Market Notices

84211CONSTRAINTS13/04/2021 02:04:45 PM

Updated generator combinations for SA system strength

AEMO MARKET NOTICE

AEMO has identified two additional combinations to meet the minimum system strength requirements in South Australia.

New combinations:
LOW_57 - 1 x Torrens Island A unit + 2 x Torrens Island B unit + Osborne GT & ST and 1300 MW limit on non-synchronous generation
LOW_58 - 3 x Torrens Island B unit + Osborne GT & ST and 1300 MW limit on non-synchronous generation

The following constraint equation has been updated with the new combinations:
S_NIL_STRENGTH_1

For more information refer to the updated limits advice (which will be published 14 April 2021):
https://www.aemo.com.au/energy-systems/electricity/national-electricity-market-nem/system-operations/congestion-information-resource/limits-advice

For further details on this constraint equation please contact ben.blake@aemo.com.au

Ben Blake
AEMO Operations
     
83382CONSTRAINTS16/03/2021 03:06:24 PM

New Victorian system normal voltage stability limit

AEMO ELECTRICITY MARKET NOTICE

AEMO has identified a new voltage collapse issue in north west Victoria. The voltage collapse occurs at Kerang or Wemen on loss of the Horsham to Murra Warra to Kiamal 220 kV line. Murra Warra wind farm also trips off as a result of this contingency.

The limit will manage post-contingent flow on the Wemen to Kerang 220 kV line to be less than 310 MVA.

The new constraint equation includes generators in south-west NSW and north-west Victoria on the left-hand side as well as Murraylink. Full details on the limits advice are to be published on 17th March 2021 on the AEMO website: https://www.aemo.com.au/energy-systems/electricity/national-electricity-market-nem/system-operations/congestion-information-resource/limits-advice

The following constraint equation will be implemented at 0700 hrs on Thursday 18th March 2021:
V^^V_NIL_KGTS

For full details on the factors this constraint equation has now been loaded into AEMO's pre-production systems.

For further details on this constraint equation please contact terry.liu@aemo.com.au

Terry Liu
AEMO Operations
     
83081CONSTRAINTS01/03/2021 03:49:15 PM

Update - Reclassification of a Non-Credible Contingency Event in Tasmania Region

AEMO ELECTRICITY MARKET NOTICE

Update - Reclassification of a Non-Credible Contingency Event in TAS Region:
Trip of any Tasmanian Transmission Line and Basslink Interconnector

Refer to AEMO Electricity market notices 47360, 47855 and 53957.

In Dec 2014 AEMO reclassified the loss of any transmission line in Tasmania and Basslink Interconnector to be a credible contingency event, for Basslink flow in the direction of Victoria to Tasmania only. This was subsequently updated to exclude faults on either of the two George Town to Pacific Aluminium 220 kV transmission lines or the George Town to Tamar Valley power station 220 kV transmission line in Jan 2015 and Jun 2016 respectively.

Following a power system event in Tasmania on 29/11/2020, and based on updated information from Market Participants, AEMO has further modified this reclassification.

AEMO will now reclassify the loss of any transmission line in Tasmania and Basslink Interconnector to be a credible contingency event, for Basslink flow in the direction of Victoria to Tasmania only.

As a consequence of this reclassification, AEMO will modify the frequency control ancillary service (FCAS) requirements for Tasmania to all require Contingency FCAS services to be sourced from within Tasmania, for Basslink flow in the direction of Victoria to Tasmania.

The following constraint equations will be updated for the above change at 1300hrs Wednesday 3rd March 2020:
F_T++NIL_ML_L5
F_T++NIL_ML_L6
F_T++NIL_ML_L60
F_T++NIL_TL_L5_DS
F_T++NIL_TL_L6_DS
F_T++NIL_TL_L60_DS
F_T+NIL_ML_L5
F_T+NIL_ML_L6
F_T+NIL_ML_L60
F_T+NIL_TL_L5_DS
F_T+NIL_TL_L6_DS
F_T+NIL_TL_L60_DS

Ben Blake
AEMO Operations
     
82983CONSTRAINTS23/02/2021 02:33:12 PM

Updates to system normal voltage collapse constraint equations in south-west NSW

AEMO ELECTRICITY MARKET NOTICE

Refer to market notices 75618 and 80103

TransGrid has advised AEMO of an update to the voltage collapse limit in south-west NSW for loss of Darlington Point to Wagga (63) 330 kV line. The limit will now include a term for Darlington Point solar farm inverters.

Additionally, AEMO has reviewed the operating margins for the two voltage collapse constraint equations in south-west NSW. The operating margin for N^^N_NIL_2 will be reduced from 45 to 30 and N^^N_NIL_3 reduced from 30 to 10.

The following constraint equations will be updated with the above changes at 1000 hrs Wednesday 24th February 2021.
N^^N_NIL_2
N^^N_NIL_3

For further details on these constraint equation please contact ben.blake@aemo.com.au

Ben Blake
AEMO Operations
82947CONSTRAINTS22/02/2021 11:10:12 AM

Update to Vic to SA transient and voltage collapse limits

AEMO ELECTRICITY MARKET NOTICE

Electranet has reviewed the system normal transient and voltage stability Heywood limits from Victoria to South Australia. The revised limits take into account improved distributed rooftop PV trip calcuations for the limits equations.

