Microgrid Power Flow Calculation And Application Considering VSC

In recent years,due to the rapid development of renewable energy technologies such as wind energy and wave energy,a large amount of distributed energy(DG)has been integrated into the power grid,forming a micro-grid structure.However,when the microgrid is in island operation mode,there is no balance node,and the power distribution mode between DGs changes,which causes the traditional power flow algorithm and the optimal power flow algorithm to fail to meet the requirements of the current new situation of the power grid.Therefore,it has become an inevitable trend to deal with DG reasonably and improve power flow algorithm and optimal power flow algorithm.In this paper,considering the use of droop control strategies in island microgrids,the research on the back-to-back power flow algorithm and optimal power flow before improvement is carried out.The details are as follows:First of all,based on the consideration of the droop control strategy adopted by the island microgrid,this paper first improves the AC microgrid forward-backward power flow calculation,introduces virtual balance nodes to solve the problem of unbalanced nodes in the island microgrid,and then introduces secondary frequency modulation Technology to solve the situation that the system frequency exceeds the allowable operating range,and finally the algorithm is verified through the IEEE33 node network.Secondly,for the power flow calculation problem of AC/DC hybrid microgrid with VSC,this paper designs an improved alternating iterative method,which uses the improved forward and backward power flow algorithm of droop control strategy to be used in the AC system,and the DC system loss As a criterion for convergence,it shows its superiority through comparison with traditional AC/DC power flow algorithms.Third,this paper takes the DG cost and the minimum system voltage deviation as the goal,and designs a two-stage multi-objective particle swarm optimization algorithm to solve the optimal power flow model.First,the optimal power flow optimization problem is solved,and then the fuzzy C-means algorithm and gray Correlation analysis processes the non-inferior solution set,and then selects the optimal compromise solution to meet the system operation requirements.The rationality of the proposed algorithm is verified by an improved 50-node example.Finally,in order to solve the problems of DG power volatility,this paper introduces DBSCAN clustering and non-parametric kernel density estimation methods to model the regularity and randomness of DG power,and then through Monte Carlo simulation(MCS)based on Monte Carlo simulation.The acceptance-rejection sampling method selects the power emitted by DG in a period of time,which provides a solution to the problem of DG power randomness.