Information Document North South Area Transmission Constraint Management ID #2013-002R

Information Document
North South Area Transmission Constraint
Management
ID #2013-002R
Information Documents are not authoritative. Information Documents are provided for information
purposes only and are intended to provide guidance. In the event of any discrepancy between an
Information Document and any Authoritative Document(s) in effect, the Authoritative Document(s)
governs.
1
Purpose
1
This Information Document relates to the following Authoritative Document: Section 302.1, Real Time
Transmission Constraint Management (“Section 302.1”). The purpose of this Information Document is to
provide additional information regarding the unique operating characteristics and resulting constraint
2
conditions and limits on the North South cutplane of the Alberta interconnected electric system.
Section 302.1 sets out the general transmission constraint management protocol steps the AESO uses to
manage transmission constraints in real time on the Alberta interconnected electric system. These steps
are referenced in Table 1 of this Information Document as they are applied to the North South cutplane.
2
General
The majority of generation in Alberta is located in the Edmonton area and areas to the north of Edmonton,
while there is substantial load in southern Alberta, including the City of Calgary. This creates a situation
where a significant amount of power flows across:
(a) the 240 kV bulk alternating current (“AC”) transmission lines between Edmonton and Calgary. As
system conditions change, the loading of these 240 kV bulk transmission lines varies; and
(b) two high-voltage direct current (“HVDC”) transmission lines with an approximate continuous
transfer capability of 1,000 MW in either direction for each link (i.e. north to south and south to
north), known as the Eastern Alberta Transmission Line (“EATL”) and the Western Alberta
Transmission Line (“WATL”). Unlike AC transmission lines, the amount and direction of power
flowing on HVDC transmission lines can be directly controlled in response to system conditions.
These transmission lines are included in the North South AC and direct current (“DC”) cutplanes. The
flows of power across the North South cutplanes are referred to as the North South cutplane flows.
In order to ensure the safe and reliable operation of the Alberta interconnected electric system, the AESO
has established operating limits for the North South cutplanes, and has developed procedures to
manage transmission constraints on the North South cutplanes.
A detailed geographical map of the North South area indicating bulk transmission lines, substations and
cutplanes is provided in Appendix 2 to this Information Document. A detailed schematic of the North
South cutplanes, including some of the pool assets effective in managing a transmission constraint, is
provided in Appendix 3 of this Information Document.
A cutplane is a common term used in engineering studies and is a theoretical boundary or plane crossing
two or more bulk transmission lines or electrical paths. The cumulative power flow across the cutplane is
measured and can be utilized to determine flow limits that approximate conditions that would allow safe,
reliable operation of the Alberta interconnected electric system.
1
“Authoritative Documents” is the general name given by the AESO to categories of documents made by the AESO under the
authority of the Electric Utilities Act and regulations, and that include binding legal requirements for either market participants or the
AESO, or both. Authoritative Documents include: the ISO rules, the Alberta reliability standards, and the ISO tariff.
2
North South cutplane was previously known as the SOK 240 cutplane.
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North South Area Transmission Constraint
Management
ID #2013-002R
3
3.1
Constraint Conditions and Limits
Non-Studied Constraints and Limits
For system conditions that have not been pre-studied, the AESO uses energy management system tools
and dynamic stability tools to assess unstudied system operating limits in real time.
3.2
Studied Constraints and Limits
Definition of North South Cutplane Flow
The North South cutplane flow with only AC facilities in service is defined as the sum of:
outflows on 922L and 926L measured at the (310P), Sundance substation
plus
outflows on 190L and 903L measured at the (320P), Keephills substation
plus
outflows on 910L and 914L at the (89S) Ellerslie substation
plus
35% of outflows on 912L at the (63S) Red Deer substation
plus
inflows on 995L at the (17S) Benalto substation
The North South cutplane flow with AC and HVDC facilities in service is defined as above, with the
following additions:
plus
positive flow (i.e., flow in a north to south direction) on WATL
plus
positive flow on EATL.
