Study On Voltage Stability Analysis And Its Application Considering Induction Motor Loads

As the primarily secondary energy resources, electric power is closely bound up with modern society. It is a vital guarantee to maintain secure and stable operation of power system for the sound development of national economy and people's normal life. Voltage stability is the essential requirement of the secure and stable operation of power system.In recent years, several large-scale blackouts due to voltage instability happened in different countries, which caused great economic losses and had serious impacts on people's lives. In China, grid-wide blackout did not arise in recent years. However, with the grid's expanding, the frequency of local power interruption due to power failure in the load center and the average economic loss in each emergency are increasing. Now, the power systems in China have entered an era of large power grid, extra high voltage, large unit size, large power plant and long distance power transmission. The nationwide power grid interconnection in China is nearly formed with the leading feature of large capacity and long distance power transmission and large receiving end power grids. With the development of grid interconnection, the growth of load in electric power receiving end systems and further deregulation of power systems, more and more voltage stability problems will be emerged in power system operation. Therefore, it is necessary to draw lessons from past domestic and foreign blackouts, to study voltage stability of power grids, especially receiving end power grids, and to analyze the precondition, influencing factors and developing process mechanism of voltage instability in theory. Meanwhile, it is required to study the appropriate on-line voltage stability indices which will work as the theoretical foundation for on-line monitoring, preventive and corrective control with the aim of avoiding voltage collapse emergencys in power systems.This thesis focuses on voltage stability analysis and its application study considering induction motor loads. The small disturbance voltage stability, short time large disturbance voltage stability and on-line voltage stability assessment are systemically analyzed and studied in theory. The important issues related with the accurate small disturbance voltage stability analysis, on-line small disturbance voltage stability indices and judgment of short time large disturbance voltage stability are resolved. The main contents are as follow: small disturbance voltage stability analysis considering static characteristic of induction motor loads; building a small disturbance voltage stability analysis mathematical model including dynamic characteristic of induction motor loads, which is used to study the influence of induction motor loads on small disturbance voltage stability; accuracy analysis of small disturbance voltage stability indices based on power flow model; study of an on-line small disturbance voltage stability index considering dynamic characteristic of induction motor loads; study on the influence of parameters of electric power receiving end systems and induction motor loads on short time large disturbance voltage stability, the results showing that induction motor loads...