Thursday, 28 February 2008
Market Outcomes: The Queensland region Frequency Control Ancillary Service (FCAS) prices ranged up to $10,000/MW/hr from dispatch intervals (DI) ending 06:00hrs to 08:30hrs on Thursday, 28 February 2008. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not materially affected.
Principal Contributors: This event was initiated at 05:43hrs by the tripping of the Armidale No.5 330kV busbar due to a fault at the Armidale – Dumaresq (8E) busbar isolator. The following transmission lines tripped out-of-service automatically:
- Armidale - Tamworth (85) 330kV line
- Armidale - Coffs Harbour (87) 330kV line
- Armidale - Dumaresq (8C) 330kV line
- Armidale - Dumaresq (8E) 330kV line
- Bulli Creek - Dumaresq (8L) 330kV line
- Bulli Creek - Dumaresq (8M) 330kV line
- Directlink DC link
The Queensland region was electrically isolated from the other NEM regions, interrupting nearly 1000MW of export from Queensland into NSW on QNI. Transfer capability between Queensland and New South Wales was re-established over a single path with the 8C and 8L lines returned to service at 06:38hrs. Loss of the QNI interconnection remained a credible contingency and contingency FCAS could not be provided from NSW to meet Queensland requirements. NEMMCO issued a market notice at 07:53hrs seeking market response to the shortfall in Queensland of Raise 6-second FCAS services. Extra Queensland FCAS services and independent reduction of the Kogan Creek generator to 350 MW for internal reasons helped to reduce the QLD FCAS prices to typical values at DI 08:30.
Market Performance: NEMMCO is investigating the power system security and market performance during the course of the event and will publish the findings in due course.
Saturday, 23 February 2008
Market Outcomes: The Queensland region saw energy price fluctuations between trading interval (TI) ending 10:00hrs and TI 16:00hrs on Saturday, 23 February 2008. The energy price reached a maximum of $9,153.61/MWh at TI 14:00hrs. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected. A market notice was issued at 15:43 hrs to alert the market that the Cumulative Price Threshold was forecast to be exceeded at 16:30 hrs based on the latest predispatch information. The threshold was not reached and the weekly cumulative price for Queensland was approximately $145,000 at the end of the day.
Principal Contributors: The Queensland region was experiencing very high temperatures with a maximum of 39 degrees at Archerfield (near Brisbane) on the day. The 30-minute market demand in Queensland reached 7993MW at TI 14:30hrs.
Approximately 2000MW of Queensland's 10,000MW available generation was offered at prices exceeding $7,000/MWh through the event. Most of the high-priced capacity was not dispatched and was available as reserve.
Transfer capability from New South Wales was restricted to 200MW on the QNI interconnector to prevent voltage collapse on loss of the largest Queensland unit (Kogan Creek). The Terranora interconnector was flowing in the southwards direction to manage the planned outage of the Alstonville to Ballina (8503 and 8507) 66kV lines in northern NSW.
The Queensland energy prices returned to typical values when the Queensland demand decreased and approximately 175MW of Queensland generation capacity was shifted to the lower priced bands between DI 15:45hrs and DI 15:50hrs.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Friday, 22 February 2008
Market Outcomes: The Queensland region saw energy price fluctuations between trading interval (TI) ending 11:30hrs and TI 17:30hrs on Friday, 22 February 2008. The energy price reached a maximum of $9,561.42/MWh at TI 15:30hrs. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
Principal Contributors: The Queensland region was experiencing high temperatures with a maximum of 33 degrees in South Queensland on the day. The 30-minute market demand in Queensland reached 8082MW at TI 16:30hrs.
Approximately 2000MW of Queensland's 10,000MW available generation was offered at prices exceeding $7,000/MWh through the event. Most of the high-priced capacity was not dispatched and was available as reserve.
Between dispatch interval (DI) ending 10:25hrs and DI 17:05hrs, supply from New South Wales was restricted to 165MW on the QNI interconnector and 30MW on the Terranora interconnector to prevent voltage collapse on loss of the largest Queensland unit (Kogan Creek) with the unplanned outage of the Lismore Static Var Compensator (SVC). During this period, local Queensland generators were re-offering their generation capacity between the different priced bands resulting in the price fluctuations.
The Queensland energy prices returned to typical values by DI 17:05 when the QNI and Terranora interconnector transfer capability increased with the Lismore SVC returning to service.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Thursday, 21 February 2008
Market Outcomes: The energy prices in Queensland region increased significantly to a maximum of $887.57/MWh at trading interval ending 15:30hrs on Thursday, 21 February 2008. At DI 15:15hrs, the price was $4994.94/MWh. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
Principal Contributors: The Southern Queensland region was experiencing high temperatures of above 30 degrees on the day. The 5-minute market demand in Queensland increased by 116MW between DI 15:10hrs and DI 15:15hrs to 7670MW. This coincided with a shift of approximately 90MW of Swanbank power station’s generation capacity to the bands priced at more than $9,900/MWh.
