Example code running in a Python for PSSE transaction

example_transaction.py

from __future__ import with_statement
import os

from transactions import transaction, psspy, PSSE_EXAMPLES
psspy.throwPsseExceptions = False

def validate_solved():
    """
    Return true if the last psse case has solved.

    I am counting iteration limit exceeded as not solved in this case.
    """
    return psspy.solved() == 0

def change_swing_bus_no_reason():
    """
    Change the swing bus to a type 2 for no reason other
    than to show the rollback in action.
    """
    psspy.bus_data_2(3011, intgar1=2)

def add_new_generator():
    """
    Add a new fake generator behind a short line to a new
    bus near the swing bus.
    """
    psspy.bus_data_2(
            3012,
            intgar1=2,   # type 2 bus.
            realar1=22)  # base kV.

    psspy.branch_data(
            i=3011,
            j=3012,
            ckt='NW',
            realar2=0.02) # line reactance X)

    psspy.plant_data(
            3012)

    psspy.machine_data_2(
            i=3012,
            id="01",
            realar1=0,   # active gen MW.
            realar3=100) # reactive gen max MVAr.
    

def main():
    psspy.psseinit(8000)
    psspy.case(os.path.join(PSSE_EXAMPLES, 'savnw.sav'))

    # adding the new generator should sovle and pass.
    with transaction(validate_solved):
        add_new_generator()
        psspy.fnsl()

    # changing the swing bus shouldn't solve and will be
    # rolled back.
    with transaction(validate_solved):
        change_swing_bus_no_reason()
        psspy.fnsl()

    print psspy.solved()

if __name__ == "__main__":
    main()