The Study Of Voltage Stability Based On Improved Modal Analysis Technique

In recent years, with the rapid development of economy, the grids become larger and larger, and this need higher requirement of security and stability. How to prevent the occurrence of voltage collapse accidents, increase stability of the grids, and improve system voltage stability margin? they are the very questions which operators are facing.This thesis amends and completes the traditional modal analysis methods, and considers the effect of different load models to voltage stability. The traditional methods only consider the participation factors of load nodes ,and doesn't consider participation information of generator nodes. To know which generators are the key generators in the current operating state, the paper modifies Jacobian matrices of polar coordinate, and adds the parts of partial reactive. Based on the previous modal analysis technique, the participation factors of generator nodes will be acquired. For getting the minimum eigenvalue of the single load node and the system weak nodes quickly, the thesis uses Thevenin equivalent theory, calculates every load node, acquires system weak node through comparison, and judges the current margin variation, and analyzes system stability and puts forward a new voltage stability index through connecting improved modal analysis method and Q-U curve.This paper introduces the flow of on-line voltage stability monitor project of the grids of Fujian province and its function. To reinforce system voltage stability of Fujian province, with reactive compensation actions, this paper uses modal analysis technique to computes the grids under stability and contingency condition, then the weak area is gotten. The simulation shows the effective of this method.