Information Document Northwest Area Transmission Constraint Management ID #2011-004R

Information Document
Northwest Area Transmission Constraint Management
ID #2011-004R
Information Documents are not authoritative. Information Documents are 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 :
(a) Section 302.1 of the ISO rules, 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 conditions and limits in two (2) regions in the northwest
area. In this Information Document the AESO has defined the northwest area as the area illustrated by
the maps in Appendix 2 and 3.
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 northwest area.
2
General
The northwest area consists of long 144 kV and 240 kV bulk transmission lines, generally with a low
degree of redundancy of transmission paths. The northwest area total generating capacity is substantially
less than the area load, leading to inflows of energy under normal operation. Some of the 144 kV bulk
transmission lines are heavily loaded.
The outage of a single bulk transmission line or a generating unit may result in voltage depressions
outside of the acceptable system operating limits set out in Alberta Reliability Standard TPL-002-AB-0,
System Performance Following Loss of a Single BES Element. The AESO can partially mitigate this risk
by ensuring a sufficient minimum amount of transmission must-run generating unit capacity is available
under contract with the AESO. The availability of transmission must-run services reduces the risk of
losing firm load due to low voltages and of a voltage collapse for certain critical transmission or
generation contingencies.
Two (2) maps of the northwest area are provided in Appendix 2 and 3. Appendix 2 provides a detailed
geographical map of the northwest area indicating bulk transmission lines, substations and cutplanes.
Appendix 3 provides a detailed view of the northwest area cutplanes including the generating units
effective in managing the regional constraints through transmission must-run dispatch or directive.
A cutplane is a common term used in engineering studies and is a theoretical boundary or plane crossing
two (2) 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 interconnected system.
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.
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 contain binding legal requirements for either
market participants or the AESO, or both. AESO Authoritative Documents include: the ISO rules, the Alberta reliability
standards, and the ISO tariff.
Posting Date: 2016-04-14
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Information Document
Northwest Area Transmission Constraint Management
ID #2011-004R
3.2
Studied Constraints and Limits
When managing a transmission constraint in the northwest area of Alberta that results from total
generating capacity of the area being substantially less than the area load, the AESO uses regional
cutplane inflow limits to manage area reliability. The AESO calculates the cutplane inflow limits for the
Grande Prairie and Rainbow Lake cutplanes in accordance with voltage requirements and bulk
transmission line transfer limits. A further description of the cutplane inflow limits for the Grande Prairie
and Rainbow Lake cutplanes is set out below.
Cutplane Inflow Limits
There are two (2) cutplanes in the northwest area; one (1) for the Grande Prairie region and one (1)
specific to the Rainbow Lake region. These cutplanes are reflected on the maps in Appendix 2 and 3. As
mentioned above, the northwest area generation capacity is substantially less than the area load, which
leads to inflows of energy into the northwest area under normal circumstances. The specific contingency
conditions and inflow limits for the Grande Prairie cutplane are set out in Appendix 4 and 5 of this
Information Document. The limits in Appendix 4 are not absolute limits as certain generating units
operating at or above minimum stable generation can provide a slight increase to the limits. The
scenarios that provide an increase to the limits are set out in Appendix 5 of this Information Document.
The Rainbow Lake cutplane inflow limits, corresponding to summer and winter seasons, system normal
conditions and certain transmission facility statuses, are provided in Appendix 6.
Operating Modes and Limits
If the Poplar Hill or Valley View # 1 generating units are either generating MW or operating in
synchronous condenser mode, the AESO increases the Grande Prairie cutplane inflow limits by the
amount specified in Appendix 5 of this Information Document. The increases contemplated in Appendix 5
are only applicable when there is a net power transfer-out of the northeast area as measured on the
Dover - Ruth Lake cutplane in the northeast area under N-0 and N-1 conditions.
Due to angular stability and voltage concerns, there is a need for the AESO to issue directives or
dispatches for transmission must-run in the northwest area to ensure that the system operating limits and
dynamic reactive reserve requirements for the Rainbow Lake region are met. These reactive reserve
requirements are set out in Appendix 7.
