Combined Control Strategy for Proportional Current Sharing in DC Microgrid Clusters
Panbao Wang, Mohamed Zaery, Di Zhao, Wei Wang, Dianguo Xu
Abstract
The integration of adjacent dc microgrids (MGs) results in the formation of a dc MG cluster which can increase the system power supply capacity. This article proposes a control strategy for dc MG clusters which combines communication-free control and distributed fixed-time control to simultaneously achieve current sharing and voltage regulation with excellent transient characteristics. Firstly, a communication-free control, which presents greater flexibility than the distributed control, is used in the dc MG layer. Subsequently, the distributed fixed-time control is used in the dc MG cluster layer to balance the output current of each MG. The optimal control parameters are obtained by using the zero-pole distribution diagram and establishing a small-signal model of the dc MGs; the stability of the proposed control strategy is also verified. Different scenarios are considered to validate the plug-and-play capability and controller performance by using a dc MG experimental prototype. Real-time hardware-in-the-loop verification containing three MGs is conducted using two RT-boxes to prove the scalability of the proposed cluster control.