The critical domain description of voltage stability of power system and its dertermination

The development and applications of wide-area measurement system (WAMS) established the foundation of on-line assessment of voltage stability in large-scale power system. This paper presents a new description of the voltage critical states-the voltage expression and the power expression, and the voltage stability domain is established. The critical domain of voltage stability is determined through the estimation of the Thevenin’s parameters of a node. Through the local measurement, the method can indirectly avoid the divergence problem caused by the Jacobian matrix singularity of load flow at the critical state. And it avoids the limitations of the conventional methods in on-line applications such as the large-scale power system, the nonlinear model inaccuracy, slow updating of large amount of data. Simulation results prove the proposed method reasonable and that it can on-line determine the critical domain of the node static voltage stability.