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 in the northwest area due to certain
unique operating conditions that exist in that area. This Information Document represents and clarifies the
application of the general provisions of Section 302.1 to the northwest area..
The protocol steps which are effective in managing transmission constraints are outlined in Table 1
below, followed by additional steps which may be required. For example, the Fort Nelson connection is
unique and the AESO may be required to take additional steps in order to curtail Fort Nelson load, as
described below.
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Information Document
Northwest Area Transmission Constraint Management
ID #2011-004R
Table 1 Transmission Constraint Management
Sequential Procedures for the Northwest Area
Section 302.1, subsection 2(1) protocol steps
Applicable to the
Grande Prairie cutplane
inflow?
Applicable to the
Rainbow cutplane
inflow?
(a) Determine effective pool assets
Yes
Yes
(b) Ensure maximum capability not exceeded
No
No
(c) Curtail effective downstream constraint
side export service and upstream constraint
side import service
No
No
(d) Curtail effective demand opportunity
service on the downstream constraint side
No
No
(e)(i) Issue a dispatch for effective contracted
transmission must-run
Yes
Yes
(e)(ii) Issue a directive for effective noncontracted transmission must-run
Yes
Yes
(f) Curtail effective pool assets in reverse
energy market merit order followed by pro-rata
curtailment
No
No
(g) Curtail effective loads with bids in reverse
energy market merit order followed by pro-rata
load curtailment
Yes
Yes
Applicable Protocol Steps
The first step in managing constraints in any area is to identify those generating units effective in
managing the constraint. All generating units and loads operating in the northwest area are indicated in
Appendix 3 (single line diagram), the generating units effective in managing constraints are identified in
Appendix 1.
Step (a) in Table 1
The effective pool assets are as shown in Appendix 1.
Step (b) in Table 1
Ensuring maximum capabilities are not exceeded is not applicable to the northwest due to the deficiency
of generation and inflow scenario.
Step (c) in Table 1
There is no effective export or import opportunity service to curtail for either the Grande Prairie or
Rainbow cutplane.
Step (d) in Table 1
There is no demand opportunity service load in the area to curtail.
Steps (e)(i) and (ii) in Table 1
Issue dispatches to effective contracted pool assets or directives to effective non-contracted pool assets
for transmission must-run.
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Northwest Area Transmission Constraint Management
ID #2011-004R
Step (f) in Table 1
Reverse merit order curtailment is not effective and therefore not required because the constraint is
caused by not having enough in-merit generation in the downstream constrained area.
Step (g) in Table 1
Curtailing effective loads with bids in reverse energy market merit order followed by pro-rata load
curtailment is available for both Grande Prairie and Rainbow cutplanes.
Additional Steps
Due to the operating characteristics of the northwest area, when managing a transmission constraint on
the Rainbow Lake cutplane, the AESO may utilize the following additional procedures:
(i) curtail applicable load in accordance with the provisions of the contract between the AESO and the
British Columbia Hydro and Power Authority (addressing Fort Nelson operation), after
implementing step (e)(i) in Table 1 set out in subsection 3(1); and
(ii) if necessary to maintain Rainbow Lake region voltage levels, follow the Grande Prairie cutplane
curtailment procedure.
5
Project Updates
As necessary, the AESO intends to provide information in this section about projects underway in the
northwest area that are known to have an impact on the information contained in this Information
Document.
6
Appendices to this Information Document
Appendix 1 – Effective Pool Assets
Appendix 2 – Geographical Map of the Northwest Area
Appendix 3 – Northwest Area Cutplane Single Line Diagram
Appendix 4 – Grande Prairie Cutplane Limits
Appendix 5 – Grande Prairie Cutplane Inflow Limits and Operating Mode
Appendix 6 – Rainbow Lake Cutplane Thermal and Transient Limits (Inflow Limits)
Appendix 7 – Rainbow Lake Region Dynamic Reactive Reserve Requirements
Revision History
Posting Date
Description of Changes
2011-06-30
Initial Release
2012-03-03
Updated to reflect transmission upgrades in the area
2012-06-14
Updated to include material content from existing section 302.4 of
the ISO rules, Northwest Area Transmission Constraint
Management
Updated to include minor drafting edits
2012-08-31
2013-01-01
2013-02-14
Updated to include Table 4 which reflects changes to the Rainbow
Lake Cutplane limits and Dynamic Reactive Reserve requirements.
