Steam pressure controlling method combining feedforward compensation open-loop with feedback close-loop control

Abstract

The invention discloses a steam pressure controlling method combining feedforward compensation open-loop with feedback close-loop control, adopting a composite control strategy combining the feedforward compensation open-loop control with the feedback close-loop control. The control strategy carries out feedforward compensation open-loop control for external disturbance, approximatively takes the external disturbance as step disturbance, takes a disturbance signal as the input of a feedforward compensator, and carries out parameter setting on the feedforward compensator so as to perform dynamic compensation to the influence on pressure caused by relative external disturbance; and the strategy carries out feedback close-loop control on internal disturbance and eliminates the influence on pressure caused by the internal disturbance through universal PID regulation. The method comprises feedforward control, feedback control and combined control of feedforward and feedback. The method is mainly applied to metallurgy RH vacuum refining devices, can effectively overcome influence of the internal disturbance and the external disturbance on pressure during steam pressure adjustment in a RH refining vacuum exhaust system, improves the control precision and the stability and guarantees smooth vacuum treatment so as to achieve a good effect of vacuum treatment.

Description

technical field [0001] The invention relates to a method applied to the steam pressure control system of the RH refining vacuum exhaust system, in particular to a steam pressure control method with feedforward compensation open-loop combined with feedback closed-loop control. Background technique [0002] During the vacuum treatment process of the RH refining furnace, one of the main technical indicators is to keep the steam pressure of the vacuum exhaust system stable. This is because the steam usage system of the vacuum pump and the requirements for steam are particularly strict: (1) The steam flow rate during vacuum pumping It must be guaranteed; (2) The steam pressure must be stable during vacuuming; (3) The steam used for vacuuming must be superheated dry steam. Therefore, steam pressure control is one of the core control technologies of RH refining, which plays a very important role in improving product quality. During the vacuuming process, the steam pump will often ...

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Problems solved by technology

During the vacuuming process, the steam pump will often open and close the pump according to the different steel types, so the usual PID control is difficult to stabilize, and there will be large fluctuations, and the feedforward compensation open-loop control and feedback closed-loop control phase A combined control method can quickly and accurately control the pressure of steam

[0003] At present, most of the steam pressure control of the existing RH refining vacuum exhaust system is the usual two-stage PID feedback control, that is, the first-stage PID feedback control is mainly used to control the pressure of the source steam to keep its pressure basically constant, which is the second stage. The first-stage adjustment eliminates the source disturbance; the second-stage PID feedback control is used to adjust the pressure of the vacuum system. Its advantage is that it is a closed-loop feedback control based on the deviation of the controlled parameter. No matter what disturbance in the system, as long as the controlled parameter deviates , the controller can be adjusted, but the controller only starts to act after the deviation occurs. It is impossible to control according to the disturbance when the disturbance occurs, that is, before the deviation of the controlled object occurs, so that the deviation does not appear. Disadvantages: The control effect of the above-mentioned control method on the disturbance of the steam pressure caused by the opening and closing of the vacuum pump in the vacuum system is slow, and the adjustment time is long, which is not conducive to production

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