火电锅炉汽水系统先进控制研究-控制理论与控制工程专业论文.docxVIP

AbstractABSTRACT Abstract ABSTRACT Because of the characteristics of large time—delay,large inertia，nonlinearity and slow time—varying in some control loops，there are plenty of difficulties when controlling a thermal power boiler object．At present，distributed control system(DCS) has been commonly adopted in large-scale thermal power units of China，and PID， cascade and feed—forward control strategies have been widely used in loop controlling． However，the parameters of most PID controllers are roughly adjusted，which can only guarantee the safety of system and satisfy the fundamental requirements，rather than improving the economic profits．The thermal power industry in China，which has a much lower energy efficiency comparing with the international advanced level，is unfortunately one of the main energy consumers and a redoubtable environment polluter．Successful applications of advanced control technology are little reports in domestic thermal power industry，although it can provide great help to both energy conservation and environmental protection． This study iS accomplished on a Sulzer monotube boiler in Yaomeng Power Co．， Ltd．Based on specific analysis of steam water system process，key loop object features and the existing scontroI schemes，two advanced control strategies are proposed at different levels in the whole control system．Firstly,a new internal model control based PID(IMC．PID)designing method was deduced，which can be used to tune the key control loop PID parameters，especially in those loops with large delay and／or large inertia．Secondly,SGPC arithmetic is used to substitute the original PID controllers in key loops or the main PID controllers in cascade loops．The former strategy,which is easy to implement，is proposed to improve the parameters of original controllers and thus a better control performance can be expected．The latter one。which needs to add advanced workstation and modify DCS configuration，is proposed to improve the whole control strategy and thus