A Study of Voltage Collapse Detection for Power Systems

The voltage instability in power system increases with power demand and over stressing of existing transmission lines nearly to their limits. A serious type of voltage instability is voltage collapse. In this paper comparative study of two techniques, namely Voltage Collapse Prediction Index (VCPI) and Sensitivity analysis to find voltage collapse vulnerability of bus in a power system is done. Load shedding is done to prevent voltage collapse in the required location and in the minimum required amount. The effectiveness of the two methods in finding the best place for load shedding and in minimizing the total amount of load required to shed is verified. The contribution of each generator to the shed load is calculated and required generation shedding is also done in order to satisfy the power balance equation. The loadability margin of each bus in the system is also considered in load shedding. In this paper the stressed version of IEEE 14 bus system is analyzed, results are compared and the VCPI technique has been selected as the best method. The analysis is done by using MATLAB programming. Keywords— Voltage collapse prediction, Loadability margin, Sensitivity analysis, Load shedding.