Power System Static Voltage Stability Analysis Base On Fast Thevenin Equivalent

With the power grid interconnection and the rapid growth of electricity demand, power systems operate closely at its limits point, and a number of large power grids incident also showed the characteristics of voltage instability, voltage stability has become one of the important factors of power system safety and stability, and it has got more and more attention.This paper introduces the background of the research, the basic theory of power system static voltage stability research, the calculation method of Thevenin equivalent parameters and the background, significance and today's situation of the power system static voltage stability research based on the Thevenin equivalent. A fast computation method of Thevenin equivalent parameters is proposed when power system under base and N-1 topology. Based on the Thevenin equivalent parameters, voltage stability analysis of the load bus can be calculated quickly. On the base of the nonlinear equations, Thevenin equivalent parameters under both base and N-1 topology can be calculated by using the value of node voltage and voltage sensitivity. This method only uses the value of voltage and voltage stability at a given time, which is different to the two point power flow method or the other similar method, the computation is simple and fast. The impedance module indicator and the minimum singular value of the study load bus can be calculated with the Thevenin equivalent parameters, so voltage stability of the study bus can be analyzed. What's more, it is convenient to consider many generators to adjust their power injection together. Test on IEEE 14 bus and IEEE 118 bus systems verify the correctness and practicability of this method.The algorithm is feasible when power system under base and N-1 topology. It uses the value of node voltage and voltage sensitivity when the system on base topology, while, on N-1 topology the value of node voltage and voltage sensitivity can be derived use Taylor's correction approach or directly to revise the node admittance matrix. When the value is got, the value of Thevenin parameter can be got by solve the four unknown parameters nonlinear equations, and the computation process is fast. The impedance module indicator and the minimum singular value of the study load bus can be calculated quickly with the Thevenin equivalent parameters, so voltage stability of the study bus can be analyzed. The algorithm can analyze the static voltage stability when the system is on base and N-1 topology, and it is convenient to consider many generators to adjust their power injection together. It can be used as a static voltage stability monitoring tool when the algorithm applied to the Power System Dispatching Center.