525 CROSSFIELD AREA OPERATION 1. Purpose

Operating Policies and Procedures
Transmission
OPP 525
OPP Issued: 2009-
525 CROSSFIELD AREA OPERATION
1.
Purpose
To provide policies and procedures for the safe and reliable operation of the transmission system in the
Crossfield/Airdrie area.
2.
Background
The transmission and generation facilities in the Crossfield/Airdrie area and adjacent area are
illustrated shown in Figure 1. Two generation facilitiesplants namely ENMAX Crossfield Energy
Centre (“ENMAX Crossfield”) and Nexen Inc # 1 (“Nexen”are) are located in the area. ENMAX
Crossfield consists of three generating assetsunits totallingtotaling 120 MW and is connected to the
Alberta Interconnected Electric System (AIES) via the Summit substation 653S. Nexen Inc. # 1 (also
known as Balzac) consists of three generating assetsunits totallingtotaling 120 MW and is connected to
the AIES via the Balzac substation T391S.
ISO transmission sSystem studies have revealed that, after ENMAX Crossfield is connected to the
AIES, 752L (Summit 653S – East Crossfield T64S) and 688L (Summit 653S – East Airdrie T199S) may
become overloaded under certain contingency conditions, and require a system remedial action scheme
(RAS) to mitigate such a contingency.
3.
Policy
3.1
General
752L remedial action scheme (RAS) and 688L RAS each will be implemented by the ISO are required
to quickly and effectively mitigate the potential overloads on 752L and 688L respectively until such
time as transmission system reinforcement are in place.is undertaken.
3.2
752L RAS
The 752L RAS will provides automatic mitigation action in relieving an overload on 752L when the
direction of line flow is towards East Crossfield T64S. The seasonal line ratings which will trigger the
752L RAS are specified in Table 1. The 752L RAS will function as follows once an overload alarm has
been received:has the following functionalities:
(a)
If the direction of line flow on 752L is towards East Crossfield T64S and:
(i) 752L tThe line flow exceeds 100% but is not greater than 110% of the seasonal line
rating for 10 seconds, then the ENMAX Crossfield generating assets will be manually run
back by the ENMAX Crossfield operator based on the RAS run-back signal to mitigate the
752L overload in response to the run back signal:,
−(ii) tThe752L line flow exceeds 100% but is not greater than 110% of the seasonal line rating for
10 minutes, then all ENMAX Crossfield generating assetsunit(s) will be automatically tripped
in a pre-defined sequence in response to the trip signal;, or
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OPP 525 CROSSFIELD AREA Operation
(iii)tThe752L line flow exceeds 110% of the seasonal line rating for 10 seconds, then all
ENMAX Crossfield generating assetsunit(s) will be automatically tripped in a pre-defined
sequence in response to the trip signal.
(b) Once the “rRun- bBack” or “tTrip” signal starts as applicable, the 752L RASit timer will not reset
until the flow decreases to 95% of the applicable seasonal rating or below for at least one second.
(c) If the 752L RAS does not function as specified in subsection (a) above, in this OPP, then the ISO
system controller (SC) will issue a directive to the ENMAX Crossfield generation operator to trip
one or more the of ENMAX generatingCrossfield generating assets, as required.unit(s as required
) in the event of overload on 752L and when the direction of line flow is towards East Crossfield
T64S.
•(d) The 752L RAS must be armed at all times by Altalink as the transmission facility owner. except
for during maintenance periods.
(e) When the 752L RAS is not available, a real-time system assessment will be performed by
the ISO to determine the necessary mitigation measures to prepare the system for the next critical
contingency.
