Research On Operation Strategy Of Railway Station District Heating System Based On Multi-objective Coupling Evaluation

In order to comply with the national carbon emission reduction trend,heating energy saving has become an important part of reducing building energy consumption and carbon emissions.During the actual operation of the railway station area heating system,there are common problems such as low thermal efficiency of the heat source,serious heat loss of the heating network,and improper operation adjustment.As a result,the heating system cannot operate in an optimal state.The heat is unbalanced and the system energy consumption remains high.According to the law of building heat consumption in the railway station area,this paper studies the operation strategy suitable for this type of heating system to meet the variable temperature demand of the heating building in the railway station area.And based on the comprehensive evaluation principle,a multi-objective coupled evaluation model for evaluating the variable temperature operation strategy of the railway station heating system is constructed,and the optimal operation strategy is optimized to ensure the safe and stable operation of the system and on-demand heating.(1)This paper takes the heating system of the railway station area as the research object,and adopts the method of questionnaire survey to collect and analyze the heat consumption characteristics of the existing railway station area buildings and the actual operation of the heating system.Demand,that is,the law of heat consumption has spatial and temporal differences;the thermal efficiency of the heating system is low,the operation adjustment is unreasonable,the on-demand heating cannot be achieved,and the energy waste is serious.(2)Establish a dynamic mathematical model of the heating system based on the principles of mass and energy conservation,including mathematical models of heat sources,water supply and return pipe networks,radiators,building envelopes and other system components,controllers,electric control valves,variable frequency pumps and so on to run the mathematical model of the adjustment equipment.Taking the heating system of a Datong railway station area as an actual example,the dynamic simulation platform of the heating system is built by using Simulink software.Compared with the measured data,it is verified that the model has high accuracy,which improves the simulation foundation for the research of operation strategies.(3)Based on the demand of building temperature change,the operation strategy of centralized mass regulation and different local regulation is studied,and the change of water supply temperature and flow is used to control the change of building indoor temperature.Among them,the centralized mass adjustment adopts the heat source climate compensator adjustment,and the local adjustment adopts three methods: electric valve adjustment,variable frequency pump adjustment and variable frequency mixing pump adjustment.The simulation analysis adopts the centralized mass regulation operation strategy and the system dynamic response under three different operation strategies.The results show that the operation strategy of centralized mass regulation alone cannot achieve the on-demand response of indoor temperature,while the centralized mass regulation coupled with local regulation of electric valve volume regulation,variable frequency pump volume regulation and variable frequency mixing pump quality regulation can all achieve on-demand response of indoor temperature.Provide a theoretical basis for the optimization of the variable temperature operation strategy of the heating system in the railway station area.(4)According to the characteristics of on-demand heating of the heating system in the railway station area,starting from the three evaluation goals of economy,energy saving and low carbon,and indoor thermal environment,the annual cost,primary energy consumption,carbon emission reduction and indoor temperature are selected to be qualified.A total of four representative evaluation indicators are used to establish a variable temperature operation evaluation system for the heating system in the railway station area.A multi-objective coupling evaluation model is established by combining the method of analytic hierarchy process to determine the index weight and the fuzzy comprehensive evaluation method.The practicability of the evaluation model is verified by the simulation dynamic response of the actual case.The results show that the optimal economic operation strategy is centralized mass regulation + local variable frequency pump regulation,and the optimal operation strategy for energy-saving and low-carbon targets is concentrated mass regulation + local variable frequency pump regulation.The optimal operation strategy of indoor thermal environment is centralized mass regulation + local variable frequency mixing pump regulation,and the optimal operation strategy of multi-objective comprehensive evaluation is concentrated mass regulation + local variable frequency pump regulation.Provide theoretical basis and methods for energy-saving operation strategy optimization of heating system.