Transient Stability Relay Models - PowerWorld

• Tracy Rolstad
Introduction
– Avista System Planning
• BSEE, Idaho, 1992
• Graduate Diploma, Naval War College, 1999
• Chair of WECC PowerWorld User’s Group
• Vice Chair WECC Technical Studies Subcommittee
• RAS/Relay Modeling Task Force Member (Chair—
Relays work group)
– Contact Information
• 509 495 4538
• tracy.rolstad@avistacorp.com

Relay “Models”…Why?

What Happened?

Our Regulator’s Words
•The word Relay is mentioned 136 times
– RAS mentioned 99 times
•The word Model is mentioned 128 times

WECC Direction
Not entirely correct,
we model some relays.
This might be worse than
not modeling relays at all.
We may not POPULATE
models for all relays.
However, we can (from a
coding viewpoint) model
any relay that exists. We
need to recognize that if
a relay can be built we
CAN model it…we MAY
choose NOT to.

The Path Forward…
• We can simulate relay behavior NOW!
– Simulate for the purposes of
operations/planning studies
• This is NOT the same as a protection system level
model of a relay
– Repeat the Above!
• These relay “models” mostly REPLACE switch
“decks” and other non-syntax based
files/scripts/code
– DO NOT CONFUSE THE ISSUE!!!! WE ARE NOT
SETTING PROTECTION SYSTEM PARAMETERS
• We want to do OUR job better, not yours
– Our=System Modeler, Yours=Protection

Existing Technology
• Present coding tools and methods can:
– Simulate ANY relay, RAS, or other protective
function that exists in the field today
• Will Power versus Won’t Power
– Digital is Digital, software code = hardware for simulation
– However, we are here to talk about existing
deployed software that requires NO
development
• Version 17 is very sophisticated in native toolset

PowerWorld Line Relay Models
• Timeline
– Nothing existed prior to Summer 2012
• Including these in stability is something that transient stability
software users were not clamoring for until the WECC MSRATF
started
– August 2012
• TLIN1 properly functioning and reporting events
– October 2012
• Added support for Impedance/Distance Relays
– December 2012
• Added Time-Inverse Over-Current Relays
• Complexity of software for basic line relays is very low
– Compare time for the complete implementation of a model
including simulation code, user interface, and help
documentation
– Pacific DC Intertie Dynamic Model 20 days
– Time-Inverse Over-Current Relay 1 day

PowerWorld Line Relay Models
• PowerWorld Simulator Version 17 includes
the following models
– Under Voltage and Frequency Relays
• TLIN1
– Impedance/Distance Relays
• DISTR1, ZLIN1, ZQLIN1, ZPOTT, ZDCB
– Out-of-Step Impedance Relays
• OOSLEN, OOSLNQ
– Time Inverse Over-Current Relays
• LOCTI, TIOCR1

PowerWorld Line Relay Models
• Line Relay Data Structure Considerations
– Model is assigned to specified end of a Branch.
Handled by field in case information displays
called Device Location which is From or To
– Multiple relays can be assigned to each end of a
branch
• Distance Relay, Time-Inverse Over-Current, Voltage,
etc…
• For some types multiple relays of same type are allowed
(introduced extra key field of Device ID)
• User Interface Considerations
– Stability tab is available on the branch dialog
– Line relay models listed

User Interface

Visualization
• Columns on Impedance Relays show
Forward Reach %
• Ability to Show Relay
Zone Visualization

Deployed Software
• PowerWorld Simulator ver 17
– Models around 37 various “relays
• Software testing is only truly valid as data is
populated by users and then relay actions are
analyzed
• The tool is ready for use NOW
• “Switch decks” are likely a thing of the past for 3
phase bolted fault “criteria studies”
– They should be a thing of the past

Present Software
• Surprisingly sophisticated considering
– Relays models are seldom populated
• These models have been around for
DECADES
• BS Bingo Alert: Paradigm Shift Ahead
•AParadigm Shift is a change from one way of
thinking to another. It's a revolution, a
transformation, a sort of metamorphosis. It just does
not happen, but rather it is driven by:
• Agents of change

The “Old” Way

The “New” Automatic Way

Apply Fault—Run—Analyze

ZPOTT Dialog & Plot

“Typical” Distance Relay

Issues (for impedance relays)
• This is “New” for Planners
– Relay data sheets are large, ~40 pages
• We need perhaps 5 numbers from these 40 pages
• What to watch for…
– Pesky instrument transformers
• Ratios
– Per unit v.s. ohms
– Methods probably vary from utility
• However,
– General practices help…90% protection Zone 1

