A quantitative evaluation method of transient voltage stability for large-scale receiving systems and its influencing factors

In recent years, transient voltage instability occurs occasionally in large-scale AC/DC mixed receiving systems which may cause serious economic losses and adverse social impact. Therefore, how to evaluate transient voltage stability when the system suffers serious disturbances poses a great challenge for safe operation of modern power systems, hi this paper, firstly the mechanism of transient voltage instability in a typical receiving-end power system, i.e., Guangzhou power grid, is discussed based on in-depth analysis. Secondly, we propose a quantitative assessment method to determine the transient voltage stability of actual large-scale power grid. The key to the quantitative evaluation method is the definition of various voltage sag indexes based on the transient voltage stability criterion under large disturbances. Based on these well-defined voltage sag indexes, the various influencing factors of transient voltage instability have been identified, including the model of comprehensive load and the type of fault As a case study, the Guangzhou power grid is used to verify the proposed method. This huge receiving-end system is simulated with PSD-BPA and the voltage sag indices are worked out under different operating conditions and disturbances to evaluate its transient voltage stability and the crucial influencing factors. The simulation results demonstrate the effectiveness of the proposed method and indices for quantitative assessment of transient voltage stability of large-scale actual system. They also give an intuitive and quantitative measure of the influence of fault type and load model on transient voltage stability.