Bidirectional Current-fed Converter for Integration of DC Micro-grid with AC Grid

Most of the loads found in various commercial installations require front end ac-dc conversion. Various storage systems and renewable sources interact with these loads and the ac grid through dc-ac converters. These multistage conversions reduce system efficiency. To avoid this, an ac distribution system can be replaced by a dc distribution system within a commercial facility. It results in improved system efficiency and reliability. This paper proposes a three-phase current-fed converter, interfacing a dc distribution system with a utility ac grid. It has bidirectional power flow capability. The converter injects or draws low ripple current from a dc micro-grid, while maintaining high power factor and low current distortion on ac grid side. It has improved reliability and size over conventional VSC. The steady state and dynamic performance of the converter is studied using MATLAB Simulink. The converter also has a limited capacity of supplying or absorbing reactive power. These limits are computed for both inversion and rectification modes of operation.