Distributed Secondary Control Strategy for Microgrid Operation with Dynamic Boundaries

Microgrids (MGs) with dynamic boundaries, also known as dynamic MGs, are able to support critical loads without energization from utility and allow system topology variation upon request. Utilization of dynamic MGs can provide more flexible solutions toward distribution system restoration from natural disasters. This paper proposes a distributed secondary control strategy for dynamic MG operation under both static topology and topology variation. The proposed control strategy aims to guarantee seamless transitions during dynamic MG reconfiguration and proper power management among distributed generators (DGs) that are grouped dynamically. Smart switches (SSWs) are utilized to identify, process, and implement the reconfiguration request. The proposed control strategy provides a framework to coordinate the operation of multiple DGs in neighboring autonomous MGs and determine the operation status of SSWs, so that no transient over-shoots are introduced as SSWs operate and DGs are able to support the system power demand proportionally. Detailed controller designs are provided. Sufficient conditions under which the proposed controllers are exponentially stable are derived and the dynamic performance of the proposed controller are validated by comprehensive case studies in MATLAB/Simulink.