Utilisation of ultra‐capacitor in load frequency control under restructured STPP‐thermal power systems using WOA optimised PIDN‐FOPD controller

This study addresses the impact of ultra‐capacitor (UC) on load frequency control of a restructured two‐area multi‐source system, incorporating conventional thermal and solar thermal power plant (STPP). The thermal system consists of single reheat turbine, appropriate generation rate constraint and governor dead band. Two generating companies and distribution companies are considered in each area. Maiden attempt has been made to use a cascade combination of integer‐order (IO) proportional–integral–derivative with filter and fractional‐order proportional–derivative (PIDN‐FOPD) controller. Performance comparison of some commonly used IO controllers with proposed PIDN‐FOPD controller reveals superiority of the latter in terms of peak deviations and settling time in policy schemes like poolco, bilateral and contract violation. A more recent optimisation technique called Whale optimisation algorithm (WOA) is successfully used for simultaneous optimisation of above controllers. Effect of UC using PIDN‐FOPD has been studied for above policy schemes and analysis explores that use of UC improves the system dynamics. Sensitivity analysis reveals that WOA optimised PIDN‐FOPD gains and system parameters are robust. It is also proved that PIDN‐FOPD parameters obtained at nominal distribution companies participation matrix (DPM) are fit enough and parameters need not be optimised for change in DPMs.