A Controller Synthesis Method to Achieve Independent Reference Tracking Performance and Disturbance Rejection Performance.

This paper deals with the conflict between the input-output response and the disturbance-output response, which cannot be completely eliminated by traditional and advanced control strategies without using the accurate process model. The inherently close association of these two responses and the unavailability of the accurate process model pose a great challenge to field test engineers of a coal-fired power plant, that is, the design requirements of reference tracking and disturbance rejection are compromised. In this paper, a novel two-degree-of-freedom controller-feedforward compensated (FC) desired dynamic equational (DDE) proportional-integral-derivative (PID) (FC-DDE PID)-is proposed as a viable alternative. In addition to achieving independent reference tracking performance and disturbance rejection performance, its simple structure and tuning procedure are specifically appealing to practitioners. Simulations, experiments, and field tests demonstrate the advantages of the proposed controller in both reference tracking and disturbance rejection, thus making FC-DDE PID a convenient and effective controller for the control of the coal-fired power plants, readily implementable on the distributed control system (DCS).

A controller design method for high-order unstable linear time-invariant systems.

This paper deals with high-order unstable systems, which are dangerous and more difficult to control. Their presence is increasingly prevalent, posing a great challenge to both traditional PID-based industrial designs and various advanced control strategies which are difficult to implement on common industrial control platforms. In this paper, the generalized desired dynamic equational (G-DDE) PID controller, developed by authors earlier, is proposed as a viable alternative. In addition to guarantee the closed-loop stability, its simple structure and tuning procedure are specifically appealing to practitioners. Simulations and experimental results show advantages of G-DDE PID in reference tracking, disturbance rejection and robustness, thus making G-DDE PID a convenient and effective control strategy for high-order unstable systems, readily implementable on common industrial platforms.

Active disturbance rejection control design for high-order integral systems.

Active disturbance rejection control (ADRC) is designed for regular processes frequently, due to its strong ability to reject disturbances and handle system uncertainties. However, ADRC design for high-order integral systems existing in many natural systems is always ignored. The controller design for high-order integral systems is different from the regular systems due to no pole in the left and right half s-planes. The ADRC design for high-order integral systems is studied to explain this question theoretically in this paper. Based on the equivalent form of ADRC, a theorem about the necessary condition of ADRC is proven which can guarantee the closed-loop system's stability. Additionally, the advantages of ADRC over proportional-integral-derivative (PID) controller in sensor noise rejection and control signal variation are analyzed theoretically. In order to achieve expected control performance for high-order integral systems, a practical design procedure of ADRC is summarized by the single variable method. Several comparative simulations and an experiment based on a ball and beam system are carried out. Running data verify that ADRC can obtain better control performance with strong robustness than PID controller. Eventually, a 100th order ADRC is designed for a 100th order integral system, and simulation results show that ADRC can be designed for high-order integral systems conveniently. Based on theoretical analyses and experimental verifications, ADRC shows some advantages for high-order integral systems.