STATE ESTIMATION USING PMU

Abstract

Phasor measurement unit (PMU) is considered to be one of the most important measuring devices in the future of power systems. The distinction comes from its unique ability to provide synchronized voltage phasor of a bus at which it is placed and the current phasors of all lines connected to that bus. The commercialization of the global positioning satellite (GPS) with accuracy of timing pulses in the order of 1 microsecond made possible the commercial production of phasor measurement units. Since, installation of a PMU and its branch current phasors are very costly, one cannot place PMUs on every bus in the power system but are to be placed at few optimal locations. Optimal placement of PMUs is one of the important problems in modern power system. The fundamental contribution of the present work is the introduction of a new technique to minimize the number of branch current phasor measurements that need to be measured by PMUs for complete and incomplete observability using Genetic Algorithm. In this work the optimal PMUs placement problem has been formulated for different cases. The formulated problem is Binary Integer Linear Programming problem. The cases include optimal placement of PM Us for Complete and Incomplete observability with and without considering Zero-injection buses. An optimization technique to minimize the number of branch current phasor measurements for complete and incomplete observability has also been introduced. GA function of MATLAB has been modified to solve Binary Integer Linear Programming problem. Simulation studies have been carried out on IEEE-14, IEEE-30 and IEEE-57 Bus systems. Finally, the mathematical model for a linear state estimation is presented. The model is especially designed for a system that is completely observable by PMUs and a Matlab program has been coded as well as a simulation has been carried out on IEEE-14, IEEE-30 and IEEE-57 bus systems for verification of the method.