Research on Power System Transient Stability Based on Asymmetric Fault Model

Transient instability accidents are one of the main reasons that disrupt stable operation of power systems and cause economic losses in power grid, and transient stability assessment is an important part of power system safety and stability analysis. Therefore, an analytical algorithm for transient stability margin is proposed in this paper based on asymmetric fault model, where additional impedance is calculated in the case of asymmetrical short circuit and network model of multi-machine system is simplified. In addition, on the basis of the simplified network model, transient stability margin index is established according to equal area criterion. Then, segmented model of aggregated work angle is proposed to further deduce analytical expression of transient stability margin so that influence of fault location and duration on stability margin under asymmetric short circuit can be analyzed. Finally, simulations are performed in four-machine system and New England system to verify effectiveness of proposed method.