Abstract: The method comprises obtaining data samples, each data sample comprising a process variable and a controller output for adjusting the process variable to reach a set-point variable; and determining if there is valve jump or stiction by calculating a jump index or a static band index; wherein calculating the jump index comprises calculating a mean of a first set of angles, each angle from the first set of angles being computed from a ratio of: a difference between a peak process variable and its preceding process variable, and, a difference between a controller output corresponding to the peak process variable and its preceding controller output; and wherein calculating the static band index comprises calculating a mean of a second set of angles, each angle of the second set of angles being computed from a difference between a controller output corresponding to a flat process variable and its preceding controller output.

Abstract: A method of qualifying performance of a conventional control valve in a process plant, the valve being controlled by a controller, the method comprising a processor obtaining data samples from a database stored on a server of the process plant, each data sample comprising a process variable, a set-point, and a manipulated variable; the processor computing a non-linearity index from the data samples and determining if the non-linearity index is greater than a threshold value; if the non-linearity index is greater than the threshold value, the processor charting a plot of the process variable against the manipulated variable and determining if the plot has an elliptical or rectangular fit; and if the plot has an elliptical fit, the processor determining if a percentage of the total number of data samples lying within a theoretical ellipse encompassed within the elliptical fit is less than or equal to a preset percentage.

Abstract: The method comprises obtaining data samples, each data sample comprising a process variable and a controller output for adjusting the process variable to reach a set-point variable; and determining if there is valve jump or stiction by calculating a jump index or a static band index; wherein calculating the jump index comprises calculating a mean of a first set of angles, each angle from the first set of angles being computed from a ratio of: a difference between a peak process variable and its preceding process variable, and, a difference between a controller output corresponding to the peak process variable and its preceding controller output; and wherein calculating the static band index comprises calculating a mean of a second set of angles, each angle of the second set of angles being computed from a difference between a controller output corresponding to a flat process variable and its preceding controller output.

Abstract: A method of evaluating a model of an industrial plant process, the method comprising the steps of: evaluating at least two out of three criteria, the three criteria consisting of: (i) a condition deviation, (ii) a quality deviation, and (iii) a priori information obtained from a fuzzy logic module; and giving an indication as to whether or not the model should be retrained.

Abstract: A method of qualifying performance of a conventional control valve in a process plant, the valve being controlled by a controller, the method comprising a processor obtaining data samples from a database stored on a server of the process plant, each data sample comprising a process variable, a set-point, and a manipulated variable; the processor computing a non-linearity index from the data samples and determining if the non-linearity index is greater than a threshold value; if the non-linearity index is greater than the threshold value, the processor charting a plot of the process variable against the manipulated variable and determining if the plot has an elliptical or rectangular fit; and if the plot has an elliptical fit, the processor determining if a percentage of the total number of data samples lying within a theoretical ellipse encompassed within the elliptical fit is less than or equal to a preset percentage.