某油气场所三相分离器的界位控制，需频繁整定PID参数但并不能取得很好的控制效果。为了提高控制精度、减少对下游流程的影响、降低维护人员的工作强度,对场站内所采用的浙大中控DCS系统的PID功能块进行改进。采用了不同于原有PID功能块积分分离的方法,当测量值与设定值之间的误差绝对值开始变小时切除PID算法的积分作用。对控制对象建立数学模型,通过Matlab软件进行仿真来验证改进PID算法的性能和此算法可能会带来的负面影响。仿真发现改进PID算法能很好地抑制因PID积分左右而引起的系统震荡,对于同一个控制对象改进PID算法对PID参数的可选择范围变得更广,极大地降低了PID参数整定的难度,控制系统的鲁棒性变得更强,但可能造成系统的误差消除速度变得非常缓慢。在实际的DCS控制系统中对改进PID算法进行了应用,取得了和仿真一致的良好效果。

For the position control of a three-phase separator in certain oil and gas field, the PID parameters need to be adjusted frequently and the control effect is not very good. In order to improve the control accuracy, reduce the impact on downstream process and reduce the work intensity of maintenance personnel,the PID function block of DCS system by Zhejiang University is improved.Different from the original method of integral separation of PID function blocks, the integral function of the PID algorithm is removed when the absolute value of the error between the measured value and the set value becomes smaller.The mathematical model of the control object is established,and the performance of the improved algorithm and the possible negative effects of the algorithm are verified by simulation with MATLAB software.The simulation results show that the improved PID algorithm can better restrain the system oscillation caused by the integral of the PID.For the same control object, the improved algorithm can choose more widely the parameters of the PID, greatly reduce the difficulty of setting the parameters of the PID,and enhance the robustness of the control system,but it may cause the speed of error elimination of the system to become very slow.The improved PID algorithm is applied in the actual DCS control system, and good results are obtained in accordance with the simulation results.