Research On The Frequency Conversion Energy Saving System Of The Central Air-conditioning

In contemporary large-scale buildings, central air-conditioning is the indispensable facility with high power, high energy consumption, and high running costs. In the circumstance of the current strained electricity supply, the rising price of power, energy conservation and emission reduction, protecting the environment, how to improve the efficiency of the central air conditioning system, reduce energy consumption and reduce running cost become a problem that we need to face. Therefore, this paper carries out the research on the frequency conversion energy saving system of the central air-conditioning.The design capacity of the central air-conditioning system is the maximum cooling load, but most of the time the system is running at part load. The majority time of central air conditioning water systems are working at constant flow mode, when the load changes, the pump is always running at full speed under design conditions, the water flow can not follow the actual load demand, resulting in huge energy wasted. Variable flow is based on the actual change requirements for water flow in air-conditioning load which means the system can track the actual load. The system will provide corresponding cooling capacity, to meet the system requirements to reduce energy consumption at the maximum. Design the scheme for water system of the central air-conditioning system.Chilled water system of central air conditioning is a typical non-linear, time-varying, multi-variable complex system, which is difficult to establish the accurate mathe matical model, the conventional control method based on the precise mathe matical model is difficult to obtain satisfactory control effect, because fuzzy control do not need precise mathematical model of controlled object, for all kinds of interference and noise have a strong suppression. This paper proposed a method based on fuzzy reasoning tuning PID controller parameters, to design appropriate adaptive fuzzy PID controller. Simulation studies show that the adaptive fuzzy self-tuning PID controller has both the advantages of high precision conventional PID, and also has quick, strong adaptability and characteristics of the fuzzy control. The result has a good dynamic and steady state characteristics.Finally, it designs the hardware and software system and realizes the water pump frequency conversion control by the Siemens S7-200 PLC as the main controller and Siemens MM440 frequency converter. It also introduces the design of the main program and its control subroutine system, and analyzes the efficiency in energy saving.