In the existing works of microgrid clusters, operation and real-time control are normally designed separately in a hierarchical architecture, with the real-time control in the primary and secondary levels, and operation in the tertiary level. This article proposes a hierarchically coordinated control scheme for DC MG clusters under uncertainty. In each MG, the tertiary level controller optimizes the operating cost in the MG by taking into account the real-time uncertainties of renewable generations and loads deviated from the forecasting data; and the primary controller responds to the real-time power fluctuations through an optimised droop curve. The hierarchically coordinated optimization problem is formulated to optimize the power set points and droop curve coefficients simultaneously under uncertainties using an adjustable robust optimization model. For the MG cluster, the energy sharing of each MG in the cluster is optimized to minimize the total operating cost and the transmission loss. The overall optimization problem is solved in a distributed manner by alternating direction method of multipliers (ADMM) where each MG entity only exchanges boundary information (i.e. the power exchange of MG entity with the MG cluster), thus information privacy and plug-and-play feature of each MG are guaranteed. The proposed approach optimally coordinates the operation and real-time control layers of a DC MG cluster with uncertainties; it achieves decentralized power sharing at the real-time control layer and distributed optimization at the operation layer, featuring high scalability, reliability and economy. Case studies of a DC MG cluster are conducted in Matlab/Simulink in order to demonstrate the effectiveness of the proposed approach.

中文翻译：

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不确定性下直流微电网集群的分层协调运行与控制方案

在现有的微电网集群工作中，通常在分层体系结构中分别设计操作和实时控制，实时控制在一级和二级，而操作在第三级。本文提出了不确定条件下DC MG集群的分级协调控制方案。在每个MG中，第三级控制器通过考虑可再生能源发电量和预测数据偏离的实时不确定性来优化MG中的运营成本。主控制器通过优化的下垂曲线响应实时功率波动。制定了分级协调优化问题，以使用可调鲁棒优化模型在不确定性下同时优化功率设定点和下垂曲线系数。对于MG集群，集群中每个MG的能量共享均得到优化，以最大程度地降低总运营成本和传输损耗。总体优化问题通过乘数交替方向方法（ADMM）来解决，其中每个MG实体仅交换边界信息（即MG实体与MG集群的电源交换），从而实现了信息隐私和即插即用每个MG的功能得到保证。所提出的方法可以最佳地协调具有不确定性的DC MG集群的操作和实时控制层。它在实时控制层实现分散的功率共享，在操作层实现分布式优化，具有高度的可扩展性，可靠性和经济性。为了证明所提出方法的有效性，在Matlab / Simulink中进行了DC MG集群的案例研究。