Research On Optimal Scheduling Of Hybrid AC/DC Multi-energy Microgrid

With the increasingly prominent problems of energy shortage and environmental pollution,it is a global consensus to develop and utilize renewable energy and promote green and low-carbon energy transformation.The development of distributed generation,hybrid AC/DC power supply,multi-energy complementary and multi-energy storage technologies is conducive to construct a clean and efficient hybrid AC/DC multi-energy microgrid(MEMG),and the stepped utilization of energy and the on-site consumption of renewable energy can be achieved by its optimal scheduling.However,the multiple uncertainties of renewable generation and load demand,complex AC/DC coupling constraints based on advanced power electronic converters,diversified demand response modes,and response characteristic difference of different energy bring great challenges to the optimal scheduling of the hybrid AC/DC MEMG.Based on this,this paper studies the optimal scheduling of the hybrid AC/DC MEMG.The main work is as follows:Firstly,for the hybrid AC/DC MEMG with the hydrogen storage system,a day-ahead scheduling model based on the two-stage robust optimization(TRO)method is constructed to deal with the multiple uncertainties of wind-photovoltaic output and AC/DC/hydrogen/heat/gas load.In this model,the operation states of energy conversion and storage equipment are determined in the first stage,and the worst scenario and corresponding equipment output scheme are determined in the second stage.Based on the strong duality theory,big-M approach,and column and constraint generation(C&CG)algorithm,the TRO model is transformed into a master problem and a slave problem with mixed integer linear form for iterative solving.The solving tool is CPLEX solver.The multi-energy complementary effect of the microgrid,and the effectiveness of the TRO model and solution are verified by simulation examples.Secondly,a day-ahead two-layer optimal scheduling model considering integrated demand response(IDR)and uncertainties of generation and load is proposed for the hybrid AC/DC MEMG with the power electronic transformer(PET).In this model,the IDR considering the difference of load response characteristics is realized based on Stackelberg game,the generation and load uncertainties are addressed by the TRO model and improved reserve constraints,and the reserve sharing mechanism of AC and DC systems based on the PET is designed.On the basis of the Karush-Kuhn-Tucker conditions,strong duality theory,and big-M approach,the two-layer game model is transformed into a single-layer robust optimization model,which is solved by C&CG algorithm and CPLEX solver.The positive influence of the IDR on the scheduling is analyzed,and the effectiveness of the uncertainty handling method and model solving method is verified by simulation examples.Thirdly,to effectively coordinate the day-ahead,intraday and real-time scheduling of the hybrid AC/DC MEMG,a multi-time-scale optimal scheduling strategy is proposed,which considers the multiple differences,including the differences of demand response resources,system scheduling objectives and prediction accuracy of generation and load in different time scales,and the difference of energy response speed.According to this strategy,the multi-time-scale optimal scheduling model of the hybrid AC/DC MEMG is established,including day-ahead robust chance-constrained optimization model,intraday stochastic optimization model and real-time hierarchical rolling modification model.Moreover,the intraday and real-time scheduling distinguish the scheduling resolutions of different energy.After linearizing the robust chance constraint model in the day-ahead scheduling,all optimization models are solved by CPLEX solver.The scheduling results in different time scales are analyzed,and the effectiveness of the uncertain optimization models in the day-ahead and intraday scheduling is verified by simulation examples.Finally,to realize the energy reciprocity among different microgrids,a hybrid AC/DC MEMG cluster syetem based on DC interconnection is constructed,and a two-layer collaborative optimal scheduling model,which considers the service of energy storage station,interconnection network topology,and generation and load uncertainties,is proposed for the microgrid cluster.The operation optimization model of the DC interconnection network aiming at group benefit maximization is given in the upper layer,while the robust stochastic optimization model of each microgrid aiming at individual benefit maximization is given in the lower layer.To realize the privacy protection and parallel optimization of microgrids,the analytical target cascading(ATC)algorithm is selected as the coordinated solving method of the two-layer optimization model.The convergence performance of the ATC algorithm is verified,and the effects of the collaborative optimization,energy storage station service and uncertainties on the microgrid cluster scheduling are analyzed by simulation examples.