Power System Modelling

[himmelstern]

Hello EGPET users

I have an doubt because for 15 years I have not used some knowledge from University college; more in power system modelling techniques.

I need to do the modelation for the power system of book [Paul M. Anderson; A. A. Fouad] Power System Control & stability; page 38; Nine Bus system

and the results from power flow are:

I found this power system modelled even in the digsilent power factory examples that come withing the software normal installation.

and on internet this and another system from books are modelled in this page:

[link Point to another website Only the registered members can access]

ETAP


DigSilent PF

the results are the same from the book; every thing it's ok at this point.

when I'm doing my self this calculations by hand; results are not the same; and I can't remember how to do it....

IE: the calculations are in the same Voltage and power base:




how I can get this results???:

[user82]

1. Calculate base impedance:

• Base impedance = V^2 / P
• Z_base = (230*10^3)^2 / 100*10^6 = 529 ohm

2. We know pu value from book is:

• R_pu = 0.0085
• X_pu =j0.072

3. We know DIgSILENT line R*X value is:

• R = 4.4965 ohm
• X = 38.088 ohm

4. Convert DIgSILENT value to pu:

• R_pu = R / Z_base
• R_pu = 4.4965 / 529 = 0.0085

• X_pu = X / Z_base
• X_pu = 38.088 / 529 = j0.072

[surgeArrester]

@himmelstern
you're expected results should be in pu or actual values?

in the shown pictures* the different values are of the impedance. as long as you have the same values* per unit wont matter.. you always change base anyways.. only that* 100mva base is used in etap..not sure in digsilent.

i think what you need to do is to check the line configuration is the same in etap and digsilent and check the tolerance values used.. in etap* the load flow study results are adjustment at positive tolerance to assume worst possible load flow.. you can just disable this tolerance in adjust tab in the study case.

if the configuration is the same and the calculated line impedance are not* you need further to check the line database... also check the temperature adjustments..

i just saw you are using user defined hahaha.. you can use the impedance in etap that way you can enter the per unit values...


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[himmelstern]

thanks both of you* user 82 thanks again