Power transfer from New South Wales was restricted to approximately 109MW on the QNI interconnector and 52MW on the Terranora interconnector to prevent voltage collapse on loss of the largest Queensland unit, Kogan Creek.
The Queensland energy prices returned to typical values by DI 15:20hrs when the Queensland market demand decreased by approximately 147MW and the QNI interconnector transfer capability was increased by 31MW.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Wednesday, 20 February 2008
Market Outcomes: The energy prices in Queensland region increased significantly to a maximum of $872.71/MWh at trading interval ending 16:30hrs on Wednesday, 20 February 2008. At DI 16:25hrs, the price was $4991.85/MWh. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
Principal Contributors: Kogan Creek generator tripped from 524MW at 16:10hrs. The Queensland region market demand for the TI 16:30 was 7234MW, the highest for the day.
Transfer capability from New South Wales was restricted to approximately 250MW on the QNI interconnector due to a power system stability limit with the Braemar Static Var Compensator (SVC) out of service and restricted to 53MW on the Terranora interconnector to manage the outage of one Directlink cable.
The Queensland energy prices returned to typical values by DI 16:30hrs when the Queensland market demand decreased by approximately 119MW and the QNI interconnector transfer capability was increased by 60MW with the Braemar SVC returning to service.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Tuesday, 19 February 2008
Market Outcomes: The South Australian region experienced high energy prices on two separate occasions in the afternoon and evening of Tuesday, 19 February 2008. The region saw a maximum price of $6087.21/MWh at trading interval (TI) ending 18:00hrs. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected. The cumulative price for South Australia was approximately $143,000 at the end of the day.
The change in the South Australia energy prices and Murraylink and Heywood interconnector flows caused prices at dispatch interval (DI) ending 17:40hrs and DI 18:05hrs to be triggered as “subject to review”. The prices were accepted as no manifestly incorrect input was identified.
Principal Contributors: The 30-minute market demand in the South Australian region reached 2,845 MW at 17:00hrs, driven by temperatures in Adelaide of up to 37.8 degrees.
The Torrens Island generator shifted 600MW of its 1150MW capacity to the bands priced near $9,000/MWh. The reason submitted with the re-offer was “PORTFOLIO OPTIMISATION:: PRICE/VOLUME TRADE OFF”. Some of this capacity had to be dispatched to supply the South Australian load, and the energy price was determined consistent with that offer. This capacity was shifted back to the lower priced bands at DI 14:35hrs.
At 17:45hrs, Torrens Island generator again shifted 820MW of its 1040MW available capacity to the expensive priced bands and shifted it back by DI 18:05hrs.
Support to South Australia with cheaper capacity from Victoria was limited to less than 370MW on the Heywood interconnector due to a power system stability limit and less than 100MW on Murraylink.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Monday, 18 February 2008
Market Outcomes: The South Australian energy prices remained above $9,950/MWh from dispatch interval (DI) ending 12:35hrs to DI 18:30hrs on Monday, 18 February 2008. The cumulative price for South Australia was approximately $134,000 at the end of this high price period. The Cumulative Price Threshold for the introduction of an Administered Price Period is $150,000.
Energy prices in Snowy and Victoria also increased to a maximum of $1791.33/MWh and $1582.57/MWh respectively at trading interval (TI) ending 16:00hrs. Counter-price flows occurred on the Snowy-Vic directional interconnector during this period however the Snowy CSP/CSC mechanism resulted in no negative settlement residue accumulation.
Principal Contributors: The southern NEM regions were experiencing high demands. The 30-minute market demand in the South Australian region reached 2,881 MW, driven by temperatures in Adelaide of up to 37 degrees. The Victorian 30-minute market demand was 8,619MW with a Melbourne temperature of 33 degrees.
Torrens Island power station was offered with 880MW of its 1040MW capacity priced at more than $9,900/MWh, and was setting the price during the high energy priced period in South Australia. Support to South Australia with cheaper capacity from Victoria was limited to less than 350MW on the Heywood interconnector due to a power system stability limit and less than 100MW on Murraylink.
