ABSTRACT
A flexible multiterminal AC/DC microgrid is based on DC network and power optimization control technology. A system architecture that adopts a star structure in the local and remote annular structure to improve power supply reliability as well as the system operational mode that includes load transfer in normal situations and fault support was proposed. Then, a coordinate control strategy of power flow was introduced for optimize output power of the distribution transformer, and a corresponding P–U droop control strategy was analyzed. Meanwhile, an optimization method of control parameters of a current inner-loop controller based on a high-order primary system model was proposed. Finally, an AC/DC microgrid case was modeled in PSCAD/EMTDC to optimize control parameters of a voltage source converter (VSC) and simulate the system transient operating conditions. Simulation results indicate that the system could realize AC and DC load transfer at the same time, and the proposed method is able to regulate power flow optimally.
