Performance of Local Shunt Controls in Transmission Grids for Transient Voltage Fluctuations

Due to the decommissioning of conventional power plants, the flexible reactive power reserve is declining in transmission grids. Local controls for capacitors and inductors are a promising technology to increase the flexibility of the remaining reactive power reserves and thus to limit fast voltage fluctuations. However, a poor parametrization of local shunt controls can lead to unnecessary switching actions and voltage limit violations. Therefore, this paper focuses on the analysis of local shunt controls to provide a robust parametrization for transient events such as power plant outages, which may lead to sudden changes of reactive power injections and thus, to voltage fluctuations. Two different delay modes are implemented and analyzed regarding hunting effects, interactions with other automated shunts or reactive power compensators, and short circuit power levels. Furthermore, the models are validated based on a complex transmission grid model for different grid utilization cases and fault locations. The results indicate the feasibility of local shunt automation. However, requirements regarding delay parameters and voltage limits must be considered to prevent unnecessary switching actions or unstable operation points. Looking forward, a suitable method to determine the optimal parameter settings for local shunt controls will be developed.