Fault Detection Technique for Lines with Series Compensation during Power Swing

Approximate coefficient-based fault detection methodology has been discussed in this paper. The methodology has been developed and tested on the power system model designed in PSCAD. The study has been carried out for lines with series compensation when the fault occurs amidst power swing. It is seen that amidst power swing the apparent impedance seen by the relay falls within its operating range causing the relay to operate amidst power swing. Using MATLAB program, different operating conditions are tested and fault detection method amidst power swing is formulated. The fault current data has been subjected to discrete wavelet transform and the sum of the approximate coefficient of all phases is used to detect the fault and generate tripping signal only during the fault.