The Energy-saving Predictive Control Method Of Cooling Plants Suitable For On-line Application

HVAC energy consumption accounts for more than half of the building's total energy consumption,and the water system energy consumption in the entire HVAC system energy consumption accounts for in the range of 30% to 80%,which has a large energy-saving space.This paper sets the cooling plant where mechanical and electrical equipment are centrally located as the object,and directly measured the relevant parameters of the cooling source and transport equipment in the air-conditioning system,by means of the intelligent management framework of Internet of Building Energy System(iBES),to achieve on-line parameters' monitoring and then to explore the method of tower-chiller-pump global control.On the basis of this method,the COP prediction model of the cooling plant system is established,and then a method based on on-line predictive control model of the cooling plant system is put forward,with the related control technology is developed.This paper introduced the intelligent management framework of iBES put forward by the Building Energy Research Institute of Dalian University of Technology,and took the cooling plant system as the test platform,which is located on a hospital in Zhejiang province,building the intelligent air-conditioning control system that was based on flattened networks and facing specific tasks.The system was compatible with both TCP/IP and MODBUS communicated protocols.It used hardware and software such as the intelligent control terminals,the intelligent field linkers,TIA Portal programming software,SIMATIC WinCC process monitoring system and EasyBuilder Pro configuration software supporting WEINVIEW touch screen.At the same time,they were used for on-line engineering application.In order to propose the global energy-saving control strategy in system,the paper first analyzed the local operating parameters of the 1# centrifuge unit,which occupied the main running time in the Hospital,with extracting a large number of off-line running data in the test system.Taking full account of terminal load changes in air-conditioning system,rapid response and safety requirements,this paper put forward a kind of energy-saving control method of cooling plants suitable for on-line application,which was respectively with supply and return chilled water temperature difference and the condensing pressure as the control parameters in the chilled side and cooling side.It was proved that the control strategy could reduce the level of energy consumption and at the same time could avoid the occurrence of the parameters' sudden changes in the system,contributing to equipment's efficient and smooth operation in system.In order to save the energy greatly in the system to the maximum extent,the paper further tried to consider the relationship between load changing and energy efficiency of the cooling plant on the basis of the proposed on-line control method,and the COP of the cooling plant system was used as the energy-saving control target in the cooling plant.At the same time,the method of double cluster T-S model identification was introduced to construct the COP prediction model,applied to the on-line energy-saving control of the monitoring system.The results of the simulation shows that the correct rate of using double clustering T-S model prediction is up to 90%,and the application of the model based on the method of the cooling plant's on-line prediction control has obvious advantages such as high predictive accuracy,good energy-saving effect,high stability,simple program application and timely response,suitable for the system's on-line application.