King Country Energy

G5 turbine replacement: innovation through simplicity

The new turbine King Country Energy installed at its Wairere power station last year has increased the plant’s efficiency by 16 per cent and its maximum power output by 21 per cent.

The project, approved in 2012, met all the firm’s targets around turbine performance and safe operations throughout the full flow range.  It also developed a control system for the site that is simple and flexible enough to become a template to standardise the control systems for KCE’s other mini-hydros and to let the firm adapt to future regulatory requirements.

KCE faced a decision to overhaul the three oldest turbines at the four-unit power station, or replace them with a new machine. The company weighed up the financial and other benefits and in 2012 approved a $2.73 million project to install a single, new TURAB turbine.

The project faced two main challenges: fitting an off-the-shelf turbine into an old building in order to minimise capital costs; and minimising the complexity of the mechanical and electrical control systems to achieve greater automation and lower future operating and maintenance costs.

State-of-the-art laser technology was used to survey the entire building and log key component locations. But building foundations that didn’t match the original plans needed to be upgraded to meet seismic ratings. The tailrace and plunge pool also had to be re-worked.

KCE says its selection of experienced contractors and a determination to find simple, collaborative solutions and processes paid off.

Among the innovative solutions was a customised ‘dogleg’ penstock to align the new unit within the existing site. Designed by PB Power and fabricated by JP Marshall, it is understood to be one of the first to use this technique in New Zealand.

Civil contractor Spartan says working within the confines of the existing building also made many conventional demolition and formwork techniques infeasible.

KCE also took key supply chain decisions to add to the commercial success of the project.

Regular conference calls kept communication going and limited ‘surprises’ between contractors and suppliers, particularly when civil issues were causing changes to designs.

Legal and insurance input from the beginning saved time and cost and ensured robust contracts from day one. New Zealand suppliers were also selected where appropriate, particularly for the control systems, to ensure they understood local market conditions and regulation and how they might evolve over time.

And rather than contracting out, KCE carried out the electrical installation and commissioning so that its staff will have an intimate knowledge of the system to deal with any future faults.

The Energy Project of the Year category is sponsored by ITL