Stability Boundary Locus Method for Load Frequency Control with Electric Vehicle Aggregator and Time Delay

Large-scale intermittent renewable energy sources are increasingly being integrated into power systems as part of global efforts toward low-carbon development. However, as the share of renewable energy in power generation grows, maintaining system frequency stability has become a more pressing challenge. To enhance the utilization of renewable energy, electric vehicles (EVs) are proposed to participate in load frequency control (LFC) through aggregators. This approach, referred to as the electric vehicle-load frequency control (EV-LFC), is the focus of this chapter. The integration of electric vehicle aggregator (EVAs) into the LFC system introduces time delays, which may affect the effectiveness of the LFC system. A significant challenge in LFC system across wide areas is communication time delay (CTD). This chapter proposes a systematic approach for finding a robust proportional-integral-derivative (PID) controller for the LFC system in power systems, utilizing the stability boundary locus method while incorporating CTD and EVA. The delay is treated as an additive uncertainty in the system model. This method satisfies sensitivity criterion to identify robust parameters for the PID controller. The proposed design ensures that the closed-loop system meets sensitivity performance constraints, thereby maintaining stability and robustness under varying operating conditions. To validate the robustness of the PID controller, stability boundary loci for parameter gains are plotted, providing a visual illustration of the feasible regions for parameter selection. The results demonstrate that the designed controller effectively addresses the uncertainties introduced by time delay and ensures reliable integration of EVA, enhancing the performance and stability of the LFC system.