How would you include currents from load/generation in calculating the bus current?

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There is no such API available. You can write your own function that returns the load or machine current calculated from the MVA load and the bus voltage.

Edit:

As an example, I wrote a script that plots the complex currents in a vector plot. See example below for bus 201 in savnw network. There are three lines, one 2W-transformer and one fixed shunt at the bus. The bus voltage is the reference angle (0 degrees).