Measurement based Voltage Stability Monitoring of Power system

Many papers discuss the voltage stability assessment of power system using power flow analysis methods. In this paper, a method for online monitoring of a power system based on measurements is proposed, which is aimed at detection of the voltage instability. Thereby an indicator is derived from the fundamental Kirchoff-Laws. Since in the transient process, at any time point, the electric power of the system is in balance, and the Kirchoff-Law is obeyed, this indicator will still work during the transient process. From the indicator, it is allowed to predict the voltage instability or the proximity of a collapse. The advantage of the method lies in the simple numerical calculation and strong adaptation in steady state and transient process. Through the indicator of voltage stability, it is easy to find the most vulnerable area in a system, to find the impacts of other loads, areas and power transactions.