Synchronous Separation Between Queensland And New South Wales

The Queensland to New South Wales Interconnector (QNI) is the main interconnection between New South Wales and Queensland, with an import capacity to Queensland of approximately 600 MW. Immediately prior to the event at 1330 hrs QNI was exporting approximately 396 MW to New South Wales. 

At around 14:06 hrs, approximately 3,000 MW of generation capacity tripped offline in Queensland causing QNI active power flow to rapidly increase, peaking at around 1,064 MW import to Queensland until the interconnector tripped. After QNI tripped, the Queensland frequency dropped to approximately 48.50 Hz. In response, AEMO observed a net reduction in load of approximately 2,300 MW in Queensland and 40 MW in Northern New South Wales . The cause of most of this load reduction is likely to be associated with the expected operation of automatic Under Frequency Load Shedding (UFLS) relays following the observed drop in frequency, but this will need to be confirmed through analysis of relay operation.