Energy-based Nonlinear Control Of Wind Power Systems

Due to the crisis of energy and the environmental pollution,people begin to look for clean energy to replace the normal fossil energy. Wind power is a clean energy which is technically mature and suitable for large-scale commercial development.So it receives widely concern.In order to meet the requirements of wind power generator connecting to power network,the capacity of wind power generator becomes larger and larger. The generator is one of the core component of wind power system.Generator and the operation quality of its control system directly decides the stability of wind power operation and the quality of output electric power.Wind power system is a strongly nonlinear system, and exists uncertain pa-rameters and interference signals.The traditional control method which is based on a set-point linearization can only guarantee the control effect in near robustly, but can't meet the control requirements of actual wind power system.Therefore, in recent years various nonlinear control methods appeared in wind power sys-tem study.Generalized Hamiltonian system,whose structure is clear and physical significance is explicit, describes a class of dynamic systems which have energy dissipation and energy exchange with their environment. because of the fact that Lyapunov candidates can be chosen from the Hamiltonian functions, Hamiltonian mothed has obvious advantages in the analysis of system stability and control design, such as stabilization control design, robust control design,adaptive control design and observer design and so on.In recent years, the Hamiltonian mothed has been widely used in power system.This paper uses Hamiltonian method to design the controller of wind power system and obtained good control effect because the controller fully considered the nonlinear characteristics of wind power system.This dissertation first introduces the basic knowledge of wind power system, including principle of maximum wind power capturing(MPPT), the technology and control strategy of wind power system.Secondly the dissertation introduces some basic definitions and theorems of nonlinear control theory and Hamilto-nian system control theory,and a brief introduction of mathematical model of two commonly used wind power systems is given too. Then, the energy-based nonlinear control of doubly fed induction generator(DFIG) wind power system is investigated.A MPPT controller is designed for DFIG wind power systems using energy shaping-damping injection method and an robust controller is proposed when the wind power system have disturbances.Finally we investigate the energy-based nonlinear control design of directly driven permanent magnet synchronous generators(D-PMSG) for wind power System.Using Hamiltonian function method ,a MPPT controller and a adaptive controller are designed for D-PMSG wind power systems. Study on simulations shows that the controllers in this disserta-tion work well.