Protection of TCSC Transmission Line by Wavelet Based Advance Mho Relay

Presence of TCSC at midpoint of line inserts a variable impedance in the line hence create serious reaching issues at the relay terminal. This paper presents a high frequency transient based scheme for fault section identification on TCSC transmission line. The fault current signals are decomposed by Discrete Wavelet Transform (DWT) to obtain detail coefficients to detect faulty section. Further a new compensated Mho relay algorithm with adaptive property is proposed to protect the TCSC line. In this scheme Mho relay compensates the impedance, inserted by the TCSC in fault loop. The constancy of the proposed adaptive algorithm is tested for different relaying conditions such as: types of faults considering wide variations in compensation level, fault resistances, inception angle, fault distance from sending end and loading levels. Extensive simulation studies indicate that the proposed relay does not show any reaching mal-operation so it is reliable, accurate and secure. Assumed test system have been simulated in PSCAD/EMTDC and generated data have used for fault section identification by a MATLAB program.