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2023-02-01 08:39:14 -0600 answered a question How to convert the P and Q values which are usually represented in actual values in PSSE.out to P.u?

It is not possible to change the unit for channels written to an outfile (.out) in PSSE.

Use a function in Plotbook to recalculate the values before plotting.

2023-01-30 11:20:01 -0600 answered a question How to fix the PF at the POI?

The slack bus generator will always inject the necessary Mvar to keep the scheduled voltage. Adjust the Mvar injection by nearby generators, fixed shunts, switched shunts, FACTS, etc., in order to change Qgen of the slack bus.

2023-01-29 11:40:02 -0600 answered a question how to change the P at the slack POI bus?

It is not clear what you want, but I assume you should change the active power generation (Pgen) in your ”system”.

2023-01-26 04:24:34 -0600 answered a question Creating Dynamic (.dyr) files

You can't generate a .dyr file from .sav. A saved case has only load flow data.

The script should enter the needed dynamic models for the converter. It can write a add dynamic data file (.dya) and then read the file to add the information to the snapshot.

Library models can be added directly with API: psspy.add_plant_model, without the need of a .dya file.

2023-01-24 16:02:31 -0600 answered a question OLTC Modeling

In addition to @acd1's answer I want to clarify that the number of steps are:

Nsteps = (Rmax-Rmin))/STEP = (1.1-0.9)/0.00606060606 = 33.

The number of tap changer positions are always Nsteps+1, i.e. NPOS = 33+1 = 34 in this case. Normally, the number of positions are odd numbers so there may be something wrong with the given data here. With 33 tap positions the steps size would be: STEP = 0.2/(33-1) = 0.00625!

2023-01-16 05:03:26 -0600 commented question Cascaded tripping of CMLDBLU2

Can you show the tripping messages?

2023-01-14 08:56:24 -0600 commented question Cascaded tripping of CMLDBLU2

What is tripping? Loads, lines, generators, etc.?

2023-01-14 08:54:09 -0600 answered a question PSS2CU1 model

The CONs are described in Note 3 in the Model Data Sheet.

2023-01-14 08:42:35 -0600 commented answer Why do it get current in other phases when i short circuit one phase (Single line to ground fault). IEC 60909 calculations

The transformer phase shift will only affect currents at the other side of the transformer. I.e., the currents at bus 4. Here there are no current at bus 4 (no generator and grounded wye-winding at bus 3.

2023-01-14 08:39:50 -0600 commented answer Why do it get current in other phases when i short circuit one phase (Single line to ground fault). IEC 60909 calculations

There is nothing missed in my example. Please take you time and model the same system yourself, and you will understand that the results are correct. You have misunderstood the theory.

2023-01-13 04:31:48 -0600 commented answer Why do it get current in other phases when i short circuit one phase (Single line to ground fault). IEC 60909 calculations

See my updated answer!

2023-01-12 06:15:53 -0600 commented question How can i import a PSSE file in POWER FACTORY?

This is a PSSE forum only!!!!

2023-01-10 12:19:51 -0600 answered a question Question about REECCU1

1: For renewable models normally Pmax is entered into Mbase of the generator, so here 30 MVA.

3: You are right. They mean 30 MW for 4 hours.

2023-01-10 12:05:04 -0600 answered a question Why do it get current in other phases when i short circuit one phase (Single line to ground fault). IEC 60909 calculations

In a network there will be currents flowing in the healthy phases at LG-faults, even if all loads and shunts are ignored.

At LG-fault the sequence currents are equal at the fault location, but the impedance and layout of the positive, negative and zero sequence systems are different.

So, normally there are currents in the healthy phases of the lines/transformers feeding the faulted bus.

EDIT: An example with a simple non-loaded system with only reactances as shown below:

image description

The Thevenin positive sequence reactance at bus 3 is 0.45 pu and the zero sequence reactance is 0.08 pu. The zero sequence reactance for the branches is 0.6 pu each, and the zero sequence reactance of each grounded transformer is 0.1 pu.

LG-fault at bus 3 gives the following results with ASCC:

