Dynamic Behavior and Stabilization of DC Microgrids With Instantaneous Constant-Power Loads

TLDR

DC microgrids use distributed power architectures where point‑of‑load converters act as instantaneous constant‑power loads, which can destabilize the main bus voltage, causing oscillations or collapse. This study investigates stability problems in DC microgrids with instantaneous CPLs and evaluates strategies to prevent such destabilizing behaviors. The authors examine mitigation techniques—including load shedding, adding resistive loads, filters, energy storage on the main bus, and control methods—analyzing their pros and cons and offering recommendations. Simulation and hardware experiments confirm the effectiveness of the proposed mitigation strategies.

Abstract

This paper explores stability issues in dc microgrids with instantaneous constant-power loads (CPLs). DC microgrids typically have distributed power architectures in which point-of-load converters behave as instantaneous CPLs to line regulating converters located upstream. Constant-power loads introduce a destabilizing effect in dc microgrids that may cause their main bus voltages to show significant oscillations or to collapse. This paper also discusses stabilization strategies to prevent these undesired behaviors from occurring. Mitigating strategies such as load shedding, addition of resistive loads, filters, or energy storage directly connected to the main bus, and control methods are investigated. Advantages and disadvantages of these methods are discussed and recommendations are made. The analysis is verified with simulations and hardware-based experiments.