Research On Dual-Mode Model Predictive Control Of Gas Collector Pressure In Coke Oven Based On T-S Model

Coke is the main raw material in the metallurgical industry. In the coking process, large amount of by-product gas will be generated from coke ovens, recycling by-product gas in the gas collecting process is an important link in the iron and steel production, which not only saves energy but reduces environmental pollution. The stability of gas collector pressure is an important parameter in the coking process, which directly affects the quality of coke, the life-time of coke ovens and enterprise benefit. The gas collecting process of coke ovens is a complex multi-variable, nonlinear and strong coupling industrial process, so it is hard to acquire good control results with traditional modeling methods and classical control theory. Currently, most steel plants use the PID control combined with the work experience of the site operators. But it suffers many troubles, such as low automation, unstable product quality and high energy consumption. Therefore, the research on the modeling and control method of collector pressure in coke oven has great significance.This paper first analyses the process of coke oven gas collection and the different factors which affected the collector pressure control. Based on it, establishing the nonlinear model of coke oven collector pressure process applies the T-S fuzzy modeling method. Antecedent and consequent of T-S model are identified apart. Fuzzy c-means clustering algorithm is used to identify antecedent parameter and structure. Consequent parameter is identified by least square method. Furthermore, T-S model is transformed to a linear time-varying state space model for the following control algorithm.Second, due to the linear time-varying state space model, this paper proposes a dual-mode model predictive control algorithm based on ellipsoidal invariant set. First the optimal controller is designed without regarding to the input constraints. Then the free future control moves is enhanced when considering the constraints. The control law can be obtained by solving an SOCP optimization problem. The scope of the invariant sets is enlarged by enhancing the additional term based on the optimal control which can guarantee the feasibility and stability of the algorithm.Finally, a control system of gas-collector pressure for coke oven is designed, the results of simulation show the gas-collector pressure can be controlled in a certain region and the effect of the control is good.