AEP is one of the nation’s largest public utilities, operating in 12 states. AEP’s corporate headquarters, a 30 story tower, is located at 1 Riverside Plaza in Columbus, Ohio. The facility which coordinates AEP’s national power distribution is mandated by the PUC to maintain operation in the event of a major power outage.
AEP achieves this requirement by operating a Rolls-Royce (Allison) 501 KB series gas turbine generator, GTG, set. The three megawatt turbo-generator is required to demonstrate availability on a monthly basis.
Given that the unit was installed two decades ago, the original electro-mechanical control systems have become obsolete, thus rendering the system reliability somewhat questionable as service and support for the controls system was not readily available.
As a trusted supplier of control systems for Rolls-Royce Energy, Rolls-Royce recommended the United Controls Group to AEP as the supplier of the Rolls-Royce Allison 501 series turbine control system upgrade. AEP awarded the turnkey project to UCG in the summer of 2010 and the installation was completed in early 2011.
In an effort to match the footprint of the old enclosure a new three bay Hoffman enclosure was selected. While a typical new installation would only require a two bay design the third bay was utilized to house a redundant 15 inch A-B PanelView Plus HMI with 64 Mb flash memory. The generator controls and protection is handled through an A-B CGCM which was also located in the third bay. The CGCM was configured with redundant ControlNet communication to the main ControlLogix 1756-L62 processor. The design also included redundant power supplies and processors. The original Woodward fuel valve was replaced with a CCC ALV10-14 valve with electric control and position feedback.
The modern digital control system provides greater flexibility, with improved data communications capability; and equipped to provide extensive system monitoring, trending, and system diagnostics.
UCG provided the Project Management with UCG’s sister company, Titan Electric assisting in the installation. The site test included a full load test against a load bank. A portable trailer mounted generator was rented and connect to the building network as backup power in the event of an outage while the GTG controls change-out was being made. The black start feature was tested as well as synchronizing and running parallel to the grid.
The project was a complete success and without incident.