Amplitude limiting method of multi-execution-loop control system

Abstract

The invention discloses an amplitude limiting method of a multi-execution-loop control system. The amplitude limiting method of the multi-execution-loop control system is characterized in that a process controller sends out a control command, the control command and a correction command sent by an automatic tracking correction loop are overlapped, and a final execution loop motion command is output after the limitation of an amplitude limiter. When the execution loop command reaches a limiting value, a judgment result is given out automatically through a judgment logic module, the correction command is started through a logic switching module, the correction command is obtained through calculation of a calculation loop and the automatic tracking correction loop, and the value of the correction command is the differential between the limiting value and a control command of the current controller. Then, the input value of the amplitude limiter is corrected through the correction command so that the input value can be always equal to the limiting value when being limited, and an execution loop timely responds to the method to adopt the correction command calculation loop, the automatic tracking correction loop, the judgment logic module used for judging whether the limitation is reached and the logic switching module when the control command moves in the reverse limited direction.

Description

technical field [0001] The invention relates to the technical field of limiting the execution loop of a multi-execution loop control system. Background technique [0002] In the production process control of electric power, petroleum, chemical industry, etc., there are many control systems with multiple execution loops, because each execution loop accepts the same control command, and the characteristics of each execution loop are different. It is often difficult to limit the amplitude of the loop, and there is a lack of reasonable limiting means. The phenomenon that the control characteristics of the control system will be directly affected by improper limiting measures often occurs. [0003] In the actual process control of the multi-execution loop control system, for the safety and stability of the control object, it is required to limit the action range of each execution loop. Since each execution loop accepts the same control command, and their respective equipment cha...

AI Technical Summary

Problems solved by technology

Since each execution loop accepts the same control command, and their respective equipment characteristics and process characteristics are different, the requirements for the range of motion of each execution loop are different, and their upper and lower limit values ​​are also different. , the limiting measures cannot be implemented on the instruction, and can only be implemented separately on the instructions of each execution loop, such as figure 1 shown

[0004] figure 1 The main problem of the limiting method shown is: under automatic control conditions, when a certain execution loop command reaches the limit value, the output command of this loop is limited and will not change after the limit value is maintained. At this time, due to the control When it is necessary to continue to adjust the same direction for other execution loops that have not reached the limit value, the control command output by the controller will inevitably continue to change in the direction that has been limited, causing the command before the limiter of the limited execution loop to be far away. Deviation from the limited value, when the control system calls back in the opposite direction, the limited execution loop needs to overcome the dead zone caused by this deviation before the callback action occurs, similar to the process of overcoming integral saturation, resulting in adjustment lag. Seriously affect the regulation performance of the control system

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