Using modular cascade DMC and balance control in the main steam temperature control of large power-plant boiler

As it is hard to put the control loop of main steam temperature in large power-plant boiler into automatic operating model, such as the #1 boiler of Pingwei power-plant, we acquired a good knowledge of the system characteristics and thought all the factors concerned over, then we took 10 factors into account and adopted modularized cascade dynamic matrix control method to solve the problem. This method solved the problem above perfectly, and its control performance index was bounded in 540±3°C, which was better than the request of national standard. To solve the off-balance of the output of the final-stage superheater, we got a new method, named balance control. These new control methods had the characteristics of online system identification, scrolling optimization and real-time feedback, so it could be used into the system with large time constant, large time delay and multiple disturbances.