Application Of EMTR Theory In Fault Location Of Transmission Line With Series Compensator

The unbalanced distribution of resources and loads makes ultra-high voltage,long-distance,and large-capacity transmission become the development trend of power systems.The following problems include transmission capacity limitation,unreasonable power flow distribution,and reduced stability.The series compensation capacitor improves the above problem while destroying the uniformity of the line,making fault location more difficult.Therefore,it is especially necessary to analyze,find and eliminate the fault points of the series compensated lines with accurate,reliable,rapid and economical devices and strategies.There are certain limitations in the fault location of series compensated lines based on traveling wave method or fault analysis method.Therefore,after considering the influence of series compensation capacitor on fault signal and the start-up time of metal oxide varistor(MOV),a novel fault location method of series compensated line based on electromagnetic time reversal(EMTR)theory was proposed in this paper.Firstly,the fault current at both ends of the line was decoupled by Karrenbauer transform and then decomposed by wavelet transform to extract the transient signal of the fault current.Secondly,the transient fault current signal was time reversed and connected to both ends of the mirror image of the line as a current source.Then the effective value of the current was calculated for each assumed fault point.Because the maximum ground current occurs at the real fault point,the point with the maximum ground current is the fault point.The simulation model of the series compensated line is established to verify the feasibility and robustness of the method.A large number of fault location results show that this method can not only obtain good accuracy,but also is not affected by the transition resistance,phase angle difference on both ends of the line,Fault time,and series compensation degree.As an important part of the method,wavelet transform should be used to correctly reflect the attenuation of traveling wave,otherwise it will lead to too large deviation between the fault location result and the real fault point.