Download 303 ALBERTA-BC INTERCONNECTION OPERATION 1. Purpose

Operating Policies and Procedures
Interconnections
OPP 303
Issued: 2008-05-01
Supersedes Interim OPP Effective: 2008-05-012007-12-12
303 ALBERTA-BC INTERCONNECTION OPERATION
1.
Purpose
To establish the requirements for operating the Alberta-BC interconnection. Matters related to transfer
limits, inadvertent energy management, available transfer capability (ATC) posting process and import
load remedial action schemes (ILRAS) utilization are dealt with in separate policies OPPs.
2.
Background
The Alberta-BC interconnection consists of the 500 kV line (1201L/5L94) between the Langdon
substation (T102S) in Alberta and the Cranbrook substation in BC, plus the 138 kV circuits between
BC’s Natal substation and Alberta’s Coleman (T799S) and Pocaterra (T48S) substations (1L275/786L
and 1L274/887L, respectively) (“138 kv interconnection facilities”). A simplified single line diagram of
the interconnections is shown in Figure 1. The IAESO is acknowledged as the Western Electricity
Coordinating Council (WECC) Path Operator for the Alberta-BC interconnection, also referred to as
Path 1.
A computerized generation shedding system is incorporated into the Energy Management System
(EMS) at the BCTC System Control Centre ( BCTC SCC). The BCTC SCC (?) system power
dispatcher has supervisory control of the remedial action scheme (RAS) and can monitor generation
shedding at the major South Interior plants and the status of the RAS. The generation shedding system
is designed so that the required amount of generation is shed to ensure that the post-contingency
transient overfrequency in the islanded area will not exceed 61 Hz per WECC criteria, and will settle to
below 60.5 Hz in less than 3 minutes.
When Alberta is supplying Elkford area load due to an outage of a transmission facility in BC, the
transmission reliability margin (TRM) will be increased and ATC decreased to avoid total transfer
capability (TTC) violations.
A list of the RAS in the Alberta Interconnected Electric System (AIES) and BC system that affect the
Alberta-BC interchange is given in Table 1.
3.
Policy
3.1
Outages
•
Planned Outages
−
•
BCTC and AltaLink must advise the ISO and the System Controller (SC) of any
planned maintenance outages for any BC interconnection facilities as set out in the
requirements of OPP 601. The accountabilities of BCTC are shown under the
heading of “Interconnected Members”, in OPP 601.
Forced Outages
−
BCTC and AltaLink must inform the SC immediately of any forced outages for any
BC interconnection facilities. The SC must inform the Vancouver Reliability
CoordinatorPacific Northwest Security Coordinator (PNSCVRC) of the forced
outage as soon as possible after it has been notified, and advise the PNSCVRC of
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Interconnections
OPP 303 Alberta-BC Interconnection Operation
any change to the operating transfer limitsystem operating limit (SOLOTC) as a
result of change in path configuration. Refer to OPP 304 for determining OTCthe
SOL under specified system conditions.
−
3.2
138 kV Tie Line Interconnection facilities Operation, when 1201L / 5L94 is out
of service
•
3.3
The 138 kV interconnection facilities may be left in service if 1201L/5L94 is removed
from service. If one of the 138 kV lines must be removed from service (that is, either
1L275/786L or 1L274/887L) while 1201L/5L94 is out of service, then the other 138 kV
interconnection line is to be opened between Alberta and BC, and Alberta operated
islanded from the WECC.
Tie lineAlberta-BC interconnection switching
•
Switching – Planned Outages
−
•
3.4
When Path 1 experiences a forced outage, the SC, as Path 1 Operator, will be
responsible for curtailing eE-tags for interconnection schedules on AB-BC tielineAlberta-BC interconnection.
Any switching involving planned outages of the Alberta-BC iInterconnection (500
kV and 138 kV lines) must be authorized by the SC in real time. The SC, as Path 1
Operator, must will inform the PNSCVRC before authorizing the removal or
restoration of Path 1. Once authorized by the SC, BCTC and AltaLink mustwill
coordinate with each other directly any real-time switching of facilities (between the
AltaLink CC and BCTC SCC). The SC wimustll be included in a conference call if
generation changes are required to enable synchronizing of the Alberta island to BC.
Switching – Forced Outages
−
If there has been a loss of 1201L/5L94, AltaLink mustwill consult with the SC
before undertaking or coordinating any switching on the Alberta-BC
interconnection. Once the SC has approved it, AltaLink will must undertake
arrangements with BCTC for switching. BCTC and AltaLink will must coordinate
with each other directly any real-time switching of facilities (between the AltaLink
CC and BCTC SCC).
−
AltaLink may coordinate directly with the BCTC SCC, without approval from the
SC, for switching following forced outages on the 138 kV interconnecting facilities
circuits (1L274/887L and 1L275/786L), if such events did not involve loss of
synchronism between BC and Alberta. The SC must be advised of such actions
immediately following the forced outage or restoration of the 138 kV elements. If
such events involve loss of synchronism between BC and Alberta, approval from
the SC is required before any switching to restore the lost circuits is undertaken. The
SC, as Path 1 Operator, will must obtain approval from the PNSCVRC before
synchronization.
Tie line1201L/5L94 restoration
•
Table 2 must be followed for energizing and de-energizing 1201L/5L94.
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Interconnections
OPP 303 Alberta-BC Interconnection Operation
3.5
3.6
Loss of teleprotection
•
AltaLink must advise the SC and BCTC SCC immediately upon the complete loss or
unavailability of teleprotection and communication elements associated with 1201L/5L94.
