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Operating Policies and Procedures Interconnections OPP 303 Issued: 2008Supersedes Interim OPP Issued : 2007-12-12 303 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. 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). A simplified single line diagram of the interconnections is shown in Figure 1. The AESO 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 (SCC). The BCTC 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 Pacific Northwest Security Coordinator (PNSC) of the forced outage as soon as possible and advise the PNSC of any change to the operating transfer limit (OTC) as a result of change in path configuration. Refer to OPP 304 for determining OTC. Filed with AUC: 2008-04-17 Page 1 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation − 3.2 138 kV Tie Line 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 is to be opened between Alberta and BC, and Alberta operated islanded from the WECC. Tie line switching • Switching – Planned Outages − • 3.4 Any switching involving planned outages of the BC Interconnection (500 kV and 138 kV lines) must be authorized by the SC in real time. The SC, as Path 1 Operator, will inform the PNSC before authorizing the removal or restoration of Path 1. Once authorized by the SC, BCTC and AltaLink will coordinate with each other directly any real-time switching of facilities (between the AltaLink CC and BCTC SCC). The SC will 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 will consult with the SC before undertaking or coordinating any switching on the BC interconnection. Once the SC has approved it, AltaLink will undertake arrangements with BCTC for switching. BCTC and AltaLink will 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 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 obtain approval from the PNSC before synchronization. Tie line restoration • 3.5 When Path 1 experiences forced outage, the SC as Path 1 Operator, will be responsible for curtailing E-tags for interconnection schedules on AB-BC tie-line. Table 2 must be followed for energizing and de-energizing 1201L/5L94. 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 Filed with AUC: 2008-04-17 Page 2 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation 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 AESO and BCTC to remove the circuit as soon as this can practically be done following a major communications failure. 3.6 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 (1201L/5L94). The MVAr flow should be equitably shared between the systems in proportion to the length of the line 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 be to maintain adequate voltage levels at both terminals. If schedule curtailments are required within the hour on the BC interconnection, they must be carried out on a pro-rata basis, if the reason for the curtailment originates on the Alberta side of the Balancing authority boundary. If the reason for curtailment originates on the BC side, the curtailment order will be by BCTC. Alberta-BC Interconnection (Alberta schemes) 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 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 the Alberta to BC power flow is greater than 940 MW. Action: − Protection trips 1201L at Langdon substation T102S − Causing a transfer trip of 5L94 at BCTC Cranbrook. Arming Requirements: − No arming requirements. The BC system does not have underfrequency tripping of 5L94 initiating at the Cranbrook substation. This scheme is local except SCADA communication for alarm. Filed with AUC: 2008-04-17 Page 3 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation 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 for 0.29 second. − And the Alberta-to-BC power flow is greater than 234 MW. Action: − • Trip 1201L at T102S. Arming Requirements: − No arming requirements. This scheme is local except SCADA Communication for alarm. Langdon overvoltage protection scheme • Overvoltage notification: − • 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: − Overvoltage protection trips 1201L at Langdon substation T102S − Causing a transfer trip of 5L94 at BCTC Cranbrook. Arming Requirements: − 3.9 No arming requirements. Alberta-BC Interconnection (BCTC schemes) 1201L/5L94 Tie Tripping RAS1 During certain conditions, BCTC SCC will arm the scheme to trip 1201L/5L94 for one contingency condition (loss of 5L92 at BCTC Selkirk). AltaLink and SC will receive a “B2S TIE TRIP SCHEME ON”. The BCTC EMS display for B2S Cranbrook will indicate the status of this RAS. This scheme uses teleprotection signals from Selkirk to Cranbrook and Langdon. Filed with AUC: 2008-04-17 Page 4 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation • Initiation: − • Action: − • Loss of 5L92 at BCTC Selkirk. This RAS will trip 1201L/5L94. Arming Requirements: − Transient stability analysis (TSA) will arm/disarm this RAS. − The BCTC 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). 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. 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 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. Natal undervoltage (backup to overpower) RAS This old scheme remains in service as a backup to the BCTC Natal 138 kV tie tripping RAS3. Filed with AUC: 2008-04-17 Page 5 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation • 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. 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. 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. 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. • 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. Filed with AUC: 2008-04-17 Page 6 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation • • 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. 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: − 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. Filed with AUC: 2008-04-17 Page 7 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation 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: − • Transfer trips 5L94 at BCTC Cranbrook. Arming Requirements: − 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 − Transfer trips 5L94 at BCTC Cranbrook. 