3.3
688L RAS
The 688L RAS will provides automatic mitigation action in relieving an overload on 688L. This RAS
will trip the breaker of 752L at the Summit 653S when the direction of 688L line flow is towards East
Airdrie T199S. and it exceeds itsThe related seasonal line ratings which will trigger the 688L RAS are
as specified in Table 1 for 10 seconds. The 688L RAS will automatically function as follows once an
overload alarm has been received:has the following functionalities:
(a)
If the direction of line flow on 688L is towards East Airdrie T199S and :
(i)
The line flow exceeds 100% but is not greater than 110% of the seasonal line rating for 10
seconds, then the ENMAX Crossfield generating assets will be manually run back based on
the RAS run-back signal by the ENMAX Crossfield operator to mitigate the 688L overload
in response to the run back signal;
,
(ii)
The line flow exceeds 100% but is not greater than 110% of the seasonal line rating for 10
minutes, then all ENMAX Crossfield generating assets unit(s) will be automatically tripped
in a pre-defined sequence in response to the trip signal, or
(iii) The line flow exceeds 110% of the seasonal line rating for 10 seconds, then the ENMAX
Crossfield generating assetsunit(s) will be automatically tripped in a pre-defined sequence in
response to the trip signal.
(b) Once the run back or trip run-back or trip signal starts as applicable, the 688L RAS timer will not
reset until the flow decreases to 95% of the applicable seasonal rating or below for at least one
second.
(c)
If the 688L RAS does not function as specified in subsection (a) above, then the ISO it is
intended, the SC will issue a directive to direct the ENMAX Crossfield operator generation
operator to trip one or more ENMAX Crossfield ENMAX Crossfield generating assets units as
required. in the event of overload on 688L and when the direction of line flow is towards East
Airdrie T199S. the AltaLink transmission operator to trip the breaker of 752L at the Summit 653S
in the event of overload on 688L and the line flow is towards East Airdrie T199S.
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OPP 525 CROSSFIELD AREA Operation
(d) The 688L RAS must will be armed at all times by AkltaLinkAltaLink as the transmission facility
owner. except during maintenance periods.for maintenance. whenever the breaker of 752L at the
Summit 653S is closed except for maintenance.
(e) When the 688L RAS is not available, a real-time system assessment will be performed performed
by ISO to determine the necessary mitigation measures to prepare the system for the next critical
contingency.
3.4
Generation directives Post 752L RAS activation
(a) After athe 752L RAS action has been triggered to mitigate the 752L overload and the RAS is
subsequently reset once the flow decreases to 95 % of the seasonal rating for a period of at least
one second, then and if transmission system conditions otherwise allow, the ISOSC will issue
directives containing quantity (MW) instructions to both ENMAX Crossfield and Nexen. Inc # 1
as both are deemed to be effective in mitigating the transmission constraints.
•(b) The quantity (MW) contained in the directives quantity (MW) instructionsreferred to in
subsection (a) will be pro rationedcalculated on as pro rata bassisbasis in accordance with the
formula set out in Appendix A, determined for ENAMX ENMAX Crossfield and Nexen Inc # 1
on a pro rata basis using the energy market dispatch level, the dispatch down service (DDS)
dispatch level and the aAncillary Sservices (AS) dispatch level for operating reserves for each of
Enmax Crossfield and Nexen in effect of the generators prior to prior to the 752 L RAS
activation. The calculation method is described in Appendix A.
•When it is required to curtail AS or energy from levels that existed prior to
752L RAS activation, AS dispatch for operating reserves will be curtailed
first before energy market dispatch.
4.
Responsibilities
4.1
ISO
•
The ISO will must review this OPP on an ongoing basis, and update the requirements
based on development of additional transmission and generation in the Crossfield/Airdrie
area.
System Controller
The SC willmust:
•
4.2
Perform the procedures as described in this OPP to manage the transmission constraints.
Transmission Facility Owner (TFO)
AltaLink willmust:
4.3
•
Arm, oOperate and maintain each of the 752L and /688L RAS to provide the
functionality as required described in this OPP; and .
•
Inform the SC immediately when the 752L RAS or /688L RAS or both or either of them
are unavailable or nonfunctional.RAS is unavailable.
Generation Facility Owner (GFO)
Each of Enmax Crossfield and Nexen must not restore any generation capacity or output that
has been curtailed in accordance with the provisions of this OPP, unless the restoration is in
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OPP 525 CROSSFIELD AREA Operation
accordance with the cancellation of a RAS related directive issued under this OPP. The GFOs
willmust :
rRestore generation only with prior permission of the SC.
In particular,
The ENMAX generation operator will:
The ENMAX generation operator must tTake immediate action to run back ENMAX
Crossfieldthe generator upon receiving the “run- back” signal from the 752L RAS.
