| With the development of economic and the people’s living, people have been more and more intelligent building, and has become the main direction of development of the century building automation. As an important part of intelligent buildings, Central air conditioning has been widely used in a variety of buildings, but because of the central air-conditioning system in addition to the crew, there are many other devices, such as electric butterfly valves, pumps, fans, temperature sensors, pressure gauges etc., any device monitoring deviation may be inaccurate temperature control, so the establishment of a state-of-the-art automated monitoring platform have become the development direction of the central air-conditioning system. This system based on the field bus technology and computer control technology, through collecting the state information and the data of field instrument, and make every subsystem site focused on the monitor, then through the configuration software to realize its dynamic display.As an important assurance measures in the normal operation of the power dispatch, central air-conditioning system of the Shanxi Electric Power Company main role is to provide a good working environment for scheduling building, against the actual situation and control requirements of the scene for power companies the paper have a reasonable analysis and design. The system adopt to advanced automatic control technology, communication technology, instrument technology and computer control technology, through the field bus PROFIBUS industrial network collect the system parameters, working state and all kinds of data information to the host computer PLC(such as the supply and return water temperature, supply and return water pressure, water pressure set, environment temperature)and then display them on the computer screen through the MPI industrial network. Staff and managers through the host computer can easily watch the working condition of the entire system and field instrumentation data, and staff send control commands to the field device through the computer, modify the system parameters based on the actual need. The system the control technique of the ambient temperature compensation, according to the real-time data of the ambient temperature, to adjust the entire system for the heat; specific, the set temperature of the system will be adjusted in real time based on the temperature of the environment, and based the result of the comparison of the real-time temperature and the setting of the pipe-net issue control commands to the appropriate control system, frequency control system in accordance with the order or change the method of the electric valve opening degree pipe-net traffic in real time so that eventually its heat exchange equilibrium is reached. The system also designed the corresponding equipment alarm output to the workers, when the system has a fault signal, system will automatically send alarm signals and cut off the fault line, enable standby equipment, improve the safety and reliability of the whole system; in addition, there are historical record and history query function in the host computer control system, they can record the alarm time and important data, and provide valid data to the technical personnel for analysis of alarm data and important data and for the further improvements of the system. PC monitoring system need to use4platform-bit machine basing on the requirements of the central air-conditioning systems respectively, in the managers office, technical director of the Office of the monitoring center, on-site control system selected S7series PLC as the control of the subsystem core and configuration software is Siemens WINCC6.2; Siemens automation equipment the is stability and security, data communications is very reliable, it meet the requirements of the control system.In this paper, the design of central air-conditioning control system has been applied in Power Company, and has met the temperature control requirements. |
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