Robust Multi-objective Operation Optimization For Multi-energy Complementary Microgrids

A multi-energy complementary microgrid is an important research project,which reflects the level of development of new power energy technologies and explores the road of harmonious development between energy and economy,society and environment.The microgrid operation optimization based on energy scheduling can effectively integrate different forms of energy and reduce energy production costs,which has been the key technology of multi-energy complementary microgrids development.However,in the face of complex operating conditions as well as internal multi-energy flow coupling and other characteristics of microgrids,the multi-energy complementary microgrid operation problem with the comprehensive optimization objectives of stability,economy and environment,might still need the thorough research.In order to solve the above problem,a hybrid configuration grid-connected microgrid including the photovoltaic generation,the combined cooling heating and power,the ground source heat pump,the battery and loads,is considered as the research object.The complicated issue of microgrid operation optimization is researched under multiple uncertainties associated to renewable energy and loads,multiple optimization objectives of economy and environment,and demand response mechanisms.Moreover,system engineering optimization is employed in this research work to develop microgrid operation optimization approaches,which lay a certain theoretical basis for establishing the microgrid operation method system with high efficiency and robustness under complex operating conditions.Also,the developed operation optimization approaches provide application references for the realization of the optimization theory in the operation of multi-energy complementary microgrids.The specific research content and achievement are shown as follows.Firstly,for the economic operation optimization problem of the microgrid under uncertainties in the electrical load tracking(ELT)and the thermal load tracking(TLT),a robust multistage economic operation optimization approach for the microgrid is proposed based on minimax regret criterion.In view of the conservatism problem of microgrid operation,a minimax regret non-linear formulation with budget of uncertainty is constructed to describe the performance of the system.To address multistage coupling features in the proposed model,the convex programming duality theorem is applied to transform unseparated constraints to separate constraints,and the multistage model is simplified as a two-layer model.Moreover,a hybrid solution method including a two-stage Lagrangian relaxation iterative algorithm and cross entropy algorithm,is developed to solve the model.Simulation results indicate that optimal economic benefit can be obtained by searching the minimum economic regret under the maximum disturbance of uncertainties,and the conservatism of microgrid operation can be effectively adjusted by the proposed approach.Secondly,in view of the multi-objective operation optimization problem of the microgrid with minimizing operational costs,carbon dioxide emissions and primary energy consumption in ELT and TLT,a multi-objective operation optimization approach for the microgrid is proposed based on heuristic scheduling rules and an improved multi-objective cross entropy algorithm.Considering that there are cooperation and game relationships among multiple objectives,which might result in operation schemes deviating from the original intention of the microgrid,then heuristic scheduling rules are designed to correct generation of Pareto schemes,reduce feasible region and improve solution efficiency.In order to guarantee the diversity and optimality of Pareto schemes,the sample section generation strategy and parameter updating mechanism are introduced to improve multi-objective cross entropy algorithm.Simulation results indicate that Pareto optimal solution sets can be obtained by solving once only,as well as the economic,environmental and energy consumption objectives can be optimized simultaneously by the proposed approach.Then,for the microgrid operation process with multiple optimization objectives under uncertainties,an integrated optimization approach of uncertainty and multi-objective in the microgrid operation is proposed based on SBM robust multi-objective optimization.Considering that the effects of stochastic scenarios are different on economic and environmental objectives,a minimax multi-objective formulation with budget of uncertainty is developed for microgrid,based on the definition of Pareto robust optimal solution.Also,a two-layer solution framework including multi-objective optimization in the inner layer and set-valued optimization in the outer layer is designed to deal with the complex structure of multi-objective bilevel programming.Simulation results indicate that the proposed approach can effectively attenuate the disturbance of uncertainties as well as achieve optimal economic and environmental benefits,and also control the robustness of Pareto schemes in a multi-objective framework.Finally,in view of the economic and environmental operation optimization problem of the microgrid with demand response programs uncder uncertainties,an operation optimization approach for the micorgrid with supply and demand cooperation is proposed based on PBM robust multi-objective optimization.Considering the insensitivity of loads to electricity price and incentive,load shifting is introduced in demand response programs,and a robust multi-objective optimization based microgrid operation model with supply and demand cooperation is developed.In order to cope with the decision variables coupling and nonlinearity in the proposed model,a strong duality based model transformation method is implemented to transform the model into a deterministic multi-objective programming of the microgrid,and multi-objective cross entropy algorithm is adopted to solve the reconstructed model.Simulation results indicate that loads scheduling can improve economic and environmental benefits,as well as reduce the stress of supply side in handling uncertainties.Also,the optimal operation benefits of microgird can be achieved by the proposed approach under uncertainties.