Irrigation Canal Downstream Water level PLC Control

This paper details the real time control in a long irrigation canal downstream water level using the SLC500 Programmable Logic Controller (PLC). The canal is divided into 7 sections, each with its own PLC regulator and associated infrastructure. Irrigation water is channeled through motorized vertical gates. Two pairs of control relays per gate are used to raise and lower the gate for all gates installed at approximately 10 miles sections from the upstream to the downstream agriculture area. Motorized gates, lower and upper pairs, are used to regulate the water flow and thus the downstream level. Fully closed vertical gates will produce continuous reduction in the downstream water level. Low downstream water level will not allow irrigation in the downstream area. Fully raised vertical gates will result in excessive irrigation in the downstream area and thus much wasted water. Adequate regulation of the vertical gates position can maintain desired downstream water levels at different times and thus support required irrigation cycles and preserve water resources at the same time. Coordination among all networked PLC's regulation sites is a must. This paper will briefly focus on the real time aspects of the irrigation canal PLC process control design and implementation. The commissioned system is successively working for years in the implementation site, which covers one of the two major delta irrigation branches from the river Nile in Egypt. An economic feasibility study was completed and reported several years prior to this project funding and implementation [4]