Innovative Control Method of Water Level Control Logic of Tianwan Phase III Deaerator

It is not rare for nuclear power and thermal power at home and abroad to configure more than two valves with different flow characteristics to adjust the level of the deaerator, and there are two traditional control ideas. One is that each regulator controls a regulating valve, the disadvantage is that the two valve switching process is generally manually implemented, and the two valves are used in combination. The second is to control the two valves as a whole by a regulator, the disadvantage is that the two valves can not be used independently, and the automatic hands-free tracking loop is complex. The original design of the deaerator level control valve of unit 5 and 6 of Jiangsu Nuclear Power Plant is the second type. Under normal circumstances, the unit load is low and the water supply demand is small, the deaerator level is controlled by the valve with small flow, and when the unit load is high and the water supply demand is large, the valve with large flow separately controls the deaerator level or the size valve jointly controls the deaerator level. In the initial design, the valve manual operator, the total manual operator, the PI regulator and other links lack the undisturbed tracking logic, which can not realize the automatic undisturbed hand switching. By setting command functions in a variety of modes, and creatively using the inverse function of command functions in various control modes, engineers cleverly designed the tracking and closed-loop time sequence to achieve automatic hands-free switching in various modes. At the same time, using the method of limiting the output range of the regulator, a set of adjusting parameters can be applied to the valve with different flow effects.