| To solve the environmental problems caused by the large-scale development and inefficient use of fossil energy,the proportion of renewable energy in the world’s energy consumption is gradually increasing.However,the intermittency and uncertainty of renewable energy generation have limited its large-scale application in the energy system.Integrated energy systems can fully utilize the coupling characteristics of various forms of energy in the production,conversion,transmission,storage,and consumption of energy to improve energy supply reliability and energy utilization efficiency,and promote the consumption of renewable energy,are gradually becoming a research hotspot.Combined heat and power(CHP)units are a type of key coupling equipment in integrated energy systems.Their reasonable optimization configuration is the key to realizing efficient energy utilization by coupling multiple forms of energy such as electricity,heat,and gas.To simultaneously consider economic and environmental factors in the optimization configuration process of CHP units and address issues such as uncertainty in system sources and loads as well as the long-term load growth,this paper focuses on multi-stage and multi-objective planning for CHP units.The main work of this thesis is summarized as follows:1)A multi-objective planning method for CHP units considering economic and low-carbon factors has been proposed.Firstly,the multi-objective planning model of CHP units is established by considering the economic objective of investment and operation costs and the low-carbon objective of total CO2 emissions.Then,based on the fuzzy membership function,the two objectives are fuzzified and transformed into a single objective planning problem to obtain the CHP unit configuration scheme with the maximum comprehensive satisfaction to achieve the purpose of comprehensively considering economic and low-carbon factors.Simulation results show that compared with single-objective planning,the proposed multi-objective planning method can coordinate the economic and low-carbon factors of investment and operation.2)An optimized configuration method for CHP units considering the uncertainties of source and load is proposed.Firstly,based on the prediction box method,the conditional probability of renewable energy output and comprehensive load demand is constructed using a large amount of historical data.The dynamic scenarios considering time correlation are generated by using the inverse transformation sampling method of multivariate normal distribution.Then,the generated dynamic scenarios are reduced by using an improved K-means clustering method to construct typical scenarios and their probabilities.Finally,by incorporating the probabilities of typical scenarios,a planning model for CHP units considering the uncertainties of source and load is established and solved.The case studies show that the proposed scenario-based optimization planning method can consider the uncertainties of source and load to reasonably configure CHP units of electric-heat-gas integrated energy system,and achieve better investment and operation economy.3)A multi-stage planning method for CHP units considering the full life cycle cost is proposed.Firstly,according to the growth characteristics of electric,heat and gas loads throughout the life cycle,the planning cycle is divided into multiple investment stages.Then,considering factors such as investment cost,operation cost,equipment residual value and time value of funds,the optimal configuration scheme for newly added CHP units at the beginning of each stage is determined with the minimum life cycle cost as the objective to meet the demand for comprehensive load growth during the planning cycle.Simulation results show that the proposed multi-stage planning method can achieve better economic effects and avoid equipment redundancy and cost waste caused by single-stage planning. |
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