The Research On Power System Voltage Stability Taking Account Of The Load Characteristic

There has been many accidents about the voltage instability that happened to the local power system and the state power system within the last few years. Therefore, Subjects around the voltage stability such as the mechanism of voltage instability, the indexes of voltage stability, the strategy to avoid the voltage instability and so on, became a hot spot to the researchers.This article dissertates the influence of the load characteristic to the power system voltage stability. It fist elaborates the significance of the research on the voltage stability, the development and the current situation about the definition and classification of the voltage stability, the mechanism of the voltage instability, and the analysis methods; and then it describes the voltage stability static analysis method in common use, including continuation power flow method, sensitivity analysis method and so on. Moreover, a method, which can evaluate small disturbance voltage stability by power flow Jacobian matrix taking account of the dynamic characteristic of the load, is recommended. This part lies the foundation for the work of theory research and engineering analysis.In the third part of this article, the traditional continuation power flow method and the direct iteration algorithm taking account of the load characteristic are applied respectively in the WSCC 9 bus system to calculate the PV curves under the conditions of single bus load increasing and multi bus load increasing, and the reason of the similarities and differences between the results calculated by these 2 methods are discussed. It proves how important it is to take account of the load characteristic when we analyze the voltage stability of the power system. At the same time it draws the conclusion that the direct iteration algorithm is an excellent method for engineering application. In the end, With the help of the small disturbance voltage stability analysis module in PSASP, This article analyzes the voltage stability of the global network using the constant power model on account of lack of the global load model parameters and analyze the local network of Changsha, Zhuzhou, Xiangtan separately using the static load models of 17 transformer station. Some valuable suggestions are given based on this work to improve the static voltage stability of power system in Hunan province.