Rewriting the Rules

Contributor: Swinerton Blogger   |   December 21, 2015
Rewriting the Rules

About an hour’s drive east of Tucson, Arizona at the intersection of Interstate 10 and State Route 186, lies the town of Willcox. Home to the Rex Allen Arizona Cowboy Museum, the ghost town of Dos Cabezas (Two Heads), and Fort Bowie National Historic Site, Willcox is now home to another notable roadside focal point: the 85 MW Red Horse Solar and Wind hybrid project.

Solar/wind hybrid farms are not unprecedented, but they are certainly rare. So when the project was planned in 2013, the developer chose two renewable energy leaders to construct the system: Swinerton Renewable Energy (SRE) for the solar installation, and Infrastructure and Energy Alternatives (IEA) for the installation of the 15 wind turbines. The developer also named Swinerton as the overall project manager. “During the duration of the project, the construction and installation went smoothly on both halves of the project,” says Brian Hoopes, Project Manager for Swinerton Renewable Energy. While many projects run into similar challenges—unexpected soil conditions, delays in getting equipment, and rough road conditions—the biggest challenge was engineering a command-and-control system to manage both the solar and wind plants as one. “You don’t see many solar/wind projects that all land on the same substation because it can be complicated,” Hoopes says. “Controllability is one of the biggest challenges you face, and it was no different on this project.”

Plant controllers allow operators to monitor the energy production of renewable energy farms. This ensures they are producing the energy promised to the investors and off-takers. It is a straightforward function—when you have separate wind and solar farms. But the situation is trickier when both the solar and wind components are producing energy through the same substation.

“Obviously, the potential problems that arise during solar-energy and wind-energy production are different,” Hoopes says. “So a wind-plant control system operates within a completely different system of parameters than does the solar one.” On Red Horse, the wind controller was provided by Vestas, the turbine manufacturer. SRE utilized its proprietary SCADA platform, SOLV®, a proven solution used on their own solar projects. But on a hybrid project, how do two disparate systems communicate with each other to provide the operator with the appropriate information to run the plant efficiently and effectively?

The best solution, of course, is to have a proprietary in-house program design team—fortunately for Red Horse—Swinerton Renewable Energy has one. When it became clear that an overall command-and-control system was necessary, Swinerton’s computer engineers set about the task of building it. After hundreds of work-hours, the team at Swinerton had created a software solution that would make the coders at Apple proud. “I can’t tell you how many conference calls we had between the wind software people and our software people,” Hoopes says. “We wanted to make sure we understood every nuance involved in monitoring the wind side of the project so the software accomplished what it needed to do. It was a monumental effort.”

Hoopes says the sophisticated software gives anyone with access immediate, real-time data on the site to ensure everything is performing as promised. The main site controller uses a distributed architecture that oversees both the Vestas controller and the Swinerton-designed SOLV controller. It has unprecedented redundancy and built-in failover algorithms. It also autonomously caps power output to the 71 MW site contractual limit, while controlling voltage and reactive power per Tucson Electric Power (TEP) requirements. It does so by issuing control command and response to both wind and solar simultaneously. This is a first of its kind for Swinerton and the
renewable industry.

“It makes everyone more efficient,” Hoopes says. “There’s no wasted time.”

TEP, the power purchaser from Red Horse, has been pleased with the early performance of the hybrid plant. Its 71 MW can power nearly 15,000 homes, helping the utility close in on its state-mandated goal of producing 15% of its power from renewable sources by 2025. “So far, the plant has been functioning as expected, and the command-and-control system is making sure it stays that way,” Hoopes says. “We’re glad to have played a role in this unusual project—and we hope to do more projects like this in the future.”