Revitalising Power Generation

Originally designed in 1977 as an 11 kV, 7 MW induction generator for Foster Wheeler, the generator operated in conjunction with a power recovery train (PRT). This PRT system, consisting of a steam turbine, blower, and an expander, recovered some of the waste energy used to drive the generator. This PRT configuration continued until 1991, when a critical need arose to supply reactive power during grid outages.

To address the system’s insufficient reactive capacity and mitigate the impact of grid outages, the solution required significant modification. The existing induction generator underwent a conversion process to enable synchronous operation. While the conversion was successful, and the generator continued to operate reliably for an impressive 33 years, it suffered operational drawbacks. For instance, high operating temperatures, vibrations, and bearing issues caused the generator’s output capacity to be reduced throughout its lifespan.

In 2023, TDC Parsons Peebles was approached to provide a new generator. The goal was to replace the ageing generator with an interchangeable drop-in replacement. This new machine would address the inherited problems, offer increased performance (11kV, 7.5MW, 8333kVA), and seamlessly integrate with the existing infrastructure. This included ensuring compatibility with the existing cabling, pipework, foundations and excitation system.

Leveraging its experience in new generator design and refurbishment, TDC Parsons Peebles’ engineering team completed a comprehensive design review. This review led to the redesign of the stator and rotor windings, an improved ventilation circuit, a redesigned shaft and base plate, and the incorporation of a new bearing design. These changes significantly improved the generator's performance, reducing the operating temperature from over 158 to 86°C and full load vibration from 6.0 to 1.3 mm/sec (rms).

The new, like-for-like replacement generator provides increased output capacity and efficiency while minimising downtime and disruption during installation.