Relay Data Location

Output

Example

Relay Data vs Power Flow Data
Devil's Gap - Ninemile is a 115 kV line. The impedance base for a 115 kV line is as follows:
ZBase = Vbase^2/SBase = (115,000)^2/100,000,000 = 132.25
In the WECC base cases, the following per unit impedance is seen
Rpu+jXpu = 0.0186 + j0.10293 per unit
Conversion to Ohms --> 2.4599 + j 13.612
Amazing! Your power flow case matches the data the relay people are using exactly!
Thus, inside simulator when you say you want "Z1P" or "Z1MP" to be 2.98 Ohms,
you must convert this to per unit as
2.98/132.25 = 0.022533 per unit
Thus, inside Simulator the respective Rf1 parameter would be 0.0225
This provides an excellent second check on power flow and relay data

X1=X, X2=R
Check with Equation
SQRT((X1^2)+(X2^2)^2)
(ATAN(X1/X2))*57.2957795

Assessment
• Will Power v.s. Won’t Power
• WE CAN MODEL RELAYS TODAY!!!!
– There is NO relay that can’t be modeled!
• Code changes might be required if users assist
developers
– Software developers are way ahead of users
• PTI: In 11 Manuals the word relay is mentioned 1017
times!
• Those who say it can’t be done…
• Let us see your fingers on a keyboard!
• Modeling of relays in the power flow
simulations is another consideration
– Will be discussed in separate presentation later

Final Word (5 minute job)

In GE *.dyd if You Like (10 min)
zpott 48025 "BEACON N " 230.00 "1 " 40090 "BELL S3 " 230.00 "5" 1 : #9 0 0 0.05 0 83.905 0.007839 0 0 0
0.004 0 83.905 0.010452 0 0 0 0.004 0 0 0 0 0 0 0.004
zpott 48031 "BEACON S " 230.00 "1 " 40092 "BELL S4 " 230.00 "4" 1 : #9 0 0 0.05 0 83.978 0.00819 0 0 0
0.004 0 83.978 0.01092 0 0 0 0.004 0 0 0 0 0 0 0.004
zpott 40519 "HATWAI " 230.00 "1 " 48197 "LOLO " 230.00 "1" 1 : #9 0 0 0.05 0 83.929 0.010746 0 0 0
0.004 0 83.929 0.014328 0 0 0 0.004 0 0 0 0 0 0 0.004
zpott 40519 "HATWAI " 230.00 "1 " 48249 "MOSCOW " 230.00 "1" 1 : #9 0 0 0.05 0 83.76 0.023706 0 0 0
0.004 0 83.76 0.031608 0 0 0 0.004 0 0 0 0 0 0 0.004
zpott 40519 "HATWAI " 230.00 "1 " 48255 "N LEWIST " 230.00 "1" 1 : #9 0 0 0.05 0 84.759 0.008928 0 0 0
0.004 0 84.759 0.011904 0 0 0 0.004 0 0 0 0 0 0 0.004
zpott 40551 "HOT SPR " 230.00 "1 " 48281 "NOXON " 230.00 "2" 1 : #9 0 0 0.05 0 83.77 0.092169 0 0 0
0.004 0 83.77 0.122892 0 0 0 0.004 0 0 0 0 0 0 0.004
zpott 48443 "VANT AVA " 230.00 "1 " 46169 "WANAPUM " 230.00 "1" 1 : #9 0 0 0.05 0 83.766 0.101925 0 0
0 0.004 0 83.766 0.1359 0 0 0 0.004 0 0 0 0 0 0 0.004
zpott 48025 "BEACON N " 230.00 "1 " 48357 "RATHDRUM " 230.00 "2" 1 : #9 0 0 0.05 0 85.221 0.034128 0 0
0 0.004 0 85.221 0.045504 0 0 0 0.004 0 0 0 0 0 0 0.004
zpott 48031 "BEACON S " 230.00 "1 " 48524 "BOULDER " 230.00 "1" 1 : #9 0 0 0.05 0 85.134 0.015858 0 0 0
0.004 0 85.134 0.021144 0 0 0 0.004 0 0 0 0 0 0 0.004
zpott 48037 "BENEWAH " 230.00 "1 " 48249 "MOSCOW " 230.00 "1" 1 : #9 0 0 0.05 0 83.764 0.058149 0 0 0
0.004 0 83.764 0.077532 0 0 0 0.004 0 0 0 0 0 0 0.004
zpott 48037 "BENEWAH " 230.00 "1 " 48317 "PINE CRK " 230.00 "1" 1 : #9 0 0 0.05 0 82.068 0.057555 0 0 0
0.004 0 82.068 0.07674 0 0 0 0.004 0 0 0 0 0 0 0.004
zpott 48037 "BENEWAH " 230.00 "1 " 48385 "SHAWNEE " 230.00 "1" 1 : #9 0 0 0.05 0 84.952 0.076419 0 0
0 0.004 0 84.952 0.101892 0 0 0 0.004 0 0 0 0 0 0 0.004
zpott 48524 "BOULDER " 230.00 "1 " 48037 "BENEWAH " 230.00 "1" 1 : #9 0 0 0.05 0 83.802 0.034308 0 0 0
0.004 0 83.802 0.045744 0 0 0 0.004 0 0 0 0 0 0 0.004

Questions?