Under-voltage load shedding scheme based on voltage stability index for distribution network

In a power system, voltage stability problem usually happen due to excess of electricity demand and deficiency of power generation. To avoid voltage instability, under-voltage load shedding can b e a last option to remove buses with instable voltage in a power system. However, the knowledge of location of the load to b e shed is important so that the optimum number of load shed may b e attainable without the possibility of over or under voltage, to happen. Voltage stability index is a reliable indicator to detect loads condition. This paper proposes an under-voltage load shedding scheme with voltage stability index approach. A distribution network energized by two DGs had been modeled in PSCAD software to test the proposed under voltage load shedding scheme. The distribution system is energized by utility grid, a mini hydro generator and a PV solar system. Case studies with islanding and a sudden change in PV power deliver have been conducted to demonstrate the effectiveness of the load shedding scheme. The results show that the proposed method is an excellent approach in order to implement a successful load shedding scheme.