Abstract:  An estimation problem of the performance benchmark is considered when the control loop is intervened by the complex nonlinearity. The nonlinearity includes control valve stiction and switching action of the protection valve. The proposed method is based on the threshold nonlinear autoregressive exogenous (TNARX) model. The input and output routine operating data are partitioned if they reaches the certain thresholds. Modeling each partitioned regime as a NARX model, then the prediction error variance as the performance benchmark can be obtained by the principle of pooled variance. By comparison with polynomial autoregressive, polynomial autoregressive exogenous and selfexciting threshold autoregressive models, a simulation example shows the effectiveness and advantage of the proposed method.

Key words:  nonlinear control systems, performance assessment, performance benchmark, TNARX model