1201L Open breaker (3-pole) transfer trip • Initiation: − • 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. Direct transfer tripping of 5L94 for loss of 5L81 and 5L82 (5L81 and 5L82 RAS) • Purpose: − 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. Filed with AUC: 2008-04-17 Page 8 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation • Initiation: − • Action: − • Loss of 5L81 and 5L82 and high Alberta to BC transfer. Transfer trip 5L94/1201L. Arming Requirements: − BCTC will arm. 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. 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 be increased and the ATC will 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 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. Filed with AUC: 2008-04-17 Page 9 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation 4. Responsibilities 4.1 ISO The ISO is responsible for: • 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 for: 4.2 • Authorizing any switching involving planned outages of the BC interconnection (500 kV and 138 kV lines) in real time. • Informing the PNSC before directing the removal or restoration of Path 1. • Authorizing 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 PNSC before any switching to restore the lost circuits. • Directing any Alberta generation changes needed to enable synchronizing of Alberta to BC. • Authorizing synchronization to the BC system. • Curtailing E-tags when Path 1 experiences forced outage. • Informing the PNSC as soon as possible of any forced outages on Path1 and advising the PNSC of any change to the OTC as a result of change in path configuration. BC Transmission Corporation (BCTC) BCTC is responsible for: • Restoring 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. • Advising the ISO and the SC of any planned maintenance or forced outages for any BC interconnection facilities. • Coordinating 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). • Issuing a curtailment order if the reason for curtailment of import and export originates on the BC side. • Conferencing 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. Filed with AUC: 2008-04-17 Page 10 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation 4.3 • Manually arming 2L294 RAS at SCC and South Interior Control Centre (SIC) only when 5L92 is out of service. TSA will 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. Transmission Facility Owner (TFO) - AltaLink The TFO is responsible for: 5. • Advising the ISO and the SC of any forced and planned maintenance outages for any BC interconnection facilities. • Coordinating with BCTC directly after getting authorization from SC any real time switching involving planned outages of facilities (between the AltaLink CC and BCTC SCC). • Coordinating with BCTC directly after getting authorization from SC any real time switching involving forced outages of facilities (between the AltaLink CC and BCTC SCC). • Coordinating 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. • Advising the SC of any actions immediately following the forced outage or restoration of the 138 kV elements. • Restoring 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. • Advising 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 impact on the rating of the interconnection. System Controller Procedures 5.1 Double contingency of 5L91 and 5L98 with 1201L in service The SC will: 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. Filed with AUC: 2008-04-17 Page 11 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation 5.2 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 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 for the current hour only. For the next hour, resume normal scheduling procedures). Normal scheduling procedures including e-Tags must be followed. 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 will: 1. Determine the flows on 887L/1L274. Filed with AUC: 2008-04-17 Page 12 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation 5.3 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 will: 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. 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: 5.5 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. Curtailing E-Tags When Path 1 experiences forced outage, the SC will curtail E-tags for the AB-BC interconnection. 5.6 Communication with the PNSC The SC will proactively maintain communication with the PNSC: 6. 1. Notify the PNSC before removing or restoring an element of Path 1. 2. Obtain approval from the PNSC before synchronizing Path 1. 3. Inform the PNSC as soon as possible of any forced outages on Path1 and advise the PNSC of any change to the OTC as a result of change in path configuration. Figures and Tables Begin on next page. Filed with AUC: 2008-04-17 Page 13 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation Figure 1 Alberta-BC interconnection Mica 5L82 5L79 138kV 2L113 Vaseux Lake Kootenay Canal 230kV 5L52 5RX5 9L79 9L59 3 3L /9 L 93 9L100 9L99 944L 945L 275S 240kV 138kV SASK DC INTERTIE BC Interconnection Metering Points ~ Nelway 230kV Waneta Seven Mile BC 2L112 USA Custer Issued: 2006-04-27 5RX4 Sheerness Generating Station 5L 94 ( 1201L) 5L96 ~ 5L51 923L 163S 840S 2L294 ~ Alcan Ingledow 1L 2L293 5L98 Meridian 923L 5L92 5L77 5L44 935L 5L91 Revelstoke 5L75 5L81 924L 370S Selkirk 500kV Ashton Creek 500 kV 93 240kV Cranbrook 500kV 230kV ~ 5L71 5L72 1201L(5L94) 138 kV System SVC 830L 777L 1L275/786L Nicola 500kV 500kV 807S ~ 132S 951L RX 28S 1L274/887L 927L 138kV 924L 48S 230kV 102 S Langdon 240kV 59S 138kV 93 240kV 911L Natal 937L 138kV 9L80 74S 917L 936L 916L 801S 950L/9L50 5S 240kV 9L20 755S 64S 901L 918L 42S 863S 9L27 914L 925L 929L 928L Alberta 63S 900L 906L B.C. 912L/9L912 934L/9L934 17S TO 87 S Gaetz 766S TO 89 S Ellerslie 910L 922L 926L 995L TO 330 P Keephills 903L TO 310P Sundance 995L 190L 995AL 62S 9L948/948L ~ Battle River 757S Generating Station 68S BPA’s Boundary Substation 2L277 USA Page 14 of 17 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 for 0.29 sec and the Alberta to BC power flow > 234 MW. This RAS will trip 1201L at T102S. 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: 2006-04-27 Page 15 of 17 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: 2006-04-27 Page 16 of 17 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 & Note 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: 2006-04-27 Page 17 of 17 Interconnections OPP 303 Alberta-BC Interconnection Operation 7. Revision History Issued Description 2008- Supersedes 2007-12-12 2007-12-12 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: 2006-04-27 Page 18 of 17