5.
System Controller Procedures
5.1
Managing the system when 752L overload alarm is received
The SC, upon receiving the 725L RAS overload alarm must, mustwill:
5.2
1.
Upon receiving the 725L overload alarm, Ccheck the system conditions, and verify the
alarm.
2.
Verify that the 752L RAS has been triggered and ENMAX Crossfield is ramping down to
alleviate the overload.
3.
If the 752L RAS is not functioning, comply with the provisions of refer to Section 5.2
below.of this OPP.
4.
Notify Operations on Call personnel as described in OPP 1303, if required and .
5.
Log the RAS operation as described in in OPP 1301.
3
Alleviating 752L overload when 752L RAS does not function as described in
this OPP
If the In the event of overload on 752L with line flowing towards East Crossfield 64S but the
RAS does not function as intended, thethen the SC willmust:
1.
Check the system conditions.
2.
Issue a directive to Direct the ENMAX Crossfield generation operator to trip one or more
one or more generating unit(s) dependingunits, depending on the real-time system
conditions, to alleviate the overload.
3.
If ENMAX Crossfield generation operator fails to comply with the directive, then issue a
directive to the AltaLink as the Ttransmission facility ownerperator to trip the
interconnection breakers.
4.
Log anythe directive(s) as required by described inin OPP 1301.
5.
Notify Ooperations on- Ccall personnel as described in OPP 1303, if required,
6.
Follow the procedures in Section 5.6 to adjust area generation, and .
4H5
6H
67. When the system returns to normal and conditions allow, cancel any the directive(s).
5.3
Managing the system when 688L overload alarm is received
The SC upon receiving 688L overload alarm willmust:
1.
Upon receiving 688L overload alarmCcheck the system conditions, and verify the alarm.
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OPP 525 CROSSFIELD AREA Operation
5.4
2.
Verify that the 688L RAS has been triggered and ENMAX Crossfield is ramping down to
alleviate the overload.the required breaker is open.
3.
If the 688L RAS is not functioning, then comply with the provisions of does not function
as required in this OPP, refer to Section 5.4
4.
Notify Ooperations on- Ccall personnel as described in OPP 1303, if required.
5.
Log the RAS operation as required by described in OPP 1301.
7H
8H9
Alleviating 688L overload when 688L RAS does not function as required in this
OPP
If the In the event of overload on 688L with line flowing towards East Airdrie 199S but the
688L RAS does not function as required, the SC willmust:
1.
Check the system conditions.
2.
Issue a directive to the Direct ENMAX Crossfield generation operator to trip one or more
generating assetsunits, depending on the real-time system conditions, to alleviate the
overload.
3.
If the ENMAX Crossfield operator generation operator fails to comply with the directive,
then issue a directive to the AltaLink transmission facility owner operator to trip the
interconnection breakers.
1.
Direct AltaLink Ttransmission operator to open the breaker of 752L at Summit 653S in
order to bring 688L within its seasonal rating.
24. Log the directive as described in OPP 1301.
10H
35. Notify Ooperations on- cCall personnel as described in OPP 1303, if required.
12H
46. When the system returns to normal and if system conditions allow, cancel the directive.
5.5
Preparing the system when 688L RAS or 752L RAS is not available
When 688L RAS or 752l 752L RAS is not available, the SC willmust:
5.6
1.
Call Ooperations on- call personnel to perform a real-time system assessment to determine
the necessary mitigation measures to prepare for the next critical contingency.
2.
Implement any necessary mitigation measures as determined in Step subsection 1.
3.
When the 688L or 752L RAS returns to normal and if system conditions allow, cancel any
mitigation measures taken under subsection in Step 2.
Adjusting area generation after the 752L RAS action has been implemented
After the 752L RAS action has been implemented and the RAS is reset once the flow decreases
to 95 % of the seasonal rating, the SC willmust:
1.
Check the 752L line load and system conditions.
2.
Calculate the Determine the appropriate generation directive quantity (MW) for the AS and
energy markets with the use of the real-time tool, and in accordance with (see Appendix A),
and if system conditions allow issue the resulting directives to each of EnmaxNMAX
Crossfield and Nexen..
