A study of reactive power margins in power system following severe generation imbalance

This paper presents a study of the impact of severe generation imbalance on reactive power margins. In particular, the focus of the study is the analysis of characteristics of the reactive power margins under two common strategies A) generation redispatch and B) load shedding when a significant loss of generation occurs in a power system. Simulation results show that, at some buses, Strategy A may yield higher reactive power margins than Strategy B. To understand this counterintuitive incident, an index is proposed to estimate the reactive power support capabilities that load buses can obtain from generation units based on the reactive power capacities of generation units and the electrical distances between load buses and generation units. It is found that the counterintuitive incident occurs when the buses of interest are close to the generation units with sufficient reactive power capacities. The analysis results are demonstrated in the IEEE 39-bus system.