Optimization Of Thermal Power Units Of Thermal Control System Tuning And Its Application

Fossil fired power plants have always been playing important roles in our electrical industry,How to ensure the units to run safely, economically, high-effectively is extremely urgent to solve.The units run with large capacity and critical parameter, systems need to be more reliable andautomatic. So that, the automation of thermopower process is becoming the reliable assure ofworking normally.Although a remarkable research activity has been devoted to the application of the industrialprocess control, the PID cofltro1 technology is still the most popular and commercially availabletype used in the industrial process control. This is partially due to its robustness to differentindustrial environment, simplicity of implementation and familiarity to many engineers. Even if itis the advanced computer Distributed Control System which is widely imported and applied inour country, PID is used as the main control method.Howevef, the adjustment or tuning of controllers poses a constant challenge to controlresearchers and engineers. The first difficult problem is that it is not easy to obtain accurateprocess models in industrial environLment, while this is the fundamental of process controllertuning. The second is that fOr a complicated system, for example, with many loops as well asmany controllers, it is very difficult to give the direct relation between the parameters ofprocesses and that of controllers. Most of practical design methods, including self tuningapproaches for PID controllers, are based on the consideration of control systems with one closedloop, lower order process model and one PID controller. In the industrial engineering, however,some control systems are so complicated, for example more than one loops with many controllers,that it is very difficult to achieve desired properties of control systems by only making use ofeither engineer's experience or pure ana1ysis methods. The third is that the lack of practical toolswhich give engineers the opportunity of combining their experience with the advanced controItechniques to tune the process controllers is also one of these problems in tuning controllers. Inthe industries, to date,the task of tuning controllers is carried out mainly by using engineeringmethod, such as Ziegler-Nichols scheme, field test and history data or engineer's experience bywhich engineers expend lots of tuning time but it is dift1cult to obtain the optimum result. For theabove reason, many thermopower control systems are not able to run as Red Lines, even not towork in automatic state over a 1ong period of time. On the other hand, the adjustment or tuning ofcontrollers need to be carried out because of the mechanical wear or the variations ofenvironment or operating mode. Therefore, studying practical and effective method to adjust ortune controllers is the urgent demand to improve the automatic level and promote the productionefficiency of thermopower processes.In view of the specific property of thermopower processes and these problems existing intuning PID controllers, a multifunctional optimization tuning instrument fOr thermal processcontrol (MOTC) has been successfully developed and widely applied because of its qua1ities inpast years, which can provided the engineers a powerful tool to handle the practical problem oftuning coITtroller so as to get a desired controI results with the optimum controllers. By means of--MOTC, larger economic benefit has been achieved, and good PfOspects has been revealing.So as to improve and extend the function of MOTC, under the support of ChineseHigh-Tech Research & Development Program, "The Application of Advanced Control Strategiesffi iii Nm%to DCS in Large-scale Power Plant and the Development of Control Software Package" andNingxia Electrical Company project, "Automatic Generation Control of No.3 Power Unit in Dabapower plam", this paPer aims at the optimization tuning fOr thermal control systems in powerplant...