控制回路中阀门黏滞故障补偿的一种新方法

A New Compensation Method for Valve Stiction in Control Loop

在过程工业领域中,阀门黏滞非线性故障会给控制回路带来振荡.针对带有定位器的控制阀门,提出一种基于过程对象的传递函数以及回路设定值的新型补偿方法,用来削弱这种振荡.首先,由回路设定值推出阀门的稳态输出位置,并监测阀门当前输出状态.然后,以阀门目标稳态输出和阀门当前输出为依据设计出补偿信号来改变阀门的输入,最终使得黏滞阀门的输出达到稳定.为了实现该补偿算法可以适应不同的设定值,对控制器的输入也进行了信号补偿.将该补偿算法应用于两个实际带有黏滞的过程回路中,发现补偿效果明显,并且具有一定的鲁棒性.

Valve stiction as a nonlinear fault in process industries will lead oscillation in the control loop. For valves equipped with locators, a new compensating method, based on the transfer function of process and the set point of the loop, is proposed to reduce oscillations. Firstly, the desired position output of the valve in steady state is calculated according to the set point of the control loop, and the current output of the valve is monitored. After that, the desired steady state and the current state of valve are taken as an input to generate the compensation signal to adjust the input of the valve, which eventually turns the sticky valve to the desired steady state. In order to guarantee the algorithm compatible with different set points, the input signal to the controller is also compensated. Two practical process feedback loops with stiction are finally used to verify the effectiveness and robustness of the proposed compensating algorithm.