Integration of Large Wind Farms at EHV (A Case Study)
Abstract
In Australia Wind Farms have generally been integrated into embedded networks at voltages of 132kV or less. The authors have been recently involved in the planning, specification and contract award technical negotiations associated with the integration of a 135MW wind farm into the South Australian 275kV network for AGL.
The new AGL Hallett wind farm is to be located adjacent to Hallett Power Station mid way between Adelaide and Port Augusta and is being integrated into the existing Hallett 275kV switch yard.
The major challenges associated with this connection involve managing the brown field 275kV interface, efficiently rolling out the wind farm, and managing National Electricity Market technical matters in the face of a changing NEM code and the a rapidly changing amount of wind turbine generation that is presently being connected in South Australia.
Hallett Power Station equipment associated with the wind farm comprises a new 275/33kV transformer, 33kV switch room, reactive plant, four feeders, and centralised O&M facilities. This new equipment is located where it does not interfere with the existing power station site infrastructure.
Preliminary load flow, fault level, protection concept design studies and NEC data compilation were all carried out on behalf of AGL prior to contract award. Similarly system studies were carried out by the TNSP-Electranet to assess wind farm interaction with nearby generators and overall system stability. This approach enabled a smooth resolution of NEC chapter five issues with Nemmco, Electranet and ESCOSA who are the three regulatory authorities with equity in the South Australian Network.
The authors address specific issues associated with the deficiencies in the current version of the Australian code and the use of international experience in markets where larger numbers of wind generators have been deployed.