Unavailability of the teleprotection on 1201L/5L94 results in slow speed tripping under
fault conditions, potential miscoordination with adjacent line protections, and the terminal
line-end reactors effectively unprotected.
•
For a catastrophic microwave failure or for a planned major microwave outage, all
permissive and direct tripping from line, overvoltage, undervoltage, breaker failure or
reactor protection and open-end keying will be lost. Even though the line would still be
protected by slower channel independent back-up protection, remote clearing for a reactor
fault would be unavailable. Therefore, it has been agreed between IAESO and BCTC
must, as agreed to, to remove the circuit as soon as this can practically be done following
a major communications failure.
VAR control
•
3.7
Curtailment of import and export
•
3.8
Under zero interchange conditions, there will generally be a MVAr flow to each system
due to the charging effect of the lightly loaded 500 kV line portion of the Alberta-BC
interconnection(1201L/5L94). The MVAr flow should be equitably shared between the
Alberta and the BC systems in proportion to the length of the line located in each
province.owned by each. Based on approximately +180 MVAr of net charging, the Alberta
share is 120 MVAr and the BCTC share is 60 MVAr. The prime purpose will must be to
maintain adequate voltage levels at both terminals.
If schedule curtailments are required within the hour on the Alberta-BC interconnection,
they must be carried out on a pro-rata basis, if the reason for the curtailment originates in
on the Alberta side of the balancing authority boundary. If such the reason for curtailment
originates on thein BC side, the curtailment order will must be carried out by BCTC.
Formatted: Not Highlight
Alberta-BC iInterconnection (Alberta schemes)
a. Langdon underfrequency – overpower RAS
Underfrequency protection is installed at the Langdon substation T102S end.
•
Purpose:
−
•
•
This scheme is in place to prevent uncontrolled separations between the AIES and
the rest of the WECC, which could result in severe stability problems in the AIES.
The underfrequency RAS scheme will must also protect the tie line from thermal
overload conditions if the disturbance is outside of the AIES.
Initiation:
−
If the T102S frequency is less than 59.0 Hz, and
−
TAnd the Alberta to BC power flow is greater than 940 MW.
Action:
Formatted: Indent: Left: 81 pt,
Hanging: 27 pt, Bulleted + Level: 1
+ Aligned at: 81 pt + Tab after: 99
pt + Indent at: 99 pt, Tabs: Not at
99 pt
−Protection trips 1201L at Langdon substation T102S c
−
Causing a transfer trip of 5L94 at BCTC Cranbrook.
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Interconnections
OPP 303 Alberta-BC Interconnection Operation
•
Arming Requirements:
−
No arming requirements.
The BC system does not have underfrequency tripping of 5L94 initiating at the Cranbrook
substation.
This scheme is locally armed with the exception of alarm functionality through the SCADAlocal
except SCADA communication for alarm.
Formatted: Not Highlight
b. Langdon undervoltage – overpower RAS
•
Purpose:
−
•
The undervoltage relay trip scheme was installed at Langdon to avoid excessive load
losses in Southern Alberta due to low voltage conditions brought on by large power
swing transfers to BC. These swings can occur for certain major system disturbances
within the WECC or the AIES.
Initiation:
At Langdon substation T102S:
•
−
If the 500 kV bus voltage is less than 425 kV on all three phases for 0.2529 second,
and.
−
TAnd the Alberta -to -BC power flow is greater than 234 MW.
Action:
Formatted: Bullets and Numbering
Protection trips 1201L at Langdon substation T102S c
•
−
Trip 1201L at T102S.
−
Causinges a transfer trip of the Cranbrook terminal
Formatted: Indent: Left: 81 pt,
Hanging: 27 pt, Bulleted + Level: 1
+ Aligned at: 81 pt + Tab after: 99
pt + Indent at: 99 pt, Tabs: Not at
99 pt
Arming Requirements:
−
No arming requirements.
This scheme is locally armed with the exception of alarm functionality through the SCADAlocal
except SCADA Communication for alarm.
Formatted: Not Highlight
c. Langdon overvoltage protection scheme
Formatted: Indent: Left: 54 pt,
Hanging: 27 pt
•
•
Overvoltage Nnotification:
Formatted: Bullets and Numbering
−
Formatted: Bullets and Numbering
Alarm: 575 kV for 0.4 second at T102S.
Initiation:
At Langdon:
•
−
Stage-1 trip: Bus voltage >575 kV for a further 5 minutes.
−
Stage-2 trip: Bus voltage >625 kV for 0.2 second.
Action:
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Interconnections
OPP 303 Alberta-BC Interconnection Operation
−Overvoltage pProtection trips 1201L at Langdon substation T102S c
−
•
Arming Requirements:
−
3.9
Formatted: Indent: Left: 81 pt,
Hanging: 27 pt, Bulleted + Level: 1
+ Aligned at: 81 pt + Tab after: 99
pt + Indent at: 99 pt, Tabs: Not at
99 pt
Causing a transfer trip of 5L94 at BCTC Cranbrook.
No arming requirements.
Alberta-BC Interconnection (BCTC schemes)
a. 1201L/5L94 Tie Tripping RAS1
•
Purpose
- During certain conditions, BCTC SCC will must arm thISise scheme to trip
1201L/5L94 for one contingency condition being the (loss of 5L92 at BCTC Selkirk).
AltaLink and SC will must receive a “B2S TIE TRIP SCHEME ON”. The BCTC
EMS display for B2S Cranbrook will must indicate the status of this RAS. This
scheme uses teleprotection signals from Selkirk to Cranbrook and Langdon.
