| Some steel mills use a large number of blast furnace gas(BFG) and coke-oven gas(COG) produced during the production to implement combined cycle power plants(CCPP), which achieves both recycling, also decreases the pollution of environment. Large size pneumatic-diaphragm control valves are used to control the mixed gas pressure in CCPP. It is difficult to keep the mixed gas pressure in system allowed range because of the restriction of pneumatic actuator hysteresis characteristic, big gas compressibility, and other factors. This is the major question to affect the normal operation of generating equipments. The electro-hydraulic actuator has characteristics of high precision, fast speed, and steady movement, so we propose the technology of electro-hydraulic servo-driven control valve aimming at the major problem. About the technology, the main research works of this paper are as follows:Firstly, this paper reviews the steel CCPP and the existing problems, introduces the control valve technology in domestic and foreign, describes composition, feature and development trend of the hydraulic servo control system, and elaborates the topic research significance.Secondly, this paper designs electro-hydraulic servo-driven system of the control valve, determines main technology parameters by calculating and selects the appropriate components. Two methods are used to bulit the mathematical model of system. Nonlinear mathematical model of system is established by utilizing the mechanism modeling method. The analysis of Bode diagram indicates that the system is stability. Physical model is built by using AMESim which is a graphical modeling simulation software. Graphical modeling method guarantees the simulation results more closer to the actual situation because it considers more details.Thirdly, a control strategy is in-depth studied after the mathematical model is built. Hydraulic servo system has problems of nonlinear and time-varying, and it often exists parameter variations and load disturbances. In order to solve the above problems, model reference adaptive control method based on generalized error in the theory of the adaptive control is applied to the system, then the adaptive control model is established. This control method requires only input and output to design system, and it ensures system stability. Matlab\Simulink is used to simulate dynamic response of the system, then implements the combined simulation by the control software interface of AMESim. The result shows that dynamic response of the electro-hydraulic servo-driven valve system meets the requirements of CCPP.Finally, the test platform of the electro-hydraulic servo-drive control valve is built. The related experimental research about performance of control vavle is carried out. The experimental research indicates that model reference adaptive controller has good anti-jamming and adaptability. The result shows that adaptive control strategy in control vavle electro-hydraulic servo-driven system of CCPP is feasible and effective completely. |
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