Study On Fault Location Schemes For Transmission Lines Based On Phase Comparison And Multiple Current Measurements

Transmission line is an important part of the power system. The fault location for transmission lines is of great significance to help power line maintenance crews search for fault point, detecte the portion insulation hidden trouble of lines timely and restore the lines’ transmission service without too much delay. However improving the fault location accuracy and reliability is able to shorten the search time, reduce the breakdown maintenance’s workload, and to ensure that the power system safe and stable operations. This study is to improve the accuracy and reliability of transmission line fault location,which based on multiple measurements and phase comparison as the main line.To solve the problem that the reliability of current fault components phase comparison is relatively low due to spectral leakage, this paper proposed a novel fault location scheme for transmission lines based on phase comparison with Kaiser self-convolution windows FFT. This scheme uses FFT program to solve the phase current fault component of multiple current measurements which are compared for determining fault section; uses excellent sidelobe characteristics of Kaiser self-convolution window to restrain spectral leakage, then the reliability of phase comparison was increased,and has the practical significance to ensure effectiveness of multi-measuring points of traveling wave fault location.The ground distributed capacitance and mutual inductance of EHV double circuit line can not be ignored,and has a great impact on the fault location. A fault location scheme based on phase comparison and traveling waves of four measurements is presented for double circuit line to improve the location accuracy and reliability, which determines fault section based on the phase comparison, and means to shorten double ends distance, obviously decreases the attenuation(distributed capacitance) and distortion(mutual inductance) of current traveling waves. In the fault section locates the fault location based on traveling waves of four measurements which is composed of two traveling waves of three measurements, achieves online determined wave velocity, and can effectively solve the problem that phase comparison misjudgment caused by polarity reversed and measurements’ fault.Since the problems in the fault location of transmission line that wave head detection algorithm existing defects,and location error is large, an accurate fault location scheme for transmission lines is proposed in the paper based on local characteristic scale decomposition(LCD) and sampling rate conversion(SRC) on fault current traveling waves of three measurements. In the scheme, the LCD is applied to decompose 1/4 period waveform of mode component of each measured current wave, and the arrival times of the initial traveling wave are detected according to the first frequency sudden arising of the first Intrinsic Scale Component obtained through decomposition. Finally, the fault point is determined based on the traveling waves of three measurements. The existing methods of fault location have not considered non integer part of the initial time which cause the quantization error about up to a few hundred meters, in this paper, firstly, the SRC of line mode component is used to reduce the quantization error before the wave head detection. Simulation results show that it possesses the advantages of high precision, great adaptability. After SRC, the location error is decreased an order of magnitude.