Single-Loop Controller Performance Monitoring

N Stanfelj, TE Marlin, and JF MacGregor. Monitoring and diagnosis of process control performance The single-loop case. Ind. Engg. Chem. Research, 32 301-314, 1993. 

The most popular tool for monitoring single-loop feedback and feedforward/feedback controllers is based on relative performance with respect to minimum variance control (MVC) [53, 102[. The idea is not to implement MVC but to use the variance of the controlled output variable that would be obtained if MVC were used as the reference point. The variation of the inflation of the controlled output variance indicates if the process is operating as expected or not. Furthermore, if the variance with a MVC is larger than what could be tolerated, this indicates the need for modification of operating conditions or process. 

An overview of single-loop CPM is presented in Section 9.1. Section 9.2 surveys CPM tools for multivariable controllers. Monitoring of MPC performance and a case study based on MPC of an evaporator model and a supervisory knowledge-based system (KBS) is presented in Section 9.3 to illustrate the methodology. The extension of CPM to web and sheet processes is discussed in Section 10.3. 

In order to monitor the performance of a single standard PI or PID control loop, the basic information in Table 21.5 should be available. 

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