A voltage instability predictor using local area measurements (VIP++)

A smart relay scheme for long term voltage instability phenomena is proposed. The method, called VIP++ is based on local area measurements and seeks to improve observability and robustness of a previously proposed voltage instability predictor (VIP) using measurements only from the bus where the relay is placed. Several strategies can be adopted to deal with the extra set of measurements from neighboring buses, and two such strategies have been explored in the paper. When the system is far from the point of collapse (PoC) the VIP++ gives an approximate distance to PoC and indicate that the distance is quite large. As the system trajectory moves closer to the actual point of collapse the method will become more accurate, and it will be more or less exact at PoC