Duke Energy has invested $4 billion in solar power since 2007. It now has more than 50 installations across the United States, generating more than 2,900 MW. “We wanted them to have a single view of the entire fleet,” said Sean Hicks, SCADA engineer, Duke Energy, to attendees of his session at Rockwell Automation TechED, this week in Orlando.
Along with reliable, real-time monitoring 24/7 from the company’s control center in Charlotte, N.C., Duke sought a new SCADA system that would give visibility to on-site operations and maintenance technicians, support control, allow emergency response, work at all the sites, and provide them all a consistent user experience, look and feel. With zero downtime.
“Duke relies heavily on OSIsoft PI,” Hicks said. “Any data tag that’s available, we want it.” A typical site might have 20,000 or more tags, and data can’t be lost due to a telecom outage. The remote control and emergency capabilities called for redundancy and security, with limited third-party access for monitoring and maintenance.
Hicks also wanted to avoid Windows servers. “Pretty much anyone can deploy a Windows-based server but maintaining and patching is a nightmare, so we want to do away with them,” he said.
Grantek Systems Integration proposed a system built on the FactoryTalk View SE platform using ControlLogix for site data acquisition and the FactoryTalk Historian ME module for on-site data buffering. “The local historian module is able to buffer the data when telecom is interrupted, and it runs OSI PI so it’s easy to connect and integrate,” said Jacob Chapman, Grantek systems engineer.
In Charlotte, six main servers provide redundancy for alarms and events, HMI and terminal service, as well as non-redundant administration, reporting and programming packages. Enterprise servers support PI API and SQL.
“The core PI server is the all-seeing eye for Duke,” Chapman said. “But it doesn’t make sense to collect all data. The FactoryTalk gateway at the site brings data into the SCADA system only if it’s needed.”
The new control center interface gives operations more real estate, information and resolution, showing key performance indicators (KPIs) and drilldowns to individual inverter status with any alarms. It shows tracker angles, weather station data, power meters and breaker status, and can show inverter outputs over time for individual or aggregate sites, nationwide.
“We can manually control the trackers, change one or all, to stow them for a windstorm,” Hicks said. “In an emergency, you can trip the entire site.”
A FactoryTalk AssetCentre implementation backs everything up every day for disaster recovery, auditing, regulatory compliance and program integrity. “If anything is changed, it can send an e-mail to the staff,” Chapman said.
The wide variety of installed equipment at generating sites means integration varies according to inverter brand, local control network (Modbus variants), and controls methodology. “One site has 866 little inverters,” Chapman said, “But we have yet to find an architecture that we have not been able to integrate.”
The main drive for the new system was to improve productivity by giving operators one view with a common look and feel, so they don’t have to open multiple views into individual sites. But it also satisfies Duke Energy’s wish list by providing historized data that can’t be lost by a telecom outage, remote control, flexibility to fit any site or hardware (new or existing), scalability for future growth, redundancy, security, scheduled reports and a disaster recovery plan that can be quickly deployed.