Short Duration Undervoltage Disturbance Ride-Through Test Procedure


AEMO has identified through analysis of recent power system events, that a proportion of distributed solar PV (DPV) disconnect in response to short duration transmission undervoltage disturbances. Given the levels of DPV installed in South Australia, a severe but credible fault near the Adelaide metropolitan area could cause disconnection of up to half the distributed PV in the South Australian region. 

Under specific conditions this would leave AEMO with very few courses of action available for secure operation of South Australia. These findings have been highlighted as part of the recently published: Renewable Integration Study report, the Minimum operational demand thresholds in South Australia Technical report and recognised by the South Australian Government and SA Power Networks (SAPN).

To reduce the potential for disruption and improve power system security, most immediately in South Australia, AEMO: 

to ensure inverters, and DPV by extension, respond appropriately during short duration undervoltage disturbance events to mitigate any further potential risks to power system security.

Development and publication of a VDRT Test Procedure is part of AEMO’s broader strategy to address DPV inverter behaviour, which also includes:

However, AEMO considers there is a pressing need to accelerate implementation of the VDRT Test Procedure in South Australia.

Test Procedure

Following feedback from the consultation, the final test procedure has been developed. The intent of the procedure is to verify the behaviour of an inverter energy system within a distributed energy resource (DER) installation during a short duration undervoltage disturbance.

The test procedure should be applied in conjunction with existing product certification testing for compliance with AS/NZS 4777.2:2015 and has been developed as a supplementary test. 

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