A transient current based double line transmission system protection using fuzzy-wavelet approach in the presence of UPFC

• We model the double transmission line system with UPFC using MATLAB/Simulink.
• Conventional relay maloperation studied and rectified using proposed algorithm.
• Fault is detected using current signal instead of impedance.
• Fault detection and discrimination time is reduced from four cycles to half cycle.
• The protection scheme is tested on transmission system in the presence as well as absence of UPFC.

This paper presents a wavelet fuzzy based protection scheme for a double line transmission system with unified power flow controller. The protection scheme makes use of current signals at both the ends of transmission line which are synchronized with the help of global position system clock. A wavelet based multiresolution analysis is used to find the detailed coefficients of these signals which are utilized to calculate fault index. These fault indexes are compared with a threshold value to detect and classify faults on transmission system. The approximate decomposition of the current signals is utilized to locate the fault using Fuzzy logic from their respective terminals. The proposed algorithm has been tested successfully for various faults at different locations.