Genetic Algorithm Based PI Controller for Frequency Control of an Autonomous Hybrid Generation System

This paper presents an autonomous hybrid generation system consisting of wind turbine generators (WTG), a diesel engine generator (DEG), fuel cell (FC), a battery energy storage system (BESS) and an aqua electrolyzer (AE). The generated hydrogen by an aqua electrolyzer is used as fuel for a fuel cell. The power system frequency deviates for the sudden changes in load and generation. The output power of DEG, FC, BESS and power absorbed by AE is regulated by using controller such that frequency of the system is controlled. Controller used is proportional plus integral (PI). GA is used for optimization of controller gains of the proposed hybrid system. The system response with GA based controller is compared with that of classical method. Investigation shows that GA based controller gives better response than the classical method Keywords-Genetic Algorithm, Aqua electrolyzer, Fuel cell, Diesel engine generator, Battery energy storage system, Wind turbine generator. NOMENCLATURE Δf System frequency deviation. Ksys Frequency characteristic constant of hybrid power system.   sys s G Transfer function of hybrid power system. DEG P Output power of diesel generators. ( ) DEG s G Transfer function of diesel generator. DEG K Gain of diesel generator. DEG T Time constant of diesel generator. FC P Output power of fuel-cell generators. FC K Gain of fuel cell. FC T Time constant of fuel cell. ( ) FC s G Transfer function of fuel-cell generators. BESS P Input power to battery energy storage system. __________________________ Manuscript received on 21 January, 2011; revised on 28 January, 2011. Dulal Ch. Das is Assistant Professor with Electrical Engineering Department, NIT Silchar, Assam, e-mail: [email protected] A K Roy is his supervisor, Professor with Electrical Engineering Department, NIT Silchar, Assam, e-mail: anjan_kumarroy @rediffmail.com N Sinha is his co-supervisor, Professor with Electrical Engineering Department, NIT Silchar, Assam, e-mail: [email protected] ( ) BESS s G Transfer function of battery energy storage system. BESS K Gain of battery energy storage system. BESS T Time constant of battery energy storage system. ( ) AE s G Transfer function of aqua electrolyzers . AE P Input power to aqua electrolyzers. AE K Gain of the aqua electrolyzer. AE T Time constant of the aqua elctrolyzer. PS Total power generation to the system. PL Average power absorbed by loads. Pe  Error in power supply and demand. M Inertia constant of the hybrid power system. D Damping constant of the hybrid power system. PWTG Power output of wind generator. ( ) WTG s G Transfer function of wind generator. WTG K Gain of wind generator. WTG T Time constant of wind generator.