North South Cutplane Operating Limits
The North South cutplane total thermal transfer capability, corresponding to summer and winter seasons,
system normal condition and certain transmission facility statuses, are provided in Appendix 4. The North
South cutplane total transfer capability is the maximum North South cutplane flow that meets the AESO
Transmission Reliability Criteria. Transient stability limts at the North South cutplane are provided in
Appendix 5.
As per section 3.1 of this Information Document, when multiple contingencies arise, operational studies
are performed in real time and the limits listed in Appendix 4 may not be applicable. In those
circumstances, the AESO will operate the system using the operating limits determined by the studies.
Measures to help mitigate a transmission element loading concern include adjusting WATL and/or EATL
power transfer, opening 138 kV transmission lines and curtailing load at specific substations as required.
4
Application of Transmission Constraint Management Procedures
While the AESO manages transmission constraints in all areas of Alberta in accordance with the
provisions of Section 302.1, not all of those provisions are effective on the North South cutplane due to
certain unique operating conditions that exist in that area. Because of those unique operating conditions,
this Information Document represents the application of the general provisions of Section 302.1 to the
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North South Area Transmission Constraint
Management
ID #2013-002R
North South cutplane, and provides additional clarifying steps as required to effectively manage
transmission constraints in that area.
If the North South total transfer capability is exceeded due to an outage to 190L or 903L, and the AESO
has already implemented the management steps set out in ID #2013-004R, Keephills/Ellerslie/Genesee
Area Transmission Constraint Management, then the AESO implements the mitigation steps in this
Information Document
The protocol steps which are effective in managing transmission constraints are outlined in Table 1
below.
Table 1
Transmission Constraint Management
Sequential Procedures for North South Cutplane
Section 302.1 of the ISO rules, subsection 2(1) protocol steps
Applicable to
the North
South
cutplane?
(a) Determine effective pool assets
Yes
(b) Ensure maximum capability not exceeded
Yes
(c) Curtail effective downstream constraint side export service and upstream constraint
side import service
Yes
(d) Curtail effective demand opportunity service on the downstream constraint side
Yes
(e)(i) Issue a dispatch for effective contracted transmission must-run
Yes
(e)(ii) Issue a directive for effective non-contracted transmission must-run
No
(f) Curtail effective pool assets in reverse energy market merit order followed by pro-rata
curtailment
Yes
(g) Curtail effective loads with bids in reverse energy market merit order followed by prorata load curtailment
Yes
Applicable Protocol Steps
The first step in managing constraints in any area is to identify those generating units effective in
managing a constraint. All of the generating units effective in managing a transmission constraint are
identified in Appendix 1. However as noted below, under certain contingencies, a specific subset of pool
assets have been identified as required to manage those constraints until the system is in a safe
operating mode.
Step (a) in Table 1
To manage a transmission constraint, the AESO uses the effective pool assets set out in Appendix 1 for
the studied conditions on the North South cutplane.
Step (b) in Table 1
Curtailing effective upstream generation pool assets to their maximum capability as per step (b) is an
effective step in managing a transmission constraint on the North South cutplane.
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North South Area Transmission Constraint
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ID #2013-002R
Step (c) in Table 1
Curtailing effective downstream constraint side export service is effective in managing a constraint on the
North South cutplane, as it mitigates the constraint by rebalancing the system. Export service is a lower
priority opportunity service and curtailing exports may alleviate the need to dispatch contracted
transmission must-run to manage this constraint.
Step (d) in Table 1
Curtailing demand opportunity service downstream of the constraint is effective in managing a constraint
on the North South cutplane. Demand opportunity service is a lower priority opportunity service and
curtailing it may alleviate the need to dispatch contracted transmission must-run to manage this constraint
Step (e)(i) in Table 1
Issuing a dispatch for contracted Calgary area transmission must-run is an effective step in managing a
North South constraint.