Transfer capability on NSW-Snowy and Snowy-Vic interconnectors was restricted by a thermal constraint equation that avoids overloading of the Upper Tumut to Murray (65) line on trip of the Lower Tumut to Murray (66) line. The high energy prices in Snowy and Victoria coincided with the period when there was an increase in the flow on line 65. This required the dispatch of the expensive generation capacity offered by Murray power station. During the period in review, most of the 1,500MW capacity of Murray power station was offered in the highest priced band of $9,999/MWh. The counter-price flows were due to a binding system normal intra-regional constraint between Tumut and Murray in the Snowy region. NEMMCO did not intervene to manage the negative residues as they were managed through the CSP/CSC mechanism.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Friday 15 February 2008
Market Outcomes: The Victoria, South Australia and Tasmania regions saw significantly high energy prices on the evening of Friday, 15 February 2008. The prices were $3247.37/MWh, $3134.83/MWh and $1735.18/MWh respectively at trading interval (TI) ending 16:00hrs. The Tasmanian region also saw a negative price of -$487.43/MWh at TI 16:30hrs. The energy and FCAS prices in other regions were not materially affected.
The change in the South Australia and Victoria energy prices and Murraylink, Heywood, Vic-Snowy and Basslink interconnector flows caused prices at dispatch intervals (DI) ending 15:55hrs and 16:05hrs to be triggered as “subject to review”. The prices were accepted as no manifestly incorrect input was identified.
Principal Contributors: A planned outage of the Wagga to Yanco 132kV (994) line and Uranquinty to Wagga 132kV (9R1) line took place from 05:05hrs to 17:06hrs. TransGrid advised at 15:35hrs that the estimated flow on the other Wagga to Uranquinty (9R2) line would be 176MW after a trip of the Wagga to Darlington Point 330kV (63) line. The 9R2 line rating was 151MW. In accordance with TransGrid's operating procedure, constraint equations were invoked to manage the line outages and the X5 tripping scheme was disabled just prior to the start of DI 15:55hrs.
One of these constraint equations was violated from DI 15:55hrs to DI 16:00hrs and bound from DI 16:05hrs to DI 17:10hrs. The flows from Snowy to Victoria reduced by just over 1000MW and energy prices increased as higher priced capacity in Victoria and South Australia had to be dispatched.
Between DI 15:55 and DI 16:00, Tasmanian generators shifted approximately 920MW of generation capacity to the bands priced at less than $0/MWh. At DI 16:00hrs the energy price in Tasmania was capped to VoLL ($10,000/MWh) with the price being set by a South Australian generator offer and Basslink was unconstrained. At the next DI, the Tasmanian energy price was negative as it was set by the local generator offers with Basslink constrained. The energy prices in Tasmanian returned to typical values after the Basslink flow reversed towards Victoria.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Friday, 8 February 2008
Market Outcomes: The Queensland energy price increased to $858.74/MWh at trading interval ending 17:00hrs. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
The movement of the Queensland energy prices to $4,994.95/MWh and a 364MW change in the QNI interconnector flows caused prices at dispatch interval (DI) ending 17:00hrs to be triggered as “subject to review”. The prices were accepted as no manifestly incorrect input was identified.
Principal Contributors: The Millmerran to Middle Ridge (9908) 330kV transmission line tripped. An outage constraint equation was invoked for DI 17:00hrs up to DI 18:30hrs to manage flows on the Braemar to Tarong (8814 and 8815) transmission lines . The constraint equation had been updated to take account of recent network changes and limits. It bound at DI 17:00 with a standard line rating value of 1096MW. Powerlink does not provide rating information to NEMMCO through a dynamic line rating telemetry system like those supported by TransEnd and SP Ausnet. In accordance with procedure, Powerlink was asked if the rating might be reviewed, taking into consideration the ambient conditions (temperature, windspeed, etc) so that the power system security limits during the forced outage could be confirmed.
Powerlink provided an updated real time rating of 1629MW - a 49% increase. The Queensland energy price returned to typical values for DI 17:05 hrs. On this occasion it is likely that the high price would not have appeared if a dynamic rating advice facility were available.
Market Performance: The high Queensland price was consistent with the information provided to NEMMCO.
Thursday, 7 February 2008
Market Outcomes: The Queensland region experienced significantly high energy prices (maximum of $6622.24/MWh at trading interval ending 16:30hrs) on the afternoon of 7 February 2008. The average price for the day was $215.98/MWh. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
Principal Contributors: The Queensland region was experiencing a tight supply/demand situation with total demand reaching 7750MW for TI 15:00hrs. Transfer capability from NSW on the QNI interconnector was restricted due to the action of a constraint equation to avoid voltage collapse for the loss of the Tarong North unit and the Terranora interconnector was limited by a thermal constraint equation to avoid overloading of the Lismore 330kV to Lismore (9U9) 132kV line on trip of the other Lismore 330kV to Lismore (9U8) 132kV line.
