IGPC-QFT Cascade Control And Its Application In Thermal Control System For Coal-fired Power Plant

Thermal system of coal-fired power plant(such as superheated steam temperature control system and unit coordinated control system)is a complicated control system,which has high inertia and long time-delay,multivariable and disturbance characteristics,and the model parameters change with the load.Which make it difficult to be controlled effectively under the traditional control algorithm.For the characteristics of superheated steam temperature control system,quantitative feedback theory(QFT)and generalized predictive control algorithm(GPC)are studied and improved.Firstly,in the process of QFT controller design,there is a tedious loop shaping process,which make the designer use it difficultly.A simple and effective method for QFT controller design is proposed to avoid the tedious loop shaping process.Secondly,when the traditional GPC algorithm is used in thermal control system,the output will appear overshoot.Meanwhile,there are complex matrix inversion operations in the GPC algorithm.The generalized predictive control algorithm is improved in this paper.Lastly,a IGPC-QFT cascade control algorithm is proposed to apply in superheated steam temperature control system.Quantitative feedback theory(QFT)is used to reduce the influence of time-varying parameters and suppress the disturbance in the leading region of the system.The improved generalized predictive control(IGPC)is used to suppress the overshoot and overcome the large inertia and large time delay in the inert region.The simulation results is compared with the traditional control algorithms,and which shows that the proposed IGPC-QFT cascade control algorithm can be well applied in superheated steam temperature control system.The unit coordinated control system is a multivariable control system and the variables in which seriously couple with each other.So feedforward compensation method is used to decouple the system.The proposed IGPC-QFT control algorithm is applied in the system.The simulation results show that this control strategy is efficientin unit coordinated control system.