Combined frequency and voltage regulation in an interconnected power system using fractional order cascade controller considering renewable energy sources, electric vehicles and ultra capacitor

This research article emphasizes the combined automatic generation control (AGC) and automatic voltage regulator (AVR) problem for an interconnected hybrid system having electric vehicles, renewable energy sources (RES) like wind, solar photovoltaic, solar-thermal in addition to conventional thermal units. A novel cascade fractional order (FO) controller named FO PID-FO PD (cascade PIAD mu-PD mu) is proposed to suppress the oscillation in AGC and AVR system whose parameters are obtained using recent optimization technique called coot algorithm (CA). Findings show that proposed cascade PIAD mu-PD mu controller outperformed PID and FO PID controllers in providing better dynamics. The CA provides improved performance compared to popularly known particle swarm optimization and firefly algorithm not only in dynamics but also in computational burden. The inclusion of practical nonlinearities made the system more oscillatory. The asynchronous HVDC link helps in improving the performance. The impact FACTS devices such as interline power flow controller and gate-controlled series capacitor (GCSC) are studied in the system and can suppress the oscillatory dynamics. For the first time, the combined GCSC and HVDC link effect is examined and improved dynamic performance. The ultracapacitor storage device showed its efficiency for regulating oscillations in the presence of RES. The proposed cascade PIAD mu-PD mu performance is evaluated for randomized load demand, wind power and solar irradiations and is seen as effective over the FO PID controller. Sensitivity analysis reveals the cascade PIAD mu-PD mu parameters are robust. Moreover, the study is also performed on OPAL-RT OP 4510 for real-time validation.