As a key part of modern power systems, DC microgrid is becoming increasingly important. Among different control methods for DC microgrid, secondary control has been widely investigated since it can guarantee both current sharing and DC bus voltage restoration. However, the existing secondary control results only consider fixed current sharing ratio among DC converters, and thus they cannot be applied to the case where an adjustable current sharing ratio is desired. Motivated by this observation, this paper presents a new distributed secondary control strategy. By imposing a time-varying droop gain and specifying the “virtual voltage drop,” this strategy is able to ensure adjustable current sharing ratio among DC converters. Moreover, the effects of time delay on the control performance is also analyzed. Three case studies and two hardware-in-the-loop (HIL) tests are provided to verify the efficacy of the presented strategy.

中文翻译：

---

分布式次级控制的时滞直流微电网的电压恢复和可调均流

作为现代电力系统的关键部分，直流微电网变得越来越重要。在直流微电网的不同控制方法中，由于可以保证均流和恢复直流母线电压，因此二次控制已得到广泛研究。然而，现有的次级控制结果仅考虑了DC转换器之间的固定的均流比，因此它们不能应用于需要可调节的均流比的情况。基于这种观察，本文提出了一种新的分布式二次控制策略。通过施加时变下垂增益并指定“虚拟压降”，该策略能够确保DC转换器之间可调节的均流比。此外，还分析了时间延迟对控制性能的影响。