离心泵变压供水系统控制模型辨识的试验研究

离心泵变压供水被认为是一种节能供水模式,但由于对其控制模型的研究不够深入,在水泵变工况运行时常常造成用户端水压不稳,推广应用受到很大限制。为提高变压运行控制系统性能,利用变频器、虚拟仪器搭建离心泵供水系统试验台,编制LabView测控程序,进行变工况下的变压和恒压模型辨识试验。根据各响应过程,通过MATLAB系统辨识工具箱建立过程模型与理论模型比较,并对比分析相同阀门开度下和不同阀门开度下变压与恒压过程控制模型的参数和结构变化。结果表明随着离心泵工况改变,变压供水控制模型是定结构的带延迟二阶模型,参数具有较大幅度的变化,其惯性、时变和时滞特性比恒压供水更大,建议针对系统暂态性能改善设计具有PID特性的变参数控制器。

Experimental study on control model of centrifugal pump variable-pressure water supply system

Variable-pressure water supply is considered to be a good operation mode to save energy. But lacking enough study on the control model results in pressure fluctuation at user side, which will restrict variable-pressure water supply for application and popularization. To improve the control quality, a step response experiment rig of water-supply system was set up based on virtual instrument and frequency converter. A LabVIEW test program was compiled to carry out the step response experiment at different openings of valve. And then process models were constructed with system identification toolbox of Matlab according to experiment data. Contrasting the theoretical and experimental models, variations among different processes were analyzed from vertical and horizontal aspects. The results showed that the variable-pressure operation had a similar variation trend in structure and parameters, and it also had more obvious inertia, time varying and hysteretic nature. So the transient state performance of the variable-pressure water supply system should be considered for design of variable-parameter controller with PID.