BC HYDRO
REAL TIME OPERATIONS
OPERATING ORDER 6T – 29
EMERGENCY MANUAL LOAD SHEDDING and PEAK LOAD REDUCTION PROCEDURES
Supersedes 6T-29 issued 10 June 2014
Effective Date:
02 July 2014
Review Year:
2015
APPROVED BY:
Denotes Revision
Original signed by:
___________________
Paul Choudhury
General Manager,
Real Time Operations
OO 6T-29
Effective Date: 02 July 2014
Page 2 of 13
1.0
GENERAL
Certain system conditions require BC Hydro to shed customer load rather than risk an uncontrolled
failure of components or cascading outages of the Interconnection. This order specifies procedures
to manually shed customer load after all other remedial steps have taken place. It also specifies Peak
Load Reduction Procedures and guidelines to trip inter-ties to protect BC Hydro system in severe
under frequency situations.
Refer to the following BC Hydro operating orders for various load shedding programs which
Emergency Manual Load Shedding (EMLS) is considered supplemental to or to be used in
conjunction with:



Note:
OO 6T-25: Operation Plan for Capacity and Energy Emergencies.
OO 6T-28: Automatic Under-Frequency Load Shedding program.
OO 6T-34: Automatic Under-Voltage Load Shedding program.
Load shedding in the Ft Nelson Area is implemented automatically due to Alberta Integrated
System conditions or directed by AESO. Refer to 3T-FNC-01 and 7D-FNN-01.
Refer to OO 1T-07B for the authority of System Operators to carry out customer firm load shedding.
This order complies with NERC Standard EOP-003 Load Shedding Plans.
2.0
RESPONSIBILITIES
The Transmission Coordinator (TC) is responsible for assessing the need and has full authority to:
 Carry out or direct the applicable Grid Operator (GO) to carry out emergency manual load
shedding as needed.
 Carry out or direct the applicable Grid Operator (GO) to off-load interties as needed.
 Direct the applicable Load Operator (LO) to begin peak load reduction as needed.
The Grid Operator (GO) is responsible for:
 Executing emergency manual load shedding directives from the TC on an emergency priority
basis.
 Executing emergency intertie off-loading directives from the TC on an emergency priority
basis.
 Taking any necessary immediate load shedding action to manage any local area risk.
Whenever possible, advise the TC prior to acting.
The Load Operator (LO) is responsible for:
 Executing for the peak load reduction directives by the TC on a priority basis.
 Taking any necessary immediate load shedding action to manage any local area risk.
Whenever possible, advise the TC prior to acting.
The System Control Manager (SCM) is responsible for:
 Assigning the TC to carry out the monthly EMLS exercise as described in Appendix 6 of this
operating order.
 Advising the Manager, Real Time Operations of any required changes to this operating order.
The General Manager, Real Time Operations is responsible for:
 Periodically reviewing the adequacy of the EMLS and Peak Load Reduction procedures with
applicable parties.
 Providing and maintaining facilities, supplemental procedures and personnel training
adequate to meet the requirements of this operating order.
OO 6T-29
Effective Date: 02 July 2014
Page 3 of 13
3.0
EMERGENCY MANUAL LOAD SHEDDING (EMLS)
EMLS is to be used when the Transmission Coordinator judges that the load must be reduced as
soon as possible. EMLS might be necessary for a number of conditions including (but not limited to):





Insufficient automatic under-frequency load shedding to arrest frequency decay.
Insufficient automatic under-voltage load shedding to prevent voltage collapse.
Inability to restore or maintain proper generation-load balance due to severe shortages of
generating capacity.
Inability to increase frequency by adjusting generation alone to permit synchronizing with
other areas.
System component overloads which cannot be rectified by other means.
For EMLS purpose, the BC Hydro integrated system is segmented into four sub-areas: Lower
Mainland (LM), Vancouver Island (VI), Northern Interior (NI), and Southern Interior (SI). For each
area, EMLS will be done in three approximately equal blocks (1, 2, and 3) with Block 1 being the first
shed. The total shedding of blocks 1, 2 and 3 shall equal one half of the estimated peak load for that
area. Appendix 1- 4 list all load components to be shed with each block in each area.
If practical, shedding should be spread over the system with all areas participating proportionately, but
the TC may order the shedding for specific areas of the system when there is a regional generation
and load imbalance.
The load shedding requirement will generally be recognized and load shedding ordered by the TC.