Updated Table 4 to reflect changes to the Rainbow Lake Cutplane
limit and Dynamic Reactive Reserve requirements. Minor drafting
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ID #2011-004R
edit to geographical map.
2014-04-03
Appendices 1 and 3 amended to reflect the decommissioning of
assets ST1 and ST2.
2014-05-12
Appendix 2 amended to reflect the addition of Chickadee Creek
259S
2014-07-29
Subsection 4.1 updated and Appendix 7 removed in its entirety to
reflect the elimination of generation capacity limits for Poplar Hill
and Northern Prairie Power Project.
2014-12-16
Appendices 1 and 3 were amended to reflect the addition of the
asset WCD1. In addition typographical errors were amended in
Note 2 in Appendix 6.
2016-04-14
Administrative updates.
Added section 3.1 to describe how the AESO assesses unstudied
system operating limits.
Revised Table 1 and 2 of Appendix 4 to remove reference to
maximum area load level used in studies.
Revised Appendix 6 and added Appendix 7 based on updated
studies.
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Northwest Area Transmission Constraint Management
ID #2011-004R
Appendix 1 – Effective Pool Assets
2
The effective generation pool assets for the Grande Prairie cutplane , listed alphabetically by their pool
IDs, are:
BCR2
BRCK
DAI1
GPEC
NPC1
NPP1
PH1
VVW1
WCD1
The effective generation pool assets for the Rainbow cutplane, listed alphabetically by their pool IDs, are:
FNG
RB1
RB2
RB3
RB5
RL1
2
An operational study in this area is being conducted and the effective pool assets will be updated following the
study.
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ID #2011-004R
Appendix 2 – Geographical Map of the Northwest Area
Zama Lake
795S
7L72
Sulphur Point
828S
Rainbow Lake
791S
1L359 7L81
Fort Nelson
852S
High Level
786S
7L133
7L93
Arcenciel
930S
7L122
Blumenort
832S
7L76
7L109
Bassett
747S
SVC
7L64
7L113
Haig
River
748S
Melito
890S
SVC
7L59
Chinchaga
779S
Keg River
789S
Ring Creek
853S
Rainbow Lake cutplane (RLC)
Kemp River
797S
7L62
7LD8
7L82
Hamburg
855S
7L63
Hotchkiss
788S
Meikle
905S
7L120
7L138
783S
878S
Kidney Lake
7L63
7L51
6L16
812S
7L106
7L131
861S
Eureka
River
839S
830S
SVC
724S
869S
7L12
7L27
6L37
7L75
800S
Fredenstal
829S
7L10
754S
Ksituan
Wesley Creek
834S
793S
West
Peace
827S
Cranberry
Lake
780S
Lubicon
7L61
9L11
858S
720S
9L56
882S
815S
Goodfare
7L22
811S
Clairmont
728S
749S
798S
727S
734S
7L32
6L57
739S
7L45/7L46
736S
Little Smoky
813S
854S
725S
SVC
7L20
7L40
735S
744S
809S
7L80
HR
Milner
740S
741S
Fox
Creek
7L199
857S
9L938
347S
720L
397S
199L
199AL
854L
To Bickerdike Chickadee
Creek
39S
259S
Posting Date: 2016-04-14
9L913
743S
851S
738S
824S
733S
9L40
742S
7L56