•
Initiation:
−
•
Action:
−
•
Loss of 5L92 at BCTC Selkirk.
This RAS will must trip 1201L/5L94.
Arming Requirements:
−
Transient stability analysis (TSA) will must arm/disarm this RAS.
−
The BCTC South Interior Control Centre (SIC) SIC SCADA can be used as a
backup to arm/disarm the RAS. The TSA auto download feature must be turned
off, if the RAS is to remain manually blocked. When armed, the operation of this
RAS results in tripping of the 5L94 circuit (and the BCTC Natal tie, if RAS3 is
armed).
b. Natal overpower RAS 3
•
Purpose:
−
To avoid low voltage conditions at Natal and/or overloading on Natal T1 and T2
for loss of 5L94 circuit, whenever the loading on 5L94 circuit exceeds 45 MW from
Cranbrook or 100 MW into Cranbrook.
The RAS consists of two power relays (out and in) at Cranbrook substation that continually
monitors the power flow on the 5L94 circuit. If the power flow on 5L94 exceeds 45 MW from
Cranbrook or 100 MW into Cranbrook, the “out” power relay or “in” power relay allows a
transfer trip signal to be sent to Pocaterra and Natal upon loss of 5L94 to trip 1L274/887L at
Pocaterra and trip 1L275/786L at Natal (1CB2).
There are two separate latch points at Cranbrook to independently arm/disarm the transfer trip
of 1L274/887L at Pocaterra and the transfer trip of 1L275/786L at Natal (1CB2). The first
point, noted above, is called Pocaterra RAS and the second is called Natal RAS. The two points
can be controllable locally or from BCTC SCC or BCTC SIC. Switching between BCTC SCC
control mode and BCTC SIC control mode can be done either at BCTC SCC or BCTC SIC.
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Formatted: Indent: Hanging: 153
pt, Bulleted + Level: 4 + Aligned at:
189 pt + Tab after: 207 pt + Indent
at: 207 pt, Tabs: 81 pt, List tab +
Not at 207 pt
Formatted: Indent: Left: 99 pt
Interconnections
OPP 303 Alberta-BC Interconnection Operation
In the BCTC SCC central control mode, only BCTC SCC has control of the two RAS arming
points. In BCTC SIC control mode (normal state), both BCTC SCC and BCTC SIC have control
of the two RAS arming points and the points will must be armed/disarmed according to
whoever accessed the point last. The BCTC-SCC dispatcher will control the two supervisory
points at Cranbrook. The BCTC TSA will arm and disarm the RAS as required. The BCTC SCC
dispatcher can manually block and “dispatcher set” the Natal and Pocaterra RAS independently.
BCTC SIC only has control if there is a failure of the BCTC SCC system. This will be done at
the direction of the BCTC SCC dispatcher.
•
Action:
−
•
To trip the two BCTC Natal 138 kV ties with Alberta.
Arming Requirements:
−
This RAS is armed and disarmed by BCTC.
c. Natal undervoltage (backup to overpower) RAS
This old scheme remains in service as a backup to the BCTC Natal 138 kV tie tripping RAS3.
•
Initiation:
−
•
•
This scheme initiates at 0.85 p.u. (117.3 kV) voltage with a 0.50 second time delay.
Action:
−
It trips Pocaterra T48S887X
−
And trips BCTC Natal 1CB2 breakers.
Arming Requirements:
−
No arming requirements.
d. Natal transformer protection scheme
•
Initiation:
−
•
For BCTC Natal transformer T1 or T2 thermal overload.
Action:
−
The inverse overload protection will trip Natal 66 kV breakers 60CB1 and 60CB2.
The RAS operation for each transformer bank is shown in Table 2.
•
Arming Requirements:
−
No arming requirements.
e. 2L294 RAS
•
Purpose:
−
To trip 5L94, 1L274 at Pocaterra and 1L275 at Natal for a controlled separation of
the Alberta system from BC on detection of a non-recoverable power swing on
2L294 during a 5L92 circuit outage.
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Interconnections
OPP 303 Alberta-BC Interconnection Operation
This RAS makes use of the out-of-step detection function of the SEL321 relays at BCTC
Cranbrook and Nelway substations. These relays will determine if the power swing on 2L294 is
non-recoverable and initiate tripping of the 5L94 circuit, the 1L274 circuit at Pocaterra and the
1L275 circuit at Natal and blocking the tripping of the 2L294 circuit. With 5L92 circuit out of
service, a power swing on 2L294 is generally due to a disturbance in Alberta. Note that if the
Pocaterra RAS arming point is blocked, the 2L294 RAS to trip 1L274 at Pocaterra will be
blocked automatically. Similarly, if the Natal RAS arming point is blocked, the 2L294 RAS to trip
1L275 at Natal will be blocked automatically.
•
f.
•
Arming Requirements:
−
The BCTC TSA will monitor 5L92 status and automatically arm/disarm this RAS.
−
This RAS can be armed manually at BCTC SCC and BCTC SIC and should be
armed only when 5L92 is out of service
5L91 and 5L98 RAS
Initiation:
−
•
•
For a double contingency of 5L91 and 5L98 in the BC system when 1201L/5L94 is
in service.
Action:
−
RAS will trip 2L112 (Nelway to Boundary) when Waneta is connected directly to
Nelway, or combined trip of 2L112 and 2L277 (Waneta to Boundary) when Waneta
is connected directly to Boundary.
−
The RAS effectively opens the BC–US eastern tie and islands part of the BC system
(between 240 and 650 MW of load with almost 2,000 MW of generation) with the
Alberta system.
Arming Requirements:
−
This RAS is armed by BCTC.
