Estimation of the bus admittance matrix for transmission systems from synchrophasor data

Abstract

This research proposes a technique for determining the bus admittance matrix Ybus for large-scale power systems from recorded synchrophasor measurements. The approach is based on recognizing that measurements of bus injection currents Ibus can be viewed as signals produced by a random process. In this manner, the corresponding bus voltages Vbus are also stochastic signals that are related through a cross-covariance matrix to the injection current vector Ibus. Using estimation techniques developed for statistical signal processing, the cross-covariance matrix is shown to be Ybus. The increasing use of synchrophasors has enabled large-scale data collection of time synchronized bus injection currents and voltages. The new Zbus estimation method is applied to the IEEE 68 bus benchmark system to demonstrate the validity of approach. The accuracy and convergence rate of the method is evaluated under conditions corresponding to wide-area synchrophasors data collection. The results indicate that the method is broadly applicable to determining Ybus and Zbus for electric power transmission and distribution systems equipped with synchrophasor data collection technology.