Research Of Performance Assessment And Diagnosis Of Control System

Now the research of control engineering domain mainly focus on model identification , design of controller and robustness of control systems, etc. Little has been done to the performance assessment of the running controllers. In fact, many running controllers can't achieve the design index. So, It is a concerned problem for local technicians and control engineers that how to obtain the performance information of the controllers from the operating data so that the performance problem can be recognized and diagnosed early. Recently, the demand of high control system performance from industry promotes the development of the research of controller performance assessment and diagnosis rapidly.Only routine closed-loop operating data and knowledge of the process time delay are needed using minimum variance as a benchmark in controller performance assessment. Controller performance assessment algorithms based on minimum variance for single loop control system , multivariate control system and cascade control system are derived in the paper. Two industrial distillation column examples are given to illustrate the methods of control system performance assessment, and the results reveal its efficiency and feasibility.The main results of the paper are the systemic performance assessment and diagnosis methods for single PID and cascade PID control system, in which the set point tracking and regulation performance are evaluated using minimum variance as a benchmark. The detection methods of oscillation and sluggishness in feedback control loop are given, in order to reduce the diagnosis range of poor performance causes. Simulation and level control experiments are given to illustrate the results.