−
The arming status can be found on the EMS display # 6007 SEL (Selkirk) and on
the video wall display.
g. Alberta tie tripping RAS for loss of 5L51 and 5L52
•
Purpose:
−
To prevent the Alberta system frequency from dropping below 59 Hz, as required
by the WECC.
This RAS allows the tripping of the BC–Alberta Interconnection for the loss of 5L51 and 5L52,
or loss of 5L51 (or 5L52) with 5L52 (or 5L51) out of service during high US-to-BC transfers.
•
Initiation:
−
•
Loss of 5L51 and 5L52, or loss of 5L51 (or 5L52) with 5L52 (or 5L51) out of
service during high US-to-BC transfers.
Action:
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Interconnections
OPP 303 Alberta-BC Interconnection Operation
−
RAS will trip the 5L94 tie if the frequency at Cranbrook is below 59.95 Hz for more
than 3 cycles.
−
Tripping of the 5L94 tie will, in turn, trip the 1L274 tie at Pocaterra (by the
Pocaterra RAS) and the 1L275 tie at Natal (by the Natal RAS) to separate BC from
Alberta.
When armed during BC system moderate-to-heavy import conditions from the US and Alcan,
this RAS will trip the 5L94 tie if the frequency at Cranbrook is below 59.95 Hz for more than 3
cycles after loss of 5L51 and 5L52, or loss of 5L51 (or 5L52) with 5L52 (or 5L51) out of service.
Tripping of the 5L94 tie will, in turn, trip the 1L274 tie at Pocaterra (by the Pocaterra RAS) and
the 1L275 tie at Natal (by the Natal RAS) to separate BC from Alberta. The separation is to
prevent the Alberta system frequency from dropping below 59 Hz, as required by the WECC.
•
Arming Requirements:
−
The BCTC SCC Energy Management System (EMS) TSA advanced application
automatically arms/disarms this RAS.
The BCTC SCC system power dispatcher is responsible for arming and disarming this RAS at
BCTC Cranbrook. When TSA is unavailable, the BCTC SCC System Power Dispatcher can
manually arm/disarm this RAS from the BCTC SCC EMS Generation Shedding display. BCTC
SIC also has SCADA control for arming and disarming this RAS at BCTC Cranbrook.
h. Cranbrook undervoltage – overpower protection
•
Initiation:
At BCTC Cranbrook:,
•
−
If the 500 kV bus voltage is less than 421 kV for at least 0.50 second.
−
There is no power supervision of the undervoltage relay at BCTC Cranbrook.
Action:
−
•
Arming Requirements:
−
i.
Transfer trips 5L94 at BCTC Cranbrook.
No arming requirements.
Cranbrook overvoltage protection scheme
Overvoltage protection will trip both ends of 5L94. The tripping settings are:
•
•
At Cranbrook:
−
Stage-1 trip: Bus voltage >575 kV for at least 5 second.
−
Stage-2 trip: Bus voltage >625 kV for at least 0.25 second.
Arming Requirements:
−
•
No arming requirements.
Action:
−
Trips 1201L at T102S
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Interconnections
OPP 303 Alberta-BC Interconnection Operation
−
j.
•
1201L Open breaker (3-pole) transfer trip
Initiation:
−
•
Transfer trips 5L94 at BCTC Cranbrook.
Three-pole opening of either 500 kV terminals of 1201L /5L94.
Action:
−
By causes other than line protection, sends a three-pole direct transfer trip to the
remote terminal.
This scheme uses teleprotection.
•
Arming Requirements:
−
No arming requirements.
k. Direct transfer tripping of 5L94 for loss of 5L81 and 5L82 (5L81 and 5L82 RAS)
•
Purpose:
−
•
Initiation:
−
•
Loss of 5L81 and 5L82 and high Alberta to BC transfer.
Action:
−
•
To disconnect the Cranbrook area from Alberta upon the loss of 5L81 and 5L82
when Alberta is exporting heavily into BC, to avoid significant generation shedding
in Cranbrook area.
Transfer trip 5L94/1201L.
Arming Requirements:
−
BCTC will arm.
l. Direct transfer tripping of Alberta – BC Ties for loss of 5L76 and 5L79 (5L76 and
5L79 RAS)
•
Purpose:
−
•
Initiation:
−
•
Loss of 5L76 and 5L79.
Action:
−
•
To disconnect 5L94, 1L274 at Pocaterra and 1L275 at Natal upon the loss of 5L76
and 5L79.
Transfer trip Alberta – BC Ties.
Arming Requirements:
−
BCTC will arm.
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Interconnections
OPP 303 Alberta-BC Interconnection Operation
3.10 TRM/ATC adjustments when the Ford Elk area load is served by Alberta
•
When 887L/1L274 is open at Natal or open between Natal and Pocaterra (T48S), the
TRM will be increased and the ATC will be reduced by the flow on 887L/1L274 from
Pocaterra to avoid exceeding the operating limits.
•
When one of the following system conditions occurs, the TRM will must be increased and
the ATC will must be reduced by the sum of the flows on 887L/1L274 and 786L/1L275
to avoid exceeding the operating limits:
1.
Two parallel transformers at Natal are out of service; or
2.
2L113 in the BC system is out of service.
3.11 Transfer Operating Guides
Supporting information for the transfer limits and associated operating guides for the AlbertaBC interconnection are outlined in OPP 304.
The transfer limits, may be subject to change due to various transmission element outages and
operating conditions in the BCTC system and AIES. The BCTC system outages are further
defined in BCTC’s System Operating Order 7T-17. Events that occur on the AIES that require
the limits to be adjusted, beyond those identified in OPP 304, will be dealt with via the AESO’s
System Coordination Plan and by the SC in real time.
