Market Outcomes: New South Wales recorded an energy price of $8345.79/MWh for the Trading Intervals (TI) ending 16:00hrs on Monday, 22 February 2010. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
Principal Contributors: The Wallerawang No.8 unit tripped from 377MW at 15:31hrs, causing a 250MW step increase in the power flow from Mt Piper to Wallerawang. A system normal constraint, preventing the post contingent overload of one of these lines, was violating for the five Dispatch Intervals (DIs) 15:40 to 16:00hrs, causing the 5-minute dispatch prices to be set at the Market Price Cap of $10,000/MWh.
Some NSW generators were constrained off by the Mt Piper-Wallerawang constraint, whilst others were either fully dispatched or ramp rate constrained. Prices returned to normal levels and the constraint violation was cleared at 16:05hrs when the rating of the Mt Piper-Wallerawang 70 and 71 lines was increased in accordance with power system security procedures and advice from Transgrid.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Market Outcomes: Queensland recorded high energy prices reaching $4083.62/MWh for the Trading Intervals (TIs) ending 12:30 to 17:00hrs on Monday, 15 February 2010. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
Negative residues of $25,756 were accrued on the Queensland to New South Wales directional interconnectors on the day. Negative residues of $16k for the New South Wales to Queensland direction were small compared to the $506k of positive residues recorded on the day
Principal Contributors: The key contributors to the high prices were high regional demand, a lightning threat to the Central to Southern Queensland interconnection and generator bidding behavior. Demand in Queensland reached 8855MW with temperatures in excess of 31ºC at Archerfield, Brisbane.
The net flows from New South Wales to Queensland during the high priced intervals were between 60MW to 120MW. The flows on the Terranora interconnector were limited as two of the three Directlink cables were out of service. The flows on the QNI interconnector were limited by a constraint that avoids voltage collapse on loss of the Kogan Creek generator.
There were no Lack of Reserve conditions and there was around 1500MW of capacity priced at more than $7000/MWh in the Queensland region. During the event Queensland generators were actively shifting their generation capacity between the different price bands, contributing to price fluctuations. At 12:05hrs, several generators shifted an additional 505MW of their combined generation capacity to bands priced at more than $7,000/MWh. At various intervals, some fast start units shifted their generation capacity to the lower priced bands in order to relieve the high prices.
From 11:40hrs, the loss of the double circuit Calvale to Tarong (8810 and 8811) 275kV transmission lines were classified as a credible contingency due to lightning in the vicinity. The constraint equation that was invoked to manage the reclassification was binding sporadically throughout the day and contributed to the price fluctuations.
Negative residues on the Queensland to New South Wales directional interconnector exceeded the threshold from DI 14:55hrs. The accumulation of negative residues was not managed because the dispatch process corrected the counter price flow by DI 15:05hrs and the accumulation was not forecast in the predispatch timeframe.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Market Outcomes: New South Wales recorded high energy prices reaching $3162.01/MWh for the Trading Intervals (TIs) ending 11:00 to 16:00hrs and a negative price of -$57.19/MWh at TI 17:00hrs on Friday, 12 February 2010. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
Negative residues of $67,700 were accrued on the New South Wales to Queensland directional interconnectors, and $68,400 on the New South Wales to Victoria directional interconnectors on the day.
Principal Contributors: Demand in New South Wales reached 13160MW with temperatures in excess of 37ºC in Sydney.
A system normal constraint in New South Wales, preventing the post contingent overload of a Mt Piper to Wallerawang 330kV line, was binding for Dispatch Intervals (DIs) 10:30 to 17:00hrs. During this time over 10,000MW of the generation offered in New South Wales was offered at negative prices. Some generators that were not constrained off by the Mt Piper-Wallerawang constraint shifted more than 500MW their generation capacity to the higher priced bands prior to the high price event. Between 7:05hrs to 13:05hrs, the Mt Piper No.1 unit had between 660MW to 700MW of its generation capacity in fixed bids to facilitate a reactive power test. The Wallerawang No.7 unit was operating at less than 300MW during the period of high prices even though it was available for 500MW. With most of NSW generation being either fully dispatched at the lower priced bands, constrained off by the Mt Piper-Wallerawang constraint, ramp rate limited or FCAS trapezium limited, generation capacity from the higher priced bands were dispatched.
For some DIs this constraint forced counter price flow on both the New South Wales to Queensland and the New South Wales to Victoria interconnectors, leading to the imposition of negative settlement residue management procedures from 11:05hrs and 11:20hrs respectively.
