Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Abstract:
This work presents a method of fault detection on high voltage transmission line which uses discrete wavelet transform of the positive sequence current signal from the line. The positive sequence current represents the current on all the three phase. The problem of reliability and accuracy in fault detection on high voltage transmission lines can be solved using this proposed method. In this work, a method of solving the problems associated with High voltage (132kV and 330kV) Transmission line fault detection is presented. Fault detection was simulated using the SimPower systems of the Matlab/Simulink software, properties of models used were well controlled with negligible deviation from real life situation. The positive sequence current which represent the three phase current on line is sampled by using a sliding window of 400 samples at 20kHz which is very high compared to the 50Hz frequency of the current, the sampled signal is analyzed by using level 5 Daubechies wavelet which closely represent a fault scenario, the sum of the energies of the wavelet decomposition are added and compared to a given threshold value which determines whether the circuit breaker trips or not. Detecting fault on high voltage transmission line can be a very difficult task but the use of Discrete wavelet transform can improve performance because; it has high fault detection speed, flexibility of setting the fault threshold which controls unnecessary tripping of the circuit breaker and its reliable because it does not depend on fault characteristics like fault resistance, fault type or position.

Keywords: transmission line, wavelet, sampling frequency, low-pass filter, trip signal

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