AEMO Pricing Event Reports - October 2014
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Electricity Pricing Event Report – Tuesday 28 October 2014
Market Outcomes: Spot prices in Tasmania reached $1,731.78/MWh and the sum of all FCAS prices reached $3,947.74/MWh for trading interval (TI) ending 0630 hrs.
FCAS prices and energy prices in other NEM regions were not affected.
Further information is provided below.
Detailed Analysis: During the morning peak demand period the Tasmanian demand increased by approximately 75 MW in two dispatch intervals (DIs) from 0615 hrs to 0625 hrs. With the Basslink flow towards Tasmania at the maximum bid capability the increase in demand had to be sourced from local generators. The Tasmanian energy price reached $10,007.49/MWh for DI ending 0625 hrs when higher priced generation had to be cleared to meet the local demand requirements.
Lower cost generation in Tasmania was limited due to the outage of Gordon PS since 5 October 2014 which typically generates up to 400 MW. Generation offered at $98.36/MWh was available from Tamar Valley OCGT however this unit required more than one DI before being able to generate. A number of units with cheaper priced generation offers were limited by their ramp up rates of 1 MW/min.
Basslink was given a target equivalent to its maximum bid transfer capability of 478 MW towards Tasmania for DI ending 0625 hrs. With insufficient headroom available, Basslink was unable to transfer FCAS. As a result, the FCAS requirement had to be sourced from local Tasmanian generators. The co-optimisation of FCAS and energy prices resulted in a price of $23,469.72/MWh for Raise FCAS services for DI ending 0625 hrs. Raise services offered at cheaper prices by a number of units were limited by their FCAS offer profiles. The constraint equation F_T+NIL_BL_R6_1 which manages Fast Raise requirements in Tasmania for loss of Basslink also violated for DI ending 0625 hrs.
The 5-minute energy price in Tasmania reduced to $44.32/MWh for DI ending 0630 hrs when load at the Nyrstar smelter reduced by approximately 70 MW, presumably in response to the high 5-minute energy price.
The Basslink interconnector received a lower target of 448 MW for DI 0630 hrs which provided the interconnector with headroom to transfer FCAS. The sum of all Raise service prices in Tasmania reduced to $5.85/MWh when the requirement for the services reduced.
The high 30 minute FCAS price was forecast in a number of the pre-dispatch schedules. The high 30 minute spot price was not forecast in the pre-dispatch schedules due to the significant differences in the wind forecasts in dispatch and pre-dispatch and the sudden load increase.
Electricity Pricing Event Report – Monday 27 October 2014
Market Outcomes: The sum of all FCAS prices in Tasmania reached $4,405.84/MWh for trading interval (TI) ending 0330 hrs.
Tasmanian energy prices as well as FCAS and energy prices for the other NEM regions were not affected.
Further details are provided below.
Detailed Analysis: The Basslink interconnector was on a planned outage from DI ending 0505 hrs on 25 October 2014 and returned to service by DI ending 1815 hrs on 28 October 2014.
Between 0230 hrs and 0445 hrs, the loss of the parallel Farrell-Sheffield 220 kV lines was declared a credible contingency due to lightning in vicinity (refer to Market Notices 46716 and 46724). The reclassification constraint sets F-T-FASH_N-2, T-FASH_N-2_HM_C and T-NIL_HM_CLOSE were invoked during the reclassification period to manage the possible simultaneous tripping of the lines.
The Tasmanian 5-minute Fast Raise service price increased to $4,414.16/MWh for all DIs between 0300 hrs to 0345 hrs, except DI 0310 hrs when the Fast Raise service requirement increased. With Basslink unavailable to transfer FCAS, the Tasmanian FCAS requirement had to be sourced from selected local generators. Up to 55 MW of Fast Raise service from John Butters, Reece unit 2 and Bastyan PS were constrained off by constraint equation F_T+FASH_N-2_TG_R6 during the high price period. This constraint, which was invoked to manage the line reclassification, violated for several intervals due to lack of available Fast Raise service from remaining Tasmanian generators. The price reduced to $0.80/MWh at DI ending 0355 hrs with the decrease in the Fast Raise service requirement.
The pre-dispatch schedules forecast high 30 minute FCAS prices for Tasmania.
