Research On Large Temperature Difference Supply Air Of High Accuracy Constant Temperature Air Conditioning System Based On DMC-PID Cascade Control

The object of this dissertation was the high accuracy constant temperature air-conditioning system of some Synchrotron Radiation Facility storage ring tunnel. Because of the constant temperature room particularity with large electromagnet equipment heat radiation and small tunnel space, large temperature difference supply air technology was adopt in the high accuracy constant temperature air-conditioning system, but also disturbance indoors and outer constant temperature room were a great many, as a result, its constant temperature precision was very difficult to achieve the anticipated effect. In order to guarantee the temperature stability of constant temperature room, disturbance characteristics, air distribution and control strategy were asked to study in the dissertation.First, according to characteristics of storage ring tunnel structure and large electromagnet equipment heat radiation, the electromagnet equipment heat radiation contribution rate of cooling water and air-conditioning systems was to study. With room temperature simplified model, the CFD simulation method was applied to analyse large temperature difference supply air effects on room index parameters and temperature dynamic response characteristics with single or much disturbance function. At last, the critical scope of each disturbance was obtained. Secondly, the CFD simulation method was applied to analyse temperature dynamic response characteristics and anti-jamming capability of different air distribution with inner or outer disturbance and both simultaneity function, and then experiment method was applied to study anti-jamming capability of air distribution and disturbance characteristics. By comparative analysis and research, the best air distribution portfolio was drawn on constant temperature room and air-conditioned room next door under different circumstances.Finally, DMC-PID cascade control strategy was adopted to apply on high accuracy constant temperature air conditioning system. When DMC-PID cascade control strategy was adopted to electromagnet equipment temperature control system, PID control was used in inner loop to overcome equipment cooling water temperature fluctuations disturbance, etc, DMC algorithm was adopted in outer loop, the control strategy could ensure electromagnet equipment temperature stability to reduce it effect on the room temperature stability. When DMC-PID cascade control strategy was adopted to constant temperature room temperature control system, PID control was used in inner loop to overcome supply air temperature fluctuations disturbance, DMC algorithm is adopted in outer loop, at last, the temperature would be controlled through the air conditioning system of electric heater. The simulation result shows DMC-PID cascade control strategy application on high accuracy constant temperature air conditioning system has feasibility and effectiveness, and the control strategy has strong robust stability, tracking performance, anti-disturbance ability characteristics.