1. 2034 Reference Case Network Reduction
Michael Bailey
WECC Staff
Western Electricity Coordinating Council

2. Western Electricity Coordinating Council
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.
Western Electricity Coordinating Council

3. 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
Western Electricity Coordinating Council

4. 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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5. Western Electricity Coordinating Council
DC Power Flow
DC approximation derived from Active Power Sub-problem of the Fast Decoupled Power Flow Approximation.
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6. Starting with PSA Model
Sub-regional focus.
Alignment with WECC PSA.
Alignment with WECC Paths.
Western Electricity Coordinating Council

7. 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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8. Western Electricity Coordinating Council
Sub-regional Focus
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9. Transmission Equivalent LinksƟj
ßij
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10. Western Electricity Coordinating Council
Path Focus
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11. Western Electricity Coordinating Council
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.
Western Electricity Coordinating Council

12. Western Electricity Coordinating Council
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.
Western Electricity Coordinating Council

13. 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.
Western Electricity Coordinating Council

14. Western Electricity Coordinating Council
Top Priority
Complete 2034 Long Term Studies.
Position for LTPT evolution without distracting from the study program work.
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15. Western Electricity Coordinating Council
Questions?
Michael Bailey, P.E. Senior Staff Engineer
Western Electricity Coordinating Council