For the purpose of absorbing renewable energy

the coal-fired power units are required to operate flexibly

and the resulting variable operating environment will lead to large nonlinearity and uncertainties of the wet desulphurization process. Particularly

the time delay will make the control even harder. Therefore

in order to achieve a more flexible control structure

a new desulphurization control strategy based on frequency retrofit is proposed. Based on the strategy

a dynamic model is obtained through field experiments. Meanwhile

in order to deal with uncertainty well and achieve safe compensation of uncertainty in the control process

an updated Gaussian process model predictive control method for time-delayed objects is proposed

and the performance of the method is demonstrated by parameter analysis and simulation experiments. Finally

the effectiveness of the proposed control strategy and control method is verified by field application.