| As fossil energy is consumed rapidly and environment problem becomes increasingly severe, thechoice of exploiting and using renewable energy to replace fossil energy has been the most practicalstrategy. Wind power, as one of the most clean renewable energy, has attracted worldwide attention anddeveloped quickly in recent years.Continuously exploiting onshore wind farms results in less and less of exploitable and economic windfields exist. Many factors as too much occupied area, destruction of vast natural vegetation, andenvironmental negative impact, forced the development of wind farms to be transferred to offshore areagradually. With the distance of offshore wind farms far away from the shore gradually, the DC electrictransmission scheme based on the voltage source converter will be the central choice for offshore windfarms. This makes exploration and research on wind power generators which can directly output high dcvoltage as inevitable demand for future wind power development. Under this circumstance, this thesis putsforward that the dual stator-winding introduction generator (DWIG) system can be applied to wind powergeneration for novel wind energy technology with independent intellectual property.The thesis focuses on key technologies for DWIG wind power system. Firstly, mathematical modelsof DWIG and basic control theories for DWIG wind power system are deeply analyzed. on that basis, anovel hysteresis current control method based on space voltage vector is proposed for further research oncurrent modulation strategy. Improved hysteresis current method avoids the influence among three legs,limits switch frequency fluctuation, make waveforms more sine, and that easy to implement and debug.Secondly, in order to realize operating under wide wind speed range and broaden the utilization ability ofwind energy under low wind speed, a novel topology for DWIG wind power system is presented. Controlstrategies under low and high wind speed area are introduced in detail. Meanwhile, optimal scheme ofexcitation capacity is given in consideration of particular topology and voltage control strategy. Thescheme helps to realize that the capacity of the system operating in the speed range of1:4is only31%. Thegrid-connected inverter supporting DWIG wind power system is also prepared for realizing grid-connectedoperation. As voltage adjustment on the dc side has been completed on the generator side, a differentdouble loop control strategy is adopted for inverter’s stable operation. The results proved the excellecentperformance of the designed grid-connected inverter. In order to regulate the prime mover to imitate windturbine in the laboratory and achieve the effect of operation in real wind fields, wind turbine simulation system composed by "Industrial Personal Computer+Data Acquisition Card+Micromaster+Asynchronous Motor" is specially designed. The maximum power tracking strategy for DWIG wind powersystem is of course discussed in the thesis, which makes the system output maximum power under differentwind speed. Moreover, an experimental platform for DWIG wind power system is built, which includes fourparts such as wind turbine simulation system, DWIG power generation system, grid inverter system, monitor anddisplay system, and so on. A series of experiments completed on this platform verify the correctness ofsimulation results, feasibility of control strategy, maximum power tracking algorithm.In addition, in order to verify the feasibility of DWIG wind power system in engineering application, a20kW prototype unit standing in actual wind field is established, which can lay a solid foudation in the futureengineering practice. Finally, analysis and investigation of operating during grid voltage dips and unbalancedconditions caused by grid fault for DWIG wind power system is completed, simulation results prove the lowvoltage ride-through(LVRT) capability of DWIG wind power system operating under grid fault. |
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