Field Performance of Kamphaengsaen Canal Automation System

Abstract

The Kamphaengsaen canal automation system (KPS CAS) was developed for real time monitoring and regulation of the flow in the canal irrigation system of Kasetsart University, Kamphaengsaen campus, Nakhon Pathom province. KPS CAS consists of five remote terminal units (RTUs) and a master station. Robogate, a low cost micro-controller embedded system was used to function as RTUs for flow monitoring and control in the irrigation canals of Kamphaengsaen campus. Two types of Robogate were used—namely, a water level control Robogate installed at a cross regulator and a discharge control Robogate installed at a head regulator. Upstream water level control and constant volume control were algorithms of KPS CAS that were used for the water level and discharge control, respectively. The master station installed at the Department of Irrigation Engineering located more than 1 km from the Kamphaengsaen canal irrigation system was designed to poll the data from the RTUs every half an hour via citizen band 245 MHz radio. The KPS CAS was tested for 600 d during the period from 10 October 2006 to 1 June 2008. The various field performances of the canal automation system were studied including the accuracy of the floating-type water level and gate positioning sensors, performance characteristics of the upstream water level control algorithm, reliability of data measurement and the overall control performance of the KPS CAS. The results showed that both sensors had a very small error of measurement. The characteristics of water level and gate adjustment of Robogate 9021 were observed at 5 sec intervals, producing more than 20,200 data records, in order to check the effectiveness of the upstream control algorithm. When the upstream water level deviated from the target water level, the gate was adjusted 4–12 times automatically, within a duration of 310–780 sec, until the upstream water level was maintained at the target level. During the test period of 600 d, 17.3% of data were missing due to unexpected disturbances and failures. The automatic mode operation was compared to the manual operation. The root mean square error of the target water level control in the automatic mode (0.009–0.013 m), was considerably smaller than that of the manual mode (0.118–0.178 m). With smaller water level fluctuations at the cross regulators, the head regulator could produce a more uniform discharge into the canal. Therefore it could be concluded that the KPS CAS is useful for flow control.