4.
Responsibilities
4.1
ISO
The ISO is responsible formust:
•
Reviewing in cooperation with BCTC, as required from time to time, the operating
requirements on the Alberta-BC interconnection and updating this OPP.
System Controller
The SC is responsible formust:
•
Authorizeing any switching involving planned outages of the BC interconnection (500 kV
and 138 kV lines) in real time.
•
Informing the PNSCVRC before directing the removal or restoration of Path 1.
•
Authorizeing AltaLink before undertaking or coordinating any switching on the BC
interconnection.
•
For events that involve loss of synchronization between BC and Alberta, obtaining
approval from the PNSCVRC before any switching to restore the lost circuits.
•
Directing any Alberta generation changes needed to enable synchronizing of Alberta to
BC.
•
Authorizeing synchronization to the BC system.
•
Curtailing eE-tags when Path 1 experiences forced outage.
•
Informing the PNSCVRC as soon as possible of any forced outages on Path1 and advising
the PNSCVRC of any change to the OTC SOL as a result of change in path configuration.
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OPP 303 Alberta-BC Interconnection Operation
4.2
BC Transmission Corporation (BCTC)
BCTC is responsible formust:
•
Restoreing any BC interconnection elements that have been automatically forced out of
service, in accordance with the recommended sequences shown in Table 2 and the
switching policy set out in Section 3.3.
•
Adviseing the ISO and the SC of any planned maintenance or forced outages for any BC
interconnection facilities.
•
Coordinateing with AltaLink directly after getting authorization from SC for any real time
switching involving planned outages of facilities (between the AltaLink CC and BCTC
SCC).
•
Issueing a curtailment order if the reason for curtailment of import and export originates
on the BC side.
•
Conferenceing with the SC for restoring of the first 500 kV circuits (either 5L91 or 5L98).
•
Arming the 5L94 Tie Tripping RAS via TSA to trip 5L94/1201L as indicated in Table 1.
•
Arming and disarming the Natal 138 kV Tie Tripping RAS via TSA.
•
Manually arming 2L294 RAS at SCC and South Interior Control Centre (SIC) only when
5L92 is out of service. TSA mustwill monitor 5L92 status and arm/disarm this RAS.
•
The BCTC SCC EMS TSA advanced application normally arms/disarms the Alberta Tie
RAS (for loss of 5L51 and 5L52). When TSA is unavailable, the SCC system power
dispatcher should manually arm/disarm this RAS from the BCTC SCC EMS generation
shedding display.
•
Arming the 5L91 and 5L98 RAS. The arming status is to be given on the EMS display
# 6007 SEL (Selkirk) and on the video wall display.
Formatted: Indent: Left: 54 pt
,
4.3
Transmission Facility Owner (TFO) - AltaLink
The TFO is responsible for:must:
•
Adviseing the ISO and the SC of any forced and planned maintenance outages for any BC
interconnection facilities.
•
Coordinateing with BCTC directly after getting authorization from SC any real time
switching involving planned outages of facilities (between the AltaLink CC and BCTC
SCC).
•
Coordinateing with BCTC directly after getting authorization from SC any real time
switching involving forced outages of facilities (between the AltaLink CC and BCTC
SCC).
•
Coordinateing directly with the BCTC SCC, without approval from the SC, for switching
following forced outages on the 138 kV interconnecting circuits (1L274/887L and
1L275/786L), if such events did not involve loss of synchronization between BC and
Alberta.
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Interconnections
OPP 303 Alberta-BC Interconnection Operation
5.
•
Adviseing the SC of any actions immediately following the forced outage or restoration of
the 138 kV elements.
•
Restoreing any BC interconnection elements that have been automatically forced out of
service, in accordance with the recommended sequences shown in Table 2 and the
switching policy set out in Section 3.2.
•
Adviseing the SC promptly that there are higher than normal risk conditions (such as
equipment alarms, equipment failures, teleprotection, communication, adverse weather,
etc.) on BC interconnection facilities, which could lead to loss of those elements and have
an effect on the rating of the interconnection.
System Controller Procedures
5.1
Double contingency of 5L91 and 5L98 with 1201L in service
The SC mustwill:
1.
Monitor the 5L91 and 5L98 RAS arming status. The arming status can be found on the
EMS display # 6007 SEL (Selkirk) and on the video wall display. If the RAS is disarmed,
call the BCTC system power dispatcher to inquire.
2.
Upon receiving an alarm: “BCH Separation”, go to the EMS display # 6007 for SEL
(Selkirk). Verify that the statuses of 5L91 and 5L98 indicate open.
3.
Verify that the EMS system automatically switched to Balancing authority constant
frequency (CF) control mode. Otherwise, manually switch it to CF control mode
immediately.
4.
Monitor system frequency to ensure that it does not exceed 61.0 Hz immediately following
the trip.
5.
Contact the BCTC Operator (Generation Desk) to ensure that the automatic generation
shedding scheme and/or manual generation ramping will reduce the system frequency to
below 60.5 Hz within 3 minutes, which is required in order to prevent generation tripping
in Alberta (refer to Table 3 in OPP 804). A loss of 5L91 and 5L98 does not suspend AGC.
6.
Request the BCTC Operator (Generation Desk) to continue generation manual ramping
until the system frequency stabilizes at 60.0 Hz.
7.