At 16:40hrs, the energy prices in NSW dropped to -$454.66/MWh when the regional demand decreased by 144MW. This resulted in negatively priced generation setting the price while other generation capacity were either ramp down limited or FCAS trapezium limited.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Market Outcomes: New South Wales recorded high energy prices of $1997.96/MWh and $1703.49/MWh for the Trading Intervals (TIs) ending 14:30 and 15:00hrs, and negative energy prices of -$264.31/MWh and -$147.22/MWh for the TIs ending 15:30 and 16:00hrs on Thursday, 11 February 2010. Queensland recorded an energy price of -$167.43/MWh for TI 14:30hrs. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
Negative residues of $83,800 were accrued on the New South Wales to Queensland directional interconnectors, and $168,380 on the New South Wales to Victoria directional interconnectors on the day.
Principal Contributors: The high prices were mostly due to price spikes of $10,000/MWh during Dispatch Intervals (DIs) 14:10 and 15:00hrs. The negative prices were due to price spikes of approximately -$990/MWh during DIs 15:05, 15:15 and 15:35hrs.
A system normal constraint in New South Wales, preventing the post contingent overload of a Mt Piper to Wallerawang 330kV line, was binding for most Dispatch Intervals (DIs) from 14:05 to 15:30hrs. The scheduled unit with the largest coefficient in this constraint equation is Wallerawang No.7 (Wallerawang No.8 was out of service). At 13:38hrs the Wallerawang No.7 unit capacity reduced from 500MW to 220MW. The unit was dispatched down at its maximum offered ramp rate of 3MW/minute. The unit moved from 492MW to 254MW over a period of 5 DIs, or 9.5MW/min average. During this time as much as 80% of the generation offered in New South Wales was offered at negative prices, and was dispatched up accordingly. This forced counter price flow on both the New South Wales to Victoria and New South Wales to Queensland interconnectors, leading to the imposition of negative settlement residue management procedures from 14:30hrs.
During DIs 14:10 to 14:40hrs counter price flow occurred towards Victoria. The constraint also caused counter price flow towards Queensland during DIs 14:10 to 15:05. At 14:10hrs over 500MW of cheaper New South Wales generation was constrained off, and the flow from Queensland to New South Wales was reduced by 760MW. The excess generation in Queensland set the negative price for the DI in that region, whilst $10,000/MWh offers from other generators closer to the Sydney load centre had to be cleared, setting the NSW regional price.
At 14:57hrs the Wellington-Mt Piper 72 330kV line tripped and about 100MW of the Wellington 330kV load was taken up by the 132kV lines out of Wallerawang, increasing the flow through the Mt Piper-Wallerawang 71 and 72 330kV lines by the same amount. The Mt Piper Wallerawang constraint was violated during DI 15:00hrs, setting the energy price for New South Wales at the Market Price Cap of $10,000/MWh. The negative price spikes occurred when the system normal constraint was not binding and allowed previously constrained off generation to set the price.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Market Outcomes: High energy prices, reaching $8823.77/MWh were recorded in South Australia during the Trading Intervals (TIs) ending 14:00 to 16:00hrs on Wednesday, 10 February 2010. Victoria recorded high prices from TI 14:00 to 15:30hrs with prices reaching $1489.18/MWh at 14:30hrs. At the end of the day the cumulative price reached $137,077 or 91% of the threshold for Administered Price.
Approximately $683000 of negative residues were accrued on the Victoria to New South Wales directional interconnectors on the day.
Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
Principal Contributors: The demand in the South Australian region reached 3079MW at 14:00hrs, due to temperatures of 37ºC in Adelaide. Wind generation in South Australia was 95MW at 14:00hrs, increasing to approximately 200MW during the period under review.
A constraint was invoked from 14:10 to 16:30hrs to manage the accumulation of negative residues on the Victoria to New South Wales directional interconnectors. An actual Lack of Reserve (LOR1) condition was declared for the South Australian region from 11:40 to 17:05hrs.
Due to lightning storms a number of parallel transmission lines in Victoria and South Australia were reclassified as credible contingencies. The Dederang-Glenrowan no 1 and no 3 lines in Victoria were reclassified and appropriate constraints were invoked from 13:55hrs. The Eildon-Mt. Beauty no 1 and no 2 220kV lines in Victoria were reclassified as a credible contingency at 12:05hrs. The Para-Robertstown and Robertstown-Tungkillo 275kV lines in South Australia were reclassified at 14:45hrs. The constraint sets that were invoked for these reclassifications were all ended at 17:05hrs.
