An approach of PI gain scheduling with hysteresis switching for the control of boiler drum level in the coal-fired power generation units

An approach, where hysteresis switching logic is used in gain scheduling of PI controller, is proposed and applied practically in the control of boiler drum level of 4× 300MW coal-fired power generation units. The parameterized candidate PI controllers are designed at a number of operating points based on on-site engineering tuning/tests, and, hysteresis switching logic, which is shown theoretically can be used with the aim that switching stops in finite time, is applied to make controller decision over those candidate PI controllers. The unit generation output is used as scheduling variable by the hysteresis switching logic. The proposed controller structure is used to control drum level of 4×300MW coal-fired power generation units at Zouxian Power Generation Inc, P.R.China.