Optimal location of voltage sags monitoring buses, based on the correlation rate between network buses with considering the probability distribution of variables.

Monitoring power system to assure its performance is of the highest priority. However, installment of measuring instruments at every single bus of the system is not cost-efficient. Therefore, this paper presents a method to determine the optimal location and the number of monitoring buses to study voltage sags by considering possible variables affecting the voltage sag depth. In this method, first considering the probability density functions of the variables that affect the depth of voltage sag, including type of fault, fault impedance, and so forth, a comprehensive database is formed by Monte Carlo method. A 4000-year simulation has been performed to attain a trustworthy database. Then, using this data, a probabilistic monitor reach area matrix (PMRA) is formed to consider the reliability of the effect of voltage sag on monitoring buses. Employing Pearson coefficient, the correlations between buses are determined. Finally, to determine the optimal number and location of monitoring buses, two conditions of the pre-defined probability of observability and pre-defined correlation rate between buses data must be considered. The proposed method is examined and verified on two test systems, the IEEE-14-bus system, and the 57-bus system. The simulation results are brought and discussed to validate the efficiency of the proposed method. [ABSTRACT FROM AUTHOR]