Recent technical advances in control, protection and interconnection of distributed power generation units imply that it is practically viable and economically profitable to keep them as backup generators in isolated operating modes. Therefore, along with the development of islanding detection techniques, seamless operation in transition between islanded and grid connected modes is required and more sophisticated control strategies are needed to recognize the existing working condition and adjust the performance to meet the strict standards of grid interconnection. This paper presents a new adaptive control structure, based on internal model control (IMC), which uses multiple models and an inherent islanding detection method through an optimized switching mechanism to tune the operation of a three-phase inverter under transitions between islanded and grid-tied conditions. By applying a power synchronization method, the system emulates the operation of a synchronous machine which is needless to rely on a phase-locked loop to synchronize during the transitions. Hardware co-simulation environment in Simulink/PLECS and Xilinx System Generator have been utilized to evaluate the transient behavior of the controller in discretized domain and verify its robustness during parameter variations and load switching conditions. Various switching rules have been applied and a comparison of their effect in transient response is demonstrated. The results, taken from several case studies, confirm the significant robustness of the proposed control methodology.

中文翻译：

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基于内部模型的三相逆变器在孤岛模式和并网模式之间的平滑过渡

最近在分布式发电机组的控制、保护和互连方面的技术进步意味着将它们作为备用发电机保持在隔离的运行模式中是切实可行的，并且在经济上有利可图。因此，随着孤岛检测技术的发展，需要孤岛和并网模式之间的无缝运行，需要更复杂的控制策略来识别现有的工作条件并调整性能以满足严格的并网标准。本文提出了一种新的自适应控制结构，基于内部模型控制（IMC），它使用多种模型和固有的孤岛检测方法，通过优化的开关机制来调整三相逆变器在孤岛和并网条件之间的转换下的运行。通过应用功率同步方法，该系统模拟同步机的操作，该同步机在过渡期间无需依赖锁相环来同步。Simulink/PLECS 和 Xilinx System Generator 中的硬件协同仿真环境已被用于评估离散域中控制器的瞬态行为，并验证其在参数变化和负载切换条件下的稳健性。已经应用了各种开关规则，并展示了它们在瞬态响应中的效果的比较。从几个案例研究中得出的结果，