Electricity Pricing Event Report – Saturday 25 October 2014
Market Outcomes: South Australian spot price reached $1,670.35/MWh while Victoria spot price went negative at -$148.63/MWh for trading interval (TI) ending 0000 hrs (on Sunday 26 October 2014).
FCAS prices and energy prices for the other NEM regions were not affected by this event.
Detailed Analysis: 5-minute dispatch price in South Australia reached $9,901.83/MWh for dispatch interval (DI) ending 2335 hrs during high demand period due to hot water load management (ripple control). Wind generation in South Australia was low at approximately 82 MW for TI ending 0000 hrs when the demand peaked at 1,582 MW.
Hallet PS and one generating unit of Dry Creek PS were given instructions to synchronise but required more than one DI before being able to generate. Cheaper priced generation was also available from Northern PS but the units were limited by ramp up rates of 3 MW/min.
The target flows towards South Australia on the Heywood and Murraylink interconnectors were increased to 460 MW and 114 MW, respectively to meet the South Australian demand. These target flows exceeded the export limits on both interconnectors set by constraint V>S_NIL_HYTX_HYTX (which limits Heywood export when the initial Heywood interconnector flow exceeds the pre-defined Heywood transformer rating) and constraint V>>SML_NIL_7A (which limits Murraylink export to avoid overloading of the Ballarat North-Buangor 66 kV line for the contingent loss of the Ballarat-Waubra-Horsham 220 kV line). The two constraints violated for DI ending 2335 hrs.
The constraint V>>SML_NIL_7A also caused targets of flow from Victoria to New South Wales on the VIC-NSW interconnector to decrease by 688 MW and Murray generation to increase by 87 MW. This resulted in excess cheaper generation in Victoria and caused dispatch price in Victoria to collapse to the Market Floor Price (MFP) of -$1,000/MWh.
The 5-minute prices in South Australia and Victoria returned to the normal levels of $27.25/MWh and $24.05/MWh, respectively, for DI ending 2340 hrs. This happened when a total of 313 MW of South Australian generation was rebid to bands priced at $0/MWh and the MFP, and approximately 102 MW of non-scheduled generation at Angaston and Port Stanvac PS came on line in response to the high dispatch prices.
Neither the high 30-minute spot price in South Australia nor the negative spot price in Victoria was forecast in the pre-dispatch schedules as they were the result of a sudden load increase that caused a spike in the 5-minute price.
Electricity Pricing Event Report – Wednesday 15 October 2014
Market Outcomes: The sum of all FCAS prices in Queensland reached $85.19/MWh, $74.25/MWh and $72.87/MWh for trading intervals (TIs) ending 0600 hrs, 0830 hrs and 0900 hrs respectively.
FCAS prices and energy prices in other NEM regions were not affected by this event.
Further information is provided below.
Detailed Analysis: The Bulli Creek-Dumaresq 8L 330 kV transmission line was on a planned outage from 13 October and scheduled to return to service on 23 October 2014. The outage introduced a risk of separation between Queensland and New South Wales. The local FCAS requirements in Queensland increased as a result to cover the loss of the remaining Bulli Creek-Dumaresq 330 kV transmission line.
The target flow of the QNI interconnector towards New South Wales was limited by constraint equation F_Q++ARDM_L5 to ensure that sufficient Lower FCAS requirement in Queensland was available in event of a contingency. The Terranora interconnector was operating at reduced capacity due to the outage of one Directlink cable since 11 July 2012. Flow across the interconnector was limited by constraint equation N_MBTE1_B which manages flow to Terranora load during the outage of one Directlink cable.
The sum of all Lower FCAS services in Queensland reached $147.33/MWh for dispatch interval (DI) ending 0555 hrs when higher priced services were dispatched to meet the local FCAS requirements. Lower regulation services offered by Stanwell and Gladstone PS at cheaper prices were limited by their FCAS offer profile.
The sum of all FCAS prices in Queensland reached $74.25/MWh and $72.87/MWh for TIs ending 0830 hrs and 0900 hrs respectively when the sum of all Lower FCAS services were between $58.11/MWh and $74.36/MWh for several DIs during the morning peak demand period. A number of generating units in Queensland were limited by their FCAS profiles. The sum of all FCAS prices reduced when the flow on the QNI interconnector towards New South Wales gradually reduced.
The high FCAS prices for TIs ending 0600 hrs, 0830 hrs and 0900 hrs were forecast in the pre-dispatch schedules.