DC Bus Voltage High-Frequency Disturbances Analysis for DC Microgrids With Long Connections

Abstract

This article examines high-frequency disturbances in interconnected converters within dc microgrids, focusing on the effects of electromagnetic interference (EMI) filters and long interconnection cables. Understanding these phenomena is essential for systems with multiple power converters as it facilitates the identification and mitigation of voltage and current oscillations. The study investigates the beating effect in dc microgrids, providing an analytical derivation of the oscillation amplitudes at the beat frequency. It also explores how interactions between long cables inductive impedance and EMI filter capacitors can influence the system performance, distinguishing it from previous works. The study examines a dc microgrid consisting of two connected cascaded buck converters. Two scenarios are analyzed: one considers no filters between the two converters, while the other includes a low-pass filter (LPF), an EMI filter, and a cable feeder between them. The proposed theoretical models are validated using a 2 kW experimental prototype comprising two interconnected buck converters. In addition, the paper presents various strategies to mitigate the beating effect in dc microgrids, discussing their effectiveness and the associated implementation challenges.