Identification nonlinear flow characteristics of main steam regulating valves

Schematic diagram to illustrate the separation and identification of nonlinear flow characteristics for the proposed method. Due to a fact that steam turbines and generators have different dynamic characteristics at different operating points, the static nonlinear flow characteristic (e.g., yellow solid lines in (a)) is overwhelmed by input and output data with dynamic characteristics, such as the blue dots in (a) and their corresponding time series are shown in (b). The key to identifying the nonlinear flow characteristic is to separate it from the linear dynamic submodels at different operating points. The separation is achieved based on some special segments, such as the steady-state segments with constant amplitudes (e.g., red solid lines in (c)), and the slope response segments with large amplitude changes (e.g., green dash lines in (c)).