Event Identification and Contingency Assessment for Voltage Stability via PMU

The operating state of power system changes dynamically due to severe change in system conditions such generation, load or line trip. Such severe disturbances effect voltage phasor, current phasor and system frequency. So, to better monitor the dynamics of large power system, wide area synchronized monitoring of voltage phasor, current phasor and system frequency is vital. For efficient real time monitoring and operation of power system, high resolution based phasor measurement units (PMUs) should be used. PMU can accurately measure node and branch phasors at high sampling rate. In this paper, application of PMUs to monitor power quality and voltage instability due to contingency is shown. The paper proposes a novel approach for contingency filtering and assessment in sense of power quality and voltage instability. The approach consists of two-block technique: first block filters out dangerous contingency; then second block assesses it for severity based upon performance index. Another application is to understand system dynamics during different kinds of disturbance such as generator trip or load rejection. To realize this logic-based approach is used for analysis. This will help the operator in real time analysis of system as a whole and in deciding the nature and location of disturbance. Overall, it will help to detect emergency condition and take necessary control action in real time. The ideas of this paper will be illustrated using IEEE 39 bus power system.