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ColumbiaGrid
System Assessment Contingency
Methodology
November XX, 2014
Table of Contents
Introduction .................................................................................................................................................. 2
Contingency File ............................................................................................................................................ 2
Format ....................................................................................................................................................... 2
Automatic Actions..................................................................................................................................... 2
Contingency Modeling .............................................................................................................................. 2
P0: No Contingency ............................................................................................................................... 2
P1: Single Contingency .......................................................................................................................... 2
P2: Single Contingency .......................................................................................................................... 3
P3: Multiple Contingency ...................................................................................................................... 3
P4 & P5: Multiple Contingency (Includes Protection Failure)............................................................... 3
P6: Multiple Contingency (Two Overlapping Singles) ........................................................................... 4
P7: Multiple Contingency (Common Structure).................................................................................... 4
WECC Adjacent Circuit Criterion ............................................................................................................... 4
Appendix A: Contingency Fields Descriptions ............................................................................................... 5
Label .......................................................................................................................................................... 5
BF: ......................................................................................................................................................... 5
B_ .......................................................................................................................................................... 5
BUS: ....................................................................................................................................................... 6
N-1:........................................................................................................................................................ 6
N-2:........................................................................................................................................................ 6
L_ ........................................................................................................................................................... 7
G_ .......................................................................................................................................................... 7
S_ ........................................................................................................................................................... 7
T_........................................................................................................................................................... 8
Cust String 1 .............................................................................................................................................. 8
Cust String 2 .............................................................................................................................................. 8
Cust String 3 .............................................................................................................................................. 8
Memo ........................................................................................................................................................ 8
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Introduction
The foundation for the Biennial Transmission Expansion Plan is the ColumbiaGrid System Assessment,
which is an evaluation of whether or not the planned transmission grid can meet established reliability
standards. Any deficiencies in meeting these standards are noted in the System Assessment and then
addressed either by the Transmission Owners themselves or through ColumbiaGrid Study Teams. This
document describes the contingencies and format that need to be provided to comply with TPL-001-4
and WECC criterion TPL-001-WECC-CRT-2.1.
Contingency File
Format
ColumbiaGrid uses PowerWorld Simulator to perform the System Assessment. All contingency files
should be provided in the PowerWorld Aux file format (.aux) and should contain both contingency
actions and automatic actions. Contact the ColumbiaGrid if this format is not available to you.
Automatic Actions
Automatic actions such as Remedial Action Schemes (RAS) need to be provided to accurately model the
effects of contingencies on the system. These schemes should be modeled as global actions in the
PowerWorld aux file format. Global actions in PowerWorld operate in a similar way to automatic
schemes in that they perform specified actions if the modeled system conditions are met (For example:
if line A & B are open then reduce generator C output). Contact ColumbiaGrid if assistance is needed in
modeling these schemes.
Contingency Modeling
Each member’s file should contain modeled contingencies to allow the study of events P0-P7 described
in Table 1 of TPL-001-4 and adjacent circuits that meet the criterion defined in the WECC regional
criterion TPL-001-WECC-CRT-2.1. Each contingency definition should follow the convention described in
Appendix A. This convention includes contingency naming instructions and various other fields used to
define the contingency type. Below is a summary of the event categories that need to be studied and
the submittal needed to meet the standards.
P0: No Contingency
This is a system normal evaluation. No events are modeled and no submittal is needed.
P1: Single Contingency
The loss of one of the following:
1.
2.
3.
4.
5.
Generator
Transmission Circuit
Transformer
Shunt Device
Single Pole of a DC Line
2
A complete P1 list needs to be submitted. All P1 breaker operated outages should be auto-inserted1
with the PowerWorld auto-insertion tool. Exemptions are breaker-to-breaker transmission circuit
outages that contain multiple powerflow branches and single pole DC lines. Ensure that non-breaker-tobreaker transmission circuit outages are removed from this list.
P2: Single Contingency
The loss of one of the following:
1.
2.
3.
4.
Opening of a line section w/o a fault
Bus Section Fault
Internal Breaker Fault (non-Bus-tie Breaker)
Internal Breaker Fault (Bus-tie Breaker)
A complete P2 list needs to be submitted. When possible these contingencies should be auto-inserted.
Auto-inserted contingencies would include bus section outages that remove one modeled bus section
and the first/last sections of breaker-to-breaker transmission circuit outages that contain multiple
powerflow branches. The remaining outages need to be manually created using the naming convention
defined in Appendix A.
P3: Multiple Contingency
Loss of a generator unit followed by System adjustments and then the loss of one of the following:
1.
2.
3.
4.
5.
Generator
Transmission Circuit
Transformer
Shunt Device
Single Pole of a DC Line
This list will be generated by ColumbiaGrid by using the defined contingencies in the P1 list. No
submittal is needed. ColumbiaGrid will combine the generator outages from P1 with each P1 outage. A
solve command2 will be inserted between the contingencies to allow for minimum system adjustments
between events (i.e. generator outage+solve+P1 outage).