9L02, 9L05
7L90
810S
Dome
6L73 7L162
844S
745S
729S 7L49 732S
7L57
794S
808S
845S
Big Mountain
823S
862S
722S
758S
6L99
6L91
787S
6L68
7L03
731S
Elmworth
7L68
790S
Poplar Hill
7L07
Grande
Prairie
cutplane
7L23
784S
730S
Rycroft
865S
To Britnell 876S
9L15
796S
7L48
7L73
7L94
7L230
234S
69S
9L939
72kV
236S 77S
To
Whitecourt
323S
144kV
240kV
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Appendix 3 – Northwest Area Cutplane Single Line Diagram
FNG1
RB1, RB2, RB3, RL#1, RB5
7L81
Rainbow Lake
791S
7L122
7L109
NPP1
Arcenciel
930S
7L113
PH1
Ring Creek
853S
Poplar Hill
790S
DAI1
Keg River
789S
7L82
Rainbow Lake Cutplane (RLC)
M
BRCK
BCR2
Hotchkiss
788S
7L38 7L120
7L58 7L62
M
M
Meikle
905S
NPC1
7L106
7L131
GPEC
Wesley Creek
834S
GOC1
M
9L11
HRM1
VVW1
VVW2
Kinuso
727S
M
9L15
M
M
Little Smokey
813S
M
Mitsue
732S
M
M
M
M
Grande Prairie
Cutplane
6L57
876S
9L56
7L56
7L90
9L02
Louise Creek
809S
9L913
720S
69S
9L05
9L40
725S
240 kV
144 kV
741S
72 kV
Electrical Path
Rainbow Lake Cutplane
Grande Prairie Cutplane
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Appendix 4 – Grande Prairie Cutplane Limits
Table 1 Grande Prairie Cutplane Limit for a Northeast Area Export
Grande Prairie Cutplane Limit for a Northeast Area Export
Contingency
Conditions
To increase the Grande Prairie import limit add the synchronous condenser
mode effect (Table 3)
HR Milner = 70MW
70 MW < HR Milner < 140 MW
HR Milner ≥140 MW
X = HR Milner output – 70 MW
No contingencies
585
585 – (0.71 * X)
535
590
590 – (0.79 * X)
535
9L11
610
610 – (0.93 * X)
545
9L15
585
585 – (0.57 * X)
545
9L02 or 9L05
485
485
485
919L or 989L
470
470 – (0.21 * X)
455
9L938 or 9L939
485
485
485
9L40
570
570 – (0.93 * X)
505
9L56
600
600 – (0.79 * X)
545
9L913
545
545 – (0.79 * X)
490
7L56
600
600 – (0.57 * X)
560
7L90
600
600 – (0.57 * X)
560
7L23
575
575 – (0.71 * X)
525
7L61
595
595 – (0.57 * X)
555
6L57
610
610 - (0.79 * X)
555
HR Milner < 70
MW
590
590
590
Little Smoky static
VAr compensator
565
565 – (1.29 * X)
475
Cranberry
static
VAr compensator
595
595 – (1 * X)
525
GPEC or
BCR2 steam
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ID #2011-004R
Examples to assist with interpretation of Table 1:
1. If HR Milner is generating at 70 MW and transmission line 9L15 is out of service then the power flow
limit into the northwest is 585 MW.
2. If HR Milner is generating at 100 MW and the region load is less than 860 MW, and transmission line
9L15 out of service then the power flow limit into the northwest is calculated as 585 – (0.57*(100 –
70)) = 567.9 MW.
3. If HR Milner is generating at 140 MW and transmission line 9L15 is out of service then the power flow
limit into the northwest is 545.
