The autonomous microgrid (MG) with multiple voltage source inverters (VSI) is operated in droop mode to share the load proportionally. These VSI controllers require higher droop constants if the feeder lines connecting the VSI to microgrid has a low X/R ratio. The higher droop gains and large loading conditions in the microgrid may exhibit instability with the low frequency power modes (LFPM). This paper details a systematic multivariable plant model of the MG using dynamic phasor modeling of power flow transfer functions to analyze the LFPM. Further, a robust supplementary multivariable controller is developed to stabilize the developed plant model, damp LFPM and improve transient power sharing performance of VSIs without affecting their steady-state power sharing. This stabilizer is developed based on Glover-McFarlane $H_{\infty }$ loop shaping robust stabilization technique with an additional pole placement constraints formulated in linear matrix inequality framework. A laboratory scale experimental validation is presented to evaluate the performance of proposed stabilizer under various operating conditions and uncertainties in the autonomous MG. Moreover, the transient power sharing performance of DGs with proposed controller was compared with that of widely used derivative droop controller.

中文翻译：

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基于下垂的自主交流微电网的鲁棒 H∞ 多变量稳定器设计

具有多个电压源逆变器 (VSI) 的自主微电网 (MG) 在下垂模式下运行以按比例分担负载。如果将 VSI 连接到微电网的馈线具有较低的 X/R 比，则这些 VSI 控制器需要更高的下垂常数。微电网中较高的下垂增益和大负载条件可能会表现出低频功率模式 (LFPM) 的不稳定性。本文详细介绍了使用潮流传递函数的动态相量建模来分析 LFPM 的 MG 的系统多变量设备模型。此外，开发了一个强大的补充多变量控制器来稳定开发的工厂模型，抑制 LFPM 并提高 VSI 的瞬态功率共享性能，而不影响它们的稳态功率共享。该稳定器是基于 Glover-McFarlane $H_{\infty }$ 回路成形稳健稳定技术开发的，并在线性矩阵不等式框架中制定了额外的极点放置约束。提出了实验室规模的实验验证，以评估所提出的稳定器在自主 MG 的各种操作条件和不确定性下的性能。此外，将具有所提出控制器的 DG 的瞬态功率共享性能与广泛使用的导数下垂控制器的性能进行了比较。