A differential protection scheme for tapped transmission line containing UPFC and wind farm

Abstract

In this paper the authors suggest a novel protection scheme for a tapped transmission line connected to wind-farm in presence of UPFC. The powerful analyzing and decomposing features of Wavelet Transform(WT) along with the accurate phasor extraction feature of Discrete Fourier Transform(DFT) has been combined to develop this useful and effective protection scheme. The whole idea of the proposed scheme is to extract third level decomposed current signals at each substation using Wavelet Transform. Then third level approximate coefficients(CA3) are reconstructed for each line current at every substation to derive operating and restraining quantities after extracting the respective fundamental phasors by using DFT. The proposed scheme has been tested on a 500 kV, teed-transmission line in the presence of UPFC and Wind Farm (as one of the substation) under various fault and operating conditions on MATLAB environment. The results given in section-V shows the feasibility of the proposed relaying scheme. To compare effectiveness of the proposed differential relaying scheme along with the conventional relaying scheme, different types of faults have been simulated at different location of the transmission line by considering three statistical metrics (i.e Dependability, Security and Yield) and result has been compared and shown in table-1.