Stability Constraints on Reliability-Oriented Control of AC Microgrids – Theoretical Margin and Solutions

Reliability is of importance for operation maintenance and cost reduction in power electronics and systems. Based on the reliability models of power devices, reliability-oriented power sharing in microgrids enforces the redistribution of power among converters to prolong the lifetime of the entire system, and droop control is typically used herein. However, this could affect the system stability, which contradicts the prerequisite of secure operation. In light of the above, this article is aimed to reveal this limitation of reliability-oriented droop control and emphasize its impact on system stability. Accordingly, a framework of stability-constrained reliability-oriented droop control is proposed, together with solutions that can help to enhance the stability. With this, the reliability of the system could be further improved without violating the stability criteria. Moreover, experimental tests and long-term reliability evaluations are included, which demonstrates that the aforementioned issues can be effectively addressed alongside with the proposed framework and solutions.