But in the event an area is islanded, the GO / LO responsible for the islanded area shall shed load as
necessary to maintain frequency. As a minimum, the TC, GO or LO will take action to avoid
sustained operation below 57.9 HZ in order to avoid serious problems for customers or
BC Hydro equipment.
Using supervisory control provided by BC Hydro Energy Management System (EMS), the operator
shall be capable of shedding all three blocks in an area in less than five minutes. Appendix 5
describes the EMS displays to be used for EMLS. The permission to operate devices needed to shed
load has been assigned to the TC in addition to the applicable GO and/or LO. The TC does not
monitor alarms associated with these devices.
A poke point to the EMLS screens can be found on each grid sector overview. Additionally, the
Transmission Coordinator Overview has a poke point to the EMLS.
System voltage shall be closely monitored and adjusted during load shedding. Manual load shedding
should continue until frequency is stabilized and line and equipment loading is within their capability. If
residential circuits are shed for more than 30 minutes, the TC or LO should use peak load
reduction procedure, if possible, to enable restoration of these residential circuits.
The terminology used by the Transmission Coordinator to order Emergency Manual Load
Shedding, if necessary, will be:
"This is an emergency. Shed Emergency Manual Shedding Block(s) _ _ _ _ _ _
for the _ _ _ _ _ _ _ _ (LM / VI / NI / SI) area immediately.”
All verbal communication involving directives to shed load will utilize formal three-part
(repeat-back) communication procedures, using English as the working language.
OO 6T-29
Effective Date: 02 July 2014
Page 4 of 13
4.0
PEAK LOAD REDUCTION
Refer to OO 6T-25 OPERATION PLAN FOR CAPACITY AND ENERGY EMERGENCIES for more
details.
During the onset of an Energy Emergency, Peak Load Reduction can help avoiding widespread
emergency load shedding. A requirement for peak load reduction will generally occur with several
hours warning. PSOSE and FortisBC shall, as necessary, initiate Transmission Voltage Customer
Emergency Load Curtailments to reduce the system load.
Also note that load shaving by voltage reduction may also be used in the distribution system, if
available. This procedure requires activation in the field and, therefore, is more suitable for longer
term load reduction.
5.0
OPENING OF INTERTIES
External Balancing Areas that are seriously under generating can pose a threat to the BC Hydro
system. Interties need to be tripped if the BC Hydro system is exporting, the frequency is
1
below 57.9 Hertz and is continuing to decline despite efforts to arrest the decay.
In such situation, the Transmission Coordinator will direct the appropriate Grid Operators to off-load
any intertie with the US, Alberta, FortisBC or Alcan where the flow of power is out of the BC Hydro
system.
1
57.9 Hz as per “WECC Coordinated Off-Nominal Frequency Load Shedding and Restoration
Requirements”
6.0
VOLTAGE CONTROL DURING EMERGENCIES
Voltage levels must be closely monitored while load is being shed. All reactive resources should be
utilized to control voltage. Circuits should be switched out of service as necessary to control if there is
an overvoltage condition when the load is dropped. (See OO 7T-22 for Voltage Tolerances) In
addition to 500 kV lines, the TC will consider cutting out 230 kV cable circuits to reduce VARs.
Lower Mainland cables contribute charging VARs as follows:
CCT U/G
Length
(km)
CCT O/H
Length
(km)
Total CCT
Length (km)
% of
CCT
U/G
% of
CCT
O/H
CCT Cable
MVAR
(3 ph at
242kV)
230kV CCTs
2L31
2L32
2L33
2L39
2L40
1.1
8.6
8.7
3.3
3.3
0.0
0.0
0.0
21.0
12.4
1.1
8.6
8.7
24.3
15.8
100%
100%
100%
14%
21%
0%
0%
0%
86%
79%
9.2
67.3
78.0
26.7
27.0
2L45
2L50
2L51(COK-BND)
2L51(HPN-BND)
2L53
2L55
2L56
2L62
2L64
6.1
7.4
9.2
7.7
7.3
11.3
2.2
0.8
7.1
0.0
24.2
0.0
0.0
0.0
0.0
32.3
12.6
8.1
6.1
31.6
9.2
7.7
7.3
11.3
34.5
13.4
15.2
100%
23%
100%
100%
100%
100%
6%
6%
47%
0%
77%
0%
0%
0%
0%
94%
94%
53%
36.4
44.8
74.4
62.8
46.9
71.6
13.5
4.7
46.3
CCT
OO 6T-29
Effective Date: 02 July 2014
Page 5 of 13
7.0
RESTORATION OF SERVICE
The GO and LO shall obtain permission from the TC prior to restoring load that was shed manually or
automatically. When the BC Hydro system is tied to BPA, the TC shall notify and consult with the Peak
Reliability (PeakRC) Reliability Coordinator (RC) prior to restoring loads shed by under frequency
relays, unless there is an automatic load restoration scheme in place.
