Goshen Area Bus Reconfiguration
To Anaconda via Peterson Flat
Tap (IPC)
To Dillon
Dubois
IPC
Amps
Reno
Big Grassy
Targhee
Drummond
Round
Valley
Bernice
West
Rexburg
n.o.
Ruby
Mudlake
Spar
Canyon
Sugar City
Rexburg
Jefferson
Arco
Rigby
BPA
Lost River
Scoville
(INL)
Idaho
Falls
Antelope
BPA
Wolverine Creek
Goshen
BPA
Blackfoot
(IPC)
161 kV
Swan Valley
Jolly Hills
Palisades
115 kV
Future 115 kV
BPA
American
Falls (IPC)
To Midpoint
46 kV
69 kV
138 kV
161 kV
230 kV
345 kV
Foreign
Owned
Kinport (IPC)
Brady
(IPC)
Sunbeam
Borah
(IPC)
Fishcreek
Threemile Knoll
Soda
Grace
Populus
Path C
Treasureton
To
Bridger
Malad
To Wheelon
To Ben Lomond/
Terminal
Presented by PacifiCorp Grid Operations
Pre-Contingency Load Shed Event
– December 4, 2013

Pre-contingency load shed required to prevent postcontingency violation on underlying 161 kV system for
loss of 345 kV source into Goshen
© 2014 PACIFICORP | PAGE 2
– Since event, PacifiCorp has taken steps to prevent
another pre-contingency load shed event.
Why was load shed required?
– NERC standard FAC-011-2 R2.1
Highest available facility rating cannot be exceeded for a
credible outage at any time.
– Peak RC enforcing these standards, via Peak RC
SOL Methodology
– To prevent NERC standards violation, amount of
load in the Goshen area reduced to level where 161
kV system could serve remaining load, and stay
within all facility ratings following contingency
© 2014 PACIFICORP | PAGE 3

Why was load shed required?
– Example from Peak RC
Emergency
Rating
4 Hour Rating
© 2014 PACIFICORP | PAGE 4
Normal Rating
Preventing future load shed
– Short Term Solutions:




Reconfiguring Goshen 345 kV bus (Completed)
Procedure to serve Goshen area load radial off 345 kV source
(Completed)
Additional relay settings on 161 kV system (Completed)
Splitting Goshen 161 kV bus to prevent complete loss of load
(Completed)
– Long Term Solutions:
Local Area Protection Scheme (Under study)
– Additional Transmission Capacity under study
© 2014 PACIFICORP | PAGE 5

Reconfiguring the Goshen 345 kV bus
– Goshen 345 kV bus had a weakness

If one breaker out of service, single contingency could
disconnect 345 kV source from 161 kV source
– Extensive engineering work performed to
reconfigure the Goshen 345 kV bus, minimize risk to
load
– Bus reconfigured: single breaker outage cannot
remove both 345 kV sources
© 2014 PACIFICORP | PAGE 6
• December 4: Goshen CB 303 was out of service for critical
maintenance
Radial load procedure
– Procedure calls for opening up 161 kV ties into Goshen 161
kV bus

If 345 kV bus is lost, all load served out of Goshen lost
Prevents pre-contingency load shedding
Not automatic
Trips all load in the area once a threshold has been exceeded
© 2014 PACIFICORP | PAGE 7
–
–
–
–
3 operated by PacifiCorp, 1 by Idaho Power
– In coordination with Idaho Power and Northwestern Energy,
relay settings placed on 161 kV ties into Goshen area to
protect 161 kV lines
– Relay settings open breakers if the elements are overloaded
– Prevents pre-contingency load shed
– Load can survive certain outage conditions versus radial
procedure
– Automatic protection: load only lost if contingency occurs
– Still trips all load in the area once threshold exceeded, if
contingency occurs
© 2014 PACIFICORP | PAGE 8
161 kV relaying
Goshen 161 kV bus split
– Solution serves portion of the Goshen area load off
east bus, leaves 161 kV ties, generation, some load
on west bus
– Each bus has own 345 kV transformer source
– If one (or both) sources lost
West bus served off the 161 kV ties
 East bus is lost
– Prevents total loss of Goshen area load
© 2014 PACIFICORP | PAGE 9

© 2014 PACIFICORP | PAGE 10
Goshen 161 kV bus split
© 2014 PACIFICORP | PAGE 11
Goshen 161 kV bus split
Risk to load
© 2014 PACIFICORP | PAGE 12
– Without bus reconfiguration, 100% of load served in
the Goshen area at risk for an N-1-1
– Preserves as much load as possible given current
transmission system
– Next two slides show amount of load at Goshen at
risk for radial and split bus configuration
© 2014 PACIFICORP | PAGE 13
Risk to load
© 2014 PACIFICORP | PAGE 14
Risk to load
Sectionalizing benefits
Palisades loop and wind generation remain online
Facilitates faster restoration
Unilateral implementation
Does not require complex relay logic
© 2014 PACIFICORP | PAGE 15
–
–
–
–
Load risk probability
– Now, 4 conditions need to occur simultaneously for load loss
at Goshen



Peak loading conditions
Minimal generation
Single 345 kV line out of service (maintenance, permanent fault)
Additional 345 kV line suffering a permanent fault
– 1-2 can occur at same time, third is rare
– Prior to PacifiCorp’s actions, only 3 of these need to occur to
trigger action (pre-contingency load shed)
© 2014 PACIFICORP | PAGE 16

– Local Area Protection Scheme (LAPS) potential
– Will require redundancy and WECC RASRS
approval
– Based on real-time system and loading conditions
– LAPS could determine required amount of load to
shed for each system condition
– An appropriate amount of load selected for loss of
345 kV source
© 2014 PACIFICORP | PAGE 17
Local area protection scheme
Additional system reinforcements
– 161 kV transmission capacity reinforcement

Goshen-Sugarmill line scheduled to be re-conductored in
November 2014
© 2014 PACIFICORP | PAGE 18
– Additional 161 kV reinforcements under study
Questions
To Anaconda via Peterson Flat
Tap (IPC)
To Dillon
Dubois
IPC
Amps
Reno
Big Grassy
Targhee
Drummond
Round
Valley
Bernice
West
Rexburg
n.o.
Ruby
Mudlake
Spar
Canyon
Sugar City
Rexburg
Jefferson
Arco
Rigby
BPA
Lost River
Scoville
(INL)
Idaho
Falls
Antelope
BPA
Swan Valley
Jolly Hills
Wolverine Creek
Goshen
BPA
Blackfoot
(IPC)
161 kV
Palisades
115 kV
Future 115 kV
BPA
American
Falls (IPC)
46 kV
69 kV
138 kV
161 kV
230 kV
345 kV
Foreign
Owned
Sunbeam
Borah
(IPC)
Fishcreek
Threemile Knoll
Soda
Grace
Populus
Path C
Treasureton
To
Bridger
Malad
To Wheelon
To Ben Lomond/
Terminal
© 2014 PACIFICORP | PAGE 19
To Midpoint
Kinport (IPC)
Brady
(IPC)