POWER SYSTEM VOLTAGE STABILITY MONITORING USING SYNCHROPHASOR DEVICES

Abstract

Voltage instability has been under scrutiny by power system researchers and planners in the recent years and is being considered as one of the major sources of power system insecurity. Voltage collapse is the process by which the voltage falls to a low value as a result of an avalanche of events accompanying voltage instability. One of the methods of voltage stability analysis is calculating the stability indices which indicate whether the voltage is nearing collapse. Different methods to calculate the index are presented in the literature. Voltage and current of the system are monitored with phasor measurement units (PMU). From the measurements of the phasor measurement unit, indices are calculated. By monitoring these indices, it can be found if the system is nearing voltage collapse limit. As the system nears the collapse limit, reactive power can be injected to control the voltage. - The index selected is VCPI(1) tested in a 2-bus system and 14-bus system modeled in RSCAD. The simulation platform used was RTDS and the index was computed using the control blocks components. The index was monitored while the load was increased; voltage at the receiving side was seen to be decreasing as the index approached 1.Reactive power was injected through a shunt capacitor at the receiving end and the index decreased to less than 1 in 2-bus system. Wide area monitoring was carried out in the 14-bus system with every bus monitored by PMU and VCP!(1) of every transmission line is calculated and monitored.