2018 01 Paper: Whakamaru Rehabilitation

Whakamaru Power Station is the fourth hydro power station in the Waikato river hydro cascade. It has served New Zealand since 1956 with a generating capacity up to 100MW from four 25MW Francis turbines and synchronous generators. Since the early 2000s it was becoming apparent that the generators were reaching end of life due to degrading stator coil insulation. A generator re-wind or full stator replacement program were the only options available to reduce unplanned outages and the risk of having to “park up” a unit due to an irreparable generator fault. Although the turbines were not yet end of life it had been recognised for some time that increasing flow through the station would help free up the river chain and give the energy traders more options for generating when the price was right. There were also significant turbine efficiency gains to be made. In 2012 approval was given to go to the market to procure new generators and to design new turbines. Now six years on and a lot of water under the bridge, two units have been successfully rehabilitated and uprated by over 20%. The remaining two units will be rehabilitated by April 2020. This paper discusses the long journey of a rehabilitation project including the innovative ideas, wins made and lessons learnt in restoring one of New Zealand’s iconic hydro power stations.

• Author: Joe Mace
• Exchange: 2018 - Albury AGL
• Company: Mercury
• Topic: Refurbishment
• Key Words: Rehabilitation