Improving power network state estimation using GPS time transfer

Abstract

Modern electrical power networks use control techniques in order to ensure the security of the network, where the security of a power network is its ability to withstand failures. Currently, an estimate of the state is computed using the method of least squares on data consisting of network structural data and a sufficient set of bus voltage magnitude and power flow measurements. It is shown that, using GPS (Global Positioning System) time to synchronize measurements, the measurement data set can be augmented with accurate voltage phase measurements. By incorporating accurate phase measurements from buses at major substations in the power network, more accurate state estimates can be computed. More importantly, however, bad measurements can be isolated more easily and removed from the estimation process altogether, yielding an even more accurate state-estimate. Accuracies of 1 mu s are easily achieved for synchronization via GPS time, giving relative phase measurement accuracies of sigma =282 mu rad. A GPS receiver and synchronization system would be very small and potentially inexpensive, as the prices of GPS receivers are decreasing rapidly. >