Research On Passivity-based Control Strategy Of Brushless Doubly-Fed Wind Power System

Brushless Doubly-Fed Machine(BDFM)is the most potential new machine to replace doubly-fed machine in wind power system owing to its advantages of giving up brushes and slip rings.According to the unique energy point of view,Passivity-Based Control(PBC)is the most prominent method in the modern nonlinear control.PBC is introduced into Brushless doubly-fed Wind Power System(BDFWPS)in this thesis and the PBC of BDFWPS is studied by theoretical derivation and simulation analysis,in which the modeling of Port-Controlled Hamiltonian with Dissipation(PCHD)system and Energy Shaping Control(ESC)are the key issues.Firstly,according to the basic structure and operating principle of BDFM,the influence of rotor harmonics on direct coupling theory is further researched,and then the correctness is illustrated by simulation and prototype experiment.Secondly,the power decoupling control of BDFM is derived based on the synchronous speed dq axis rotary coordinate system model by establishing dynamic mathematical models in three-phase stationary coordinates and two-phase rotary coordinates.Thirdly,ESC is introduced based on the concept of passivity and PBC,and the physical significance and design principle of structure matrix and dissipation matrix are analyzed.Fourthly,BDFWPS is divided into machine-side and grid-side subsystem,and the feedback interconnections of mechanical,electrical,converter and filter reactance subsystem are further used to deduce the machine-side and grid-side PCHD model of BDFWPS.Fifthly,the ESC strategies of BDFWPS machine-side and grid-side are designed based on the analysis of their control objectives,and the validity and controllable dissipative value are simulated.The results are compared with those of the traditional PI control,and show the effectiveness of the machine-side and grid-side ESC.And then,low voltage ride through can be realized by adjusting controllable dissipation value with slight grid voltage drop.Compared with the traditional PI control,ESC has better robustness and simplifies the setting process of PI parameters.Beginning from the basic theory and traditional PI control of BDFM,this thesis introduces nonlinear PBC,which not only provides a new view and idea about the BDFWPS control,but also expands the applicable range of PBC.The achievement of this thesis builds up a foundation for the nonlinear robust control of wind power system and is significant for the development of high-performance wind power control.