Research On Dynamic Optimal Dispatching Of Islanded/Grid-connected Microgrid

With the continuous development of science and technology,the global energy crisis and environmental pollution have also followed.Renewable energy such as solar energy and wind energy have developed rapidly due to their clean and pollution-free characteristics.Therefore,the microgrid system with new energy generation as the core arises at the historic moment.However,because the microgrid technology is not perfect,only single objective or static scheduling of microgrid system can not guarantee the security and reliability of microgrid operation,so it is of great significance to study a more comprehensive microgrid optimal scheduling method.In view of the different influences of different models on the optimization of microgrid optimal dispatching and the problems of traditional intelligent algorithms that are easy to fall into local optimality,slow convergence speed,and poor accuracy in multi-objective optimization,a new type of biological heuristic swarm intelligence algorithm is applied—— Grey Wolf Optimization Algorithm(GWO),which has the characteristics of strong convergence,few parameters,and easy implementation.Its optimization performance for different models is better than Particle Swarm optimization(PSO).Based on this,this article mainly studies the multi-objective dynamic optimal dispatch of microgrid in combination with GWO,and conducts in depth research on the multi-objective dynamic optimal dispatch of microgrid in islanded operation and grid-connected operation mode.The main contents are as follow:(1)In this thesis,the typical microgrid system structure is summarized,and the working principles and mathematical models of wind turbines,photovoltaic generators,diesel generators and battery energy storage systems in the microgrid system are analyzed.(2)In this thesis,the background and principle of the Grey Wolf Optimization are introduced,the mathematical model of the algorithm is constructed,and the parameter optimization steps of the algorithm in the dynamic optimization dispatch of the microgrid are explained.Finally,GWO is compared with PSO.The results show that GWO has faster convergence speed,higher accuracy and is not easy to fall into local optimum.(3)The dynamic optimal dispatch of islanded microgrid based on GWO is studied.In order to solve the problem that the power capacity of islanded microgrid system is small,diesel generators need to be started frequently,and a single load change will have a significant impact on the power balance of microgrid,this thesis sets the minimum operation cost and maximum environmental benefit of microgrid system as the objective function,analyzes the operation and maintenance cost of each distributed unit in the system,establishes constraint conditions and calculates the operation and maintenance cost combined with GWO global optimal solution.Finally,the system is divided into six different scenarios,and different dynamic optimization scheduling strategies are formulated for each scenario.(4)A multi-objective dynamic optimal scheduling model of grid connected microgrid is established.Aiming at the problem of interactive power and cost between grid connected microgrid and large power grid,this thesis firstly analyzes the cost of each distributed generation,and constructs three different objective functions,namely,the lowest operation cost of microgrid system,the lowest pollutant treatment cost and the maximum comprehensive benefit.The different objective functions are solved by GWO algorithm,and the system operation conditions are divided into four different types of scenarios are studied,and different optimal scheduling strategies and optimal output schemes are formulated for each scenario.Finally,the advantages and disadvantages of microgrid in islanded operation mode and grid connected operation mode are compared and analyzed,and the advantages and disadvantages of the two operation modes are obtained.