Predictive out-of-step relay based on equal area criterion and PMU data

This paper proposes a novel-predictive and setting-free out-of-step protection technique based on synchronized phasor measurements and equal area criterion. Generator instability is predicted by comparing the acceleration and deceleration areas corresponding to the fault and postfault conditions, respectively. For each generator, the acceleration area during fault condition is calculated directly using the generator output power and rotor angle in real time. As soon as the fault is cleared, the deceleration area is predicted based on estimating the postfault Thévenin equivalent of the power network. The proposed technique is verified on the New England 39-bus test network. The effect of the proposed technique on improvement of the power network stability is compared with that of the well-known impedance-based out-of-step relay.