In a Nutshell
SA is considered to be in an energy crisis following the state-wide power outage event that occurred on 28 September 2016 (Black system) and a heatwave that occurred in early February which led to the load-shedding of 90,000 South Australians.
The Australian Energy Market Operator (AEMO) published their final report regarding the Black System on the 27th of March 2017. The following day the State Government introduced legislation to address inadequacies relating to the load-shedding event.
Background - The Black System
Extreme weather conditions involving a severe thunderstorm outbreak occurred on the afternoon of 28 September 2016.
This weather system produced high wind speeds and the formation of tornadoes. A sequence of events related to these weather conditions caused the loss of supply of power to SA.
In the wake of this event, the AEMO undertook to investigate the causes of the Black System in order to address any underlying issues with the system.
Causes of the Black System
The AEMO have reported that the Black System was caused by over protective wind turbine settings being triggered, which caused a significant reduction in power generation.
More specifically, the loss of power was caused by the following sequence of events:
- Two tornadoes almost simultaneously damaged a single 275kV transmission line and a double circuit 275kV transmission line.
- This damage caused the transmission lines to ‘trip’ and resulted in six voltage dips on the SA grid within a two-minute period.
- This number of voltage dips triggered a protection feature to be activated on eight wind farms in SA.
- The activation of this feature resulted in a significant sustained generation reduction of 456 megawatts over a period of seven seconds.
- In order to account for this reduction in windfarm output, a significant increase in imported power flowing through the Heywood Interconnector was necessary.
- The rapid increase in flow through the Victoria-SA Interconnector activated a protection scheme, which tripped the Interconnector offline.
- SA was ‘islanded’ as it became separated from the National Electricity Market. The remaining generation was outweighed by the e connected load and therefore the island frequency could not be maintained. Consequently, all supply to SA was lost.
The AEMO made 19 recommendations to address the issues relating to the SA power system.
The recommendations focused on implementing:
- changes to the generator licensing conditions in South Australia and the National Electricity Rules to address generator performance standard issues;
- more rigorous weather monitoring systems in order to trigger reassessment of power system contingencies; and
- controls aimed at preventing separation from the National Electricity Market by closely monitoring abnormal flows on the Heywoo Interconnector.
Moving forward, the AEMO will also focus more generally on conducting ongoing reviews, tests and investigations in relation to existing generation and network equipment and systems in order to provide the AEMO with the information necessary to predict how systems will respond to severe weather conditions.
Load-shedding – New legislation introduced
In early February 2017, SA experienced a heatwave which led the AEMO to predict that the available energy supply in SA would be insufficient for the demand.
Accordingly, the AEMO directed that certain SA customers needed to be load-shed in order to make up for the excess demand that was being experienced. An error led to additional customers being cut off from electricity as well.
This event prompted the SA Government to introduce the Emergency Management (Electricity Supply Emergencies) Amendment Bill 2017 on 28 March 2017.
If passed, the legislation will enable the Energy Minister to direct electricity generators to supply electricity when required. Additionally, it would provide the Minister with the power to instruct the AEMO to control flows over the Interconnector. It is asserted that this power will allow the power supply to be restored to SA if a similar event were to occur.
The legislation provides for an interesting relationship between the management of a national scheme and a national market operator and a State Government being a party to the scheme but asserting a power to direct the market operator (albeit supposedly in limited circumstances). The constitutional basis of the legislation could even be questionable.