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ID #2011-004R
Table 2 Grande Prairie Cutplane Limit for a Northeast Area Import
Grande Prairie Cutplane Limit for a Northeast Area Import
Contingency
Conditions
HR Milner=70 MW
70 MW < HR Milner < 140 MW
HR Milner ≥140 MW
X = HR Milner output – 70 MW
No contingencies
565
565 – (0.36 * X)
540
555
555 – (0.21 * X)
540
9L11
590
590 – (0.64 * X)
545
9L15
545
545
545
9L02 or 9L05
440
440
440
919L or 989L
405
405
405
9L938 or 9L939
460
460
460
9L40
530
530 – (0.71 * X)
480
9L56
575
575 – (0.29 * X)
555
9L913
550
550 – (1.43 * X)
450
7L56
570
570
570
7L90
570
570
570
7L23
550
550 – (0.36 * X0
525
7L61
560
560
560
6L57
580
580 – (0.29 * X)
560
HR Milner < 70 MW
560
560
560
Little Smoky static
VAr compensator
540
540 – (1.14 * X)
460
Cranberry static
VAr compensator
570
570 – (0.86 * X)
510
GPEC or
BCR2 steam
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ID #2011-004R
Examples to assist with interpretation of the Table 2:
1. If HR Milner is generating at 70 MW and transmission line 9L11 is out of service then the power flow
limit into the northeast is 590 MW.
2. If HR Milner is generating at 100 MW and the region load is less than 860 MW, and transmission line
9L11 out of service then the power flow limit into the northeast is calculated as 590 – (0.64*(100 –
70)) = 570.8 MW.
3. If HR Milner is generating at 140 MW and transmission line 9L11 is out of service then the power flow
limit into the northeast is 545 MW.
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Information Document
Northwest Area Transmission Constraint Management
ID #2011-004R
Appendix 5 – Grande Prairie Cutplane Inflow Limits and Operating Mode
Table 3 below sets out the power flow limits if the Poplar Hill or Valley View (VVW1) generating units are
operating in either synchronous condenser mode or MW generation mode:
Table 3
Increase to Grande Prairie Transfer Limit IF the Northeast Area is Exporting
System Conditions
PH1 in
synchronous
condenser
mode or
1
generating
MW
VVW1 in
synchronous
condenser mode or
either VVW
generating unit is
1
generating MW
Both PH1 and VVW1 in
synchronous condenser
mode or both generating
2
stations are generating
MW
System normal
+30
+20
+45
HR Milner contingency
+10
+0
+20
Note:
1. Generating units are considered in generating mode if they are above their minimum stable
generation.
2. It is accepted that any combination of the following meets this requirement:
a. PH1 is on synchronous condenser mode/generating MW; or
b. VVW1 is on synchronous condenser mode or either VVW1 or Valley View 2 generating units are
generating power.
Examples to assist with interpretation of Table 3:
1. For any limit calculated in Appendix 4 and when VVW1 is in synchronous condenser mode or is
generating MW, for system normal conditions, the limit calculated from Appendix 4 is increased by 20
MW.
2. For any limit calculated in Appendix 4, if PH1 is generating at some level or in synchronous
condenser mode, and HR Milner is out of service, the cutplane limit is increased by 10 MW.
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ID # 2011-004R
Appendix 6 – Rainbow Lake Cutplane Thermal and Transient Limits (Inflow Limits)
Condition
Line out of
service
N-0
Arcenciel
Sync
Condenser
No Rainbow Lake region One or more Rainbow Lake
units on line
region units on line
Summer
Winter
Summer
Winter
115
135
115
135
7L58
83
83
73
7L62
83
83
73
7L59
75
86
67
7L64
83
83
71
7L93
None
Either in service
or out of service
1
73
1
73
1
67
62
1
62
80
70
85
75
86
120
138
7L106
128
128
110
110
7L131
128
128
110
110
7L113
71
80
81
93
N-1
7L82
Out of
Service
1
1
1
1
Note:
1. Transient stability limits are not exceeded.
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Appendix 7 – Rainbow Lake Region Dynamic Reactive Reserve Requirements
Condition
N-0: System Normal
N-1
Posting Date: 2016-04-14
Element Out of
Service
One or more Rainbow
Lake region units on
line
Minimum Dynamic
Reactive Reserve
(MVAr)
No Rainbow Lake
region units on line
Minimum Dynamic
Reactive Reserve
(MVAr)
None
30
30
Arcenciel SVC
30
30
High Level SVC
30
30
7L131
20
30
7L106
20
30
7L82
20
30
7L113
20
30
7L64
20
20
7L59
20
20
7L93
20
20
7L58
38
38
7L62
38
38
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