Restoration of TVC load affected by Peak Load Reduction is the responsibility of PSOSE and
FortisBC, in consultation with BC Hydro RTO.
8.0
REVISION HISTORY
(This order is also posted on BC Hydro’s External website)
Revised By
TMN
Revision Date
4 September 2009
DSM
CAP
DSM
MPP
MPP/MH
17 September 2009
09 September 2010
01 October 2010
21 September 2011
09 December 2011
MPP/LR/HQ
13 December 2011
MPP
MPP
MPP
MPP
05 September 2012
19 July 2013
10 June 2014
03 July 2014
Summary of Revision
New Operating Order combining 6T-29A, 6T-29B, 6T-29C,
6T-29D and 6T-29E.
Revised LM, NI and SI appendices.
BCTC changed to BC Hydro.
Appendix 3 – EMLS Block 3 - updated.
Annual Review Performed.
Updated for CYP T3. Additional updates in Appendix 1 and
2 (EFM shutdown).
Updated Lower Mainland Block 3, Southern Interior Block 3,
remove EFM from Vancouver Island Blocks and minor
updates.
Annual Review Performed.
Annual Review Performed.
Annual Review Performed.
Updates to Appendix 1, Section 2.0; Appendix 3, Section
3.0; Section 1.0; Appendix 4, Section 1.0
OO 6T-29
Effective Date: 02 July 2014
Page 6 of 13
Appendix 1
EMLS – Lower Mainland Area
1.0
EMERGENCY MANUAL SHEDDING BLOCKS
Manual load shedding may require up to 50% of the area load to be shed in 3 blocks within 5 minutes.
The shedding described in the table in Section 2 is in order of priority within each block.
If under frequency load shedding has occurred, some of the loads may already have been shed. Bold
and underlined stations and/or their loads are part of the automatic under-frequency load shedding
scheme and might have been tripped should this auto shedding scheme have operated. MW (auto) in
the table summarizes the amount of load shed by automatic under frequency load shedding.
Voltage should be monitored frequently while load is being shed. At the direction of the TC, circuits
should be cut out as necessary to control the voltage.
Once load shedding complete, switching should commence to restore station service to affected
stations.
2.0
EMERGENCY MANUAL LOAD SHEDDING PROCEDURE
Shedding should be carried out using the EMLS_OV screen as shown in Appendix 5 (Figure 1). The
real time loading on each element to be shed is shown on the screen. Follow the steps in sequential
order as listed in these tables to shed each block:
Device
EMLS Block 1
at CYP open
at WLT open
at ALZ open
at BND open
60CB5, 60CB9
60CB13 (T2, 60L89)
60CB6, 60CB7 (open one
feed to CAP, GLR, HCT, JLN,
JRI, NOR, NVR, SWP, VDK)
60CB2, 60CB3 (T1)
60CB5, 60CB6 (N.O.)
