Tuesday, 31 January 2012
Market Outcomes: Queensland experienced an energy price of $301.78 per MWh for trading interval (TI) ending 1400 hrs.
Energy prices for the other NEM regions and FCAS prices were not affected by this event.
Prior to the incident, a constraint equation managing post-contingent load on the Calvale–Wurdong No. 871 was constraining off generation in Queensland and forcing counter-priced flows from Queensland to New South Wales on the QNI interconnector.
Approximately $75,500 of negative residues accrued on the Queensland to New South Wales directional interconnector during dispatch intervals (DIs) 1350 hrs to 1400 hrs.
Principal Contributors: Queensland experienced a price of $1342.03 per MWh during dispatch interval (DI) ending 1350 hrs.
The constraint managing the 871 line flows constrained off generation in Queensland. Rebids for Gladstone power station moved 295 MW of generation into bands priced at approximately $11,000 per MWh for DIs 1350 to 1400 hrs. With some units being ramp rate up constrained, these offers set the price for one DI.
Predispatch did not forecast the high prices, as the new generation offers were received at approximately 1341 hrs.
The Queensland energy prices returned to lower levels from DI ending 1355 hrs due to a slight decrease in demand and a change in the offer profile of Gladstone power station from 1400 hrs.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Sunday, 29 January 2012
Market Outcomes: Queensland experienced energy prices of $2079.70 per MWh and -$48.50 per MWh for trading intervals (TIs) 1430 hrs and 1500 hrs respectively.
Energy prices for the other NEM regions and FCAS prices were not affected by this event.
Prior to the incident, a constraint equation managing flow on the Calvale–Stanwell No.855 line was constraining off generation in Queensland and forcing counter-priced flows from Queensland to New South Wales on the QNI interconnector. The dynamic rating on the 855 line reduced from 791 MVA at 1410 hrs to 721 MVA at 1430 hrs.
Approximately $1,055,000 of negative residues accrued on the Queensland to New South Wales directional interconnector during DI 1415 hrs. During TI ending 1430 hrs AEMO managed the accumulation of negative residues during dispatch intervals (DIs) ending 1420 hrs and 1425 hrs (refer to Market Notices 37527 and 37528).
Principal Contributors: For TI ending 1430 hrs, the constraint managing 855 line flows violated in DI ending 1430 hrs, resulting in the 5-minute dispatch price reaching $12,315.34.
For TI ending 1500 hrs, the constraint equation invoked to manage the accumulation of negative residues reduced the transfer from Queensland to New South Wales from 950 MW to 900 MW during DI 1450 hrs. This resulted in prices reaching -$833.15 per MWh during that DI.
The Queensland energy prices returned to normal levels from DI ending 1455 hrs after the dynamic rating of the Calvale–Stanwell No. 855 line increased to above 780 MVA.
Predispatch did not forecast the price fluctuations as it was caused by the change in the dynamic rating of the Calvale-Stanwell No. 855 line.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Friday, 27 January 2012
Market Outcomes: Queensland experienced energy price fluctuations in trading intervals (TIs) ending 1300 hrs to 1500 hrs. The price peaked at $509.09 per MWh at 1300hrs and decreased to -$195.35 per MWh at 1500 hrs.
Energy prices for the other NEM regions and FCAS prices were not affected by this event.
Approximately $299,411 of negative residues accrued on the Queensland to New South Wales directional interconnector between TIs 1230 hrs to 1530 hrs. AEMO managed the accumulation of negative residues from dispatch intervals (DIs) ending 1225 hrs to 1230 hrs and from DIs ending 1255 hrs and 1555 hrs (refer to Market Notices 37471 and 37484).
Prior to the incident, the dynamic rating of the Calvale–Stanwell No. 855 line was reducing from 769 MVA at 1155 hrs to 696 MVA at 1205 hrs.
Principal Contributors: For TI ending 1230 hrs, the constraint equation that manages post-contingent load on 855 line bound causing the dispatch price to exceed $900 per MWh in DIs ending 1205 hrs and 1220 hrs. Approximately 1000 MW of Queensland generation capacity was shifted to lower priced bands, resulting in prices below -$450 per MWh in DIs ending 1225 and 1235 hrs. The half-hour spot price for TI ending 1230 hrs was $160 per MWh.
For TI ending 1300 hrs, the 855 line constraint bound again causing prices about $900 per MWh in DIs ending 1250 hrs, 1255 hrs and 1300 hrs. The half-hour spot price for TI ending 1300 hrs was $509.09 per MWh.
For subsequent TIs, volatile dispatch prices continued until around 1600 hrs as the 855 line constraint and large amounts of generation offered at negative prices interacted. Dispatch prices varied between around $1300 per and -$900 MWh.
The Queensland energy prices returned to normal levels from DI ending 1600 hrs after the dynamic rating of the Calvale–Stanwell No. 855 line increased to above 800 MVA and relaxed the binding constraint equation.
Predispatch did not forecast the price fluctuations as it was either caused by the change in the dynamic rating of the Calvale-Stanwell No. 855 line or the change in new generation offers.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Tuesday, 24 January 2012
Market Outcomes: Tasmania experienced an energy price of $1526.64 per MWh for trading interval (TI) ending 1530 hrs. South Australia and Victoria experienced moderately high prices as a result of this incident.
