Real time voltage stability prediction of smart grid areas using smart meters data and improved Thevenin estimates

Abstract

One of the important factors of power delivery disruption is voltage instability. As loads increase, the grid is pushed toward instability and the voltage drops. Once instability is reached, the area will experience a blackout. Many methods exist which can be used to determine grid stability. One popular technique used for estimating the maximum available power as well as grid area stability, without knowing the grid model, uses the concept of the Thevenin equivalent circuit. The maximum power can be used to support demand response methods. In addition, it is possible to use the Thevenin parameters to determine how reactive power compensation affects the maximum power. Existing Thevenin equivalent techniques use aggregate load measurements, which provide poor estimates of the Thevenin equivalent parameters. This affects the accuracy of the available maximum power estimate.The objective of this paper is to take advantage of individual load measurements from smart meters to provide improved estimates of the Thevenin parameters. Additionally, a new real time stability index that alerts utilities when the system approaches instability is proposed.The proposed improved Thevenin estimates and stability index were tested using an IEEE 30 bus power system. The simulation results show that the new estimator is capable of generating better Thevenin parameters estimate than the classical method. The results also show the ability of the proposed stability index in predicting voltage instability ahead of time to give utilities the chance to react properly before a blackout takes place.