Possible issue with scaling published voltage in helics load using basevoltage

User wasn't able to get the voltage value published for a load in volts to change with the basevoltage parameter -- published value was still pu. Remind @nightlark to look into the issue.

Start by reproducing the reported HELICS load behavior using the basevoltage parameter and compare the published voltage with the expected volts or per-unit value. The issue names no files or tests, so identify the relevant load and publication entry points before determining how the behavior should be corrected.

Written by the indexing model from the issue text.