Cascade control scheme for frequency control of wind-integrated multi-area multi-machine AC/DC-interlinked power system with deregulation

Integrating wind power into the automatic generation control (AGC) of deregulated power system introduces significant operational challenges and complicates coordinated load–frequency control among independent operators. Although various AGC strategies exist, limited research focuses on advanced AGC frameworks capable of managing active power imbalances in deregulated environments. This paper addresses these challenges by proposing a cascade control scheme designed to reduce frequency oscillations and tie line active power deviations in a multi-machine, multi-area interconnected power system under deregulated conditions. Initially, the system is analyzed with areas interconnected by AC tie lines and later extended to a configuration with both AC and HVDC links to enhance power transfer in an open market scenario. Wind power integration is also considered, introducing frequency deviations but without participation in price-based market operations. The cascade controller’s performance is evaluated across various market scenarios, including contract violation case along with bilateral and unilateral, demonstrating its advantages over traditional PID control in minimizing frequency and active power deviations to improve stability of the system. Optimal gain parameters for both controllers are identified using the Rao algorithm with integral square error as cost function of the optimization problem, highlighting the cascade scheme’s effectiveness in maintaining stability in a deregulated, wind-integrated power system.