Frequency Control Ancillary Services (FCAS) prices for Tasmania and FCAS and energy prices for the other NEM regions were not affected.
Principal Contributors: Tasmania experienced a price of $8973.62 per MWh during dispatch interval (DI) ending 1525 hrs when a constraint equation violated.
The constraint equation manages provision of frequency raise services during high interconnector transfers through Basslink towards Victoria to cover generation tripping by the Network Control Special Protection Scheme (NCSPS) in Tasmania. The constraint equation reduces the interconnector flow towards Victoria and constrains off generation capacity on the west coast of Tasmania.
Prices returned to lower levels during DI 1530 hrs when 1473 MW of generation capacity in Victoria was offered in response to the price change in Victoria, which lowered transfers into Victoria via Basslink.
The constraint equation associated with the NCSPS did not bind or violate in the 1430 hrs pre-dispatch run due to higher than forecast demand in Victoria.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Sunday, 22 January 2012
Market Outcomes: Victoria experienced an energy price of -$117.79 per MWh for trading interval (TI) ending 0800 hrs.
Frequency Control Ancillary Services (FCAS) prices for Victoria and FCAS and energy prices for the other NEM regions were not affected.
Prior to the event, the Hazelwood No.4 500/220 kV transformer had been taken out of service for scheduled work.
Principal Contributors: Victoria experienced negative prices reaching -$134.68 per MWh during dispatch intervals (DIs) ending 0735 to 0800 hrs.
From DI ending 0735 hrs an additional 551 MW of generation in Victoria was offered in negative price bands. During the affected DIs interactions between constraint equations managing the transformer outage and post contingent stability for the loss of a Hazelwood to South Morang 500kV line reduced transfers from Victoria to New South Wales and Tasmania, required transfers to Victoria from South Australia on the Heywood interconnector and constrained on generation in the Latrobe Valley.
With excess generation capacity in Victoria, negatively priced generation offers set the price for one TI. Prices returned to normal levels with an increase in morning demand and a change in the offer profile of Victoria.
The outage constraint associated with the Hazelwood No. 4 transformer did not bind in the 0700 hrs pre-dispatch run, since the forecast demand for Victoria was approximately 170 MW lower than the actual demand for TI 0800 hrs. As a result the negative prices for TI 0800 hrs were not predicted in pre-dispatch.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Sunday, 15 January 2012
Market Outcomes: Queensland experienced an energy price of -$45.02 per MWh for trading interval (TI) ending 1300 hrs.
Energy prices for the other NEM regions and FCAS prices were not affected by this event.
Approximately $96,000 of negative residues accrued on the Queensland to New South Wales directional interconnector during TI 1230 hrs. AEMO managed the accumulation of negative residues from dispatch interval (DI) ending 1240 to 1310 hrs (refer to Market Notices 37325 and 37326).
Principal Contributors: Queensland experienced a price of -$429.45 per MWh during DI 1240 hrs.
A constraint equation that manages the post-contingent load on the Calvale–Wurdong No. 871 constrained off generation in Queensland whilst forcing flow on the QNI interconnector towards New South Wales. With higher 5-minute prices in Queensland, negative residues accumulated on the Queensland to New South Wales directional interconnector during TI 1230 hrs. A negative residue management constraint equation was invoked for DI ending 1240 hrs and reduced the flow on QNI towards New South Wales with 107 MW. With some units being ramp rate down constrained, a negatively priced offer set the price for one DI.
The Queensland energy prices returned to normal levels from DI ending 1245 hrs once generating units were no longer limited by their ramp down rate of change.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Friday, 13 January 2012
Market Outcomes: Queensland experienced an energy price of $333.00 per MWh for trading interval (TI) ending 1000 hrs.
Energy prices for the other NEM regions and FCAS prices were not affected by this event.
Principal Contributors: Queensland experienced a price of between $1415.78 per MWh during dispatch interval (DI) ending 0935 hrs.
Energy demand in Queensland was high throughout the day due to hot weather. A constraint equation that manages the post-contingent load on the Calvale–Wurdong No. 871 constrained off generation in Queensland and limited the flow on the QNI interconnector towards Queensland. Gladstone power station rebid 440 MW of generation into bands priced at over $1300 per MWh for DIs 0935 to 1000 hrs. With some units being ramp rate constrained, these expensive offers set the price for one DI.
Predispatch did not forecast the high prices, as the new generation offers were received at approximately 0925 hrs.
The Queensland energy prices returned to lower levels from DI ending 0940 hrs once fast start units received instructions to start, and generating units were no longer limited by their ramp up rate of change.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Thursday, 12 January 2012
Market Outcomes: Queensland experienced energy prices of $1387.58 per MWh and $459.47 per MWh for trading intervals (TIs) ending 1000 and 1430 hrs.
Approximately $850,000 of negative residues accrued on the Queensland to New South Wales directional interconnector during TIs 1000 hrs and 1430 hrs. AEMO could not manage the accumulation of negative residues, as the $100,000 threshold value for doing so was reached in one Dispatch Interval (DI) ending 0935 hrs. The threshold value was again exceeded during TI 1430 hrs, when negative residues accumulated in DIs 1405 and 1410 hrs only.
