Frequency Control in Microgrids with Electric Vehicles: Multistage PID Controllers Integrated with Adaptive Type-2 Fuzzy Logic for Uncertain Operating Conditions

This paper proposes an efficent frequency control strategy for hybrid microgrids (MGs) integrating renewable energy sources (RES), including photovoltaic (PV) generators, wind turbine generators (WTG), plug-in hybrid electric vehicles (PHEV) and diesel engine generators (DEG). A new multistage proportional-integral-derivative (MPID) controller, tuned with Type 2 Fuzzy Logic (T2-FL), is developed to solve the problems caused by intermittency of renewable energy sources (RES) and load fluctuations. The proposed controller achieves superior frequency stability by dynamically adjusting control parameters to adapt to real-time disturbances. Various simulations are performed using MATLAB/Simulink with an MG model in various operating scenarios, including multistage load disturbances, wind and solar generation variability, and PHEV integration. Compared to conventional PID controllers and optimization-based tuning methods such as particle swarm optimization (PSO) and cuckoo search algorithm (CSA), the MPID-T2-FL controller achieves a 75% reduction in peak frequency deviation, a 60% reduction in settling time and an 80% improvement in integral time absolute error (ITAE). In addition, the proposed controller manages system stability in 5 seconds, outperforming fractional order PID (FOPID) and PSO-tuned PID controllers, which took 8 and 11 seconds, respectively. Furthermore, using PHEV batteries as mobile energy storage systems (MESS) improves frequency control and reduces dependency on non-renewable DEGs by 40%. The controller mitigates disturbances, keeping the system frequency within ±0.002 Hz under stochastic RES fluctuations. Analysis of the control strategies found that the ability of T2-FL to control uncertainties significantly improves the performance of the MPID controller compared to type-1 fuzzy logic (T1-FL), which has a slower response (settling time of 17 seconds). This confirms the capability of the new proposed MPID-T2-FL controller as a reliable, efficient, and robust solution for frequency control in MGs.