In order to smoothly connect to permanently disturbed grids, DFIG-based wind turbines must precisely synchronize the voltage induced at their open stator with that of the grid. Hence, aiming at addressing the still unpublished task of synchronizing DFIGs to simultaneously unbalanced and harmonically distorted grids, a phase-locked loop (PLL)-less and naturally chatter-free sliding-mode control (SMC) algorithm is proposed. The strategies developed so far were formulated considering synchronous reference frames. However, by designing a stationary reference frame-based solution, decomposition into positive- and negative-sequences and harmonic components is avoided. As a result, a relatively straightforward control structure with strong potential for industrialization is obtained, consisting of a single voltage loop per component with just one parameter to be tuned. The stability and robustness resulting from its application are analytically studied under both uncertainties and disturbances. Additionally, a simple method for rotor positioning, independent of grid disturbances, is provided. Simulation over a 2-MW DFIG model and rapid control prototyping (RCP) over a 7-kW DFIG experimental rig are carried out. In this way, the performance and robustness of the suggested control scheme are validated under both unbalanced and harmonically distorted grid voltage, substantial parameter deviations, and varying wind speed and grid frequency profiles.

中文翻译：

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DFIG 同步到不平衡和谐波失真电网的滑模控制算法

为了平滑地连接到永久受干扰的电网，基于双馈风机的风力涡轮机必须精确地将其开路定子处感应的电压与电网的电压同步。因此，针对将 DFIG 同步到同时不平衡和谐波失真的电网的尚未发表的任务，提出了一种无锁相环 (PLL) 且自然无颤振的滑模控制 (SMC) 算法。迄今为止制定的策略是在考虑同步参考框架的情况下制定的。然而，通过设计基于静止参考系的解决方案，可以避免分解为正序列和负序列以及谐波分量。结果，获得了具有强大工业化潜力的相对简单的控制结构，每个组件由一个电压回路组成，只需调整一个参数。在不确定性和扰动下，对其应用所产生的稳定性和鲁棒性进行了分析研究。此外，还提供了一种独立于电网干扰的简单转子定位方法。对 2 MW DFIG 模型进行了仿真，并在 7 kW DFIG 实验装置上进行了快速控制原型 (RCP)。通过这种方式，建议的控制方案的性能和鲁棒性在不平衡和谐波失真的电网电压、大量参数偏差以及变化的风速和电网频率分布情况下得到验证。提供了一种独立于电网干扰的简单转子定位方法。对 2 MW DFIG 模型进行了仿真，并在 7 kW DFIG 实验装置上进行了快速控制原型 (RCP)。通过这种方式，建议的控制方案的性能和鲁棒性在不平衡和谐波失真的电网电压、大量参数偏差以及变化的风速和电网频率分布情况下得到验证。提供了一种独立于电网干扰的简单转子定位方法。对 2 MW DFIG 模型进行了仿真，并在 7 kW DFIG 实验装置上进行了快速控制原型 (RCP)。通过这种方式，建议的控制方案的性能和鲁棒性在不平衡和谐波失真的电网电压、大量参数偏差以及变化的风速和电网频率分布情况下得到验证。