Research On Control Strategy And Modeling Of Permanent Magnet Direct-Drive Wind Power System

Nowadays, energy shortages and environmental pollution have been two major issues of concern around the world. Clean green renewable energy is an important way to solve these two problems, so it has been a large-scale development and application. Wind energy as a green pollution-free, extensive resources and renewable energy technology is mature, the rapid development in recent years has reached. Permanent magnet direct drive wind power generation system due to its high energy conversion efficiency, simple structure, high reliability and flexible grid control, etc., has become one of the main development direction of current technology in the field of wind power. In this paper, permanent magnet direct drive wind power generation system for the study, mainly for system modeling and control strategies to conduct research and focuses on the largest wind tracking system and grid control issues.Paper firstly introduces the present situation of wind power industry development and the status of wind power technology research currently and focuses on comparing the current VSCF two main models of double-fed wind turbine type and direct-drive type of advantages and disadvantages; Then introduced the direct-drive wind power system topology’s composition as well as the topology of the converter, and the use of back to back dual PWM converter topology as this thesis’s core. Finally, according to the characteristics and operation mechanism of each part of the system, the establishment of a permanent magnet direct drive wind power system mathematical model, including wind turbine model, permanent magnet synchronous generator model, the DC link model, full-power converter models.The third chapter analyzes the system-side converter main functions. For the the generator side of the track to achieve maximum wind power are analyzed in detail, and the existing control strategies were improved. Specific control strategy uses a dual-loop control mode with outer speed loop and inner current loop:the outer loop of the speed is used the maximum wind power track strategy, the inner loop of the current is used to zero d-axis control strategy for the control of synchronous generator. For the converter control SVPWM modulation is used, the ultimate in Matlab/ Simulink simulation environment to build a simulation model of the whole system, the generator side of the control strategy is simulated to verify the the maximum wind power tracking control strategy and validity and effectiveness of dual-loop control strategy.The fourth chapter analyzes the gird-connected technology of the permanent magnet direct drive wind power generation system, and the grid side control strategy also uses a dual-loop control mode with outer voltage loop and inner current loop. The outer voltage loop, mainly in order to stabilize the DC bus voltage, the inner current loop uses the grid voltage oriented vector control to realize the grid-connected of active and reactive power control. According to the wind speed changes the DC capacitor voltage for both power imbalance voltage fluctuations, coordinated control strategy is proposed to control the active power output of the generator, the feedback to the grid side control, to achieve the purpose of stable DC voltage. The grid side model is built in Simulink platform as also, and the two control strategies of the network side were simulated, verified the correctness and effectiveness of the coordinated control strategy.