Distributed control of orthogonal current components among converters in an autonomous microgrid

Power sources in a microgrid must be controlled in coordination with each other in order to meet optimization requirements and satisfy the operating criteria of the microgrid as a whole. Droop control of power sources is a known solution for distributed and coordinated control of power electronic converters to share active and reactive power in a microgrid. In this paper, current-based droop control is extended to all major current components i.e. active, reactive, unbalanced and harmonic. Current Physical Component theory is used for decomposition of current into orthogonal components. Each current component can be dedicated to various power sources in any percentage, which enables operation optimization of the microgrid. A higher-level controller sets droop parameters of local controllers by the use of a low-speed communication link. By setting the slope and bias of the droop characteristic line for all current components, this higher-level control, along with specifying the percentages of current components, improves the quality of voltage at the load bus.