PLC-based canal automation

Presented at the 2002 USCID/EWRI conference, Energy, climate, environment and water - issues and opportunities for irrigation and drainage on July 9-12 in San Luis Obispo, California.Includes bibliographical references.A short history of canal automation is given. PLC-based canal automation is relatively new. Advances in PLC-based canal automation are listed. Also listed are some of the remaining challenges. Recent advances have been made in understanding unsteady flow simulation procedures, the form of the control algorithms used, the tuning procedures for these control algorithms, and the field programming of the algorithms into PLCs. The experiences of the Cal Poly Irrigation Training and Research Center (ITRC) in automating a variety of canals with upstream and downstream control are given

SCADA and related technologies

Presented at SCADA and related technologies for irrigation district modernization, II: a USCID water management conference held on June 6-9, 2007 in Denver, Colorado.SCADA systems in irrigation districts have focused on remote monitoring and remote control. In many districts, the remote control is manual, but in others the automation of structures is enabled through the usage of distributed control for the automation of individual structures. This paper presents the concept of an expanded, "umbrella" SCADA system that will perform the standard functions of remote control and remote monitoring, and will also incorporate information flow in the field for operators. The umbrella SCADA system will mesh the equipment-equipment information into an equipment-program-personnel network

Advances in PLC-Based Canal Automation

A short history of canal automation is given. PLC-based canal automation is relatively new. Advances in PLC-based canal automation are listed. Also listed are some of the remaining challenges. Recent advances have been made in understanding unsteady flow simulation procedures, the form of the control algorithms used, the tuning procedures for these control algorithms, and the field programming of the algorithms into PLCs. The experiences of the Cal Poly Irrigation Training and Research Center (ITRC) in automating a variety of canals with upstream and downstream control are given

Algorithm theory

Presented at SCADA and related technologies for irrigation district modernization: a USCID water management conference on October 26-29, 2005 in Vancouver, Washington.Includes bibliographical references.A major constraint for implementation of automated canal control is the complicated, tedious, and potentially error-ridden task of programming the control algorithm and associated overhead into PLCs (Programmable Logic Controllers). A typical control program may easily occupy 100 pages of Ladder logic that must be painstakingly developed and programmed. The most common argument in favor of Ladder logic - that local electricians can get into the program and modify it if needed - is flawed because (1) local electricians do not understand the logic, and (2) Ladder cannot easily perform many mathematical tasks that are simple in other programming languages. In addition, the Ladder programmed on one brand of PLC is not directly programmable onto another brand because each brand has its own variation of the Ladder language. ITRC's approach to canal automation simulation includes building a model with an excellent hydraulic simulation program, characterizing each pool for storage and resonance, Matlab optimization of the control logic's parameters based on hydraulic properties, and writing the logic in ISaGRAF. These services cannot be performed by integrators, who rarely, if ever, understand the theory behind modern canal control. This has been misunderstood by districts when planning their long-term canal automation strategy, putting at stake large investments into the controller and software programming

Electric Motor Efficiency under Variable Frequencies and Loads

This paper details a study performed by the Irrigation Training and Research Center to determine motor performances under varying speeds [induced by a variable frequency drives (VFD) controller] and loads. A further goal of the study was to provide sufficient information to designers so that they could estimate total pumping plant power usage with a VFD-controlled installation. Motors were tested with a VFD as well as across-the-line. On average, the relative efficiency of the electrical system with a VFD may be approximately 8% lower than the relative efficiency of a properly designed, full-load across-the-line system. If one considers actual field operating conditions this 8% is misleading because overall energy savings can be obtained with VFDs due to their ability to properly adjust speeds to meet actual field conditions