P4 & P5: Multiple Contingency (Includes Protection Failure)
Loss of multiple elements caused by a stuck breaker (P4) or the failure of a non-redundant relay (P5)
attempting to clear a Fault on one of the following:
1. Generator
2. Transmission Circuit
1
Several contingencies that are suggested to be auto-inserted such as generators and shunt devices often
represent multiple devices in the powerflow case. In order to maximize the quality of the contingency files it is
preferred to screen the case with the auto-inserted contingencies. Violations found from these contingencies will
be reviewed individually to determine if the violation persists with the loss of single units.
2
Whenever a system adjustment is allowed between events ColumbiaGrid will insert a solve command that allows
all elements in the system to adjust (such as reactive shunt devices and LTCs). This is not an assumption of a
defined system adjustment. Violations found in conjunction with these outages will be sent to the interested
parties to determine if additional system adjustment would prevent the violation from occurring.
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3. Transformer
4. Shunt Device
5. Bus Section
A complete P4/P5 list needs to be submitted. All contingencies will need to be manually created as they
open multiple elements. These lists are combined because the vast majority of P4 outages are identical
to P5 outages in the steady state cases. When identifying the contingency type in the field assigned to it
(see Appendix A) “P4/P5” should be used for contingencies that apply to both categories.
P6: Multiple Contingency (Two Overlapping Singles)
Loss of one of the following followed by System adjustments:
1.
2.
3.
4.
Transmission Circuit
Transformer
Shunt Device
Single Pole of a DC Line
Then loss of one of the following:
1.
2.
3.
4.
Transmission Circuit
Transformer
Shunt Device
Single Pole of a DC Line
This list will be generated by ColumbiaGrid by using the defined contingencies in the P1 list. No
submittal is needed. ColumbiaGrid will combine the appropriate outages from P1 with a solve command
inserted between the contingencies to allow for minimum system adjustments between events.
P7: Multiple Contingency (Common Structure)
Loss of:
1. Any two adjacent circuits on a common structure for more than 1 mile
2. A bipolar DC line
A complete P7 list needs to be submitted. All contingencies will need to be manually created as they
open multiple elements.
WECC Adjacent Circuit Criterion
Loss of any two transmission circuits in a common right-of-way that meet the criterion in WECC TPL-001WECC-CRT-2.1.
A complete adjacent circuit list needs to be submitted. All contingencies will need to be manually
created as they open multiple elements.
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Appendix A: Contingency Fields Descriptions
Field
Label
Cust String 1
Purpose
Contingency name. Includes a prefix of BF:,B_, BUS:, L_,G_, N-1:, N-2:, S_,or T_
Indicates RAS (Remedial Action Scheme)
Cust String 2
Indicates VSRI (Voltage Stability Reactive Insertion)
Cust String 3
Cust String 4
Cust String 1
Cust String 2
Cust String 3
Cust String 8
Cust String 9
Memo
Description of known mitigating actions, or special instructions
ColumbiaGrid questions or corrections
Contingency Category (i.e. P1-P7 or Adj)
Indicates a grouping for system area (Used by ColumbiaGrid)
Utility that submitted the contingency (Used by ColumbiaGrid)
Date of last review/update to the contingency
Main Grid Contingency (500 kV and 345 kV)
Description of known mitigating actions, special instructions, or any additional
information supplied by the contingency owner
Label
This field is the identifying field. It is used to name the contingency. Each contingency will need to
contain a prefix specific to the type of contingency. All user entered prefixes will need to contain a
colon, and all auto-inserted prefixes are defaulted to contain an under bar (_). Each of these prefixes is
described below.
BF:
A prefix of ‘BF: ‘will need to be used to designate breaker failures. The name of each breaker failure will
need to first contain this prefix, followed by the breaker ID, and finally the facilities taken out of service
for this event.
BF:
Breaker ID
Facilities Out
Prefix
The breaker designation
A description of the facilities removed from
service for this event
Examples:
BF: 240-10 South 230 kV, Creston-South-Talbot N
BF: 4526 Echo Lake-Monroe-Custer
BF: A1098 South Tacoma 230 kV, White River & Fredrickson lines
B_
A prefix of ‘B_’ is used to identify auto-inserted bus outages. This is the default insertion prefix followed
by the name of the bus and the nominal voltage in kV.
Examples:
B_MALIN500
B_SCHULTZ500
B_TACOMA500
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BUS:
A prefix of ‘BUS: ‘ is used to designate manually created bus outages. The name of each bus outage will
need to first contain this prefix, followed by the bus name, and the nominal voltage of that bus.
BUS:
Bus Name
Nominal Voltage
Prefix
The bus name
The nominal voltage of the bus
Examples:
BUS: Smokey PT 115 kV
BUS: Andrew York East Bus Section 115 kV
BUS: Sand Dunes 230 kV
Bus contingencies that remove only one modeled bus from service in the powerflow case should not use
the ‘BUS:’ prefix. They should be automatically inserted with the ‘B_’ prefix (see B_).
