This paper presents a droop-based controller for grid-tied three-phase inverters. The controller allows to regulate the inverter output power while operating grid-tied, to support the local grid voltage while operating islanded, and to seamlessly transition into this latter mode of operation. Remarkably, the use of the traditional droop control scheme for per-phase power control would lead to unequal frequencies among the phase voltages, which is not acceptable. Instead, the proposed controller allows independent power references tracking at each of the phases of a three-phase inverter while grid-tied and a proper transition into the islanded operation. Per-phase power control is crucial for several services in modern smart power networks, like demand-response and distributed unbalance compensation. The paper also reports the stability analysis of the whole control system and outlines a procedure for the design of the involved regulators. Simulation and experimental results considering a laboratory-scale prototype are reported and discussed to validate the proposed controller.

中文翻译：

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用于平稳过渡到孤岛运行的每相功率控制器

本文提出了一种用于并网三相逆变器的基于下垂的控制器。控制器允许在并网运行时调节逆变器输出功率，在孤岛运行时支持本地电网电压，并无缝过渡到后一种运行模式。值得注意的是，使用传统的下垂控制方案进行每相功率控制会导致相电压之间的频率不等，这是不可接受的。相反，建议的控制器允许在并网时在三相逆变器的每一相上跟踪独立的功率参考，并适当地过渡到孤岛运行。每相功率控制对于现代智能电网中的多项服务至关重要，例如需求响应和分布式不平衡补偿。本文还报告了整个控制系统的稳定性分析，并概述了相关调节器的设计程序。报告并讨论了考虑实验室规模原型的模拟和实验结果，以验证所提出的控制器。