CynicalSuka's profile - activity

still not convinced! In unloaded system no current should flow in other phases. Only Delta-star transformer can make the fault current on one phase of star side to flow in two phases on delta side. thats the theory

11.2.5.2 Effect of Neglecting Transformer Phase Shift <-----section of PSSE PAG Vol 1

i think you may have missed some important things in your example. Transformer connection codes and phase shift! According to theory there should be current in only A and C phase coming from Bus 4. PSSE PAG Vol 1 has a nice section dedicated to wrong SC calculations if phase shift is ignored.

Why do i get current in B and C phase if only A phase is grounded. By theory current in B and C phase should be zero if all loads and shunts are ignored.

All loads set to zero. All shunts set to zero. I get current in other phases when i short circuit one phase only meaning single line to ground phase. By theory current should only flow in faulted phase as all the loads are open circuited, all shunts are ignored in all sequences etc

Models documentation says 0 ≤ TMAX < 1.5 and -0.05 ≤ TMIN < 0.5. How could that be. Pmax is always less than Mbase. so Tmax can be 1 at maximum

How to calculate limits for governor models. for example how do i calculate Tmin and Tmax of DEGOV model given i know Pmin, Pmax, and MVA of the generator.

significantly deceasing DELT also fixes this issue but with the added disadvantage of very very long simulation times.

....calculations done by the PSSE

i think i solved it. it definitely was a numerical instability. I decrease tolerance in dynamic settings to 0.00001 from 0.0001 and now everything flat. 0.0001 tolerance was causing the simulation to capture very small deviations of the order of 0.0001 which i beleive is inherent of the numerical...

yes as i said this is from small example 25 bus case. just testing some things out. so i put data from PAG-II. but what is the issue. even with Xd"=0.25 facing same issues

201 'GENSAL' 1 5.0000 0.50000E-01 0.60000E-01 5.0840 1.0000 1.5000 1.2000 0.40000 0.15000 0.12000 0.30000E-01 0.25000 /

Yes. Both are GENSAL.

As i said when i decease DELT significantly everything becomes flat. 0.00001 is my delt. Of course it takes ages even to get to 5 seconds.

Well my case do have sws and user-defined hvdc. But to leave no doubt i disabled them too. Infact right now i am just testing with simple example case which is 25 bus having only 2 generator just to test some things out. Just to check maybe something not right with simulation settings.

Don't think that i have that much small time constants. But will double check

Disabled all exciter and governor models. Getting same results. No change. See a change when i decrease DELT significantly.

my case has no initial condition suspects. Vmax Vmin etc limits are all correct. one strange thing that i noticed. when i make DELT=0.00001 then everything becomes flat. voltage, angle, etc. i ran the simulation for 5 seconds. perfect flat. although it took ages

I have a case which is perfectly initialized but unperturbed dynamic simulation for the system is not what it should be. I should get constant value for power, angle etc. in unperturbed conditions but values keep changing haphazardly. Could be numerical instability. But my integration time step is also very small. so, no idea what it is. hope someone could clarify what is wrong with my case.

Similar problems for other machines too.

The error: Model TGOV1 Bus 20100 [FPCL 132.00] Machine "1 " : initialized out of limit(s) PMECH(I)

it is clear that Vmax should be 0.80 or greater. i put 0.81 but still getting initialized out of limit error. i have to put 0.83 or greater for this error to be removed. this only happens in 33.4 version. in 33.9 it initializes without any error

Load flow data of that machine: Bus Number BusName VSched (pu) PGen (MW) PMax (MW) PMin (MW) QGen (Mvar) QMax (Mvar) QMin (Mvar) Mbase (MVA) 20100 FPCL 132.00 0.9800 55.0002 55.0000 17.3330 37.1853 37.1850 -29.0590 68.75

Governor Data of one of the machine: Model Name Model Identifier Type R T1 (>0)(sec) V MAX V MIN T2 (sec) T3 (>0)(sec) Dt TGOV1 20100 [FPCL 132.00] 1 Stnd 0.0600 0.1000 0.8100 0.2600 2.1000 5.0000 0.0000

And this happens only for governor models. Would be glad if someone could help. i have to make TRATE of GGOV1 from 300 to 301 and then suspect error is removed. but case initializes with no error TRATE=300 in 33.9 version

My case built and initialized with no errors on work PC having version 33.9 shows multiple initialization errors on another PC having 33.4 version. Same case perfectly initializes on version 33.9. Some things that i dug up while trying to solve the issue. e.g if Vmax of some governor is correctly tuned in 33.9 version, that value shows initialization out limit error in 33.4 version. if Vmax=0.80 in 33.9 version i have to make it 0.83 or 0.84 in version 33.4 for this error to be removed. So, i have to do this tuning exercise again and again. Extremely annoying. Anyone else facing same issue?