| The development of integrated energy system(IES)is an important path to build a clean,low-carbon,safe and efficient modern energy system and realize low-carbon development,as well as an important goal for the current energy structure transformation.In the energy planning of the 13th and 14th Five-Year Plan for China,it is also clearly pointed out that the planning and operation optimization research of IES should be promoted to realize multi-objective coordinated control of flexible,stable and economic operation of the system.However,with the continuous development of IES,the system is confronted with multiple uncertainties on both sides of source-demand due to the increasingly complex system structure,dynamic change of energy demand and intermittent and random renewable energy,etc.It brings certain impacts and challenges to the design and operation coordinated optimization of IES,and is an important issue that cannot be ignored.At the same time,the integration of high proportion of renewable energy makes the system present the characteristics of strong uncertainty and high randomness,which put forward higher demand for system flexibility.Therefore,this thesis focused on the IES and the source-demand double-sided multiple uncertainties of the system,explored the flexibility of the IES,and prposed the general collaborative optimization methods of single system and regional multi-system.This thesis provided support for the theoretical research and practical application of integrated energy system.The main research contents are as follows:(1)Comprehensive Quantitative Assessment of Uncertainty in IES.This thesis firstly established a universal and comprehensive quantitative evaluation model for the effects of multiple uncertainties on the system from six aspects:system cost,system equipment capacity,system operation,system risk,system operation flexibility and comprehensive energy efficiency.Secondly,the influence degree of multiple uncertainties was analyzed by global sensitivity analysis.Finally,the correlation between multiple uncertainties was studied and analyzed.The results showed that the existence of uncertainties would significantly affect the capacity results and operation scheduling of the system.Ignoring uncertainties in collaborative optimization research tends to lead to sub-optimal optimization results and operational risk.The global sensitivity analysis showed that the impact of energy demand uncertainty is greater than that of renewable energy output uncertainty and has weak correlation between the two.(2)Collaborative Optimization of IES under Multiple Uncertainties.Considering the different characteristics of multiple uncertainties,this thesis proposed a method and framework for collaborative optimization of design and operation under multiple uncertainties based on stochastic programming-information gap decision theory.Short-term uncertainties were dealt with by stochastic programming,while long-term uncertainties were dealt with by information gap decision theory.Secondly,the proposed method framework provided risk-averse operation scheduling strategy and risk-seeking operation scheduling strategy,which can provide flexible scheme reference for system designer while risk management was carried out.The results showed that the proposed method not only guaranteed the calculation accuracy,but also improved the solving efficiency by nearly 10 times.It is effective and universal.(3)Research on Flexibility of IES under Uncertainties.Aiming at the high demand of flexible regulation,safety and economic operation of the system after high proportion of renewable energy is connected into the system,this thesis firstly established system flexibility evaluation indexes covering all aspects of the system "source-network-load".Secondly,a system multi-objective collaborative optimization model considering economy,flexibility,low carbon and risk was developed based on the proposed flexibility evaluation system.The results showed that through multi-objective optimization,flexible regulation of the system,economical low-carbon operation and 10%improvement of the renewable energy utilization can be realized.(4)Regional-level Multi-agent IESs Interaction Study.This thesis focused on the coordinated interaction of multi-IESs in the region.Firstly,a system group structure was established which includes different system structure types,different energy utilization forms,different building types and different renewable energy permeability.Meanwhile,an operation strategy which considered the heterogeneous multi-energy flow coupling within the regional system group and emphasizeed the source-demand interaction was proposed.Secondly,in order to improve the overall performance of the region and the coordinated interaction among multiagents,an optimal dispatching model of regional system groups based on Nash bargaininggame theory was established.Thus,a multi-energy coordination and distribution transaction mechanism were formed.The results showed that through coordinated interaction,different energy categories and advantages among multiple agents had been effectively utilized to meet energy demand,while achieving overall performance improvement of each agent and region(cost and emission decreased by 9.94%and 13.84%),promoting large-scale development. |
