Study on closed-loop transient stability emergency control based on wide area measurement

In this paper, a method, which is essential in initiating emergency control measures, is proposed for fast and accurate online detection of transient instability based on real-time measurement. Under a certain disturbance, the candidate critical cluster of power system is predicted and refreshed at each sampling step. The method identifies the loss of synchronism at each time step by observing the geometric characteristic of the post-fault trajectory of the generalized one-machine equivalent system. A new structure of the emergency control scheme relies on SIME (for Single Machine Equivalent). It is unnecessary to calculate the unstable equilibrium point and some limitations caused by the time-invariant assumption are also eliminated. Simulations are carried out on the IEEE 50 generator test system and a real power system. The results indicate that the proposed method has the features of reliability and effectiveness in preventing the system from the loss of synchronism.