The revised limits equations will be implemented to the following equations at 1000 hrs Tuesday 23rd February 2021.
V::S_NIL_TBSE_1
V::S_NIL_TBSE_2
V^^S_NIL_TBSE_1
V^^S_NIL_TBSE_2
V^^S_NIL_MAXG_1
V^^S_NIL_MAXG_2
V^^S_NIL_MAXG_3
V::S_NIL_MAXG_1
V::S_NIL_MAXG_2
V::S_NIL_MAXG_3


For further details on this constraint equation please contact diyoni.hoole@aemo.com.au

Diyoni Hoole
AEMO Operations
82819CONSTRAINTS10/02/2021 12:25:04 PM

Update to Vic to NSW voltage collapse limit

AEMO ELECTRICITY MARKET NOTICE

Refer to Market Notice 78621

AEMO has completed a further review of the system normal voltage stability limit for loss of all APD potlines for flows from Victoria to New South Wales. The revised limit is the result of improved reactive modelling in southern NSW which could potentially mean higher transfers into NSW under some generation/load scenarios.

The revised constraint equation includes generators in southern NSW and hydro generation at Mt. Beauty on the left-hand side as well as VIC1-NSW1. Full details on the limits advice are to be published on 11/02/2021 on the AEMO website: https://aemo.com.au/energy-systems/electricity/national-electricity-market-nem/system-operations/congestion-information-resource/limits-advice

The constraint is most likely to bind when there is low Vic demands and high transfers to NSW. When it binds it will restrict Vic to NSW transfers and Hume NSW unit.

This revised limit will be implemented to the following constraint equation at 1000 hrs Thursday 11th February 2021.
V^^N_NIL_1

For further details on this constraint equation please contact terry.liu@aemo.com.au

Terry Liu
AEMO Operations
82115CONSTRAINTS13/01/2021 08:37:07 AM

Update to Voltage Stability limits for Murraylink transfers from South Australia to Victoria

AEMO ELECTRICITY MARKET NOTICE

ElectraNet has advised AEMO of revised voltage stability limits for Murraylink transfers from South Australia to Victoria.

Refer to Market Notice 82079.

The existing limit of 160 MW on Murraylink will be replaced with two voltage stability limits. Only one of the limits would apply depending on whether or not the Monash capacitor banks are available and in-service for switching.

The following constraint sets and equations will be implemented at 1000 hrs Wednesday 13th January 2021:
- constraint set S-NIL containing constraint equation SVML^NIL_MH-CAP_ON.
- constraint set S-MH_CAP (renamed from S-NIL_MN-CAP_OFF) containing constraint SVML^MH-CAP_OFF (renamed from SVML^NIL_MH-CAP_OFF).

Constraint set S-NIL will remain invoked at all times.
Constraint set S-MH_CAP will only be invoked when Monash Capacitors are not available for switching and are out of service or if one or both capacitors are out of service.

The existing equation SVML^NIL_160 in the S-NIL set will be removed.

For full details on the factors these constraint equations have now been loaded into AEMO's pre-production systems.

For further details on these new constraint equations please contact diyoni.hoole@aemo.com.au.

Diyoni Hoole
AEMO Operations
82079CONSTRAINTS12/01/2021 06:12:01 AM

Update to Voltage Stability limits for Murraylink transfers from South Australia to Victoria

AEMO ELECTRICITY MARKET NOTICE

ElectraNet has advised AEMO of revised voltage stability limits for Murraylink transfers from South Australia to Victoria.

The existing limit of 160 MW on Murraylink will be replaced with two voltage stability limits. Only one of the limits would apply depending on whether or not the Monash capacitor banks are available and in-service for switching.

The following constraint sets and equations will be implemented at 1000 hrs Wednesday 13th January 2021:
- constraint set S-NIL containing constraint equation SVML^NIL_MH-CAP_ON.
- constraint set S-NIL_MN-CAP_OFF containing constraint SVML^NIL_MH-CAP_OFF.

Constraint set S-NIL will remain invoked at all times.
Constraint set S-NIL_MN-CAP_OFF will only be invoked when Monash Capacitors are not available for switching and are out of service.

The existing equation SVML^NIL_160 in the S-NIL set will be removed.

For full details on the factors these constraint equations have now been loaded into AEMO's pre-production systems.

For further details on these new constraint equations please contact diyoni.hoole@aemo.com.au.

Diyoni Hoole
AEMO Operations
81296CONSTRAINTS17/12/2020 12:26:52 PM

Update to system strength requirements in North Queensland

AEMO ELECTRICITY MARKET NOTICE

Refer to market notice 80324

AEMO and Powerlink are continuing to investigate system strength requirements in North Queensland.


A revision to the constraint equations will be implemented at 0900 hrs Friday 18th December 2020.

The new combinations are now published in a limits advice document on AEMO's website: For more information refer to the new limits advice: https://www.aemo.com.au/energy-systems/electricity/national-electricity-market-nem/system-operations/congestion-information-resource/limits-advice

This advice contains all the combinations for Queensland for system normal cases.

The constraint equations in the Q-NIL set of the form below will be modified:
Q_NIL_STRGTH_XXX

For further details please contact James Lindley at james.lindley@aemo.com.au or Simon Taylor at businessdevelopment@powerlink.com.au

Mya San
AEMO Operations
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