基于实测水位和流量数据的渠道控制模型参数辨识与验证

    Identification and verification of the parameters for canal control model based on measured water level and flow

    • 摘要: 针对传统渠道控制模型推导求解复杂,难以在实际工程中应用的问题,该研究以渠道积分延迟(Integrator Delay,ID)模型和积分延迟零(Integrator Delay Zero,IDZ)模型为研究对象,利用递推最小二乘法对2种渠道控制模型进行了参数辨识和分析。结果表明,参数辨识方法可以简单、有效地获取渠道系统的控制模型;在模型试验中,辨识误差基本分布在(−1,1)cm之间,在南水北调原型工程中,辨识误差基本分布在(−2,2)cm之间;2种辨识模型的均方误差均小于7.675×10-5 m2,且针对水流变化复杂的大型渠道工程,IDZ模型的辨识精度和稳定性整体高于ID模型。该研究结论对于渠道控制建模理论及控制器设计方法具有一定的参考价值,可应用于灌区或调水工程的输配水渠道系统建模。

       

      Abstract: A canal control model can be considered as a mathematical expression to represent the dynamic relationship between the canal building-gate-flow. The accuracy of the model determines the design effect of the controller. In view of the traditional canal control model, it is difficult to solve the problems which are complicated and difficult to apply in the actual engineering. In this study, a small canal monitoring system was first developed to conduct model tests. A parameter identification method was used to identify the canal control model, and then to verify the accuracy of the identification model. The parameter identification method was extended to the prototype project of South-to-North Water Diversion Project to further verify the reliability of parameter identification. Two typical flow conditions were designed in the model test, including the forward step condition and the reverse step condition, in order to fully observe the response of water level in the canal pond to the flow change, and thereby obtain the input and output information of the model. During the test, water level gauges and flow meters were used to monitor the water level and flow information in the test canal in real time, and then the monitored information was transmitted to the central monitor for storage. In the prototype project, the observation data were provided by the Administration of the Middle Route of South-to-North Water Diversion Project. The Integrator Delay (ID) model and the Integrator Delay Zero (IDZ) model were used in the control model, while, the Recursive Least Square (RLS) method was used in the identification method to identify and analyze the measured data. The results showed that recursive least squares were feasible to identify the parameters of canal control models (ID, IDZ), according to the principle of system identification in a model test and prototype observation. In the model test, the identification error was basically distributed between (-1, 1) cm, and the mean square error was less than 1.492×10-5 m2. The identification results were highly consistent with the measured values, and the identification data of ID model and IDZ model were similar. This was mainly because the flow rate in the test canal was small, together with the single flow change and the low frequency flow without obviously high frequency. In the prototype project of South-to-North Water Diversion Project, the identification error was basically distributed between (-2, 2) cm, and the mean square error was less than 7.675×10-5 m2. The identification data was still in high agreement with the measured value. However, when the water flow in the canal changed dramatically, the IDZ model can capture this change trend, while the ID model cannot reflect it. This was mainly because, when the water level changed drastically, the vibration frequency of water wave was faster, and the water flow was in high-frequency motion, so the response accuracy of the IDZ model was higher, which also proved its applicability to high-frequency water flow. Therefore, the IDZ model has better identification accuracy and stability than the ID model, particularly for large-scale canal projects with drastic changes in water flow. The findings can provide a certain reference for the modeling theory in the canal control and controller design, thereby to the modeling of the water transmission and distribution canal system in irrigation areas or water diversion projects.

       

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