In the unlikely event that generation shedding/manual ramping fails to reduce the system
frequency to an acceptable level, such that it jeopardizes generation tripping and/or
equipment damage, direct AltaLink Operator to open the Alberta-BC tie. Take this
extreme action only if required to prevent uncontrolled Alberta generation tripping and
cascading system outages. Consider the Alberta supply and demand situation to ensure
that this is not detrimental to the Alberta system before taking this action.
8.
After the system frequency has stabilized at 60.0 Hz, check the flow on the Alberta-BC
interconnection. Contact the BCTC Operator to agree on the acceptable tie flow. (BC may
want to export to Alberta due to the excess generation capability in the islanded BC area.
The associated risk is the tripping of 1201L/5L94, which will island the small portion of
the BC South Interior system. The risk to the Alberta system is acceptable as long as the
import or export is no greater than the limits presented in OPP 304. This schedule is good
DRAFT 2 Issued for Stakeholder Consultation: 2009-09-10
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Interconnections
OPP 303 Alberta-BC Interconnection Operation
for the current hour only. For the next hour, resume normal scheduling procedures).
Normal scheduling procedures including e-Tags must be followed.
5.2
9.
Resume external spinning and contingency reserve schedules.
10.
Manually ramp Alberta generator(s) to achieve the agreed upon Alberta-BC
interconnection tie flow, in coordination with BCTC.
11.
Approve e-Tag curtailments of energy transactions over the Alberta-BC interconnection
submitted by BCTC. (If the e-Tag curtailments are not actively approved, they will be
approved by default.)
12.
Notify the Operations on-call person.
13.
If the islanded situation extends beyond the current hour, confirm with BCTC on the
ATC for the upcoming hours and re-post the ATC accordingly
14.
Coordinate with the BCTC Operator as 5L91 and 5L98 are restored.
15.
After the restoration of 5L91 and 5L98 and the islanded situation is removed, switch back
to Tie Line Biased (TLB) control mode and resume normal procedures for Alberta-BC
interconnection scheduling and operation.
TRM/ATC adjustments when the Ford Elk area load is served by Alberta
When the Ford Elk area load is served partially or entirely by Alberta, the SC mustwill:
5.3
1.
Determine the flows on 887L/1L274.
2.
Increase TRM and decrease ATC by the flow on 887L/1L274 from Pocaterra (T48S).
Keep TTC as scheduled and re-post the hourly Alberta to BC ATC as described in
OPP 304.
3.
When the outage element(s) have been returned to service, decrease TRM and increase
ATC by the flow on 887L/1L274 from T48S and re-post the hourly Alberta to BC ATC
as described in OPP 304.
TRM/ATC adjustments when two parallel transformers at Natal or 2L113 are
out of service
When two parallel transformers at Natal or 2L113 in BC Hydro’s system are out of service, the
SC mustwill:
5.4
1.
Determine the flows on 887L/1L274 and 786L/1L275.
2.
Increase TRM and decrease ATC by the sum of the flows on 887L/1L274 and
786L/1L275. Keep TTC as scheduled and re-post the hourly Alberta to BC ATC as
described in OPP 304.
3.
When the outage element(s) have been returned to service, decrease TRM and increase
ATC by the sum of the flows on 887L/1L274 and 786L/1L275 and re-post the hourly
Alberta to BC ATC as described in OPP 304.
138 kV Tie Line Operation, when 1201L / 5L94 is out of service
If 1201L/5L94 is out of service and one of the 138 kV lines (that is, either 1L275/786L or
1L274/887L) is also out of service then the SC will open the remaining 138 kV line (i.e., either
1L275/786L or 1L274/887L) between Alberta and BC.
DRAFT 2 Issued for Stakeholder Consultation: 2009-09-10
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Interconnections
OPP 303 Alberta-BC Interconnection Operation
5.5
Curtailing interconnection transactions within the hour
If an outage of the transmission/generation facility as referenced in OPP 304 Table 1, Table 4 or
Table 5 occurs within the hour of the interconnection transaction and the net transaction
exceeds the import or export ATC limits, the SC will:
1.
Curtail the e-Tags on a pro-rata basis to the amount not exceeding the ATC limits.
2.
Notify the BCTC operator.
3.
Enter the revised schedule setting on EMS.
5.56 Curtailing E-Tags
When Path 1 experiences forced outage, the SC will curtail eE-tags for the AB-BC
interconnection.
5.67 Communication with the PNSCVRC
The SC mustwill proactively maintain communication with the PNSCVRC, including without
limitation the following:
6.
1.
Notify the PNSCVRC before removing or restoring an element of Path 1.
2.
Obtain approval from the PNSCVRC before synchronizing Path 1.
3.
Inform the PNSCVRC as soon as possible of any forced outages on Path1 and advise the
PNSCVRC of any change to the OTC SOL as a result of change in path configuration.
Figures and Tables
Begin on next page.
DRAFT 2 Issued for Stakeholder Consultation: 2009-09-10
Page 14 of 18
Interconnections
OPP 303 Alberta-BC Interconnection Operation
Figure 1
Alberta-BC interconnection
Mica
Selkirk
500kV
Ashton
Creek
500 kV
5L82
5L79
138kV
5L92
2L2 94
~
Ingledow
Vaseux
Lake
5RX5
9L79
9L80
9L59
/9
L9
33
945L
28S
927L
951L
9L99
240kV
138kV
SASK
INTERT
BC Interconnection Metering Points
Nelway
230kV Waneta
Kootenay Canal
230kV
5L52
~
Seven Mile
BC
2 L112
USA
Custer
Issued: 2008-05-01
163S
5L 94 ( 1201L)
5L96
~
5L51
5RX4
275S
2L293
Alcan
5L98
Meridian
923L
840S
5L91
5 L77
5L44
935L
923L
2L113
Revelstoke 5 L75
5L81
924L
370S
5L72
132 S
240kV
Cranbrook
500kV
230kV
~
5L71
SVC
1L
93
830L
1L275/786L
500kV
1201L (5L94)
