Modeling And Power Smoothing Control Of Direct Drive Permanent Magnet Wind Power-Fuel Cell Hybrid Power System

The globe is facing the pressure of energy crisis, environmental pollution and climate change. The application of new energy resources to power generation then becomes the topic of the era of power industry development. DDPMWPS (direct driving permanent magnet wind power generation systems) which is the most promising in wind power system and SOFC (solid oxide fuel cell) which boasts the greatest commercial prospects in fuel cells are chosen in this paper as the research objects. Hybrid power generation systems composed of DDPMWPS and SOFC are built, and the control strategy is proposed in accordance with the setting power under all wind speed situation. In the research, SOFC is used to smooth DDPMWPS’output power fluctuations under all wind speed situation, and the simulation wave form is also presented. The research provides theoretical references for new energy power control of distributed power generation system in the future..First of all, a dynamic model of10MW variable speed direct drive wind turbines is built on matlab, which consists of wind speed model, power conversion model and drive train model based on two-mass mathematical model. As the prime mover of the wind-power generation system, this model will be helpful for further researches on the power characteristics of DDPGWPS and grid-connected control technique.Electrical mathematical model and space state d-q control model are established, and the DDPMWG (direct drive permanent magnet wind generator) electrical parameter of10MW is identified through simulation. Under constant wind speed, the control principle and parameters’setting about the rotating speed and output power control of DDPMWG are researched by means of BOOST-CHOPPER circuit. The mathematical model and control circuit are built by using PWM bridge rectifier circuit to control PMWG’s rotor speed and power decoupling. And a controlling circuit controlling the active power is proposed based on the three-layer PI control structure, with the outer layer as the power control loop, the middle-layer as the rotor speed control loop and the inner-layer as the current control loop. This control method makes direct use of the excellent linear relation between the power and the rotation speed of DDPMWG for control, which therefore shows better control performance and realizes the steady control strategy more easily. The simulation analysis shows that compared with BOOST-CHOPPER, PWM with three-layer PI control structure has faster control response speed, higher electromagnetic utilization and better stator current sine wave characteristics.Mathematical model and simulation control circuit of PWM inverter decoupling control are built. Two power control methods of gird-connected power generation are analyzed.10MW DDPGWPS is established based on the previous analysis and parameters setting. On this basis, an intelligent control strategy with any given value of power under all wind speed situation and based on three-layer PI control is provided. By means of this strategy, when the wind power reaches the setting power, it shall be outputted in the setting power, and when the wind power fails to reach the setting power, the rotate speed shall be limited to the speed corresponding to the largest wind power, so as to trace the largest wind power. At the mean time, the incontrollable power can be prevented. A fast, simple and highly-efficient maximum wind power tracking method is put forward, which has improved the maximum power tracking method according to the setting power control strategy and enhanced the tracking accuracy without reducing the tracking speed. Further more, a novel control strategy is given to smooth the setting output power fluctuation by virtue of the considerable inertia of DDPMWG when it is higher than the rated wind speed. The correctness of the above-mentioned control strategy is testified through simulation.Lumped mathematical model of SOFC is built based on the concentration polarization voltage and active polarization voltage, and the matlab simulation of steady-state voltage and current characteristics is given. The control circuit with SOFC connected to grid is established based on hysteresis comparison method and dynamic load response performance is researched by simulation. With the randomness of the wind speed, the sunken fluctuation of the DDPGWPS output power appears when the wind power is insufficient. The real-time power complementation control strategy is proposed. The sufficient power and rapid load tracking characteristics composed of SOFC multi modules are used to smooth DDPGWPS output power fluctuations, and the simulation wave form is given.A wind-hydrogen hybrid power system is proposed for isolated islands, which can supply high-quality green energy through using wind energy, fuel cell, diesel generator, and an aqua electrolyzer with alternative energy facilities. The generated hydrogen by an aqua electrolyzer is used as fuel for a fuel cell so that wind can be fully utilized. Simulation results verify the feasibility of the system.