Lamb County deploys load control for polyphase irrigation pumps


Delbert Smith,
CEO, Lamb County
Electric Cooperative
Littlefield, TX, U.S.A. and Vancouver, BC, Canada — (METERING.COM) — December 18, 2009 – Lamb County Electric Cooperative has contracted to expand its Tantalus Utility Network (TUNet®) for smart grid applications to include coordinated measurement and control of large load irrigation equipment, in addition to residential advanced metering.  

Lamb County, an agricultural community located in north Texas, will use the Tantalus system to selectively curtail power on irrigation pumps when its generation and transmission supplier is faced with critical energy shortages, and then validate that the curtailment has occurred. Farming is the lifeblood of the local economy and intelligent management of irrigation pumps is critical. Using TUNet, the utility will determine the aggregate load on groups of pumps in operation and then remotely curtail power to selected pumps in order to meet the curtailment requirements of the supplier.

Providing the flexibility to enact just enough curtailment and to select where it comes from will help Lamb County manage energy usage while minimizing any disruptions to its members.

“When peak events occur, the ability to quickly identify where load can be shed and confirm the exact amount of power shed adds precision and speed to load control activities,” said the cooperative’s general manager and CEO, Delbert Smith. “Putting control in the hands of the cooperative helps ensure that load shedding is evenly distributed among participants, so no single farm is unduly disrupted.”  

Previously, load control was initiated by the supplier using an independent system to shut off power to some polyphase devices on the system and did not verify that energy reduction had taken place. The Tantalus system identifies which pumps are in use and how much power they are drawing so the utility gets a clear picture of where it can shed load, and can also validate the extent of participation.  

Tantalus’ intelligent addressing capability makes it possible for a utility to communicate in a coordinated fashion with meters and associated load control modules anywhere in the service area over the two-way, wireless TUNet network. Lamb County can quickly obtain both the current load of an individual pump and the sum of all pumps in a select group, and then issue a curtailment command to one or more groups for a specified amount of time. Because some large farms operate as many as 40 separate sprinkler systems, the cooperative can assign pumps to different groups so that irrigation on a single farm is not halted entirely. Time stamped records provide empirical proof of which meters were involved, so the utility can quantify success with its supplier and compensate members equitably for participating, depending on how many pumps were involved and how much power was curtailed.

Benefits beyond load control include visibility if an irrigation pump has been off line for an extended period of time, which may indicate equipment failure or incorrect settings.  

Rollout to all 6,600 polyphase meters and demand response participants is scheduled for completion by April 2010, in advance of the growing season. Old polyphase meters will be replaced by TUNet-enabled GE kV2c+ solid state meters. Utility staff manage curtailment events via a web-based application that communicates with polyphase meters and load management switches attached to pumps. The coop will also complete its residential advanced metering by the end of August.