138 kV
System
924L
RX
777L
Nicola
500kV
102 S Langdon
240 kV
59S
911L
138 kV
138 kV
1L274 /887L
93
3L
240 kV
48S
230kV
937L
138kV
Natal
950L/9 L50
74S
917L
936L
916L
801 S
9 44L
901L
5S
42 S
9L20
755S
64S
925L
929L
918L
240kV
9L27
9 14L
63S
928L
Alberta
912 L/ 9L912
900L
906L
B. C.
TO 87 S
Gaetz
934L/9L934
17S
766 S
TO 89 S
Ellerslie
910L
922L
926L
995L
TO 330 P
Keephills
9 03L
TO 310P
Sundance
995L
190L
995AL
62S
9L948/948L
~
Battle River 757S
Generating
Station
68S
BPA’s
Boundary
Substation
2L277
USA
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Interconnections
OPP 303 Alberta-BC Interconnection Operation
Table 1
RAS in the AIES and BC system that affect the Alberta-BC interchange
Area
Name of the Scheme
Description
Alberta-BC
Interconnection
(Alberta
Schemes)
Langdon Underfrequency –
Overpower RAS
RAS operates if the Langdon 102S frequency <59.0 Hz and
the Alberta to BC power flow >940 MW.
Operation of RAS will trip 1201L / 5L94 at Langdon causing a
transfer trip of the Cranbrook terminal.
Langdon Undervoltage –
Overpower RAS
RAS operates at the Langdon substation 102S, if the 500 kV
bus voltage <425 kV on all three phases for 0.259 sec and the
Alberta to BC power flow >234 MW. This
Operation of RAS will trip 1201L at T102S causing a transfer
trip of the Cranbrook terminal..
Langdon Overvoltage
Protection Scheme
RAS sends alarm if 500 kV bus voltage >575 kV for 0.4 sec at
Langdon 102S.
Tripping occurs at:
• Langdon Stage 1: 500 kV bus voltage >575 kV for a further 5
minutes.
• Langdon Stage 2: 500 kV bus voltage >625 kV for 0.2 sec.
1201L/5L94 Tie Tripping
RAS 1
RAS is armed for a possible contingency of 5L92 in the BCH
system.
AltaLink and SC will receive a “B2S TIE TRIP SCHEME ON”
Operation of the RAS results in a trip of 1201L/5L94.
Natal Overpower RAS 3
RAS prevents a low voltage condition at Natal and/or
overloading on Natal T1 and T2 for loss of 5L94 circuit.
RAS is armed whenever the loading on 1201L/5L94 exceeds
45 MW from Cranbrook or 100 MW into Cranbrook
Operation of the RAS results in a trip of the two Natal 138 kV
ties with Alberta for a loss of 1201L/5L94.
Natal Undervoltage (Backup
to RAS3) RAS
This scheme initiates at 0.85 p.u. (117.3 kV) voltage with a
0.50 second time delay.
Operation of the RAS results in a trip of the Pocaterra
48S887X and Natal 1CB2 breakers.
Natal Transformer
Protection Scheme
RAS operates on overloading Natal transformer T1 or T2.
Operation of RAS results in tripping 138 kV breakers 1CB1
and 1CB2.
2L294 RAS
RAS operates on detection of a non-recoverable power swing
on 2L294 during an outage of 5L92.
Operation of the RAS results in a trip of 1201L/5L94,
887L/1L274 at Pocaterra and 786L/1L275 at Natal.
5L91 and 5L98 RAS
RAS operates for a loss of 5L91 and 5L98 in the BC system
will result to trip 2L112 or combined trip of 2L112 and 2L277.
Operation of RAS results in opening the BC – US eastern tie
and islands part of the BC system with the Alberta system.
Alberta Tie Tripping RAS for
Loss of 5L51 and 5L52
RAS operates for a loss of 5L51 and 5L52 in the BC system
during high US to BC transfers.
Operation of RAS results in a trip of 1201L/5L94.
Alberta-BC
Interconnection
(BCTC
Schemes)
Issued: 2008-05-01
Page 16 of 18
Interconnections
OPP 303 Alberta-BC Interconnection Operation
Area
Name of the Scheme
Description
Cranbrook Undervoltage Overpower Protection
Tripping occurs at:
• Cranbrook, if the 500 kV bus voltage <421 kV for at least
0.50 sec.
• There is no power supervision of the undervoltage relay at
this terminal.
Operation of the RAS results in transfer trip of 5L94 at
Cranbrook.
Cranbrook Overvoltage
Protection Scheme
Tripping occurs at:
• Cranbrook Stage 1: 500 kV bus voltage >575 kV for at least
5 sec.
• Cranbrook Stage 2: 500 kV bus voltage >625 kV for at least
0.25 sec.
Operation of the RAS results in tripping 1201L at Langdon and
causes a transfer trip of 5L94 at Cranbrook.
1201L Open Breaker (3Pole) Transfer Trip RAS
Three-pole opening of either 500 kV terminal of 1201L /5L94,
by causes other than line protection, sends a three-pole direct
transfer trip to the remote terminal.
Direct Transfer Tripping of
5L94 for Loss of 5L81 and
5L82 (5L81 and 5L82 RAS)
This RAS allows direct tripping of 5L94 for the loss of 5L81
and 5L82, if both Alberta to BC transfer and the required
generation shedding are high.