Between DI 14:50 and DI 15:05, approximately 236MW of Queensland generation capacity (including Millmerran and Tarong generators) shifted their generation capacity from the lower priced bands to bands priced at more than $7,000/MWh. Kogan Creek generator was out-of-service from approximately 09:10hrs on the day.
The simultaneous trip of the Calvale to Tarong (8810 and 8811) 275kV transmission lines was classified as a credible contingency from DI 15:45hrs to DI 16:50hrs due to lightning in the vicinity. The initial constraint equation that was invoked between DI 15:45hrs to DI 16:30hrs to manage the line reclassification was designed to apply for the shoulder season. The constraint equation for the summer season had been updated for the recent Greenbank to Middle Ridge line augmentation. This constraint equation was invoked between DI 16:35 to DI 16:50 but did not bind in dispatch.
The energy prices in Queensland returned to typical values when the summer constraint equation was invoked and Queensland generators shifted their generation capacity to the lower priced bands.
Market Performance: Power system security was maintained throughout the event. NEMMCO is investigating the circumstances of the shoulder season constraint being invoked. A Market Event Report will be published to report the findings.
Monday, 4 February 2008 (Morning)
Market Outcomes: The Queensland region experienced an energy price of -$500.34/MWh at trading interval ending 04:30hrs. The maximum Queensland Frequency Control Ancillary Service (FCAS) prices for lower 6-second service was $1025.06/MW/h at DI 04:15hrs and for lower 5-minute service was $1020.82/MW/h at DI 04:20hrs. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
The movement in the Queensland energy price to -$1000/MWh and QNI interconnector flow caused prices at DI 04:15hrs to be triggered as “subject to review”. The prices were accepted as no manifestly incorrect input was identified.
Principal Contributors: The simultaneous trip of the Bulli Creek to Dumaresq 8L and 8M 330kV transmission lines was reclassified as a credible contingency from DI 04:10hrs to DI 05:35hrs, due to lightning in the vicinity. This reduced the target flow on the QNI interconnector by approximately 506MW flowing in the Queensland to New South Wales direction.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Monday, 4 February 2008 (Afternoon)
Market Outcomes: The South Australia, Victoria and Tasmania regions experienced energy prices of $1543.57//MWh, $1469.09/MWh and -$102.22/MWh respectively at trading interval ending 14:30hrs. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
The change in the South Australia and Victoria energy prices and Murraylink and Heywood interconnector flows caused prices at DI 14:20hrs to be triggered as “subject to review”. The prices were accepted as no manifestly incorrect input was identified.
Principal Contributors: Some South Australian and Victorian generators shifted their generation capacity to the bands priced at more than $7,000/MWh from DI 14:00hrs when the southern NEM regions were experiencing a tight supply/demand situation. At DI 14:15hrs, supply from the northern NEM regions through the Vic-Snowy interconnector was restricted due to a constraint equation for the outage of the Lower to Upper Tumut (64) 330kV transmission line.
Tasmanian generators shifted approximately 890MW of their generation capacity to the bands priced at $0/MWh at DI 14:25hrs. This contributed to the negative prices in Tasmania.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Monday, 4 February 2008 (Evening)
Market Outcomes: The Queensland region experienced an energy price of $1,689.02 /MWh at trading interval ending 19:00hrs. Each of the Frequency Control Ancillary Service (FCAS) lower contingency prices (lower 6-second, lower 60-second and lower 5-minute) in Queensland was above $9,990/MWh at dispatch interval (DI) ending 18:55hrs. The FCAS prices for some of the lower contingency services remained above $1,000/MWh until DI 20:30hrs. Energy and FCAS prices in other NEM regions were not affected.
The movement in the Queensland energy price to $9,999.50/MWh and change in QNI interconnector flows caused prices at DI 18:55hrs to be triggered as “subject to review”. The prices were accepted as no manifestly incorrect input was identified.
Approximately $38,000 of negative settlement residues were accrued on the Queensland to NSW directional interconnector at TI 19:00hrs.
Principal Contributors: The simultaneous trip of the Braemar to Tarong (8814 and 8815) 275kV transmission lines was reclassified as a credible contingency from DI 18:50hrs to DI 22:05hrs due to lightning in the vicinity. This introduced a 376MW increase in the target flows of the QNI interconnector in the Queensland to New South Wales direction at DI 18:55hrs.
The simultaneous trip of the Bulli Creek to Dumaresq (8L and 8M) 330kV transmission lines was reclassified as a credible contingency from DI 17:55hrs to DI 21:45hrs, due to lightning in the vicinity. This resulted in an increase in Queensland lower contingency FCAS services requirements to cover the loss of the QNI interconnector.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
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