Author
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Clemmens, Albert |
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Wahlin, Brian |
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Submitted to: Workshop on Modernization of Irrigation Water Delivery Systems
Publication Type: Proceedings Publication Acceptance Date: 10/21/1999 Publication Date: N/A Citation: N/A Interpretive Summary: Water is becoming a scarce resource, and water districts are under pressure to use water more judiciously. Improved operation of water resources facilities, such as canals and reservoirs, has been touted as necessary for making proper use of these limited water supplies. Operation of irrigation- water delivery systems can be improved by providing canal operators with better tools for determining control actions. One such tool is computerize automatic control of canal gates. While canal automation may appear simple in concept, it is actually a complex technical problem. This complexity has led to a large gap between theory and practice. A technical committee of the American Society of Civil engineers developed test cases to evaluate the performance of various canal control algorithms (controllers). This paper presents the results of these tests for a variety of simple canal controllers. It is demonstrated that more centralized controllers are more effective than a series of local controllers (one for each canal pool). These results will be useful to irrigation districts, consultants, and the Bureau of Reclamation. Technical Abstract: A new class of downstream feedback controllers has been developed. With this class, a particular controller is chosen by selecting which controller coefficients to use. Values for these coefficients are tuned with optimization. These controllers range from a series of simple proportional- integral (PI) controllers to complete centralized control. Several controllers within this class were tuned with the same quadratic performance criteria. The resulting controllers were then applied to the ASCE test cases for canal 1. Since these controllers are tuned with identical performance criteria, it is easy to compare the performance of the various controllers. The restriction placed on minimum gate movement caused most of these controllers to oscillate. Differences between actual and assumed canal and gate properties also reduced controller performance. More centralized controllers, and ones that deal with delays, handle unscheduled flow changes better than a series of local controllers. A good compromise between controller performance and complexity are controllers that pass feedback for a given water level to the gate at the upstream end of the pool (i.e., that used for downstream control of an individual pool) and one additional gate each upstream and downstream. |
