Compensating method for control loop oscillation due to viscosity property of valve

Abstract

The invention discloses a compensating method for control loop oscillation due to viscosity property of a valve. The compensating method comprises the following steps: (1) after the control loop generates oscillation due to viscosity property, switching the loop to an open-loop mode and outputting a control signal m(t); (2) correspondingly processing the control signal m(t) and a process output signal y(t) to obtain a variable relationship within at least one complete oscillation period; (3) adopting a He viscoelastic model, obtaining a value of a target position vss of the valve according to the relationship of the control signal m(t) and a viscous parameter fd as well as the variable relationship in the step (2), and further obtaining an expected value mss of the control signal; (4) compensating the control signal m(t) until the control signal reaches an estimated value ^mss of the expected value. According to the compensating method, realizing time for a two-step process can be effectively shortened, negative effects to a process loop in a compensating process are lowered, the compensating precision can be regulated according to the practical needs, and important practical value is realized while the efficiency of the production process is improved.

Description

technical field [0001] The invention relates to the field of valve viscous compensation of process control loops, in particular to a compensation method for control loop oscillation caused by valve viscous characteristics. Background technique [0002] Oscillation problems in industrial circuits seriously restrict the improvement of economic benefits of enterprises. In order to detect and solve oscillation problems in time, oscillation monitoring, oscillation control and compensation are imperative. Studies have shown that 20% to 30% of control loop oscillations are caused by control valves. The viscous characteristic Sticiton of the control valve is the most common nonlinear characteristic, which will affect the performance of the control system to varying degrees. Hysteresis is also one of the most difficult problems to overcome in control valves. It will cause oscillations in the control loop, resulting in reduced product quality, increased energy consumption, and accele...

AI Technical Summary

Problems solved by technology

The most common implementation method is to obtain the process gain through three two-step moves, and its limitations are also very obvious. First, it is necessary to wait for the process output to stabilize after each move, especially for objects with a large delay. Realize the two-step method, in addition, the amplitude of each movement is very large, which will have a certain negative impact on the process during the compensation period

Images