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OPP 525 CROSSFIELD AREA Operation
3.
Put transmission limiters to Nexen # 1 and ENMAX Crossfield in the Dispatch Tool (DT)
as calculated in subsection Step 2.
1. 34. Direct Nexen Inc # 1 to the generation directive quantity (MW) as
calculated in Step 2 if system conditions allow.
54. Direct ENMAX Crossfield to the generation directive quantity (MW)
as calculated in Step 2 if system conditions allow
4.
6. 4 Choose the ENMAX Crossfield and Nexen # 1 constrained zone in the DT for
releasing the DDS dispatch and enter the amount of the constraindconstrainedt down
generation (CDG).
.
5.
75. 5 Log the directives as described in OPP 1301.
6.
86. 6. When the system returns to normal and if system conditions allow, cancel the directives
referred to in Section 2.
13H4
.
7.
7. If one or more generating assets may be tripped instead of generation runback, then
more MW generation than normally required for generation runback will be tripped. The
SC, therefore, may adjust the calculated safe operating generation level depending on the
real-time system conditions.
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Transmission
OPP 525 CROSSFIELD AREA Operation
2009. 6.
Figures and Tables
Figure 1: Crossfield Area Transmission System
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OPP 525 CROSSFIELD AREA Operation
Table 1
AltaLink Transmission Line Ratings
Transmission
Line
752L
Winter2
Summer1
100% Line
Rating
MVA
119
688L
121
110% Line
Rating
MVA
131
N.A133
100% Line
Rating
MVA
136
142
110% Line
Rating
MVA
150
N.A.156
1. The summer period is from May 1 to Oct 31
2. The winter period is from Nov 1 -– Apr 30
7. Revision History
Issued
Description
2009-
New
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OPP 525 CROSSFIELD AREA Operation
Appendix A
Calculation of pPost 752L RAS activation generation directive quantity
(MW) based on pro-rata of generating assets effective in mitigating the
transmission constraint
1. . MW Dispatch Quantities Conditions prior to 752L RAS activation
• Energy market dispatch (MW) to ENMAX Crossfield prior to the RAS activation = E1
• AS dispatch (MW) to ENMAX Crossfield prior to the RAS activation = A1
• DDS dispatch (MW) to ENMAX Crossfield prior to the RAS activation = D1
• Energy market dispatch (MW) to Nexen Inc #1 prior to the RAS activation = E2
• AS dispatch (MW) to Nexen Inc #1 prior to the RAS activation = A2
• DDS dispatch (MW) to Nexen Inc #1 prior to the RAS activation = D2
• The sum (MW) of the energy market dispatches, and AS dispatches and DDS dispatches to
ENMAX Crossfield and Nexen # 1 =T
=T = (E1 + A1 + D1) + (E2 +A2 + D2)
=T
2. . Conditions after the 752L RAS is reset when the line decreases to 95 % of the seasonal rating
• Measured (EMS value) ENMAX Crossfield net generation level (MW) after the 752L RAS is reset = N
• At that instant, the safe operating generation level (MW) from both ENMAX and Nexen Inc # 1
= N + E2
= G1
Note 1: When 752L line flow exceeds 100% but is not greater than 110% for 10 minutes or the line flow exceeds
110% for 10 seconds, one or more generating units may be tripped instead of generation runback. Under this
scenario, more MW generation than normally required for generation runback will be tripped. The SC, therefore,
may adjust the calculated safe operating generation level depending on the real-time system conditions.
3. . Calculate pro-rata generation directive quantity (MW) to ENMAX Crossfield and Nexen Inc #1
• Applying the pro-rata policy, the sum of energy market dispatch (MW) and AS dispatch (MW) to
ENMAX Crossfield is limited to G * (E1 + A1 + D1)/ T
• Applying the pro-rata policy, the sum of energy market dispatch (MW) and AS dispatch (MW) to
Nexen Inc #1 is limited to G * (E2 + A2 + D2)/ T
•Direct ENMAX Crossfield and Nexen Inc # 1 to the above calculated directive level with AS being
curtailed first before energy.
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