Keeping control at power station

Edited by the Engineeringtalk editorial team Jun 6, 2002

Control system for Wairakei geothermal power scheme comprises dual redundant servers with automatic failover at each of the three sites.

Contact Energy owns and operates the Wairakei geothermal power scheme, comprising three separate power stations.

The first station, commissioned in 1958, is situated above a large geothermal system containing water at temperatures up to 240C.

Currently, about 5000tonne/hr of fluid is taken from the reservoir.

The second was commissioned in 1989.

The most distinctive feature of this station is the 105m high cooling tower.

Because little heat or mineralised separated geothermal fluid is discharged to natural waterways, it has developed an environmentally friendly reputation.

The last was commissioned in 1996 and is supplied with steam from the Wairakei field.

Contact initially installed an IFix control system from GE Fanuc to monitor and control the plant.

In 2002, Contact enhanced this system by adding IPower Scada from Catapult Software.

The Scada system is reasonably complex: it comprises dual redundant servers with automatic failover at each of the three sites.

Communications between Scada computers and their local data sources (PLCs and RTUs) is via dual 100Mbyte dedicated Scada LAN.

About 20 client workstations can access Scada data at any of the sites.

The clients and servers across all three sites are linked by another LAN and WAN.

The system also uses GE Fanuc's Proficy IHistorian data repository system, along with GE Fanuc's Proficy Portal web-based reporting system.

Database and display enhancements across the sites are carried out by Catapult Software from its Auckland office.

"IFix's distributed open client-server architecture is ideal for operating and managing our geothermal power plant installations, from the steam fields right through to the power station generators", said Murray Hill, Generation Engineer, Contact Energy.

"We enhanced IFix with IPower because of the purpose-built operator dialogues, automated configuration and other useful features such as control tagging".