Australian Blackout Event On Sep 28th 2016 Alex Lee Operations Planning Engineer 3/29/2018 Objectives Identify factors that contributed to the cause of the Australian Blackout Event Identify steps of restoration that were used during this event Recognize market impacts associated with the blackout event Identify lessons learned from the event PUBLIC
2 Australian Energy Market Operator (AEMO) AEMO was established on July 2009 Gas Markets Victorian Declared Wholesale Gas Market (DWGM) Short Term Trading Market (STTM) National Gas Market Western Australia Gas PUBLIC NonAEMO National Electricity Market Electricity Markets
National Electricity Market (NEM) since Dec. 1998 Wholesale Electricity Market (WEM) since Sep. 2006 Wholesale Electricity Market Northern Territory Western Australia South Australia Queensland New South Wales Victoria Tasmania
3 Challenging Terrain in Australia Mainland is 70% desert Weak Long Transmission Network with numerous radial systems source: AEMO website, www.aemo.com.au PUBLIC 4 ERCOT vs. NEM High Level Overview Queensland 9,508 MW (2016/17) $78/MWh TX South Australia 3,397 MW (2010/11)
$93/MWh New South Wales 14,764 (2010/11) $67/MWh Victoria 10,490 (2008/09) $53/MWh Tasmania 1,884 MW (2008) $56/MWh 77% Coal back in 2003 as well. PUBLIC 5 Blackout Event Sep. 28th 2016 @ 16:18 Sequence of event (16:16:46 16:18:15) 1. Extreme weather caused transmission faults.
2. Significant voltage dips caused Wind Generators to reduce output. 3. Heywood Interconnector (AC Tie) exceeded its limit and automatic power system protection operated. 4. System imbalance resulted in the state-wide blackout (1,895 MW of demand) in South Australia. PUBLIC 6 South Australia Cyclone: Sep. 28th-30th 2016 Wind speed: 40-60 mph with gusts up to 70 mph common (similar intensity to a weak tropical storm). Reports of isolated 85 mph gusts. Two weeks prior, Adelaide experienced flooding. This acted to loosen the soil, resulting in greater ease in trees, power lines, and towers coming down.
Widespread thunderstorms, cloud to ground lightning strikes (20,000+), damaging hail, and heavy rainfall (flooding). Strongest storm to hit South Australia in 50 years. Adelaide PUBLIC Ike in 2008 was Category 2 hurricane with highest wind speed of 145 mph. 7 Historical Cyclone Path since 1969. PUBLIC
South Australia never experience a cyclone Infrastructures may have weak resistance to weather events. 8 Pre-Event System Configuration Load: 1,895 MW (850,000 customers) South Australia Generation Mix (MW) 330 613 Thermal Generation AC = 525
DC Tie Limit 220 Wind Generation Import from Victoria 883 AC Tie Limit 600 source: AEMO, Final Report SA Black System 28 September 2016. PUBLIC 9 Transmission Line Faults Six system faults on four lines, three ultimately lost. Fault # Time kV Line
Voltage Dip @ Davenport 1 16:16:46 66 Northfield Harrow 85% 2 16:17:33 275 Brinkworth Templers 60% 3
16:17:59 275 Davenport Belalie 40% 4 16:18:08 275 Davenport Belalie 40% 5 16:18:13 275
Davenport Mt Lock 40% 6 16:18:14 275 Davenport Mt Lock 40% Davenport 3-4 5-6 2 1 *note: RED indicates that line remained out of service after the fault. source: AEMO, Final Report SA Black System 28 September 2016.
PUBLIC 10 Six Voltage Disturbances 100 seconds data 41 sec 15 sec Davenport 1 2 3-4 5-6 2 3 4
1 56 source: AEMO, Update Report Black System Event in South Australia on 28 September 2016 PUBLIC 11 Wind Generation Reduction 10 seconds data 4 5 6 source: AEMO, Final Report SA Black System 28 September 2016. PUBLIC 12
Low-Voltage Ride-Through (LVRT) Purpose: remain connected and provide voltage recovery support. Threshold: typically 80 90 % of normal voltage. LVRT Withstand Capability PUBLIC 13 Wind Generation Reduction (Continued) LVRT 42 MW of expected reduction through normal transient ride-through response 456 MW of unexpected sustained wind reduction
20 MW Over-Speed Trip Typically 55mph or more source: AEMO, Final Report SA Black System 28 September 2016. PUBLIC 14 Heywood Interconnector (AC Tie) Trip Flow increased from 525 MW to approximately 900 MW Limit = 600 MW Tripped on Automatic Loss of Synchronism Protection Mechanism 5 seconds data 5 6 source: AEMO, Final Report SA Black System 28 September 2016. PUBLIC
15 Frequency Collapse 2 seconds data Immediate loss of ~900 MW caused rapid Rate of Change of Frequency (RoCoF), 6-7 Hz/ sec. 6 49 Hz Under-Frequency Load Shedding (UFLS), which is triggered at 49 Hz, is capable of arresting RoCoF up to 3 Hz/ sec. source: AEMO, Preliminary Report Black Start System Event in South Australia on 28 September 2016
PUBLIC 16 Restoration Process: AEMO 1. Identify state of the power system 2. Secure any islands and devise restoration plan 3. Provide auxiliary supply to power stations 4. Restore load 5. Prepare transmission network 6. Continue 3-5. PUBLIC 17 Restoration Plans Initiate two parallel plans at 16:30 (T+12min) : Damaged Transmission SRAS #2 DC Tie Use System Restart Ancillary Service (SRAS)
#1. SRAS #1 Use AC Tie. AC Tie PUBLIC 18 System Restart Ancillary Service (SRAS) #1 SRAS #1 requested to start at 16:37 (T+19min) 1 small unit (24 MW) & 1 large unit (128 MW) Successful test on May 21st 2016 Small unit is not capable of energizing the transformer required to energize the 275 kV transmission network Circuit breaker for the large unit was closed but subsequently tripped five times due to in-rush current on the large generator side Soft-Started during test vs. Hard-started during real blackout source: AEMO, Final Report SA Black System 28 September 2016.