60CB14 (T2)
60CB9 (T3)
60CB7, 60CB1
60CB6 (T2)
60CB11, 60CB3
60CB4 (T3)
25CB4,25CB5, 25CB6
(T4/T1)
12CB1, 12CB2 (N.O.),
12CB3, 12CB4 (T1)
12CB5, 12CB6 (N.O.),
12CB7, 12CB8 (T2)
Affected Stations
MW
(man)
25
MW
(auto)
0
NXC, SWP, JRI, VDK,
DCV, NVR, ERW, NOR,
JLN, CAP, GLR, HCT
350
135
CHK, SMW, TMO, ALZ
203
50
BND
131
0
Total Block #1
709
185
HSB, LBY
OO 6T-29
Effective Date: 02 July 2014
Page 7 of 13
Device
EMLS Block 2
at KI1 open
at KI2 open
at MAN open
at MAN open
at SPG open
60CB10, 60CB15 (60L31)
60CB1, 60CB20 (60l32)
2CB4, 2CB5 (2L64)
60CB3, 60CB4 (T1)
60CB6, 60CB7 (T2, 60L43)
60CB9, 60CB10 (T3)
(60L46/38)
2CB1, 2CB2 (2L55)
2CB4, 2CB5 (2L53)
2CB3, 2CB6 (2L56)
at NEL open
at COK open
MW
(man)
MW
(auto)
KI1, LF1,SEA,
RIM, YVR,RSR, GDK,
UNS,
UNY
234
88
CSN, SPG
MAN
236
182
0
93
Total Block #2:
652
181
MW
(man)
MW
(auto)
CSQ, DGR, MUR
(Vancouver downtown
load)
496
130
NEL (distribution load)
190
135
COK (distribution load)
180
176
Total Block #3:
866
441
ALL LM BLOCKS TOTAL
2227
807
2CB1, 2CB6 (2L44)
Device
EMLS Block 3
at MUR open
at CSQ open
Affected Stations
2CB1, 2CB9 (2L50)
2CB3, 2CB4 (2L31)
2CB2 (T1)
2CB5, (T2)
2CB6, 2CB7 (T3)
2CB1 (2L20)
12CB3, 12CB35 (T3)
12CB34, 12CB12, 12CB2
(T2)
12CB1 (T1)
25CB41, 25CB42 (T4)
25CB43, 25CB44 (T5)
25CB32, 25CB34 (T3)
Affected Stations
OO 6T-29
Effective Date: 02 July 2014
Page 8 of 13
Appendix 2
EMLS – Vancouver Island Area
1.0
EMERGENCY MANUAL SHEDDING BLOCKS
Manual load shedding may require up to 50% of the area load to be shed in 3 blocks within 5 minutes.
The shedding described in the table in Section 2 is in order of priority within each block.
If under frequency load shedding has occurred, some of the following loads may have already been
shed.
Voltages should be monitored frequently while load is being shed. At the direction of the TC, circuits
should be cut out as necessary to control the voltage.
At the pulp mills, the thermal mechanical pulping (TMP) load is shed. PAL is 30 MW and CFT is 20
MW in block “A”. PAL “B” is the 25 kV residential load.
Once load shedding complete, switching should commence to restore station service to affected
stations.
EMLS
Block
Load or Station
1
GTP-A PAL-A CFT-A
2
GTP-B PVO
3
PAL-B
NFD
120 MW
HSY-A
HSY-B HSY-C
Approximate
Total Maximum
Block MW
CLD-A
292 MW
ESQ-A
304MW
TOTAL
2.0
716 MW
EMERGENCY MANUAL LOAD SHEDDING PROCEDURE
The manual load shedding should be performed from the VI Manual Load Shedding screen as
shown in Appendix 5 (Figure 2). It is based on the same load shed matrix used by the VI Automatic
Under-Voltage Load Shedding scheme. The VI total actual real time load is displayed on this screen at
the bottom. The VI load change (shed) can be calculated by comparing the VI load display reading
before and after the load shedding.
The load shedding screen has 12 non-EMLS blocks and 3 EMLS blocks. The automatic (AUVLS)
scheme sheds loads displayed in the non-EMLS blocks 1 to 8. Non-EMLS blocks 9 to 12 are used by
the VI Grid Operator to shed load for local system requirements. The blocks are identified by the
yellow color border. Each block can be tripped by a single push button that would send trip signal to
appropriate breakers at the load locations.
OO 6T-29
Effective Date: 02 July 2014
Page 9 of 13
Appendix 3
EMLS – Northern Interior Area
1.0
EMERGENCY MANUAL SHEDDING BLOCKS
Manual load shedding may require up to 50% of the area load to be shed in 3 blocks within 5 minutes.
The shedding described in the table is in order of priority within each block.
If under frequency load shedding has occurred, some of the loads may already have been shed.
Voltage should be monitored frequently while load is being shed. At the direction of the TC, circuits
should be cut out as necessary to control the voltage.
Once load shedding complete, switching should commence to restore station service to affected
stations.
