Study On Combined Scheduling Strategy Of District Energy Station Aiming At Economic Operation

Comparing with traditional heating and air-conditioning system,district energy system has advantages of high energy utilization efficiency,fine environmental effect,etc.The system can realize unified planning and unified management of heating and cooling by using the reasonable scheduling strategy,and also provides a platform for the energy saving technology of scale effect,the use of natural energy and renewable energy,etc.The application and the research of district energy system also attract more attention.In this paper,a district energy system scheduling strategy aiming at the objective of economic operation and considering to the usage rate of primary energy,which based on load prediction models and practical operation efficiency model is proposed.The study take the Sino-Singapore Tianjin eco-city 2# station as engineering example,and provide not only basis for the optimization and improvement of existing district energy station,but also guidance for new-built district station.Concrete research contents:The performance COP of the various load conditions of each energy supply equipment in the energy station has been transformed to the economic indexes by combining with the local energy price system;the subsystem scheduling priorities are given here: the combined cooling heating and power(CCHP)supply system has the best economic performance,which should be used firstly.The second one is the energy storage system.And the ground source heat pump(GSHP)system is slightly better than the electric refrigeration system.When cooling capacity is insufficient,the electric refrigeration system is used for adjusting the pick load.The paper then turns to the energy supply and load demand matching during the combined operations of district energy system,basing on load prediction models.A district energy system is set up combined operation scheduling with the minimum operation cost of full time as the objective,and the operational mode is obtained by optimal scheduling under the trend of design load and the trend of actual operation load.Under the trend of design load,cost saving rate of the optimal scheduling mode is obviously better than existing scheduling mode,when CCHP is considered to use,the cost saving rate is 2.3%,27%,42% and 53% under the load rate of 75%?60%?45% and 30%,respectively,when without considering CCHP,the cost saving rate is 2.3%,9%,13% and 17% under the load rate of 75%?60%?45% and 30%,respectively.When CCHP is considered to use,the economic performance of the system is better than the CCHP is not considering,and the lower the load rate,the higher the cost saving rate.Under the trend of actual operation load,cost saving rate of the optimal scheduling mode has the same result.When CCHP is considered to use,the cost saving rate is 24%,32%,49% and 61% under the load rate of 75%?60%?45% and 30%,respectively,when without considering CCHP,the cost saving rate is 6%,9%,23.5% and 31% under the load rate of 75%?60%?45% and 30%,respectively.When CCHP is considered to use,the economic performance of the system is better than the CCHP is not considering,and the lower the load rate,the higher the cost saving rate.