Contact Energy's wider Te Mihi project
The steamfield project is part of Contact Energy's $750 million programme of investments to expand the use of the Wairakei steamfield. It includes the construction of a new geothermal power station, Te Mihi, which will produce 166 MW. Once the station is completed, older parts of the Wairakei geothermal station will be decommissioned, so the gain in output will be 114 MW, enough to power over 100,000 homes. As part of ABB's commissioned reinjection site project, the steamfield was developed so that separated geothermal water can be reinjected back into the steamfield and reused. Environmental benefits resulting from this work includes preventing the used water from the steamfield, which can reach over 100 degrees, finding its way into the Waikato River.
Te Mihi steamfield
ABB's reinjection plant solution
The solution needed to be suitable for the environmental conditions of the geothermal site, as well as offering the ability to be maintainable over the lifetime of the plant. It was also essential that ABB met Contact Energy's strict performance requirements.
ABB's integrated offering included engineering and architectural system design, supply of product, commissioning and conformance testing.
ABB's ability to provide the balance of plant including transformers, medium voltage primary switchgear, low voltage switchgear, drives and the 800xa control system, gave Contact Energy the ease of dealing with one supplier, particularly for procurement and delivery. ABB's automation technology is also future proof, in that the 800xA control system offers greater compatibility and functionality for future installations.
Liquid-cooled low harmonic variable speed drives
ABB's liquid-cooled low harmonic variable speed drive (VSD) technology, previously only used in the marine and offshore industries in New Zealand, was also of particular benefit to Contact Energy, who needed to meet stringent environmental requirements and utility harmonic standards. With a 6 MV VSD load in one plant, with six drives in total, this plant includes the largest low voltage VSD system installed in New Zealand at 1400 kW.
| The drives had three key advantages. The first advantage was that the totally enclosed liquid cooled cabinet meant that the VSDs were not susceptible to high levels of hydrogen sulphide on site, therefore treatment of the air to remove hydrogen sulphide was not required for drive cooling. The second key advantage was that the compact size allowed a smaller switchroom to be constructed. Thirdly, the low harmonic drives allowed harmonic standards to be met without external filters or special transformers. | ABB's liquid cooled low harmonic variable speed drive technology |
Contact Energy's Mathew Staddon, commented, "ABB delivered a solution for the electrical requirements for the Te Mihi steamfield reinjection plant that was cost effective and on time. The option ABB gave to have 1.4 MW LV liquid cooled VSDs will reduce ongoing running costs and simplify operations".
To combat the site's highly corrosive environment, ABB's transformers were coated in a specially developed paint system to ensure greater protection, and tinned coating was used for the control wiring. These measures ensure the longevity and performance of the products in harsh conditions.
ABB's Unigear medium voltage switchgear |
ABB's transformers - locally manufactured in New Plymouth |
| ABB's involvement in the new Te Mihi geothermal power station ABB is pleased to announce its supply of key products for Contact Energy's new Te Mihi reinjection station. ABB will be supplying generator step-up transformers, unit and auxiliary transformers, generator circuit breakers, low voltage and medium voltage switchgear and relays, and a distributed control system. |
