Power oscillation compensation by TCSC

A major grid disturbance occurred in the Northern grid of Indian power grid on 30^th July 2012, causing a blackout in northern region. The main cause was the malfunctioning of distance relay due to power swing, weak interregional corridor and multiple outage of lines. In this paper a power swing is compensated by thyristor controlled series capacitor (TCSC) to prevent the unnecessary tripping of line due to power swing and avoid cascading tripping and unforeseen blackout. The power swing is compensated by installation of TCSC at optimum location and controlling the impedance of line by changing its reactance; the oscillation is also damped out by TCSC. The distance relay used for power swing protection does not issue the trip command due to power swing compensation. The TSCS model is simulated for power swing compensation and gives the expected results and prevents the blackout in electricity grid. This paper describes the compensation technique for mho relay to protect the transmission line under power swing.