Study On Power System Voltage Stability Based On Synchrophasor Measurements

With the rapid development of economy and the progress of science and technology in recent years, the scale of the power grid becomes larger and larger and the transmission of power has been characterized by high voltage and large capacity. The problem of voltage stability of the power system is crucial for power system security. Since 1990s, the advent of phasor measurement unit (PMU) and wide area measurement system (WAMS) is a new method for power system analysis and control. It is a hot topic to study voltage stability based on wide area measurement system. Therefore, this thesis studies the voltage stability of power system based on synchrophasor measurements.By studying the references about voltage stability at home and abroad, it is gotten that voltage stability indexes are put forward by using voltage instability characteristics, therefore this thesis needs to study voltage instability characteristics, and then the analyze which method is suitable for the PMU. The voltage stability index based on synchronized phasor is finally put forward.This thesis firstly studies the analysis methods voltage instability mechanism from 3 aspects:load, reactive power and on load tap changing transformer. After that, the simulations of widely-used voltage stability indexes that are gotten from voltage instability characteristics are carried out. Based on the simulation results, the characteristics of these indexes are analyzed and the conclusion is that indexes based on the branch power flow equations have good adaptability for PMU. At last, by analyzing the simulation results, the new method is proposed to measure the voltage stability based on the branch power flow equations. The validity of this method is verified by simulation in simulation systems.