Research And Application Of Power Plant In DCS Control System

With the rapid development of science and technology, the enhancement of environmental protection consciousness and the strategic thought of sustainable development, In the future development requires that we should use resource utilization that is maximum in the limited energy. Large coal-fired power plants is China's important energy industry and pillar industry, which has the important position of energy consumption. Industrial control scheme adopts PID feedback control loop of linear control algorithm, but that is a simple one degree of freedom controlle. Traditional PID control is not ideal in the system when require rapid setpoint response ability and interference suppression ability at the same time.Distributed Control System at present because of the wide range of Control and centralized monitoring management, such as be used in large thermal power plants in China, this paper combined with the DCS System to control the power plant system and the controller to improve the output process. This article first make simple explanation for the power generation process of boiler of heat-engine plant and theory of unit work. It is clear that the purpose and requirements of control process. The main process of boiler control system is divided into four section do a detailed analysis: the drum water level control, optimal fuel air ratio control, the boiler steam pressure constant control, boiler furnace pressure constant control. Second considering mutual influence of each part to the control system, actual object is modeled and design different control loop's thoughts:(1) Adjusting ratio of fuel and air volume to increase the combustion efficiency, It is not appear lack of oxygen or oxygen burning in the control process to wastes the energy.(2) Cascade control system is used for steam pressure control with inside and outside, which could fast and stable recovery constant in susceptible mutation of fuel.(3) Hearth pressure constant system through the mutual adjustment for both boiler induced draft fan and blower, thus designing blower as the main control circuit and induced draft fan as error interference to reduce interference signal so as to improve control accuracy. By using Simulink simulation setting above three different 2-DOF-PID controller parameters in control systems and compared to traditional PID control output figure can be learned that two degree of freedom controller can simultaneously meet two aspect of set ting value and anti-interference characteristics. At last, through the actual configuration and application for DCS control system in Coal-fired power plants, The scene data shows that two degree of freedom controller is the optimization measures of improvement for traditional control.The essay focuses on the difficulties in process and method that different control system design two degree of freedom PID controller parameters combined with the practical experience,and two degree of freedom PID controller with the basis of quickly stable system has more strong anti-interference. The structure of two degree of freedom PID is simple and practical, low cost high control precision, enhance the robustness of the system, and has a good development in DCS industrial control fields.