A DC-Side Fault-Tolerant Bidirectional AC-DC Converter for Applications in Distribution Systems

Abstract

This paper proposes an ac-dc converter for dc distribution systems. The proposed converter has a simple structure, offers bidirectional power flow capability, and is robust to dc-side faults. Based on the developed dynamic model, the converter is current-controlled in a rotating reference frame, meaning it is also protected against ac-side faults. Insight on the design of the specific control parameters for proper operation of the various control loops is also provided. Furthermore, it is shown that the minimum permissible dc-link voltage of the converter is the same as that of a conventional voltage-sourced converter. Time-domain simulation studies in the MATLAB and Simulink software environments, as well as a 1.25- $kW$ experimental prototype confirm the effectiveness of the proposed converter under various normal and faulted operating scenarios.

Keywords

• AC fault
• ac-dc converter
• current-mode control
• dc distribution systems
• dc fault
• dc microgrids