Statistical quality control for the evaluation of the uniformity of microsprinkler irrigation with photovoltaic solar energy

Abstract

The objective of this work was to evaluate a microsprinkler irrigation system with water pumping by photovoltaic system, through uniformity coefficients and the total energy produced (W h) by the system using the statistical quality control, comparing the Shewhart control charts, Exponentially Weighted Moving Average (EWMA) and Cumulative Sum (CUSUM) and classifying the processes using the process capability index. The work was developed in the laboratory, with two distinct systems, with and without energy storage. For each of these systems, 25 tests were performed, with constant pressure and voltage and current measurements during the tests. Different spacing between microsprinklers were simulated for the test data, determining the six treatments used: T1: 1.0m × 1.0m spacing with energy storage; T2 spacing of 1.0m × 1.5m with energy storage; T3: spacing of 1.5m × 1.0m with energy storage; T4: 1.0m × 1.0m spacing without energy storage; T5: 1.0m × 1.5m spacing without energy storage; T6: spacing of 1,5m × 1,0m without energy storage. The energy produced (W h) in the system without energy storage was superior, however, it is recommended to use the system with energy storage due to the smaller variability and reliability, besides keeping the electrical system stable, in relation to the voltage, not damaging the hydraulic pump as in the treatments without energy storage. As far as the spacing's are concerned, the smaller the uniformity of the irrigation system. The control charts were adequate to diagnose the treatments under control, and the EWMA were relevant to detect the small variabilities resulting from the tests. The process capability index was relevant for classifying the processes used. The statistical quality control was adequate to determine the variability of the processes, recommending using the system proposed in T1 treatment, due to its lower variability in relation to the control graphs, greater uniformity of water distribution and higher classification in relation to the capacity index the process.