Optimal Real-Time Pump and Irrigation Scheduling for Center-Pivot Sprinkler Systems

Chou, Frederick N. -F.; Labadie, John W.; Heermann, Dale F.; ,

Optimal Real-Time Pump and Irrigation Scheduling for Center-Pivot Sprinkler Systems

by Frederick N. -F. Chou, Colorado State Univ, United States,
John W. Labadie, Colorado State Univ, United States,
Dale F. Heermann, Colorado State Univ, United States,

Document Type: Proceeding Paper

Part of: Computerized Decision Support Systems for Water Managers

Abstract:

A comprehensive scheduling algorithm is presented for optimally integrating irrigation and pump operational decisions in center-pivot sprinkler systems. Dynamic programming successive approximations (DPSA) is applied to optimal timing of center pivot operations which minimizes energy costs subject to maintaining required system pressures and favorable soil water levels for maximum crop yield. Discrete 'reaching' dynamic programming is imbedded within the DPSA procedure for selecting optimal pump combinations for several interconnected pump stations in order to minimize pumping cost over each scheduling period. Costs due to both energy consumption and peak power demand are considered, as well as diurnal variations in billing rates. Peak power demand costs are commensurated with energy costs through use of a 'smoothing' penalty term in the objective function. Application of the algorithm to a large farm in eastern Oregon with over 100 center pivots results in an estimated 33% savings in pumping cost and 17% reduction in irrigation water over two historical billing periods when compared with actual practice.

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