Overcurrent protection of distribution system with distributed generation [articol]

Abstract

This paper presents the digital protection technique based on combined d-q transform and Wavelet singular entropy to detect short circuit faults in distribution system with distributed generation. The direct axis and quadrature axis transformation is applied to three phase current signal and the resulting d-q current is analysed through Wavelet Packet Transform. Due to the increased size of current vector, their analysis is more complicated and time consuming. The Singular value decomposition and Shannon entropy is applied to wavelet packet coefficients to decrease vector size of the current. This technique provides enough information to identify and discriminate fault, islanding and grid reconnected condition. This method requires less sampling rate and hence it is simple and requires less hardware and computation time. This method is immune to fault inception angle and fault location. This method is tested in distribution system with distributed generation. To test the proposed method, faults are numerically simulated in MATLAB/SIMULINK and it is compared with recent technique.