Research On Multi-objective Optimal Scheduling Strategy For Multi-microgrid System

With the increasing number of electric vehicles in China,it is urgent to explore an effective control strategy to eliminate the impact of large-scale disordered charging of electric vehicles on the power grid.Micro network as a kind of efficient use of distributed generation and effective form to carry electric vehicle access,through the flexible control technology can not only improve the given ability of renewable energy,and can improve power supply quality and reliability,so for single piconets and multiple piconets system coordinated control strategy research has become the main content of micro network technology development.First of all,this paper proposes an orderly charging strategy for EVs based on the time-of-use price mechanism to ensure that the system can immediately dispatch EVs that enter the charging field at any time in view of the different charging goals of the grid side and the user side.Under the time-of-use electricity price mechanism,this strategy takes meeting users’ charging demand as the premise,selects the minimum variance of load curve and the minimum charging cost as the optimization objectives,and optimizes the charging mode and charging period of electric vehicles.The effectiveness of the proposed strategy is verified by the simulation analysis of a typical residential area.Secondly,in view of the traditional micro network two stage control strategy can’t adapt to the future of huge amounts of distributed power supply and load in micro network state information processing,high fan output at night can cause stress to the power grid scheduling and quickly run out of energy storage battery may be out of the running problem puts forward the control strategy of three phase double micro network and the constraint of battery discharge.This strategy realizes the local processing of micro-grid information to the greatest extent,improves the autonomy and security of information of micro-grid,simplifies the interactive data between micro-grid layer and power grid layer,improves the reliability of communication,and reduces the pressure of data processing on the control center of power grid layer.The effectiveness of the proposed two-layer control strategy and the battery discharge constraint is verified by the simulation analysis of a typical industrial park micro-grid.Finally,to solve the problem that the traditional demand-side response mechanism has poor application effect due to the non-uniform electricity demand of individual user groups,a coordinated scheduling strategy of multi-micro grid system based on reward and punishment mechanism is proposed.The upper optimization objective is to minimize the comprehensive operation cost(including the transaction cost between each micro grid and the power grid,the deviation penalty and the reciprocal power adjustment compensation)and the network loss of the micro grid,while the lower optimization objective is to minimize the operation cost of each micro grid.Taking a two-micro grid system with electric vehicle as an example,the simulation results are analyzed in terms of active power loss of the multi-micro grid system and output power of each unit in the micro grid,etc.,and the effectiveness of the proposed coordination strategy is verified.