Research on improved auto-tuning of a PID controller based on phase angle margin

In order to realize the fast and efficient tuning of the proportional-integral-derivative (PID) controller parameters in power plants, this paper thoroughly analyzes the problems existing in the relay characteristic method based on the phase angle margin auto-tuning method (PM method), and proposes an improved PM auto-tuning method for the most common first order plus dead time (FOPDT) model in practical engineering applications. The improved algorithm proposes the design of the target phase angle margin and the method of plant identification. Then, the optimization algorithm is used to calculate the correction coefficient of the setting formula to obtain the PID controller parameters that minimize the integrated time absolute error (ITAE) indexes of the control system. Finally, through the auto-tuning experiment on the generalized control model of the main steam temperature system, it is verified that the improved algorithm is superior to the traditional PM method and Ziegler-Nichols method (Z-N method), and is with a fast and stable control performance. (authors)