Central Arizona Project Supervisory Control System

The Central Arizona Project (CAP), one of the nation's largest water conveyance systems, is designed to deliver much of Arizona's allotment of Colorado River water for municipal, industrial, and agricultural uses in central and southern Arizona. The size and nature of the CAP dictates the use of a computer‐based programmable master supervisory control (PMSC) system as the primary means of operating the aqueduct. A dual‐computer master station is connected to remote terminal units (RTUs) located at each pumping plant, checkgate, and turnout. Through the RTUs, the master station can send instructions to, and receive information from, any point along the • aqueduct. Complex scheduling models generate pump, checkgate, and turnout schedules for the entire aqueduct system. These scheduling models are based on a constant volume philosophy of operation to keep the system responsive to changes in demands. Optimization models can modify these schedules to take advantage of the less expensive off‐peak power costs. The PMSC will also monitor the aqueduct depths and flows measured in the field and compare them to those predicted in the scheduling models. If a large enough divergence occurs, the dispatcher is alerted and predetermined reaction procedures are implemented to shut down or stabilize the aqueduct.