Application Of Adaptive PID Control In The Feed Water Control System Of 350MW Supercritical Units

With the growth of electricitydemand,as well as energy and environmental requirements,China’s thermal power construction began to large capacity,high-parameter large units closer.Since the introduction of subcritical thermal power unit technology in the 1980 s,China has made some experience in its improvement,optimization and development,and made 300 MW and 600 MW subcritical thermal power units become the main unit of domestic thermal power generation.Subcritical units still have two outstanding problems: high energy consumption and pollution of the environment.This has become a bottleneck restricting the development of China’s power industry.Therefore,drawing on the most advanced technology in the world,developing and developing supercritical and ultra-supercritical thermal power units is the most effective way to improve the thermal efficiency of thermal power units,realize energy saving and improve environmental protection.Boiler water supply control system is one of the main control systemsin the thermal power plant,its task is to adjust the boiler feed water flow.Water supply control system performance advantages and disadvantages for the unit’s safety,stability,economic operation has an important impact.In recent years,with the increase of the capacity of the unit,the heat load of the boiler heating surface has been greatly improved,and the influence of the boiler load on the water supply is intensified,and the dynamic characteristic of the system is greatly changed.It is difficult to establish a precise model for the dynamic characteristics of the boiler,such as large time-varying and non-linear,and it is difficult to control with the traditional control method.In addition,in order to adapt to the larger time-varying and non-linearity of the controlled object and the change of the control equipment,it is necessary to switch the controller comparison band frequently in the water supply control process.,Even so,conventional water supply control system is also very difficult to achieve a rational control effect.Therefore,there is an urgent need for a fast control method with strong robustness,relatively simple algorithm and self-tuning of controller parameters.This paper introduces the adaptive PID controller for supercritical boiler feed-water control object.In the process of unit commissioning,the adaptive PID model is designed and simulated experimentally.It is applied to the debugging of supercritical units.The parameters are set and input automatically.The traditional PID controller parameter tuning method is based on the acquisition of the object mathematical model,based on a certain set of principles to determine the PID parameters,but in the actual industrial process control,many controlled process mechanism is more complex,with a high degree of non-linear,Time-varying uncertainty and pure lag and so on.This requires that in the actual control,not only the PID parameter tuning does not depend on the object mathematical model,and the PID parameters can be adjusted online to meet the real-time control requirements.Adaptive PID control is an effective way to solve this problem.Adaptive PID control absorbs the advantages of adaptive control and conventional PID control,which is a combination of both.First,it has the advantages of automatically identifying the parameters of the controlled process,automatically setting the parameters of the controller,and adapting to the parameters of the controlled process.Secondly,it has the advantages of simple structure,good robustness and high reliability.Site personnel and design engineers are familiar with the advantages.The two advantages of adaptive PID control make it an ideal automation device in process control,which is a direction for people to study the object and the development of adaptive control.