Control Strategy Research And Application For Steam Temperature System Of Ultra Supercritical Double Reheat Units

With the increasingly severe global energy problem and the rapid growth of the economy.The demand for environmental protection,energy saving and emission reduction technology is becoming higher and higher.Therefore,in the electrie power industry,the high efficiency and clean ultra supercritical double reheat technology units have attracted the attention of a large number of technicians.The double reheat technology,on the one hand,improves the efficiency of the power plant and reduces the consumption of coal,and at the same time,reduces the emissions of harmful and polluting gases,and achieves the goal of energy saving and emission reduction with high standards.Meanwhile,the new technology needs higher control requirements for all the intermal systems of the generating unit.The safe and stable operation of the high parameter unit must be guaranteed by the suitable control systems.In this paper,the structUre and dynamic characteristics of the steam temperature system of the super supercritical double reheat unit are studied,and the following research is carried out in view of the control strategy of the steam temperature system.(1)In determining the state space model of a load state of the system under study,the H2/H? robust zero error tracking control strategy,namely in the controller of the control strategy,not only contains the system state feedback,but also eontains the integral on the tracking error,in order to avoid integral saturation control system is still in the final joined the anti windup module,the H2/H? robust anti windup device without error tracking controller,effectively eliminates the static error tracking system tracking reference output.(2)In the actual industrial process,the state of the system is not necessarily all measurable,even is not measurable,which will affect the implementation of the design control strategy.In addition,when the identification model is deviated from the actual system model,the control strategy based on the identification model will not achieve better control strategy or even make the system stable.For these two reasons,a H2/H? robust observer system based on flull dimensional state no difference tracking control strategy,namely in the derivation process control strategy,to join the state observer,the system identification error between the model output and the actual output of the system into account,the H2/H?robust observer system based on full diaensional state no difference tracking the control strategy can effectively solve the unmeasured states and the problem of model error.(3)In this paper,the ultra supercritical double reheat steam temperature system is a nonlinear system.In this paper,a system state space model with load variation is used to approximate the nonlinear steam temperature system.Aiming at the time-varying state space model,design a memoryless state feedback control law,the control law with redundant structure,and introduces the rolling optimization of predictive control idea in the structure of the controller,according to the real-time adjustment of parameters controller changes system model of the system.The stability of the control strategy is proved in the time domain.A memoryless state feedback H2/Hx predictive control strategy with strong robustness is obtained.(4)Similarly,on the basis of memoryless state feedback H2/H? predictive control strategy,a full dimensional state observer is added.That is to add state observation part in the derivation of control strategy to solve the problem of system state uncertainty and model error.(5)Still for the nonlinear system of ultra supercritical double reheat steam temperature,the fuzzy T-S model is used to approximate the nonlinear model,and the design of robust fuzzy H2/H? control strategy based on T-S model,combining the method of solving the optimization problem of linear matrix inequalities and multi-objective evolutionary strategy method in solving multi-objective H2/H? optimization problems at the same time to optimize the H2 performance indicators and H? performance indicators,get the multi-objective optimization problem of the Pareto front solutions,according to the performance requirements of the control system in order to obtain a solution to choose the appropriate controller parameter optimization.The H2/H? robust performance of the multiobjective fuzzy robust control is better.(6)In the multi-objective H2/H? fuzzy robust control strategy,the system's full dimensional state observer is added.That is to add state observation part in the derivation of control strategy,and solve the problem of system state's uncertainty and model error.Improve the field practicality of control strategy.(7)Based on the three control strategies with state observer and integral saturation,the cascade control structure of superheated steam temperature and the coordinated control system of reheated steam temperature system are designed respectively.Finally,the robustness of the three control strategies of the superheated steam temperature system and the reheated steam temperature system is tested respectively,and the robustness of the model parameter mismatch is obtained.The conclusion is that the multi-objective H2/H? fuzzy robust control strategy is more suitable for the field control system.