Real Time Detection and Control of Loss of Synchronism using Energy Function Criterion and Phase Sequence Exchange Technique

Abstract

Transient instability is a well-known problem in a power grids. The severe faults in the power grid may lead to blackout, if proper out-of-step protection is not implemented. Phase sequence exchange (PSE) is a newly developed emergency control technique, in which power electronic devices are used to change the phase sequence, thereby reducing the power angle of an equivalent dual power supply system by 120° and preventing the system from becoming unstable. This paper proposes a fast and accurate technique for controlling PSE devices by generating switching signals using local measurement after detection of unstable swings and shows the effectiveness of PSE in stabilizing a multi-machine system. The proposed technique uses energy function for determining unstable swing. The proposed technique has been tested on the IEEE 39-bus test system on a real-time digital simulator (RTDS), and the results show that the proposed control technique for the PSE device is effective.