[grmtrkngtn]

Description

The PF electrical demand previously included only the power-supply loss associated with ohmic heating, while the ohmic power itself was still added to the plasma thermal balance. This caused the whole-plant power balance to gain an amount exactly equal to p_plasma_ohmic_mw.

The fix accounts for the full wall-plug power required to supply ohmic heating, while only the PF supply losses contribute to secondary heat.

See #4419

************************ Power balance for power plant *************************

IN
Fusion power (MW) (p_fusion_total_mw) 1.67020126538901764e+03 OP
Energy multiplication in blanket and shield (MW) (p_blkt_multiplication_mw) 2.47869045393520537e+02 OP
TOTAL (MW) (p_nuclear_total_mw) 1.91807031078253817e+03 OP

OUT
Net electric (MW) (p_plant_electric_net_mw) 3.50000000004303502e+02 OP
Heat rejected by main power conversion circuit (MW) (p_turbine_loss_mw) 1.36108730187131050e+03 OP
Heat rejected by other circuits (secondary heat) (MW) (p_plant_secondary_heat_mw) 2.06983008906924198e+02 OP
TOTAL (MW) (p_plant_out_mw) 1.91807031078253817e+03 OP
Power plant overall imbalance (MW) (p_plant_imbalance_mw) 0.00000000000000000e+00 OP

---

We can see the power imabalance is correct now

Checklist

I confirm that I have completed the following checks:

• My changes follow the PROCESS style guide
• I have justified any large differences in the regression tests caused by this pull request in the comments.
• I have added new tests where appropriate for the changes I have made.
• If I have had to change any existing unit or integration tests, I have justified this change in the pull request comments.
• If I have made documentation changes, I have checked they render correctly.
• I have added documentation for my change, if appropriate.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 49.73%. Comparing base (e2d0521) to head (02f11a1).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4664   +/-   ##
=======================================
  Coverage   49.73%   49.73%           
=======================================
  Files         151      151           
  Lines       30297    30297           
=======================================
  Hits        15069    15069           
  Misses      15228    15228           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[ajpearcey]

I can be very misinformed, but why does electrical losses in the PF coil depend linearly on the plasma resistivity?

[grmtrkngtn]

This term is intended to represent the power-supply loss associated with transferring the ohmic heating power to the plasma, rather than a resistive loss in the PF coils themselves.

Since the plasma ohmic heating is

P_ohmic = V_loop * I_p = I_p^2 * R_plasma ​

and therefore depends on the plasma resistance, a fixed power-supply efficiency gives a loss

P_ohmic * (1/η_psu − 1)

The PF coil/busbar losses are accounted for separately in pfpowermw.

[chris-ashe]

Looking here for some reason we only say there is resistive heating power if their is inductive current drive. What happens in the ST case when there is no inductive flattop?

[chris-ashe]

The logic makes sense but I think we need to sort out the proper order for the calculations and how we treat when the source of the ohmic heating power comes from. As at the moment it only works inductive machines