The Dederang-Glenrowan 220kV reclassification constraint limited the flow towards South Australia to between 60MW and 200MW for most DIs during the TIs 14:00 to 16:00hrs, and constrained off a number of Victorian generators. A voltage stability constraint for South Australia had a lesser impact on the flow on the Heywood interconnector, binding for two DIs during the high priced period. The reclassification constraint forced flow from Victoria towards New South Wales, causing the accumulation of negative residues on the Victoria to New South Wales interconnector. From DIs 15:40 to 16:00hrs negative residue management restricted this counter price flow to between 200 and 250MW. A number of thermal constraints were binding during the high priced period. One of these constraints, avoiding the overload of the Robertstown transformer no 1 on the loss of the Robertstown-Para and Robertstown-Tungkillo 275kV lines, violated for the two Dispatch Intervals (DIs) 14:55 and 15:00hrs.
During the high priced period between 320MW and 390MW of South Australian generation was offered in bands priced at more than $9000/MWh. The high demand in South Australia and the reclassification of the Dederang-Glenrowan no 1 and no 3 lines in Victoria were the main contributors to the high prices. For most DIs cheaper generation in Victoria was constrained off and expensive generation offers had to be cleared in South Australia.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Market Outcomes: High energy prices, reaching $9999.92/MWh were recorded in South Australia during the Trading Intervals (TIs) ending 13:00 to 18:30hrs on Tuesday, 9 February 2010. Victoria recorded high prices from TI 14:30 to 17:00hrs with prices reaching $7847.30/MWh at 16:30hrs. At the end of the day the cumulative price reached $123,500 or 82% of the threshold for Administered Price.
Approximately $1.1M of negative residues were accrued on the Victoria to New South Wales directional interconnectors on the day.
Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
Principal Contributors: The demand in the South Australian region reached 3193MW at 16:30hrs, due to temperatures of almost 39ºC in Adelaide. Wind generation in South Australia was only 18MW at 13:00hrs, increasing to approximately 200MW in the early evening. Temperatures of 32ºC were recorded in Melbourne and Victorian demand peaked at 9552MW at 14:00hrs.
An actual Lack of Reserve (LOR2) condition was declared at short notice for South Australia from 16:36hrs to 17:15hrs. The short notice was due to the reclassification of the Dederang-Glenrowan no 1 and no 3 lines in Victoria as a credible contingency at 16:10hrs. An actual Lack of Reserve (LOR1) condition was declared from 17:30 to 18:15hrs.
Two voltage stability constraints limited the transfer from Victoria to South Australia to between approximately 220MW and 440MW during the high priced periods. Two constraints, avoiding the overload of Dederang to Murray No.2 330kV line for loss of the parallel No.1 line, limited flow towards Victoria on the VIC-NSW interconnector to between approximately 50MW and 290MW between Dispatch Intervals (DIs)14:30 and 16:10hrs. At 16:10hrs the Dederang to Glenrowan 220kV reclassification constraint was invoked. Some Victorian generation was constrained off, the flow towards South Australia was reduced by 200MW, and flow was forced (counter-price) from Victoria towards New South Wales. The constraint violated for two DIs, and was binding from 16:25 to 18:30hrs. Negative settlement residue management procedures were invoked but delayed due to concerns about network security management.
During the high priced period over 400MW of South Australian generation was offered in bands priced at more than $9000/MWh. The high demand, South Australia voltage stability constraints and the reclassification constraints in Victoria ensured that the expensive generation offers were cleared in South Australia and prices were set accordingly.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Market Outcomes: High energy prices, reaching $8430.79/MWh were recorded in South Australia during the Trading Intervals (TIs) ending 11:30 and 15:00 to 17:30hrs on Monday, 8 February 2010. Victoria recorded high prices from TI 15:00 to 16:30hrs with prices reaching $6481.89/MWh at 16:00hrs. At the end of the day the cumulative price reached $43000 or 29% of the threshold for Administered Price.
Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
Principal Contributors: The demand in the South Australian region reached 3045MW at 16:30hrs, due to temperatures of almost 38ºC in Adelaide. Wind generation in South Australia was 58MW at 11:30hrs, increasing to approximately 200MW in the late afternoon. Temperatures of 35ºC were recorded in Melbourne and Victorian demand peaked at 9577MW at 16:00hrs. An actual Lack of Reserve (LOR1) condition was declared for South Australia from 11:28hrs to 18:25hrs.
