for example in IEEE 39 dynamic simulation G1=100MW at t=0s load in bus 3 is 75MW and then G1=150MW at t=0.5s load in bus 3 changes to 75MW and then G1 return to 100MW at t=1s load in bus 3 changes to 20MW print the dynamic curves for G1
The output from the generator is determined by the turbine power (PMECH). The variable PMECH(MC) may be updated by code in CONEC subroutine during a simulation but that needs some Fortran code and a compiler.
Instead I propose that governor model IEESGO is used for update of PMECH as you wish during the simulation. With the parameters I have chosen below the model will instantaneously update PMECH after changes to GREF. The script is adapted to savnw test case, but the concept can be used for any case.
psspy.case('savnw.sav')
psspy.rstr('savnw.snp')
psspy.cong(0)
psspy.conl(0,1,1,[0,0],[ 80.0,0.0, 20.0, 80.0])
psspy.conl(0,1,2,[0,0],[ 80.0,0.0, 20.0, 80.0])
psspy.conl(0,1,3,[0,0],[ 80.0,0.0, 20.0, 80.0])
ibus = 3011
gid = '1'
dp = 50. # MW change for generator
ierr, mbase = psspy.macdat(ibus, gid, 'MBASE')
# add dummy governor without droop and time constants
psspy.add_plant_model(ibus,gid,7,r"""IEESGO""",0,"",0,[],[],11,[0.0,0.0,0.05,0.0,0.0,0.0,0.0,0.0,0.0,1.0,0.0])
psspy.machine_array_channel([-1,6,ibus],gid,"")
ierr = psspy.strt(0, 'test1.out')
psspy.run(0, 0.5,0,1,0)
psspy.increment_gref(ibus,gid, dp/mbase)
psspy.run(0, 1.0,0,1,0)
psspy.increment_gref(ibus,gid,-dp/mbase)
psspy.run(0, 2.0,0,1,0)
The following Figure shows how PMECH for the studied generator is updated during the simulation.
PMECH is always in pu generator base (Mbase=1000). The turbine power is here temporarily increased with 50 MW (50/1000=0.05 pu) at t=0.5 s and reset again at t=1 s.
EDIT:
Since the post is revived, I can improve by showing the block diagram of IEESGO:
With the selected parameter all blocks except the limiter block are ignored. Speed input signal is blocked and the output PMECH only depends on Po and Pmax and Pmin. Those limits are set to 1 and 0 in the script above. Note, set Pmin negative if you want to set negative PMECH.
PMECH will immediately follow Po with no time delay. Any number of step changes can be made on PMECH during the simulation using API increment_gref or change_gref.
It is thereby very easy to manually update the turbine power of a generator using this governor model and parameters.
The annotated diagram really helps to understand!
You can use machine_chng_2 to change machine data, and load_chng_4 for load changes during dynamic simulations for PSS/E 33 at least.
Thanks for the clarification. I'm not 100% sure, but this sounds like the dynamics data controls the power output, and you'd have to use the change_var or such methods. In order to do that, you'd need to first check which dynamics models your system is using and consult MODELS.pdf.
The below code snippet has been made as per the details of the original question.
Note 0: The method for changing the real power generation in dynamic simulation is based on @peroflofl 's answer.
Note 1: psspy.scal2 works fine for dynamic simulation as far as load increments are concerned. It however, does not change the dynamic generation values for me. So in such a case @peroflofl's code does the job. I have added a slightly modified version of his code into this snippet.
Note 2: Any slashes in the command below ' \ ' are used to split the command in multiple lines in Python2
# Housekeeping code before running the simulation for efficient changing of loads and generations.
genBus = 1
loadBus = 3
subsystemNum = 1
ierr = psspy.bsyso(subsystemNum, loadBus) #Adding Bus 3 to Subsystem 1. It is assumed that a subsystem identified by that number has not been created.
ierr, mbase1 = psspy.macdat(genBus, '1', 'MBASE')
# add dummy governor without droop and time constants to Bus 1
psspy.add_plant_model(genBus, '1', 7, r"""IEESGO""", 0, "", 0, [], [], 11, \
[0.0,0.0,0.05,0.0,0.0,0.0,0.0,0.0,0.0,1.0,0.0])
psspy.machine_array_channel([-1,6, genBus], '1' ,"")
ierr = psspy.strt(0, 'ieee39_outfile.out')
psspy.run(0, 0.5, 0, 1, 0) #It is assumed that your initial values of Bus 1 generation and Bus 3 load are already set
changeType = 1 # Parameter for psspy.scal_2. Use 2 for Percent change and 3 for Incremental change. I've used 1 since you need to specify a new value.
loadChange = 75 # New load should be 75 MW
ierr, totals, moto = psspy.scal_2(subsystemNum, 1, 0, \
[psspy._i, 2, 0, 1, 0], \
[loadChange, changeType, 0.0, 0.0, 0.0, -0.0, 0.0]) # Now Bus 3 PLoad is 75 MW.
genChange = 100 # New generation should be 100 MW
psspy.increment_gref(genBus, '1',genChange/mbase1) # Now Bus 1 PGen is 100 MW.
psspy.run(0, 1.0, 0, 1, 0) # Run till 1.0 s
loadChange = 20 # New load should be 20 MW
ierr, totals, moto = psspy.scal_2(subsystemNum, 1, 0, \
[psspy._i, 2, 0, 1, 0], \
[loadChange, changeType, 0.0, 0.0, 0.0, -0.0, 0.0]) # Now Bus 3 PLoad is 20 MW.
psspy.run(0, 2.0, 0, 1, 0) # Run till 2.0 s
Assuming you are using dyntools.CHNF to record the dynamic simulation state variable values, you may then plot POWR 1 [BUS 1 BasKV_val]1 values from the .xlsx file using your preferred progarmming software.
May be you can make a workaround by creating an artificial generator that is not actually there in reality but will serve you to make changes in load? If the simplifications of this artificial generator are o.k. with you may be it is a good compromise. You will disconnect this generator at times when the load needs to increase and you will increase the governor reference (Pmech power) mechanical power of this generator when your load needs to decrease.
i am trying to find ways to change generator output values using PSAS, however load changes can be done using ALTER command...
Asked: 2015-12-05 00:49:19 -0500
Seen: 7,600 times
Last updated: Mar 04 '22
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