Mode Switching-Induced Instability of Multi-source Feed DC Microgrid

TL;DR

This paper investigates how mode switching affects voltage stability in multi-source DC microgrids, analyzing the instability mechanism and proposing a control strategy to enhance system stability through mode scheduling.

Contribution

It provides a general analysis framework for mode switching-induced instability in multi-source DC microgrids and introduces a novel control method based on mode scheduling.

Findings

Positive feedback causes instability during switching.

Switching strategy impacts voltage stability.

Proposed control improves stability in simulations and experiments.

Abstract

In DC microgrids (DCMGs), DC-bus signaling based control strategy is extensively used for power management, where mode switching plays a crucial role in achieving multi-source coordination. However, few studies have noticed the impact of mode switching and switching strategies on system voltage stability. To fill this gap, this paper aims to provide a general analysis framework for mode switching-induced instability in multi-source DCMGs. First, manifold theory is employed to analyze the stability of the DCMG switched system. Subsequently, the instability mechanism and its physical interpretation are explored. The positive feedback activated by the decreasing DC bus voltage during the switching process leads to instability. Switching strategy may inadvertently contribute to this instability. To improve stability, a novel control method based on mode scheduling is proposed, by adjusting switching strategy and thereby correcting the system trajectory. Finally, both real-time simulations and experimental tests on a DCMG system verify the correctness and effectiveness of theoretical analysis results.