Step (e)(ii) in Table 1
Issuing a directive for non-contracted transmission must-run is not considered effective in managing a
constraint on the North South cutplane because the AESO does not see a need to conscript additional
transmission must run.
Step (f) in Table 1
Curtailing effective upstream pool assets using the reverse energy market merit order, followed by
pro-rata curtailment, is effective in managing a constraint as it reduces the flow on the North South
cutplane.
Step (g) in Table 1
Downstream load curtailment as per step (g) is effective in managing a North South constraint. During
certain events, and supply shortfall events in particular, the AESO first implements the procedures of
Section 202.2 – Short Term Adequacy and Supply Shortfall, making every effort to serve firm load. At that
point, the AESO monitors the North-South cutplane flow limit exceedance, continuing to serve firm load,
but only if the risk to the Alberta interconnected electric system is acceptable.
5
Project Updates
As necessary, the AESO intends to provide information in this section about projects underway in the
North-South area that are known to have an impact on the information contained in this Information
Document.
6
Appendices
Appendix 1 – Effective Pool Assets
Appendix 2 – Geographical Map of the North South Area
Appendix 3 – North South Single Line Diagram and Cutplane
Appendix 4 – North-South Cutplane Total Thermal Transfer Capability
Appendix 5 – SOKAC/SOKDC Transient Stability Limit
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North South Area Transmission Constraint
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ID #2013-002R
Revision History
Version
Posting Date
Description of Changes
1.0
2014-02-27
Initial Release
2.0
2014-04-03
Updated to include effective pool asset ANC1
3.0
2014-06-03
Updated to include effective pool asset NRG3
4.0
2015-07-14
Update to include transmission line 1081L in Appendix 4 and
addition of the Johnson 281S substation and transmission line
1081L in the geographic map and single line diagram.
5.0
2015-12-08
Updated to include reference to two new HVDC lines, EATL and
WATL. Section 2 revised to describe the Alberta interconnected
electric system with addition of the HVDC lines. Definition of North
South cutplane flow in section 3.2 updated to contemplate the flow
with HVDC lines in service, and to describe how the AESO may
adjust WATL and/or EATL power transfer to mitigate an overload
concern. Appendix 1 updated to include SCR5 and SCR6. Maps in
Appendices 2 and 3 updated. Appendix 4 updated to include
North-South cutplane limits with HVDC lines in service. Appendix 5
added to provide transient stability limits.
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North South Area Transmission Constraint
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ID #2013-002R
Appendix 1 – Effective Pool Assets
The effective pool assets for the North South cutplane, listed alphabetically by their pool IDs, are:
ALS1
HRM
TCO2
ANC1
KH1, KH2, KH3
SCR1, SCR5, SCR6
APS1
MEG
SD1
BCR2