AT BUS      3     [C           400.00] AREA    1  *** FAULTED BUS IS:      3     [C           400.00] ***   0 LEVELS AWAY ***
 PRE  FAULT (kV L-G)  VA:/230.94/30.00
 POST FAULT (kV L-G)  V+:/124.90/30.00  V-:/106.04/-150.00  V0:/18.85/-150.00  VA:/0.00/0.00  VB:/201.99/-68.05  VC:/201.99/128.05
 THEVENIN IMPEDANCE, X/R  (PU)  Z+:0.000000+j0.450000, 9999.999  Z-:0.000000+j0.450000, 9999.999  Z0:0.000000+j0.080000, 9999.999
                                                  X------------------------------------LINE TO GROUND (LG) FAULT-----------------------------------X
 X----------- FROM ------------X AREA CKT I/Z         /I+/   AN(I+)     /I-/   AN(I-)     /I0/   AN(I0)    /3I0/   AN(I0)   RE(Z0)   IM(Z0)  APP X/R
      2     [B           400.00]    1 1   AMP/PU      73.6   -60.00     73.6   -60.00     14.7   -60.00     44.2   -60.00 0.000000-0.200000 9999.999
      2     [B           400.00]    1 2   AMP/PU      73.6   -60.00     73.6   -60.00     14.7   -60.00     44.2   -60.00 0.000000-0.200000 9999.999
      4     [D           135.00]    1 1   AMP/PU       0.0     0.00      0.0     0.00    117.8   -60.00    353.5   -60.00 0.000000 0.000000  0.00000
 INITIAL SYM. S.C. CURRENT(I''k)(RMS)     AMP        147.3   -60.00    147.3   -60.00    147.3   -60.00    441.8   -60.00
                                                  --------------------------------------------------------------------------------------------------
 X----------- FROM ------------X AREA CKT I/Z         /IA/   AN(IA)     /IB/   AN(IB)     /IC/   AN(IC)                     RE(ZA)   IM(ZA)  APP X/R
      2     [B           400.00]    1 1   AMP/PU     162.0   -60.00     58.9   120.00     58.9   120.00                   -0.00000 0.236364 9999.999
      2     [B           400.00]    1 2   AMP/PU     162.0   -60.00     58.9   120.00     58.9   120.00                   -0.00000 0.236364 9999.999
      4     [D           135.00]    1 1   AMP/PU     117.8   -60.00    117.8   -60.00    117.8   -60.00                   -0.01540 0.108889  7.07254
 INITIAL SYM. S.C. CURRENT(I''k)(RMS)     AMP        441.8   -60.00      0.0     0.00      0.0     0.00
 ---------------------------------------------------------------------------------------------------------------------------------------------------

There is only fault current in phase A at bus 3 (441 ... (more)

2022-12-30 05:27:08 -0600 answered a question Tripping of synchnous machine in psse

Model NRCGP3U may be used to supervise and trip generators in an area, zone etc.

Check the DYRE-file for any call of 'NRCGP3U'.

Check also spreadsheet Dynamics Data - Protection Models - Machine for any tripping models.

Edit:

Check if option "Scan generators exceeding speed deviation threshold" is enabled in Dynamic Simulation Options:

image description

However, the progress window trip message looks like this so it is not causing your trip:

 Machine 1  at bus    3018: PU speed Deviation=    0.05057; PU overspeed Threshold=    0.10000
 MACHINE 1  AT BUS   3018 [CATDOG_G    13.800] TRIPPED AT TIME = 1.4300
2022-12-23 07:46:04 -0600 commented answer 2 Winding raw to psse switches from and to bus

For 3-winding transformers, all windings have tap changer data.

2022-12-23 07:44:30 -0600 commented answer 2 Winding raw to psse switches from and to bus

Yes, there is no sorting for 3-winding transformers: I = winding 1; J = winding 2, K = winding 3.

2022-12-23 02:23:32 -0600 answered a question 2 Winding raw to psse switches from and to bus

In raw data bus I is the "Winding 1" bus and bus J is the "Winding 2" bus. Winding 1 is the winding where the tap changer is located. So, the first bus number (I) is always Winding 1 bus in raw data.

In PSSE the transformers are sorted with the lowest bus number as "From Bus" and the other as "To Bus". Here the location of the tap changer (at Winding 1) is defined by the check box "Winding 1 on From end". If I > J, then J becomes "From bus" and I becomes "To bus".

2022-12-22 13:44:17 -0600 answered a question Dynamics of starting a generator

It is the correct way to do the black start simulation.

Every generator to be connected to the system during the simulation must be on-line as stand-alone islands in load flow, i.e., each generator bus is a swing. Note, one island for each generator to be synchronised.

Synchronising is done during simulation by switching on the step-up transformer. Each generator will have 0 pu speed deviation (50/60 Hz) up till the point of synchronisation. Be sure to synchronise when the frequency and the bus rotor angles of the two transformer buses (generator bus and high tension side) are fairly close.

2022-12-22 13:22:52 -0600 commented question Tripping of synchnous machine in psse

Can you show the tripping message from Progress Window?

2022-12-12 08:41:33 -0600 answered a question how to duplicate a network element

It can be done in the GUI:

  1. Select a transformer in the 2 Winding spreadsheet
  2. Ctrl-c to copy the data to the clipboard
  3. Click the first column on the empty last line
  4. Ctrl-v to paste the data.
  5. Change the id from e.g. 1 to 2
  6. Press enter to exit edit mode

A transformer can be duplicated in python in the following way:

  1. Write raw data for the subsystem consisting of ibus and jbus
  2. Change id of existing transformer
  3. Read raw data files with existing transformer

The python code:

import os

def duplicate_transformer(ibus,jbus,ickt='1',ickt2='2'):
    """ Duplicates 2W transformer ickt between ibus and jbus
    """
    rdcfile = 'copy_transformer_dummy_file'
    # Write data for existing transformer to raw data files
    psspy.bsys(11,0,[0.0,0.0],0,[],2,[ibus,jbus],0,[],0,[])
    psspy.rawd_2(11,0,[1,1,1,0,0,0,2],0,rdcfile+'.rac')
    psspy.rwsq_2(11,0,[1,1,1,1,1],0,rdcfile+'.seq')
    # Change id of existing transformer
    psspy.mbidbrn(ibus,jbus,ickt,ickt2)
    # Read raw data files with existing transformer
    psspy.rdch(0,rdcfile+'.rac')
    psspy.resq(rdcfile+'.seq')
    # Delete raw data files
    os.remove(rdcfile+'.rac')
    os.remove(rdcfile+'.seq')

# Duplicate transformer in savnw network
duplicate_transformer(152,153,'1','2')
2022-12-09 00:59:14 -0600 commented answer Primary response generation change

The limitation is in the governor model, It is called Vmax, Tmax, Pmax or something else.

