Analysis and distributed control of power flow in DC microgrids to improve system efficiency

摘要

DC Microgrid attains popularity in integrating renewable energy sources and batteries. It also has the potential to achieve higher efficiency than ac power grid with optimized power flow. In this paper, a general dc microgrid is modeled based on a cluster of general dc nodes, which includes constant power renewables generation, droop-controlled voltage source and different kinds of load. Then the dc power flow is solved for optimization. A voltage restoration method based on consensus algorithm is used to restore the voltage deviation from droop characteristic. An enhanced current regulator is adopted to guarantee the accurate load sharing even under the influence of sensor drift and line resistance. A tie line power flow control method is proposed to regulate the tie line power directly and increase the system efficiency at light load condition. All the considered methods only need the local information and the information from its nearest neighbor thus the system expendability is guaranteed. Simulation and experiment results are provided to validate the proposed methods.