Distributed Optimal Power Dispatch for Islanded DC Microgrids With Time Delays

Abstract

This paper proposes a fully distributed fixed-time control approach fulfilling the economic operation of DC microgrids (MGs) and considering time delays. A distributed cost optimizer is developed for maintaining MG’s economical operation through equalizing DGs’ incremental costs (ICs) while addressing DGs’ capacity limits within a fixed settling time unrelated to the initial values. Besides, a fixed-time voltage regulator is presented to restore MG’s average voltage for preserving generations-demands power balance. For further improvement of the system stability to oppose time delays, Artstein’s reduction technique is employed for transforming the delayed system to a delay-free one. Accordingly, the proposed controller has an improved dynamic performance and lower integral squared error (ISE) than the existing fixed-time controller, especially with high time delays. Comprehensive convergence analysis confirms that the proposed controller is fixed-time stable regardless of the initial conditions. Extensive simulation case studies are carried out to verify the superiority of the developed controller.

Keywords

• DC microgrids
• economic dispatch
• fixed-time control strategy
• Artstein’s transformation