Research On Distributed And Coordinated Optimal Operation Of AC/DC Hybrid Microgrid

AC/DC hybrid microgrid(MG)develops rapidly in recent years due to its efficient integration and management of large-scale distributed energy resources(DERs).As a key technology of AC/DC hybrid MG,how to achieve the optimal operation and coordinated control of AC/DC hybrid MG has become a problem that needs to be solved.Different from the optimal operation of AC MG or DC MG,the coordination between AC MG and DC MG needs to be considered for AC/DC hybrid MG.Thus,the coordinated optimization of AC/DC hybrid MG is studied in this thesis.For single and isolated AC/DC hybrid MG,a distributed optimization method based on the consensus algorithm is proposed.A structure of single AC/DC hybrid MG including wind turbine(WT),photovoltaic(PV),micro-hydro(MH)and biogas generators(BG)is designed,which aims at reducing the power conversion loss.Based on the multi-agent system,a distributed control framework is presented.The convex optimization model is solved by the “Leader-Follow” consensus algorithm.The incremental cost of distributed generator(DG)is selected as the consensus variable.In order to reduce the conversion loss,the solution process is divided into two stages to meet AC load and DC load respectively.Finally,a numerical example shows the reasonability and feasibility of the proposed distributed optimization method.For multiple AC/DC hybrid MGs,a multi-agent system(MAS)based hierarchical and decentralized coordination optimization method is proposed.Based on the architecture of multiple AC/DC hybrid MGs,a three-level MAS including distribution network(DN)level,MG level and distributed generation(DG)level is presented.On the DG level,the DG agents monitor own operational states and obtain the optimal results from MG agent for own output power management.On the MG level,the independent optimization is implemented based on the Mixed Integer Linear Programming(MILP),and the consensus algorithm is utilized in the coordinated optimization.On the DN level,DN agent performs power exchange with AC/DC hybrid MGs to balance the load demand when needed.The distributed energy management platform is developed by Java Agent Development Framework(JADE)platform to simulate the optimal operation of AC/DC hybrid MGs.The proposed method realizes the economic operation of AC/DC hybrid MGs and the results show the rationality and availability of the proposed optimization method.