Research On Power Capacity Optimization Allocation Of Grid-connected Microgrid

With the increasing demand for energy in all countries,increasing the development and utilization of renewable energy has become an inevitable choice for all countries in the world.At present,distributed energy has become a key way of efficient utilization of renewable energy.However,as more and more distributed energy is connected to the power system,the adverse impact on the normal operation of the power system is more and more obvious.The emergence of microgrid can effectively manage distributed energy,so as to reduce the impact on the power system and ensure the local consumption and utilization of distributed energy.Compared with off-grid microgrid,grid-connected microgrid is connected with superior power grid,which can greatly improve the reliability and economy of power supply of microgrid.The optimal allocation of power capacity of microgrid is a key issue to be dealt with in the planning of grid-connected microgrid.The planning results will be related to the operating efficiency and reliability level of microgrid in the future.Therefore,this thesis studies the optimal allocation of power capacity of grid-connected wind-solar storage micro-grid,and the main work is as follows:(1)The basic theory of power capacity optimization allocation technology of micro-grid is studied,and reliability evaluation indexes such as self-balancing rate,proportion of annual electricity exchange with superior network and proportion of unmet load are constructed in the capacity allocation process of grid-connected micro-grid.The topology structure of grid-connected wind-landscape storage microgrid is described,and the mathematical model of each unit of the microgrid is established.(2)The optimal allocation method of power capacity of grid-connected microgrid is studied.Taking the annual comprehensive economic cost of the system as the optimization objective,the constraints of switching power between the micro grid and the superior grid,the constraints of supply and demand balance,and the constraints of lithium-ion battery energy storage operation were considered in the constraint conditions,and the reliability evaluation indexes established in the previous chapter were taken into account to develop the operation strategy of grid-connected wind-solar storage micro grid.Aiming at the disadvantages of poor population diversity and easy to fall into local optimal,the grey Wolf optimization algorithm is improved.Through three test functions,the results show that the improved grey Wolf algorithm has better convergence performance in solving multi-variable and multi-local optimal problems.Finally,the concrete flow of the improved gray Wolf algorithm to solve the capacity allocation problem is given.(3)Using MATLAB software programming simulation.Firstly,the improved grey Wolf algorithm,particle swarm optimization algorithm,whale algorithm and original grey Wolf algorithm were used to calculate the optimal solution of power capacity configuration of the micro grid,and the effectiveness of the improved grey Wolf algorithm to solve this kind of problem was verified.Then,under the same reliability constraints,the improved grey Wolf algorithm is used to solve the optimal configuration of off-grid and grid-connected wind-landscape storage microgrids in this region.The results show that the economic cost of grid-connected microgrids is lower.Secondly,the influence of the grid switching power limit and different blackout penalty factors on the optimal allocation of the power capacity of grid-connected microgrid is analyzed.The results show that the increase of grid switching power limit will lead to the increase of the reliability of the microgrid and the decrease of the cost,but the dependence on the superior grid is very strong.The increase of penalty coefficient will lead to the increase of microgrid reliability and cost.In addition,the sensitivity analysis of different unsatisfied load proportion constraint and self-balancing rate constraint to the annual comprehensive economic cost of microgrid is also carried out.Finally,the influence of load participation on demand side response on power capacity configuration is analyzed.