Multi-objective Optimization Operation And Algorithm For Integrated Energy System

With the increasing attention to environmental protection issues and the improvement in power quality requirements.The single-objective optimization,which only considered economics,could not keep up with the requirements of modern power system operation control.Contemporary power systems need to consider the cost of power generation,the environmental protection of power generation,the safety,reliability and stability of power grids,and the reduction of active power losses,simultaneously.Therefore,the study of the multi-objective optimization in power systems has practical guiding significance for the operation of today's power grids.Moreover,with the development and utilization of large-scale micro-grid and distributed energy,energy is transmitted to various users through the energy system with the grid as the backbone network.For this reason,the coordination and optimal scheduling of renewable energy has become the focus of scientific research in various countries.In order to realize the energysaving and emission-reduction requirements of power generation in contemporary society,it is necessary to comprehensively coordinate and optimize the entire energy system from sourcenetwork-load to achieve the best economic optimization and environmental protection.In view of these two multi-constrained,nonlinear,large-scale and complex optimization problems,this paper studies from simple power flow optimization to the complex coordinated optimization of integrated electricity-Natural Gas System with Microgrid(Integrated Electricity-Natural Gas System with Microgrid,IENGS-M),to establish the operational optimization model step by step.The research method is simulated and analyzed from the basic NSGA-? algorithm to the modified NSGA-? algorithm search mechanism and the decision-making part after optimization.The following two aspects of research have been carried out from shallow to deep.(1)A mathematical model of multi-objective power flow optimization problem for power systems is established.The operational optimization objectives of today's considerations cannot fully reflect the economic,environmental,safety,and reliability status of the power systems.In this paper,five objective functions are used to represent the attributes of the certain aspect of the power system,and many equations and inequality constraints are considered in the optimal power flow optimization process.A novel improved NSGA-? algorithm(modified NSGA-?,MNSGA-?)is proposed to solve the optimal power flow optimization poblem.The effectiveness and feasibility of the proposed improvement strategy are verified by simulation in IEEE-30 system and IEEE-57 system.The improvement strategy can not only accelerate the convergence speed of the algorithm,but also enhances the convergence effect of the algorithm.This paper also compares the simulation results with the optimization results of other algorithms.In addition,several multi-objective optimization performance indicators are used to evaluate the impact of the improved strategy on the convergence,distribution and extensiveness of the algorithm.(2)A multi-objective framework for coordinated optimization scheduling of IENGS-M was established.In the model framework,the basic equipment such as the eleticity network,gas network and the connection equipment of the two networks are modeled in detail,and the rotation reserve of the microgrid part is considered.Not only that,this paper also proposes the coordinated optimization scheduling scheme of IENGS-M.The simulation results of the coupled15-node gas network and 39-node grid system with microgrid are used to verify the effectiveness of the algorithm and the proposed coordinated optimization scheduling.Both economic and environmental aspects have better overall performance.The line faults and system faults of the joint system are analyzed,and the rationality of the proposed model is further verified,and the stability of the system can be maintained even under fault conditions.