NPC1
SD2
BRA
NPP1
SD3
BCRK
NRG3
SD4
ENC1, ENC2, ENC3
MKRC
SD5
DAI1
IOR1
SD6
DOW
MKR1
SCL1
ECO4
NX02
VVW1VVW2
GPEC
PH1
GN1, GN2, GN3
PR1
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Appendix 2 – Geographical Map of the North South Area
792L
726L
838L
835AL
835L
40S
WETASKIWIN
729L
7L77
285S
EAST CAMROSE
526S
BUFFALO
CREEK
Viking
729L
Wetaskiwin
716
L
926L
922L
757L
80L
848L
80L
7L25
7L171
733L
852L
504S
QUEENSTOWN
853L
924L
161L
356S
MILO
923L
180L
255S
VULCAN
Page 7 of 11
1005L
935L
Vulcan
944L
951L
324S
28S CASSILS
WEST
BROOKS
Brooks
121S
BROOKS
2075S
NEWELL
795L
1038L
339S
DUCHESS
763L
1037L
435S
BASSANO
227S
CUTTING LAKE
1036L
897L
500 kV HVDC Transmission Line
253S
BLACKIE
237S
FOOTHILLS
High
River
1201L
Existing 500 kV Transmission Line
753L
65S
HIGH
RIVER
Bassano
1053
L
931L
933L
1106L
727L
13L 727L
142S
MAGCAN
812L
Existing 240 kV Transmission Line
132S
WARE JUNCTION
179S
GLEICHEN
927L
918L
80
L
928L
906L
512S
HARTELL
Transmission
Line
431S
HUSSAR
831L
Black Diamond
9L24
886L
CAVALIER
525S
CARSELAND
Okotoks
803S
BULLPOUND
853AL
158L
428S
NAMAKA
151S
STRATHMORE
1L
85
392S
BLACK DIAMOND
Existing 69 kV Transmission Line
Information Document
7L143
7L159
929L 901L 925L
932L
Strathmore
765L
102S
LANGDON
936L
510S
BENNETT
511S
850LCROSSINGS
678S
OKOTOKS
807S
SHEERNESS
9L
801S
29
ANDERSON
946S
OAKLAND
609S
WHEATLAND
74S
JANET
7L85
9L933
9L934
9L950
186S
DRY CREEK
42S
SARCEE
6L09
804S
WINTERING HILLS
611L
CALGARY
963S
COYOTE LAKE
Drumheller
Airdrie
291S
COCHRANE
Settlements
6L15
64S
EAST CROSSFIELD
653S
SUMMIT
284S
NOSE CREEK
199S
EAST AIRDRIE
776S
RICHDALE
6L09
763S
HANNA
7L128
802S
MICHICHI CREEK
Cochrane
86
0L
15
0L
Hanna
6
6L5
Carstairs
Crossfield
T793S
HORSE CREEK
Existing 138 kV
7L137
Three Hills
Didsbury
373S
189L MADDEN
272S
SPRINGBANK
768S
ROWLEY
770S
THREE HILLS
281S
JOHNSON
316S WEST
CROSSFIELD
Substations
6L12
775S
SULLIVAN LAKE
Trochu
Olds
152S
DIDSBURY
3L
Coronation
773S
CORONATION
114S
GHOST PINE
Bowden
55S
OLDS
148S
256S
HARMATTAN SCHANTZ
L
113
Castor
9L59
9L
71
Sundre
20S
GHOST
759S
CASTOR
615S
HALKIRK
Innisfail
412S
EAGLE CREEK
L
56
9L948
953L
948S
HEATBURG
Penhold
214S
INNISFAIL
DICKSON
DAM
873S
MARION
LAKE
769S
STETTLER
863S
PAINTEARTH
972S
TINCHEBRAY
6L02
760S
DELBURNE
7L16
535S
JOFFRE
Stettler
536S
63S
RED DEER BROOKFIELD
580S
SYLVAN LAKE
531S
SCHRADER
CREEK
9L20
9L93
2L
91
482S
HAYNES
637L
575S
SUNDRE
7L701L
80L
87S
GAETZ
Red
Deer
17S
BENALTO
870L
755S
CORDEL
6L03
Sylvan
Lake
766S
NEVIS
L
775
758L
99
534S
5L
717L ECKVILLE
703
L
296S
ROSYTH
756S
BIGFOOT
Lacombe
876L
1325L (WATL)
903L
190L
212S
N.E. LACOMBE
332S
ELLIS
656S
CLIPPER
764S
HEISLER
WOLF CREEK
Bashaw
958S
WEST
LACOMBE
Bentley
Sedgewick
137S
SEDGEWICK
6L05
Rimbey
262S ROCKY
MOUNTAIN HOUSE
7L702
Ponoka
198S
BLACKFALDS
378S
CAROLINE
Killam
702L
429S
NELSON LAKE
331S
PONOKA
99
5L
61
L
704L
Daysland
297S
RIMBEY
252S
JARROW
223S
STROME
542S
ERVICK
701L
910L
914L
964S
PIGEON LAKE
395S
NORTH
HOLDEN
Camrose
86S
BIGSTONE
805L
837L
454S
BUCK LAKE
299S
KINGMAN
Millet
449S
BONNIEGLEN
174L
301S
QUEENSLAND
701L
325S
LEDUC
7L65
7L
50
Leduc
