Research On Fractional-order PID Control Methods Based On Binarycoded Extremal Optimization And Their Applications

The modeling and control methods based on fractional-order calculus theories have obvious advantages than those based on integer-order calculus,so these methods have been widely attracted attention and researched recently by academic and industrial areas.How to design optimal fractional-order controllers to obtain optimal control performance is of great theoretical and practical significance,so it has been one of research hot and open issues in control fields.The existing research works from the perspectives of evolutionary computation have provided a novel and effective research idea for optimal design and operations of real-world engineering control systems,but the related research works are still limited.As a novel evolutionary algorithm,extremal optimization(EO)has been successfully applied to manybenchmark test problems and real engineering optimization problems.However,there is no reported research work concerning the applications of EO in optimal design of fractional-order controllers for complex control systems.Consequently,this thesis focuses on a novel optimal design method for fractional-order PID(FOPID)controllers and its applications in standalone microgrid systems from the perspectives of EO.The main research works and novel ideas are summarized as follows:(1)A novel binary-coded EO algorithm called BCEO here has been proposed for continuous optimization problems.The experimental results on some typical benchmark test functions have shown BCEO performs better than binary-coded genetic algorithm(BCGA)and binary-coded particle swarm optimization(BCPSO).(2)A novel BCEO-based FOPID design method called BCEO-FOPID here has been firstly presented for complex control systems.The superiority of BCEO-FOPID to BCGA-FOPID/PID and PSO-FOPID/PID has been demonstrated by the simulation results on different type control systems with integer-order and fractional-order plants in terms of control performance and computational effeciency.(3)By extending the basic idea of BCEO-FOPID to standalone microgrid systems,a novel fractional-order frequency control methodbased on BCEO has been developed.The simulation results on a mircogird system have further demonstrated the proposed method in this thesis performs better than BCGA-FOPID and recently reported fuzzy FOPID methods based on PSO in terms of transient-state control performance.Furthermore,BCEO has fewer adjustable parameters,simpler operations and higher computational efficiency.