Advanced Control Strategy Research Of Gas-steam Combined Cycle Unit

The gas-steam combined cycle unit has attracted worldwide attention due to its ability of solving problems such as low energy utilization and serious environmental pollution.Because of its advantages of high efficiency,low pollution,low cost and quick start-stop,it has an irreplaceable position in the power industry.In order to achieve good control effect,advanced control strategy should be applied to the combined cycle unit—a multivariable,strong coupling and complex dynamical characteristic system.The implementation of control strategy relies on the mathematical model of the system,so it is necessary to establish a model with high precision and simple structure.Learning and researching the modeling and control strategy of combined cycle unit plays an important role in the current energy saving and emission reduction in our country and breaks the foreign monopoly of gas turbine.Therefore,firstly,the subspace identification algorithm is introduced in this paper,and then uses this method to obtain the parameters of the state space model of the system.The models of the combined cycle unit obtained by using this identification algorithm are not only high in accuracy,but also simple in structure.Then the constrained model predictive control strategy is applied to the control of the identified state space models.The results prove that the predictive control algorithm can overcome the strong coupling characteristics effectively and achieve a good control effect.However,this control algorithm has a long running time due to the large amount of online computation.Therefore,this paper optimizes the structure of the quadratic programming problems used in the ordinary predictive control algorithm,and then puts forward a fast predictive control algorithm by combining the improved primal barrier method with the warm start method.The fast predictive control algorithm can reduce the complexity of online computation and decrease the rolling optimization time.The improved algorithm is applied to the combined cycle unit,and the simulation results show that the operating speed of the system is effectively improved with the precondition of guaranteeing good control performance.