| Wind power generation technology is one of the hot spots in the field of new energy power generation. In recent years, wind power generation has developed rapidly. Different from traditional thermal power generation, fluctuation and intermittent and other shortcomings of wind speed will cause a side effect to the grid which can not be ignored. Synchronous generator can provide support of voltage and frequency to the grid. If the wind turbine have the external characteristics of the synchronous generator, problems that the wind power system connects to the grid will be solved. Not only has an important significance to the development of wind power generation, but also plays a guiding role to other distributed energy sources.Firstly, as a new kind of generator, the dual stator-winding induction generator(DWIG) is introduced, also, the mathematical model is given. Then the voltage control strategy of DWIG which is based on indirect stator flux oriented strategy is researched. Under this strategy, the generator can output stable high DC by power winding. As we know, stable DC is one of the necessary conditions to realize high performance of inverter. Meanwhile, it is helpful to realize Virtual Synchronous Generator(VSG) control strategy.Energy Storage System(ESS) plays an important role in realizing VSG technology. The type, capacity, and control strategy of ESS will deeply affect the performance of the system. Comparing with different kinds of ESS and the application occasion of them, the best suitable ESS for this system is chosen. Consider the energy of the rotor releases in synchronous generator when participating in the frequency modulation, the capacity of the ESS can be calculated. The outer loop of the bidirectional DC/DC converter is power loop instead of voltage, which is helpful to realize the energy exchange between ESS and DC bus. Not only help the wind turbine reflect the characteristics of synchronous generator, but also support the voltage and frequency of the grid.Based on the second order model of synchronous generator, the algorithm of VSG is researched. The control strategy of adjusting frequency and voltage under grid-connected are also analyzed. The reliability of the system will not be reduced when the VSG strategy is applied. Then, the simulation model of DWIG wind power generation is built in MATLAB/Simulink, the results show that:(1) when the output power of the system is affected by the wind speed fluctuation, the ESS can stabilize the output power of wind turbine;(2) inverter that with VSG algorithm shows the characteristic of virtual inertia which will help to simulate the damping effect to frequency variation in synchronous generator. Finally, to verify the feasibility of DWIG wind power generation system, the experimental platform is built, the results of experiments show the correctness and validity of control strategies. |
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