Energy prices for the other NEM regions and FCAS prices were not affected by this event.
Principal Contributors: Queensland experienced prices of $12500 per MWh during dispatch intervals (DIs) ending 0935 hrs.
Energy demand in Queensland was high throughout the day due to hot weather. The dynamic rating of the Calvale– Wurdong No. 871 line was reduced from 801MVA at 0920 hrs to 715 MVA at 0930 hrs. The rating change caused the constraint equation that manages the post-contingent load on the Calvale–Wurdong No. 871 line to bind, and to eventually violate. The constraint equation constrained off generation in Queensland and limited the flow on the QNI interconnector towards Queensland during the affected DI.
Predispatch did not forecast the high price at 1000 hrs, as it was caused by the change in the dynamic rating of the Calvale– Wurdong No. 871 line.
The Queensland energy prices returned to lower levels when approximately 1800 MW of generation offers were rebid into negative price bands and a number of generating units were no longer limited by their ramp up rate of change.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Wednesday, 11 January 2012
Market Outcomes: South Australia experienced negative energy prices for trading intervals (TIs) ending 0200 to 0230 hrs, and 0430 to 0530 hrs, reaching -$161.36 per MWh for TI 0500 hrs.
Energy prices for the other NEM regions and FCAS prices were not affected by this event.
Principal Contributors: South Australia experienced negative prices for a number of dispatch intervals (DIs) during the affected TIs.
South Australian demand was between 1240 MW and 1309 MW, with substantial wind generation of up to 875 MW. Transfer on the Murraylink and Heywood interconnectors was limited to between 156 MW and 332 MW towards Victoria by constraint equations managing the post-contingent loading of one of the Robertstown 275/132 kV transformers, and one of the South East 275/132 kV transformers.
The high prices were not forecast in predispatch as it was due to varying wind conditions in south east South Australia that intermittently caused the constraint equations to bind.
With excess generation capacity in South Australia, negatively priced generation offers set the price during the affected TIs. Prices returned to normal levels with an increase in morning demand.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Tuesday, 10 January 2012
Market Outcomes: Queensland experienced high energy prices for trading intervals (TIs) ending 1400 hrs and 1430 hrs of $2892.65 per MWh and $311.81 per MWh respectively.
Energy prices for the other NEM regions and FCAS prices were not affected by this event.
Principal Contributors: Queensland experienced prices of between $1610.49 per MWh and $12500 per MWh during dispatch intervals (DIs) ending 1355 hrs and 1405 hrs.
Energy demand in Queensland was high throughout the day due to hot weather. The dynamic rating of the Calvale–Stanwell No. 855 line was reduced by 50 MVA at 1355 hrs. The rating change caused the constraint equation that manages the post-contingent load on the Calvale–Wurdong No. 871 line to bind, and to eventually violate. The constraint equation constrained off generation in Queensland and limited the flow on the QNI interconnector towards Queensland during the affected DIs.
Predispatch did not forecast the high prices, as it was caused by the change in the dynamic rating of the Calvale–Stanwell No. 855 line.
The Queensland energy prices returned to lower levels from DI ending 1355 hrs once fast start units received instructions to start, and generating units were no longer limited by their ramp up rate of change.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Monday, 09 January 2012
Market Outcomes: Queensland experienced high energy prices for trading intervals (TIs) ending 1130 hrs and 1230 hrs of $380.61 per MWh and $387.62 per MWh respectively.
Energy prices for the other NEM regions and FCAS prices were not affected by this event.
Principal Contributors: Queensland experienced prices of $1682.23 per MWh and $1671.87 per MWh during dispatch intervals (DIs) ending 1130 hrs and 1230 hrs.
Energy demand in Queensland was high throughout the day due to hot weather. A constraint equation managing the post-contingent load on the Calvale–Wurdong No. 871 line on trip of Calvale–Stanwell No. 855 line was constraining off generation in Queensland and limited the flow on the QNI interconnector to 244 MW towards Queensland during the affected TIs. A communication problem on the Terranora interconnector constrained it to 60 MW towards New South Wales.
Prices were higher than predicted in predispatch due to a higher than forecast demand.
The Queensland energy prices returned to lower levels from DI ending 1245 hrs once fast start units received instructions to start.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Sunday, 08 January 2012
Market Outcomes: South Australia experienced an energy price of -$139.85 per MWh for trading interval (TI) ending 0800 hrs.
Frequency control ancillary services prices and energy prices for the other NEM regions were not affected.
Principal Contributors: South Australia experienced a negative price of -$908.50 per MWh during dispatch interval (DI) ending 0740 hrs.
South Australian demand was 1207 MW during TI ending 0800 hrs, with substantial wind generation of up to 776 MW. An increase in wind generation caused a constraint equation to bind which reduced the interconnector transfer to Victoria.
With excess generation capacity in South Australia, negatively priced generation offers set the price for one DI during the affected TI. Prices returned to normal levels with an increase in morning demand.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
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