Transmission Line Geometry and Impedance/Losses

[cyriousn]

I've recently been building out different geometries in SKM Enhanced Transmission Line Model tool and have been tracking varying reactance values shown below in ohms per mile. For our application we have a 230kv line that travels for a distance of about 11 miles and I'm wondering if anyone knows of any other configurations that may be able to help cut down on the reactance. We are considering option 3A or 3B at this time. Thanks!

1A: H frame single circuit - 0.05443 + j0.76244
1B: H frame (bundled) single circuit - 0.02723 + j0.59044
2A: Single Circuit on Monopole with 2 phases on one side, third phase on the other - 0.05442 + j0.76556
2B: Single Circuit (bundled) on Monopole with 2 phases on one side, third phase on the other - 0.02722 + j0.59363
3A: Single Circuit but split between two sets of conductors, each on a separate side of the pole - 0.02720 + j0.34576
3B: Single Circuit but split between two sets of conductors, each on a separate side of the pole but bundled - 0.01360 + j0.25999

 

[FacEngrPE]

6 phase circuit on single tower
So Far only a few installations. Reported to have some advantages in limited rights of way situations.
Revisiting Six-phase Line Transmission

Attached
Performance Evaluation of Six-Phase Power Transmission Line With Limited Right-Of-Way

 

[FPelec]

We have recently introduced a new class of low-impedance towers, called "5F" and characterized by high Surge Impedance Loading (SIL), low EMFs and reduced Right-of-Way (ROW) requirements. These towers are a specific type of split-phase structure that utilizes 5-conductor bundles.
For a 230 kV line, the reactance is 0.195 Ω/km (at 50 Hz) or 0.376 Ω/mile (at 60 Hz), and the SIL is approximately 300 MW.
Ampacity attains 2500 A (summer rating / 30°C ambient temperature, with our standard 40.5 mm ACSR conductors), corresponding to 1000 MW.
The cost is lower than that of an equivalent double-circuit line or a single circuit split across two conductor sets. The overall height is also less than that of a double-circuit tower.
The first installations are currently underway in mainland Italy and Sardinia, covering several hundred kilometers.

You can find more information at the following links:

https://ieeexplore.ieee.org/document/10194723

(In Italian, but easily translatable with Google Translate):

https://www.electroyou.it/fpalone/wiki/i-sostegni-5-fasi-soluzione-innovativa-per-la-riduzione-dei-cem-analisi-delle-curve-di-loadability

https://energiaelettrica.aeit.it/eesj/archi_user/docs/pap_magissue_65.pdf