excitation systems models 2019 - wecc · excitation systems many location options for different...
TRANSCRIPT
Excitation Systems
Models
2019
November 21, 2019
Shawn Patterson
Bureau of Reclamation
PPMVDTF
▪ AVRs raise/lower excitation as far as necessary to control terminal voltage
▪ Excitation changes can force operation of a machine beyond its capability
▪ Excitation Systems incorporate automatic limiters to prevent operation beyond what is desired, e.g.,
• Overexcitation Limiter
• Underexcitation Limiter
• V/Hz Limiters
• Voltage limiters
• Stator Current Limiters
2
Review
▪ WECC database excitation system models currently do not incorporate excitation limiters
▪ There is little in the collection of plant models in the database to prevent a generator from behaving unrealistically during simulations
▪ Simulation results in these cases are wrong. Always on the optimistic side.
▪ Solution: Get the excitation limiters modeled
3
Models for Studies
4
Generator Capability
Nothing to prevent modelsfrom operating here
Or here
5
Voltage Dependency
Limiters and limiter modelswill properly accountfor voltage dependency(Think MOD-025)
▪ Excitation models in use do not include the
control points needed to interact with limiters
6
Problem
▪ IEEE working group issued standard 421.5,
which defines some standard limiter models
▪ All existing excitation system model
structures were redefined to include the
necessary limiter control points
▪ Some new excitation models were also
included
7
Solution, Part 1
8
Limiters – OEL2
To excitation system model
9
Limiters – UEL2
To excitation system model
10
Excitation Systems
Many location options for different limiter signal inputs
▪ Add limiter models to the software libraries
▪ Add or modify excitation system models to
software libraries to work with the limiters
▪ Solution, part 3:
• Use the models. Duh!
11
Solution, Part 2
▪ Limiter models to be added
• 2 UELs, 4 OELs, 2 SCLs
▪ Lots of models in the libraries need to be added/modified to work with the limiters
• 17 standard models used in WECC cases
• 6 new standard models not yet used in WECC
▪ This is a significant task, so prioritizing based on popularity in a recent WECC case:
12
Solution Problem
13
Popularity
▪ OEL2, UEL2, UEL1, OEL4, OEL5, OEL3
▪ ST1, ST4, AC8, AC7, DC1
• 84% of total
▪ AC1, DC4, ST6
• 10% of total
▪ DC2, ST2, AC2, AC5, AC6, ST5, ST3, AC4, ST7, AC3
• 6% of total
▪ AC9, AC10, AC11, ST8, ST9, ST10
• New Models
▪ PF1, PF2, VAR1, VAR2
• Controllers
▪ SCL1, SCL2
• Limiters
▪ New Stabilizers
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Suggested Implementation Priority of 421.5
Models
▪ Updated models will have the same list of
parameters and will work the same way
▪ Only the limiter connections are new
▪ The existing models can be replaced in the
software and database
▪ Add new versions or replace old versions?
15
Old vs. New