Direct Transfer Tripping of
Alberta – BC Ties for Loss of
5L76 and 5L79 (5L76 and
5L79 RAS)
This RAS allows direct transfer tripping of 5L94, 1L274 at
Pocaterra and 1L275 at Natal for the loss of 5L76 and 5L79.
Table 2
Guidelines for 5L94 (1201L) line energizing sequences for various operating cases. Use the
reverse sequence to de-energize the line
Condition
Line Energizing
Lead End Terminal
Maximum Voltage at Lead End
Before Energizing the Line
System Normal
Cranbrook (preferred)
530 kV
Langdon (second choice)
252 kV with –250 MVAr room on SVC
(i.e., SVC at or above 0 + MVAr)
Cranbrook (preferred)
530 kV
Langdon (second choice)
248 kV
Langdon RX Out of Service
Langdon (only choice)(Note 1)
248 kV with –400 MVAr room on SVC
(i.e., SVC at or above +150 MVAr)
Cranbrook 5RX4 Out of Service
Cranbrook (preferred)
530 kV
Langdon (second choice) (Note1)
248 kV with –250 MVAr room on SVC
(i.e., SVC at or above 0 + MVAr)
Cranbrook (preferred) (Note 1)
510 kV
Langdon (second choice) (Note 1)
248 kV with –400 MVAr room on SVC
(i.e., SVC at or above +150 MVAr)
Langdon SVC Out of Service
Cranbrook 5RX5 Out of Service
Issued: 2008-05-01
Page 17 of 18
Interconnections
OPP 303 Alberta-BC Interconnection Operation
Condition
Line Energizing
Lead End Terminal
Maximum Voltage at Lead End
Before Energizing the Line
5L92 Out of Service
Langdon (only choice)
252 kV with –250 MVAr room on SVC
(i.e., SVC at or above 0 + MVAr)
Cranbrook 5RX4 and 5RX5 Out
of Service
Langdon (only choice) (Note 1 and 2)
248 kV with –400 MVAr room on SVC
(i.e., SVC at or above +150 MVAr)
Langdon SVC and Cranbrook
5RX4 Out of Service
Cranbrook (only choice)
530 kV
Langdon SVC and Cranbrook
5RX5 Out of Service
Cranbrook (only choice) (Note 1)
510 kV
Langdon SVC and Langdon RX
Out of Service
Langdon (only choice) (Note 1)
236 kV (Note 3).
Langdon RX and Cranbrook
5RX4 Out of Service
Langdon (only choice) (Note 1)
248 kV with –400 MVAr room on SVC
(i.e., SVC at or above +150 MVAr)
Langdon RX and Cranbrook
5RX5 Out of Service
DO NOT ATTEMPT TO ENERGIZE
BCTC System Normal,
Black out in Calgary including
Langdon, Langdon SVC OOS
(Cranbrook 5RX5 and Langdon
RX connected)
Cranbrook (only choice)
510 kV
(see Note 4 for operating procedure)
Note:
1. Single Pole Reclosing (SPR) on 5L94 (1201L) may not succeed if one of its two line reactors (with its associated
neutral reactor) is not available for service. Bypassing of only one neutral reactor at either end of the line is
expected to result in an unsuccessful single pole reclose.
2. Consider energizing for emergencies only. It will be difficult to keep Cranbrook voltage below 550 kV after 5L94
(1201L) is energized.
3. This is below the normal operating limit. Unless the voltage can be reduced to 236 kV at Langdon prior to picking
up the line do not energize the line.
4. Under the direction of the SC, the following operating procedure is for energizing 5L94 (1201L) from Cranbrook
during restoration of the Calgary Area:
• BCTC to block the Single Pole Trip and Reclose (SPTR) of 5L94 (1201L) at Cranbrook and the SC to confirm
with AltaLink CC that the SPTR of 5L94 (1201L) at Langdon (102S) is blocked.
• BCTC to adjust the Cranbrook 500 kV bus voltage to a level less than 510 kV. This may require all Ashton Creek
reactors, Nicola reactors and Cranbrook 12 kV reactors in service and the adjustment of Revelstoke, Mica,
Seven Mile and Kootenay Canal generator terminal voltages.
• ENMAX and AltaLink, following direction from the SC, to establish a de-energized system load island, consisting
of a transmission path from Langdon to ENMAX 2 Sub and connected load of approximately 20 MW at 2 Sub.
The purpose of the load island is to control voltages in the Calgary area, upon energization of 1201L.
• BCTC to energize 5L94 (1201L) from Cranbrook.
• After 5L94 (1201L) is energized, additional load may be picked up in the Calgary area to help control the high
voltages and to provide power to substations and generating plants.
• After Alberta generation has been connected and 5L94 (1201L) ceases to be a radial supply, then BCTC will
enable the SPTR of 5L94 (1201L) at Cranbrook and the SC to confirm with AltaLink CC that the SPTR of 5L94
(1201L) at Langdon is enabled.
Issued: 2008-05-01
Page 18 of 18
Interconnections
OPP 303 Alberta-BC Interconnection Operation
7.
Revision History
Issued
Description
2009-
Supersedes 2008-05-01
2008-05-01
Supersedes 2007-12-12
2007-12-12
Approved for interim implementation; supersedes 2006-04-27
2006-04-27
Supersedes 2005-07-27
2005-07-27
Supersedes 2004-12-07
2004-12-07
Supersedes 2003-07-28
2003-07-28
Revised to ISO Operating Policies and Procedures
Issued: 2008-05-01
Page 19 of 18