197S
BARDO
13L50 (EATL)
739L
632L
858L
834L
149S Beaumont
NISKU
Devon
538S
BUFORD
709S
VEGREVILLE
780L
283S
VIOLET GROVE
330p
GENESEE
384S
KEYSTONE
Vegreville
Tofield
522S
COOKING LAKE
17
4L
730L
104L
712L
905L
673L
Drayton
Valley
Mundare
293S
BERNESE
45S
BRETONA
87
DOME
89S
4L
ELLERSLIE
908L
909L
1209L
Two Hills
987S
CLOVER BAR
904L
510S
SUNNYBROOK
956S
WATT LAKE
127S
BRUDERHEIM
422S
WESTWOOD
EDMONTON
1202L
776L
Lamont
Fort
Saskatchewan
92S
VISCOUNT
805S
JASPER
Stony Plain
320P
KEEPHILLS
2029S
HEATHFIELD
9L960
9L961
13S
DEERLAND
Gibbons
99S
NORTH ST.ALBERT
432S 105S 905L
CARVEL BILBY
124L 156L
19S
WABAMUN
310P
21S SUNDANCE
MARION
808L
792L
913L
799L
235S
ENTWISTLE
735L
Morinville
352S
ONOWAY
131S
MOON LAKE
12S
HEARTLAND
Bon
Accord
338S
CHERHILL
171S
REDWATER
Redwater
7L92
Legal
66
6L
498S
TILLEY
10
0L
10
35
L
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Information Document
North South Area Transmission Constraint
Management
ID #2013-002R
Appendix 3 – North South Single Line Diagram and Cutplane
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North South Area Transmission Constraint
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ID #2013
Appendix 4
Table 1 – North-South Cutplane Total Thermal Transfer Capability (MW)
The table below provides the conditions and the thermal transfer limits (MW) at the North South cutplane.
Summer
Winter
Outage
SOKAC
SOKDC
SOKAC
SOKDC
N-0
2100
2900
2138
3024
190L
1550
2350
1753
2584
900L
1580
2380
1757
2540
901L
1
1820
2620
1931
2683
903L
1
1550
2350
1755
2582
906L
1820
2620
1885
2641
910L
1410
2210
1693
2529
914L
1410
2210
1634
2556
918L
1660
2460
1876
2632
922L
1550
2350
1720
2376
925L
1820
2620
1932
2677
926L
1550
2350
1719
2376
928L
1820
2620
1885
2644
929L
1820
2620
1932
2677
932L
1760
2560
1933
2685
1081L
1760
2560
1847
2602
1082L
1770
2570
1941
2681
1083L
1430
2230
1719
2544
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North South Area Transmission Constraint
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ID #2013
Summer
Winter
Outage
SOKAC
SOKDC
SOKAC
SOKDC
WATL
1820
2520
1894
2580
EATL
1820
2520
1910
2696
Note:
1
If the North South total transfer capability is exceeded due to an outage to 190L or 903L, and the AESO
has already implemented the management steps set out in ID #2013-004R, Keephills/Ellerslie/Genesee
Area Transmission Constraint Management, then the AESO implements the mitigation steps in this
Information Document.
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ID #2013
Appendix 5
Table 2 – North South Cutplane Transient Stability Limits
The table provides the conditions and the Transient Stablity Limits (MW) at the North South cutplane.
SOKAC
Outage
SOKDC
SOK Limit
(MW)
Contingency
SOK Limit (MW)
Contingency
N-0
3104
N/A1
3164
N/A1
914L
2881
910L
3114
N/A1
922L
3010
910L
3112
N/A1
926L
3010
910L
3112
N/A1
EATL
None
None
3125
N/A1
WATL
None
None
3132
N/A1
Note:
1. North area generation maximum capacity is reached before SOK transient stability limit is
established.
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