Research On Methodologies Of Energy Management And Optimal Operation Of Microgrids

With the increasingly severe energy,environment and climate problems,developing the renewable energy has become a widespread consensus all over the world.As a powerful approach to efficient utilization of distributed renewable energy sources,microgrids have been getting good opportunities for development.However,microgrids are exposed to a large number of uncertainties,bringing significant challenge for their operation.In addtion,a reasonable market mechanism for the orderly participation of microgrids and the coordination with distribution network is needed for the emerging subjects under the power market environment.This thesis focuses on the energy management and optimal operation of microgrids under uncertainty.The main work is listed as follows:1)A two-layer energy management method with multi-time scale for stand-alone microgrid composed of diesel generators,wind turbine generator,biomass generator and an energy storage system is proposed.The heuristic optimal scheduling model considering the uncertainties of sources and load is established in the optimal scheduling layer based on the ultra short-term prediction of wind power and load and the state of charge of the battery,to minimize the cost of microgrid.The response capability for the significant forecast deviation and instantaneous fluctuation of wind power and load is guaranteed in the real-time control layer to limit the power generation of diesel generators and ensure the safety operation of the system.In the end,the effectiveness of the proposed method has been verified through a hardware in the loop simulation.2)Considering the day-ahead forecast uncertainties of sources and load demands,a two-stage robust model is established to handle the day-ahead operation optimization of the grid-connected microgrid.The solvable robust form is derived based on strong dual theory and linear modeling method.Meanwhile,a parameter,named the budget of uncertainty,is introduced to adjust the level of conservatism of the robust solution against the modeled uncertainty.Comparing with the deterministic optimal scheduling strategy,the proposed method is more robust and capable to resist the volatility risk of real-time market price.3)Relying on the market economy theory and game theory,two interaction mechanism for the coordinated operation of microgrids and distribution network are proposed.Firstly,a stackelberg game model,in which the microgrids are acted as the price taker,is built based on price incentive mechanism.The distribution network operator realizes the economic and safety operation of the system based on power flow optimization and price optimization,and the microgrid operators minimize the cost through the robust model and internal trading mechanism;Secondly,the strategic bidding optimization of microgrids in electricity distribution market is formulated when considering the microgrids as price maker.The Nash equilibrium of the market is achieved based on dynamic game method.Finally,the simulation of the coordinated operation of microgrids and distribution network under the two modes is carried out on the IEEE-33 bus system to validate the effectiveness of the proposed method.