State-level power sector model

Feature Request

Currently PyPSA-USA only provides county-level and ReEDS BA-level power sector modeling. It would be so cool if it can model the power sector at the state-level.

Suggested Solution

The current cluster_network.py only supports reeds_zone and county for topological_boundaries. Adding state support requires itl_state and itl_costs_state files, but the code link used to generate the data (https://github.nrel.gov/pbrown/TSC) is broken.

Maybe we can generate state-level transmission data by aggregating existing reeds_zone data, and this would involve:

1. Sum capacities across all zone pairs between states
2. Distances calculated based on geometric centers and unit costs calculated based on distance-weighed averaging

However, I'm uncertain whether this aggregation approach would introduce significant errors, and whether there are better alternatives. Besides, I'm not sure if further changes are needed.

Additional Info

No response

Start with current cluster_network.py and trace how topological_boundaries currently handles reeds_zone and county. Investigate the missing itl_state and itl_costs_state inputs and whether existing reeds_zone data can support the proposed aggregation, noting that the linked TSC generator is unavailable. Done would mean a reviewed design and working state-level modeling support with appropriate transmission data.