Maintenance of power system security continues to be a key challenge for the national electricity market.
- In the period 2017/18, the frequency performance of the system has continued to degrade. Some elements of the frequency operating standard were not met in both the mainland and in Tasmania during 2017/18.
- To maintain sufficient levels of system strength (a property of the power system that resists changes in voltages in response to a change in loading conditions) in South Australia, AEMO has been required to use a number of market interventions, including constraining off asynchronous generation like wind and solar generators, and issuing directions to operate synchronous generators, like gas and diesel generators. These system strength interventions come at a significant cost to consumers.
- Another security issue that arose during the reporting period is voltage control in South Australia and Victoria. AEMO is currently managing over voltages with short term manual de-energisation of high voltage transmission lines, combined with directions to generators. These manual line switching interventions can come at a cost to consumers, by impacting on the ability of the transmission system to effectively transport energy within and between regions.
Over the 2017/18 period, the reliability of electricity supply continued to be maintained with no unserved energy over the period. However, this was in part due to the activation of the Reliability and Emergency Reserve Trader (RERT) on two occasions to maintain the power system in a reliable operating state. Prior to 2017/18, the RERT had only been procured three times and had never been activated.
The Panel is not aware of any incidents where AEMO's management of power system security has resulted in a safety issue with respect to maintaining the system within relevant standards and technical limits.