PUBLIC 19 System Restart Ancillary Service (SRAS) #2 SRAS #2 started automatically Successful test on Apr 19th 2016 Pre-defined path required energizing damaged transmission lines and AEMO did not send instruction to start Emergency diesel generator which is used to start the unit tripped after 15 seconds of operations due to a stator earth fault which severely damaged the diesel generator Highly suggestive of lightning being the cause of the fault source: AEMO, Final Report SA Black System 28 September 2016. PUBLIC 20 Restoration from AC Tie
8 # Time Energization Event 1 17:23 (T+1h 5min) AC Tie (Heywood South East #2 275 kV) 2 17:33 (T+1h 15min) South East Tailem Ben 275 kV 3 18:06 (T+1h 48min) Tailem Bend Tungkillo 275 kV 4 18:09 (T+1h 51min) Tungkillo Para 275 kV 5 18:28 (T+2h 10min)
Para Torrens Island 275 kV 6 18:42 (T+2h 24min) AC Tie (Heywood South East #1 275 kV) 7 5 4 3 7 23:52 (T+7h 34min) 2 1,6 PUBLIC 8 09/29 12:15 (T+19h 57min)
Numerous other events Tungkillo Robertstown 275 kV Numerous other events Davenport Bungama 275 kV 21 Load Restoration Sept 29th 18:25 (T + 1d 2h 7min): Blackout condition terminated source: AEMO, Final Report SA Black System 28 September 2016. PUBLIC 22 Market Suspension From Sept. 28th 16:25 to Oct. 11th 22:30 (13 Days) Market suspension occurs under three conditions: Blackout in the region Directed by the participating jurisdiction Provisions of the National Electricity Rule (NER) has become impossible to meet
Termination of Market Suspension occurs when none of the above three conditions exists AND AEMO evaluates that another market suspension is unlikely to occur within 24 hours. PUBLIC 23 Market Suspension Market Prices Spot Energy and Ancillary Service Prices are based on a published schedule of average prices for the region Suspension pricing schedule = Ave. of previous four billing weeks. Determined on weekly rolling basis and published for following 14 days where possible Separates weekdays and weekends source: AEMO, Update Report Black System Event in South Australia on 28 September 2016 PUBLIC
24 Market Suspension Market Prices (Continued) Prices in neighboring regions must be adjusted to ensure no negative settlement residues accrue (price capping) source: AEMO, Update Report Black System Event in South Australia on 28 September 2016 PUBLIC 25 Market Suspension Congestion Management Oct 1st: AEMO requested generators to continue submitting bids AEMO manually dispatched generators as close as possible to economic merit order. Manually dispatched generators may be entitled to compensation amount PUBLIC 26
Lessons Learned Optimize the ride-through settings on wind resources AEMO worked with wind generators and changed the setting from 3-6 faults to 9-20 faults within 2 minutes. Evaluate severe contingencies (N-X) during projected extreme weather AEMO created contingencies for multiple wind trips/reductions Control flow to the region during extreme weather South Australian Government directed AEMO to limit flow on AC Tie, RoCoF < 3 Hz/sec Ensure proper operation of Black Start Resources Review the Market Suspension process and pricing methodology PUBLIC 27 Lessons Learned Lessons AEMO
ERCOT AEMO worked with wind generators and changed Optimize the ride-through the setting from 3-6 faults settings on wind resources to 9-20 faults within 2 minutes. Sent out RFI for VRT. Actual past event of 475 MW of wind reduction dropped 92 MW of firm load on UVLS relays. Evaluate severe N-X Created contingencies for contingencies during multiple wind projected extreme weather trips/reductions. Already doing. South Australian
Government directed AEMO to limit flow on AC Tie, RoCoF < 3 Hz/sec. Already doing. Control flow to the region during extreme weather Ensure proper operation of Align real and test Black Start Resources procedures. N/A. Review the Market Suspension process and pricing methodology NPRR 850, Market Suspension and Restart. PUBLIC Improve procedures for
long market suspension. 28 Questions? PUBLIC 29