N-1:
A prefix of ‘N-1: ‘is used to designate manually created single contingencies. The name of each single
contingency will need to first contain this prefix, followed by the name of the from bus, followed by ‘ – ‘,
followed by the name of the to bus, followed by the nominal voltage of the line. In the case of a three
terminal line, ‘3TM’ will need to precede the name of the from bus, and all three bus names will be
listed.
N-1: Type (only for 3
terminal lines)
From
Bus
To
Bus
Nominal Voltage
Prefix
From Name
To Name
The nominal voltage of the line
3TM for three terminal lines only
Examples:
N-1: 3TM Aberdeen-Cosmopolis-Satsop PK 115 kV
N-1: 3TM Monroe-Echo Lake-SnoKing 500 kV
N-1: Ancient Lake-Frenchman 115 kV
N-1: Benewah-PineCreek 230 kV
Single contingencies that remove only one line from service in the powerflow case should not use the
‘N-1:’ prefix. They should be automatically inserted with the ‘L_’ prefix (see L_).
N-2:
A prefix of ‘N-2: ‘is used to designate manually created common mode outages. The name of each
common mode contingency will need to first contain this prefix, followed by ADJ for adjacent circuits, or
CMS for common structures, then the name of the from bus of the first line, followed by ‘ – ‘, followed
by the name of the to bus of the first line, and then the nominal voltage of the first line, followed by a
comma, and then the name of the from bus of the second line, followed by ‘ – ‘, followed by the name
of the to bus of the second line and finally the nominal voltage of the second line.
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N-2: Type
First Element
Second Element
Prefix
FromName1 – ToName1
kV1,
FromName2 – ToName2 kV2
ADJ for adjacent circuits;
CMS for common structures
Examples:
N-2: ADJ Bothell-North 115 kV, Bothell-Viewland 115 kV
N-2: ADJ Coulee-Columbia #3 230 kV, Coulee-Olympia 300 kV
N-2: CMS Bothell-Canal 115 kV, Shoreline-Viewland 115 kV
N-2: CMS Maple Valley-Duwamish 230 kV, Covington-Duwamish 230 kV
L_
A prefix of ‘L_’ is used to identify auto-inserted single line outages. This is the default insertion prefix
followed by the name of the from bus, the nominal voltage in kV of that bus, a ‘-‘, the name of the to
bus, the nominal voltage in kV of that bus, a C and the circuit ID of the line.
Examples:
L_ENTIAT115-SSHORETP115C1
L_FORD115-LONGLAKT115C1
L_FTLEWS115-FTLEWCTL115C1
L_LEXINGTN115-SHAWNCC115C1
Participating utilities will need to specify which of these contingencies are not valid and removed from
the auto-generated list. Reasons for invalidity include: taps along a line with no breakers, already
defined N-1 contingencies that may contain additional actions.
G_
A prefix of ‘G_’ is used to identify auto-inserted single generator outages. This is the default insertion
prefix, followed by the name of the bus, the nominal voltage in kV, and the unit identifier.
Examples:
G_COULEP1213.8U01
G_COULEP1213.8U02
G_COULEP3413.8U03
S_
A prefix of ‘S_’ is used to identify auto-inserted single shunt outages. This is the default insertion prefix,
followed by the name of the bus, the shunt id, and the nominal voltage in kV.
Examples:
S_KEELERs 500
S_KEELERW1 230
S_KEELERW2 230
S_KEELERW3 230
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T_
A prefix of ‘T_’ is used to identify auto-inserted single transformer outages. This is the default insertion
prefix, followed by the name of the from bus, the nominal voltage in kV of the from bus, a ‘-‘, the name
of the to bus, the nominal voltage in kV of that bus, a C and the circuit ID of the transformer.
Examples:
T_ALLSTON500-ALLSTNW230C1
T_ANCIENTL230-ANCIENTL115C1
T_WELLS115-WELLSB2230C1
T_WINDRDG230-WINDRDG115C1
Participating utilities will need to specify which of these contingencies are not valid and removed from
the auto-generated list. Reasons for invalidity include already defined N-1 contingencies that may
contain additional actions.
Cust String 1
The first custom string field for the contingency, Cust String 1, will be used by participants to indicate the
category of the contingency (P0-P7 for TPL outages or ADJ for the WECC adjacent circuit criteria).
Cust String 2
The second custom string field for the contingency, Cust String 2, will be used by ColumbiaGrid to
indicate a group or system area that the contingency belongs to. This is used primarily for postprocessing and filtering contingency results.
Cust String 3
The third custom string field for the contingency, Cust String 3, will be used by ColumbiaGrid to indicate
the utility that submitted the contingency. This should help track contingency definitions, and simplify
the process of recreating contingency lists each year.
Memo
The memo field will be used by participants and ColumbiaGrid for descriptions of known mitigating
actions, special instructions, or to describe any additional information.
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