscillations",as to realize automatic fault location. At the same time,the simulations on ATP program show that the algorithm of multi-resolution morphological gradient-correlation function which used for fault location can endure the influences of various factors,including fault distances,inception angles, fault path resistances,and have high location reliability and accuracy.