The Research Of A New Coordinated Control Strategy Used For Once-through Boiler

Based on the controlled plants of coordinated control system in a once-through thermal power plant, a new control strategy based on TF(Turbine Following) is proposed and investigated. The mathematical model for the controlled plants of coordinated control system in a power plant is developed, and the simulation results are given to demonstrate the effectiveness of the proposed model. The simulation results for the five conventional control methods are given and analyzed. With the proposed new control strategy based on TF control method, the boiler thermal storage can be fully made use of to improve the response speed to the changing of unit demand, and the main steam pressure can be kept at a satisfied level to ensure the safety operation of units. In the new control strategy, an derivative compensating element is added outside the closed-loop, and the error signal of unit power is introduced into the turbine side, which makes the set point of main steam temperature changes correspondingly, and therefore the boiler thermal storage can be utilized. Based on fuzzy control principle, the proportional gain of the derivative compensating element can be automatically adjusted online according to the changing amplitude of the unit power demand. Simulation results are given to validate the feasibility and effectiveness of the proposed approach.