Two voltage stability constraints limited the transfer from Victoria to South Australia to between approximately 180MW and 400MW during the high priced periods. A system normal constraint, avoiding the overload of Dederang to Murray No.2 330kV line for loss of the parallel No.1 line, limited flow towards Victoria on the VIC-NSW interconnector to approximately 200MW during the high priced periods. From 14:30hrs to 17:30hrs approximately 360MW of South Australian generation was offered in bands priced at more than $9000/MWh.
The high demand in South Australia and Victoria and low wind generation in South Australia resulted in the expensive offers being cleared and prices were set accordingly.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Market Outcomes: New South Wales experienced high energy prices during Trading Intervals (TIs) ending 10:30 to 12:00hrs, reaching $5540.90/MWh at 12:00hrs, and a negative price of -$98.53/MWh during TI 13:00hrs. Energy and Frequency Control Ancillary Service (FCAS) prices in other NEM regions were not affected.
Approximately $1.68m and $4.90m of negative residues were accrued on the New South Wales to Queensland, and the New South Wales to Victoria directional interconnectors on the day.
Principal Contributors: Initial conditions included moderately high NSW demand around 11000MW, the Mt Piper 330/132kV transformer out of service (opening the 132kV tie between the Mt Piper and Wallerawang 330Kv switchyards), Wallerawang No.8 unit out of service and Wallerawang No.7 500MW unit capacity initially limited to 240MW. Due to some 132kV line outages in the Energy Australia network supplying the Sydney CBD, contingent overloads began appearing on the 330kV cables supplying the CBD from Sydney South. At 10:20 hrs the Kemps Creek Sydney South (13) 330kV line was taken out of service to reduce the flow on these cables for the rest of the day. This action also had the effect of temporarily increasing the flow beyond secure limits on the Mt Piper-Wallerawang (70 and 71) 330kV lines to supply Sydney South. Generator ramp rate restrictions caused the relevant constraint equation to be violated for three DIs (10:30 to 10:40hrs inclusive) before NEMDE was able to rebalance NSW generator targets. Export flows on the interconnectors to both NSW and Queensland had to be increased and replaced with expensive NSW generation to achieve secure conditions.
At 10:30hrs, 6200MW of NSW generation was offered in negative price bands. Negative offers increased to 8500MW at 10:35hrs, and 10600MW at 10:40hrs. Once secure conditions were achieved, the marginal value of the constraint equation reduced over the next three DIs, allowing the negative offer prices to set the regional price for DIs 10:55hrs to 11:05hrs. The Mt Piper constraint and a voltage stability constraint (for loss of Kogan Creek) forced flows of up to 276MW from New South Wales to Queensland, and up to 1015MW to Victoria. From 10:55 to 11:05hrs, the management of negative residues reduced the flow on the VIC-NSW interconnector towards Victoria to 500MW. There was also a 650MW reduction in NSW demand between 11:00 and 11:05hrs, which was restored by 11:20hrs.
By 11:20hrs, the level of negatively priced offers in NSW had reduced to 10300MW. The Mt Piper-Wallerawang constraint equation bound again leading to the second period of near-MPC prices for DIs 11:30hrs to 11:45hrs. A 300MW reduction in regional demand at 11:54hrs for 5 minutes caused the regional price to return to normal levels. The capacity offered at less than $25/MWh in NSW increased by 500MW from 11:55hrs to 12:30hrs.
The negative price during TI 13:00hrs was due to a price of -$996.81/MWh at DI12:45hrs. The Mt Piper 330/132kV transformer was returned to service at 12:40hrs, reducing the flow on lines 70 and 71 by 100MW and relaxing the Kemps Creek-Sydney South (13)) outage constraint. Unconstrained generation in the negative price bands became marginal and prices were set accordingly.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Market Outcomes: Tasmania experienced negative energy prices reaching a low of -$990.91/MWh for the Trading Intervals (TIs) ending 11:30 to 13:00hrs, and between 14:00 and 17:00hrs on Wednesday, 3 February 2010. The Tasmanian energy price averaged -$76.01/MWh over the day. South Australia and Victoria experienced high energy prices during TIs 14:00 to 17:00hrs, reaching $2040.63/MWh and $2176.88/MWh respectively. FCAS prices and energy prices for Queensland and New South Wales were not affected.