EMLS
Block
Station
1
CRD
WSN
2.0
Device
60CB3, 18, 11, 13
(Check CRD transfer bus)
60CB2, 3
Affected
Stations/Circuits
CRD
MW
Load
160
60L338 (BCM,
HCR, FMC- 50%) *
60L310
60L392
Sub Total
60
16
236
SCK
RUP
60CB6, 7
60CB10, 15
* Advise FMC to shed all load
after EMLS is completed
2
BLW
MFE
GLN
TKW
2CB2, 6
1CB1, 6
1CB2, 3
1CB9, 11
2L307
1L366, 368
1L384
1L396
Sub Total
105
5
23
47
180
3
RBF
FHS
BVY
25CB11, 13
25CB1, 25CB2
60CB1, 3, 9, 11
KDS
2CB1, 2CB3
RBF (25KV Load)
FHS
60L354 (CHF)
BVY (25 kV load)
2L319 (MML) +
2L320 (KMI)
Sub Total
30
20
26
24
70
170
TOTAL
586
EMERGENCY MANUAL LOAD SHEDDING PROCEDURE
Shedding should be carried out using the EMLS OV screen as shown in Appendix 5 (Figure 1). The
real time loading on each element to be shed is shown on the screen. Follow the steps in sequential
order as listed in the above table to shed each block:
OO 6T-29
Effective Date: 02 July 2014
Page 10 of 13
Appendix 4
EMLS – Southern Interior Area
1.0
EMERGENCY MANUAL LOAD SHEDDING BLOCKS
Manual load shedding may require up to 50% of the area load to be shed in 3 blocks within 5 minutes.
The shedding described in the table is in order of priority within each block. The SI West area peak
load approximately 770 MW and the SI East Area peak load is approximately 160 MW.
If under frequency load shedding has occurred, some of the loads may already have been shed.
Voltage should be monitored frequently while load is being shed. At the direction of the TC, circuits
should be cut out as necessary to control the voltage.
Once load shedding complete, switching should commence to restore station service to affected
stations.
EMLS
Block
1
Affected Circuits/Stations
1L219 - KWD (28 MW)
Device
VVW 1CB2, 1CB10
DUG 1CB6
Approx.
MW Load
28
(KWD load may be offset by generation.
Shedding is only required if KWD is importing)
60L288 – EV1
NTL 60CB15
23
60L287 – CFE
ELK 60CB5
5
Total: 56
2
1L55 - HVC/STL/LLD
HLD 1CB3, 1CB4
100
1L244 – WBK
NIC 1CB15, 1CB16
75
60L284
60L298
60L299 – JOE/SPL/MYE
CBK 60CB7, 60CB8
KBY 60CB4
CBK 60CB5, 60CB6
51
Total: 226
3
DUG
T1, T3 and T4 25 kV Feeders
110
T1 and T3 25 kV Feeders
DUG 25CB1, 2, 4 &
7
BKL 25CB1, 25CB3
BKL
VNT
T5, T6 25 kV Feeders
VNT 25CB6, 5 & 8
55
60L283 - FST/MVL
2.0
CBK 60CB8, 60CB9
KBY 60CB3
TOTAL
66
15
Total: 301
528
EMERGENCY MANUAL LOAD SHEDDING PROCEDURE
Shedding should be carried out using the EMLS OV screen as shown in Appendix 5 (Figure 1). The
real time loading on each element to be shed is shown on the screen. Follow the steps in sequential
order as listed in the above table to shed each block.
OO 6T-29
Effective Date: 02 July 2014
Page 11 of 13
Appendix 5
EMLS Screen Displays in EMS
Figure 1: EMLS Overview Display (EMLS_OV, SCADA)
OO 6T-29
Effective Date: 02 July 2014
Page 12 of 13
Figure 2: VI Manual Load Shedding (LOADSHED_VI, SCADA)
OO 6T-29
Effective Date: 02 July 2014
Page 13 of 13
Appendix 6
EMLS Monthly Exercise
In order to increase and maintain readiness for an emergency condition in which an emergency manual load
shedding routine (as per OO 6T-29) is required, a monthly simulation exercise of the Emergency Manual Load
Shedding is required.
The simulation will include the selection of the appropriate circuit breakers for tripping and allowance for the
time required for the actual trip execution.
The Transmission Coordinator shall lead the exercise. He/she may choose to carry out the entire exercise or
delegate any portion of the exercise to appropriate Grid Operator(s) by issuing manual load shedding
directives.
Please record the time (minutes, seconds) required for completion of the simulated shedding of each load
block.
Request
Time
Area
Initials
Time for
Block 1
Time for
Block 2
Time for
Block 3
Report Time
LM
VI
NI
SI
Transmission Coordinator: ___________________
Date performed: _________________
System Control Manager: _____________________
This exercise is to be completed by the third Sunday of each month.
Return completed form to: Asher Steed