The Study And Emulation Of The Building Control System Based On PLC

With the development of information technology, building control system is applied to great quantities of all kinds of community and CBD area. The application of PLC in the building control system greatly improves the stability, reliability, flexibility and maintainability of building control system. However, it is difficult to set up the environment for debugging because the PLC hardware is too expensive.In this paper, based on the object-oriented programming ideas, the PLC simulation platform of Siemens s7-200 series is set up under the development environment of Visual c + +.In the first part, the current research situations of building control system and PLC simulation at home and abroad are introduced. It includes PLC basic structure and working principle of PLC, and how to implementation the simulation of each part,ultimately form a PLC simulation platform. Programmers can write programme of statement list directly, or change the ladder diagram program design written into statement table, and then directly lead into the simulation system. The results of program operation can be directly observed by simulation interface without hardware. The preliminary debugging on procedure can greatly save the time of debugging programmer,and improve the enforceability of the program. The feasibility of the simulation platform is verified in a concentrated cooling and heating project from a CBD area in a city. The load forecasting that cannot be achieved in the simulation platform and the optimization of control strategy are studied separately in this project. Load forecasting can be carried by using Elman neural network. The distribution proportion of dynamic load can be worked out with the optimal toolbox after the system modeling.The operation cost of this control strategy saves about 17% than strategy of the unit or ice storage tank priority.