The Difgen control system was supplied by Zeropex, which specialises in water turbines, and recovers energy from water pressure in pipelines.
Essentially, a hydro turbine resists incoming water, controlling its flow and in turn driving the generator, which produces power synchronised to the grid supply via ABB's 37kW variable-speed drive.
In a little detail, the Pen y Cefn plant is gravity fed with raw water at up to 11 bar from a nearby storage reservoir into an open dissolved oxygen flotation tank. Previously, pressure was reduced via a pressure reduction valve.
Now, the Zeropex hydro turbine provides for accurate control of flow or pressure, preventing water hammer and surges via the modulating control system.
"We use ABB drives in our products because the company has an excellent reputation within the UK water industry," comments Duncan Collins, of Zeropex.
"They also have supplier agreements with most water companies, meaning that our control systems meet the required electrical standards," he adds.