A Research Of Multi-source Distirbuted Coordinated Control For DC Microgrids

Microgrid is an effective solution to increase the penetration of the distributed renewable energy generation and improve the reliability of power supply,which has a great economic and social value.With the increasing of dc distributed generation systems and dc loads such as solar renewable energy sources,energy storage systems,LED light,electric vehicles,the dc microgrid has drawn more attention recently by domestic and overseas scholars.Compared with ac microgrids,the dc microgrid has less energy conversion stages,which can improve energy efficiency and economy operation of system.In the future,dc microgrids will be widely implemented in residential complexes,industry systems and commercial buildings.Nowadays,how to realize the coordination between the various distributed generations in the system and ensure the stable operation of the system has become a hot area.Therefore,it has a great practical significant to design a multi-source coordinated control strategy with high flexibility and stability.This paper is organized as follows.Firstly,the research status are introduced and summarized.Secondly,the modeling and control strategies of dc nature distributed generations(including photovoltaic cells and batteries)and the corresponding interface power electronic converters(including DC-DC chopper and DC-AC converter)are analyzed,then the topological structure and hierarchical control architecture of the dc microgrid has also been introduced.For the maximum use of renewable energy and the system economic operation,a multi-source distributed coordinated control strategy considering demand side response is proposed,units in the dc microgrid can adaptively change their operation states based on the global dc bus signaling(DBS,which is the dc bus voltage)with plug and play feature.Furthermore,in order to reduce the operating cost of the system,when the electricity price is high,the energy storage systems can autonomously sell more power to the ac grid.On the contrary,when the electricity price is low,the energy storage systems buy more power from the ac grid.In order to further solve the voltage fluctuation caused by the traditional DBS coordinated control and the unreasonable distribution of output power of multiple energy storage units caused by line impedance,a multi-source distirbuted coordinated control strategy for the islanded dc microgrid based on discrete consensus algorithm is proposed.Finally,the effectiveness of proposed coordination control strategy is verified by the lab-scale DC microgrid platform in Tianjin University.