Linear quadratic type optimal dynamic feedforward-feedback PID control system based on closed-loop identification model and control method thereof

Abstract

The invention discloses a linear quadratic type optimal dynamic feedforward-feedback PID control system based on a closed-loop identification model and a control method thereof. The method comprises the following steps of sampling field closed-loop operation data, identifying an ARX model in a closed-loop manner, and converting the ARX model into a discrete time state space model capable of observing a standard shape, and obtaining a measurable disturbance quantity feedforward control model; designing a quadratic type performance index; minimizing the performance index to obtain a linear statefeedback control matrix; calculating the state quantity estimation of the measurable disturbance quantity, and further obtaining a feedforward control law of the linear optimal quadratic type dynamicfeedforward controller; and combining the linear quadratic type optimal dynamic feedforward controller with a PID controller to design a feedforward-feedback PID control system. The control method disclosed by the invention is suitable for the dynamic feedforward design of a non-minimum phase system; the feedforward control law is designed by utilizing the quadratic type performance index, and agood and flexible feedforward control law can be obtained. By combining with an industrial field PID control system, the change on the field control strategy is small, and the method has good application prospect.

Description

technical field [0001] The invention belongs to the field of thermal automatic control, and relates to a dynamic feedforward-feedback PID control system design suitable for non-minimum phase systems, in particular to a linear quadratic optimal dynamic feedforward-feedback based on a closed-loop identification model. Feedback PID control system control method. Background technique [0002] Feedforward-feedback control strategy is widely used in the control of thermal power units because of its simple and stable mechanism. Optimizing the feedforward-feedback control strategy is a powerful way to improve the deep peak-shaving capability of thermal power units. Restricted by factors such as model accuracy, most feedforward controllers in industrial sites use static feedforward controllers, and their feedforward compensation performance is limited. Many thermal systems such as deaerator water level and coal mill air volume control models have the characteristics of large time d...

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Problems solved by technology

[0003] Purpose of the invention: Aiming at the problem that the transfer function model of the non-minimum phase system of the thermal power unit is limited due to the right half plane zero point in the design of dynamic feedforward, and the performance of the static feedforward controller is limited, the present invention is based on linear quadratic adjustment A dynamic feed-forward controller in the form of a discrete state space is designed by using a discrete state space controller, which solves the problem that the traditional dynamic feed-forward controller is difficult to apply to non-minimum phase systems, and combines with the on-site PID control system to obtain a feed-forward-feedback PID control system. Improving its control performance without changing the control strategy of the industrial site

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