2034 Reference Case
Network Reduction
Michael Bailey
WECC Staff
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Power Flow History
• Numerical methods in power flow analysis has
dramatically evolved in parallel with advances in
computer and computing technologies.
• Computational burden of solving power flow and
optimal power flow equations for large networks
still a challenge.
• Numerical power flow approximation techniques
have been developed and used to overcome this
computational burden since 1962 when the first
optimal power flow formulation was derived by
J. Carpentier.
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Power Flow Approximation Techniques
Some power flow approximation techniques
that are widely used today include:
• Fast De-coupled Power Flow
• Linear Approximations
• Mixed Integer Programming
• Sparse Matrix Methods
• Network Reductions
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Full Network Power Flow Equation
• Fast de-coupled
approach to
solving the power
flow.
• Basis for DC
power flow
analysis.
• Basis for Linear
Optimal Power
Flows.
Power Flow Equations
Power Flow Jacobian
Zero Approximations
Power Flow Decoupling
Active
Reactive
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DC Power Flow
• DC approximation
derived from Active
Power Sub-problem
of the Fast
Decoupled Power
Flow Approximation.
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Starting with PSA Model
• Sub-regional focus.
• Alignment with
WECC PSA.
• Alignment with
WECC Paths.
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Starting with PSA Model
• Continuity with WECC
PSA with Regard to Hub
Aggregation and
Transmission Paths.
• Continuity with
Common Case with
regard to Generating
resources.
• Continuity with Power
Flow as a reduced nodal
network model.
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Sub-regional Focus
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Transmission Equivalent Links
Equivalent
Transmission
Tie-line
State-Area 1
State-Area 2
Aggregate
Generator
Ɵi
Aggregate
Generator
Adj
EQ
Adj
ßij
Aggregate
Load
Aggregate
Load
Ɵj
Tuned Boundary
Flow Impedances
Select oval and
type. Control handles change width
& height of oval.
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Path Focus
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The Network Reduction
• Boundary flows match
to within 1% of full
network model.
• Focus on paths not
corridor siting.
• Corridor proxies
associated with paths.
• Better traceability to
Common Case and the
LCRA cases.
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Accessibility of LTPT
• Right size the LTPT Modeling focus.
• Move the Transmission Corridor Optimization
into the WECC “Environmental and Cultural
Data Viewer”
• Make the LTPT accessible to stakeholders for
their use.
• Staff (initial) maintains default functionality
and modeling data.
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Proposed GIS Data Viewer Enhancements
Proposed changes to the “Environmental and
Cultural Data Viewer” are:
• Phase 1 – Provide capability to upload GIS
corridors.
• Phase 2 – Implement a persistent corridor
library.
• Phase 3 – Provide corridor optimization.
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Top Priority
• Complete 2034 Long Term Studies.
• Position for LTPT evolution without
distracting from the study program work.
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Questions?
Michael Bailey, P.E.
Senior Staff Engineer
[email protected]
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