PUMPS
In the ag pivot market, for example, manufacturers are utilizing cloud telemetry to control and coordinate pivots, pumping equipment, canal gates, flowmeters and crop sensors. There are many features of cloud telemetry that provide real value for irrigation managers. Having the information in a cloud database allows sophisticated algorithms to mine the data to generate reports, create advanced control logic and construct dashboards that can be viewed from any web-enabled device. A user’s password automatically determines which dashboard data is presented and in what language and local time. There are numerous advancements resulting from the integration of pump stations and pivot controls.
W ELIMINATE PRESSURE OVERLOAD
Pump selection, regardless of the market, usually factors in a worst-case scenario of the irrigation system’s hydraulic requirements. This includes the maximum head loss due to elevation and the maximum friction loss based on the highest anticipated flow. In reality, the irrigation system only operates in this worst-case scenario for a fraction of its running time.
If the pump station is set to a single regulate setpoint based on this worst-case scenario, tremendous energy is wasted because the station is providing more pressure to the irrigation system than is needed. Advanced pumping systems can be programmed to adjust the pump output to compensate for these varying requirements.
For example, in deep well pump systems, the depth to water can vary greatly due to pumping drawdown and seasonal variations in the aquifer level. This maximum anticipated depth to water must be factored into the pump total dynamic head required even though the depth to water may be less for much of the watering cycle. By utilizing a variable frequency drive on the pump with a pressure transducer at the surface, the control system will be able to adjust the pump speed to precisely meet the irrigation system pressure requirements and reduce energy consumption. The controls can also monitor motor current and limit the pump rpm to avoid overload and prevent the pump from running too far out on its curve.
MANAGE SYSTEM DEMANDS
In many scenarios, the land irrigated by pivots has significant elevation changes. Locating a pressure transducer at the end of the pivot allows the VFD-controlled pump to modulate its output to maintain the desired pressure at the pivot regardless of its location in the field. This eliminates the wasted energy that would result when there is over- pressurization in the low elevation areas of the field.
In larger systems where a centrally located pump station supplies water to multiple pivots with varying pressure requirements, determining the pressure required from the pump station is a more complicated task. Through today’s technology, it is possible to monitor which pivots are running and the pressure at each running pivot. Based on that cloud data, a control algorithm calculates the pressure regulate setpoint required and relays it to the pump station to ensure that the pressure supplied to the irrigation system exactly meets the requirements of the running pivots.
Measured energy savings of 25%-30% have been realized by this closed loop control method.
While this concept originated in the agricultural market, it is proving to be equally effective in the golf and landscape markets. These systems utilize transducers mounted on nodes in the piping system, and through coordination with the irrigation controls, the pump station’s pressure setpoint is adjusted to maintain the minimum desired pressure in the piping nodes where irrigation is occurring.
hile many in the irrigation industry may perceive that agricultural pumping systems are less sophisticated than their golf and landscape counterparts, in many ways the ag market has led the development of new control technologies for irrigation pumping systems. This, in turn, has helped growers better manage their pump systems and improve irrigation efficiency, while also saving on pumping energy costs.
irrigationtoday.org
Spring 2021 | Irrigation TODAY 9
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