Voltage security constrained look-ahead coordination of reactive power support devices with high renewables

Reactive power support devices (RPSDs) such as capacitor banks and Static Var Compensators (SVCs) play a pivotal role in ensuring system voltage security. In large power systems with high penetration of renewables, the variability brought about by the renewables requires more coordination among these reactive power support devices. In this paper, we investigate the benefits of look-ahead coordination of both continuous-state and discrete-state RPSDs across multiple control areas. The objective is to coordinate multiple RPSDs in anticipation of near-term net load variations in order to minimize the costs of RPSD operations and transmission losses. Constraints include ensuring voltage security with respect to a set of possible contingency scenarios. This problem is first formulated as a Mixed Integer Non-Linear Programming (MINLP) problem and then approximated as a Mixed Integer Quadratic Programming (MIQP) problem via power flow Jacobian matrix. The validity of the solution to the MIQP problem is verified by solving AC power flow equations. The proposed approach is examined on the IEEE 24-bus Reliability Test System (RTS) system. Critical discussions on the impacts of wind uncertainties are provided, and a linear approximation approach is proposed to estimate the impacts of wind fluctuations on voltage magnitudes.