Tri-State Case Study: Nexus OnCore Improves Time, Money & Reliability

Tri-State Generation and Transmission Association had site control systems going obsolete and older operating systems presented security concerns. In addition, the confidence in the previous controller solution wasn’t high since it could be down for an extended period of time. It was time for an upgrade and the Nexus OnCore† Control System was selected to replace the older, obsolete control systems.

Two of Tri-State Generation and Transmission Association’s (Tri-State) power generation plants (Limon Generating Station in Limon, Colorado and the Frank R. Knutson Generating Station in Brighton, Colorado) had GE^® Fanuc 9030 balance of plant control systems (DCS) from 2002, that were obsolete and needed to be replaced. In addition, the associated control system HMI was running on Microsoft Windows^®7 operating system that is no longer supported by Microsoft^®, which presented security concerns. Tri-State also had low confidence in the existing control systems since they could be in a down state for extended periods of time, which was not acceptable under any circumstance. 

The final requirement was that the new control system had to be able to integrate with Tri-State’s’ new GE Fleet Monitoring system.

Tri-State chose to go with the Nexus OnCore Control System at both their Knutson Generating Station and their Limon Generating Station. The RTU communication (previously all hardwired) was replaced and is now DNP3. Additionally, Tri-State was given AGC control as part of the DNP3 link (analog setpoints instead of just min/max loads).  Tri-State also gained additional and different communications capabilities such as: EGD between Mark VI, EX2100; and the Nexus OnCore Control System and Modbus to Allen Bradley at Limon and local Historian and remote OSI PI at Tri-State’s headquarters.

Tri-State was able to save money on their capital expenditures by choosing to go with the Nexus OnCore Control System since it was substantially less expensive than alternative solutions. 

The Nexus OnCore Control System was intuitive and very easy to learn and use and that allowed Tri-State staff to quickly come up to speed and be productive rapidly. 

The Nexus OnCore HMI was installed on Microsoft Windows 10 computers so that Tri-State could secure them properly and there would not be any concerns about the operating system being supported by Microsoft.

Tri-State installed their new GE Fleet Monitoring System and the Nexus OnCore Control System easily integrated with it.

"I didn't want to be on the 'if it fails we're down for 6 months' side of it. ... This is something that we're looking at as a 10 to 15 year solution. ... It's pretty intuitive, it's user friendly, we have hot swapped some modules (on the fly) without suffering any down time. ... Do I think it's a great product? Yes, I do. ... Great product delivered by a responsive group of people." -Bob Locke - Combustion Turbine Group Operations Supervisor - Tri-State Generation & Transmission Association

Nexus Controls LLC (formerly GE Energy Controls Solutions) exists as the collective experience and history of multiple companies whose expertise, knowledge and lineage spans 150 years. Our global team of domain experts are in 44 countries on all six continents and have successfully delivered over 11,000 successful projects in the power, oil & gas and various industrial markets.

† Registered trademark of Baker Hughes in one or more countries.