Approximately $23,800 of negative residues were accrued on the Victoria to New South Wales directional interconnectors on the day.
Generators in the Tasmanian region owe approximately $3.6M to AEMO for the day’s energy operations due to the negative prices, and the market customers are to be paid an estimated $2.6M in the spot market. Intra-regional settlement residue was -$300k for the Tasmanian region on the day.
Principal Contributors: During the affected TIs Tasmanian generators offered between 1200MW and 1900MW in negatively priced bands. During TI 13:00hrs, 1400MW of generation was offered at close to the Market Floor Price (-$1000/MWh). During TIs 13:30 and 17:00hrs, between 1000MW and 1700MW of generation was offered at -$1000/MWh, whilst local demand was approximately 600MW.
The Hazelwood-Loy Yang No.1 500kV line outage was extended. The constraint managing this outage forced transfer on Basslink to Tasmania during the TIs 11:30hrs to 12:30hrs. During TIs 14:00hrs to 17:00hrs Basslink was exporting approximately 550MW of generation to Victoria. Excess generation in the negatively priced bands could not be cleared in full and prices were set accordingly.
The high prices in South Australia and Victoria were due to a number of price spikes during the affected TIs. At 13:35hrs Murray power station shifted 1450MW of generation to offer bands priced at approximately the market floor price. This caused a system normal constraint, invoked to avoid exceeding the continuous rating of the No.1 Dederang 330/220kV transformer, to reduce flow on the Murraylink and VIC-NSW interconnectors towards Victoria. The Hazelwood - Loy Yang constraint bound at various DIs constraining off as much as 700MW of negatively priced generation in Victoria’s Latrobe Valley. The two constraints limited flow towards Victoria to approximately 30MW on Murraylink and to a maximum of 167MW (at TI 14:00hrs) on the VIC-NSW interconnector.
Offers of $9100/MWh had to be cleared from a large generating station in north-eastern Victoria and the prices were set accordingly.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
Market Outcomes: Tasmania experienced negative energy prices reaching a low of -$999.64/MWh for the Trading Intervals (TIs) ending 13:00 to 17:00hrs on Tuesday, 2 February 2010. The Tasmanian energy price averaged -$44.04/MWh over the day. South Australia and Victoria experienced high energy prices during TIs 15:30 to 16:30hrs, reaching $3322.12/MWh and $3555.10/MWh respectively. FCAS prices and energy prices for Queensland and New South Wales were not affected.
Generators in the Tasmanian region owe approximately $2.2M to AEMO for the day’s energy operations due to the negative prices, and the market customers are to be paid an estimated $1.5M in the spot market.
Principal Contributors: During the affected TIs Tasmanian generators offered between 1759MW and 1956MW in negatively priced bands. From DIs 14:10hrs to 17:00hrs this negatively priced generation was offered at close to the Market Floor Price (-$1000/MWh), whilst local demand was approximately 600MW. Basslink was dispatched to its upper transfer limit of 594MW of generation to Victoria during the affected TIs. Excess Tasmanian generation in the negatively priced bands could not be cleared in full and the negative prices were set accordingly.
During TI 15:30 and 16:00hrs prices reached $1412.96/MWh and $1338.89/MWh in Victoria and South Australia respectively. The Hazelwood-Loy Yang No.1 500kV line was on a scheduled outage until 17:00hrs and a constraint managing this outage was constraining off approximately 780MW of cheap generation in the Latrobe Valley. Basslink was preferentially dispatched into Victoria due to the negative prices of Tasmanian generators combined with the Basslink energy offer price being near the Market Floor Price. More expensive offers from the remaining generators had to be cleared setting the price in Victoria and South Australia.
The high prices during TI 16:30hrs were mostly due to three price spikes at DIs 16:05, 16:10 and 16:20hrs. At 16:00hrs Murray power station shifted 1350MW of generation to offer bands priced at approximately the market floor price. This caused a constraint, invoked to avoid the overload of a Dederang to Murray 330kV line for trip of the other, to bind between DIs 16:05hrs to 16:20hrs. The constraint limited flow to Victoria on Murraylink and on the VIC-NSW interconnector.
During the three affected DIs, these two binding constraints constrained off cheaper generation in Victoria, whilst reducing flow into Victoria. Offers of $9100/MWh had to be cleared from a large generating station in north-eastern Victoria and the prices were set accordingly.
Market Performance: Outcomes appear to be consistent with the dispatch offers and power system conditions during the event.
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