Voltage sag source location in high-voltage power transmission networks

Voltage sags is among the most concerned power quality problem in power systems. Online voltage sag state estimation is used to assess voltage sags at non-measured buses. However, due to the constraint of cost, the power quality meters available to sag estimation are much fewer than the number of buses. It makes the sag estimation problem underdetermined in nature. In this situation, conventional least-square based estimators are unable to obtain reliable estimates. This paper proposes a new method to estimate voltage sags at un-metered busses based on underdetermined state estimation theory. By exploiting the spatial sparsity of fault locations, the paper shows the underdetermined sag estimation problem can become observable. The proposed method is tested in IEEE 30-bus power system.