A simultaneous phase sequence exchange control method based on transient energy function

Emergency control systems can ensure the power grid stable operation. Phase sequence exchange (PSE) is a recently developed emergency control technology. In this article, a numerical search algorithm for finding PSE is proposed to reduce the maximum unbalanced energy of the system. This method can quickly identify the generator requiring PSE and obtain its power angle threshold without traversing all critical units. After fault clearance, taking the energy at the closest unstable equilibrium point as the critical energy of PSE, even if it is conservative when assessing the system stability, PSE is still conducive to the system stability. The complex search process of the controlling unstable equilibrium point is thus unnecessary. When the power angle reaches the threshold value, the selected generator PSE at the same time, which reduces the unbalanced energy and restrains the out-of-step system. Three test systems verified the proposed control method is effective.