Leader Selection in Robust Pinning-based Distributed Control for Islanded Microgrids

Distributed control has shown considerable effectiveness for microgrid secondary control. Components under distributed control scheme communicate with each other to cooperatively achieve secondary control objectives. Despite the ample amount of research, most existing work requires all controllable components to actively participate in control, which may result in excessive communication burden and unnecessary computational complexity. Recently, pinning-based distributed control has been proposed, where only a fraction of the components, termed leaders, provide secondary control services. Although such work has conceptual benefits, the control performance heavily depends on the choice of leaders, but how to make the choice is not clearly studied. Additionally, most pinning-control work assumes no modeling error or disturbance, and this may introduce further deviations from the expected performance. There is in lack of an approach to optimally decide leaders taking into consideration of these concerns. This paper proposes a novel approach to design a pinning-based controller that uses the smallest amount of leaders to achieve satisfactory control performance and robustness to disturbances. We quantify the control performance and show that spatial position of a component in the physical and communication graph can influence the control performance. Modeling error and disturbance are explicitly considered in models as well as in control design process. The control design problem is formulated and solved by a mathematical programming problem. The effectiveness of the proposed work is shown by a case study.