2022-12-08 02:41:10 -0600 answered a question Getting unresolved external symbol error during creation of dll file

Since line id is a character the value is stored in array CHRICN.

Try:

CALL BRNINT(ICON(M),ICON(M+1),CHRICN(M+2),'STATUS', STATUS, IERR)
2022-12-06 07:09:15 -0600 commented answer User defined model of line relay

No, PTI doesn't publish such information.

2022-12-06 03:28:47 -0600 answered a question User defined model of line relay

Use KM to get the line information:

CALL GETFTC(KM,II,JJ,ID)

returns the bus sequence numbers II and JJ and the line ID. The external bus numbers are:

IBUS = NUMBUS(II)
JBUS = NUMBUS(JJ)
2022-12-05 13:35:49 -0600 answered a question frequency control and HVDC link

The two VSC-HVDC library models do not have any frequncy control built-in.

With model VSCDCT you can add an external signal modulating the power order. For that you can use an auxiliary signal model in PSSE´s library.

2022-11-28 02:18:02 -0600 commented answer How to obtain and hold the value of STATE/VAR at a certain time?

Under the same IF statement put VAR(L+1) = STATE(K+x)

2022-11-25 02:58:10 -0600 commented answer How to obtain and hold the value of STATE/VAR at a certain time?

In mode 1: VAR(L)= -1. In mode 3: IF(ETERM(MC)<0.2 AND VAR(L)<-0.5) VAR(L)=TIME. This will store the first time voltage goes below 0.2 pu in VAR(L).

2022-11-25 00:59:54 -0600 commented answer How to obtain and hold the value of STATE/VAR at a certain time?

Why are you using DSRVAL to get the time? It is already available in common variable TIME.

2022-11-24 10:35:55 -0600 answered a question How to obtain and hold the value of STATE/VAR at a certain time?

Do you want to write your own user moderl version of REECAU1?

The simulation time is already available in variable TIME, so there is no need for DSRVAL.

At each time step the value of the STATE is in the STATE array. I don't understand the question.

2022-11-24 10:22:06 -0600 answered a question FLOW1 function output not matching with Load Flow Solution

You don't have exactly the same solution in load flow and at initialisation. The generators and loads are converted the load flow is solved with TYSL. This explains the difference in the line flow values. Very normal and shouldn't cause any initial conditions suspect.

Which STATE has suspect conditions? What kind of block is it (lag, integrator, washout, etc)?

What are the STATE and DSTATE values?

2022-11-24 10:09:10 -0600 answered a question Character to Integer Conversion for PSSE

Branch id entered as character, e.g. '1', will be stored in CHRICN. If branch id is entered as an integer in DYRE-file the value is stored in ICON. Try the following

IF (CHRICN(I+2).EQ.'$$') WRITE(CHRICN(I+2),'(I2)') ICON(I+2)

where I+2 is the index of the branch id. This line will convert integer id to character id in array CHRICN

In this way the id will always be stored in CHRICN.

2022-11-23 06:38:42 -0600 commented answer How to calculate limits for governor models

The manual is misleading in this aspect. Maximum Pmech (e.g. governor parameter Tmax, Pmax or Vmax) should be set a value corresponding to Pmax in load flow. Too many examples show Tmax=1 or higher, which is wrong.

2022-11-22 13:41:02 -0600 answered a question How to calculate limits for governor models

Of course the limits for DEGOV can be calculated from those data.

Tmax = Pmax/Mbase

Tmin = Pmin/Mbase

If RSORCE>0, the limits should be slighlty adjusted with the resistive losses in the generator.

2022-11-21 07:11:54 -0600 commented answer Unperturbed dynamic simulation is not stable.

Same data as typical data in manual PAG-II. Except for Xd" which is 0.25 in manual.

2022-11-20 01:10:52 -0600 commented answer Unperturbed dynamic simulation is not stable.

Can you show the GENSAL data?

2022-11-18 04:50:10 -0600 answered a question VSC-HVDC in pss/e v33.4

There is no message in progress window when reading the DYRE file?

2022-11-18 04:48:30 -0600 commented answer Unperturbed dynamic simulation is not stable.

So, still unstable with only two generator models! Which model are you using?

2022-11-18 04:44:50 -0600 answered a question frequency control with HVDC model

This post is redundant. See post "Modulate Power in a VSC Converter" .

2022-11-17 10:59:59 -0600 commented answer Unperturbed dynamic simulation is not stable.

Do you have SWS, HVDC or FACTS models?

2022-11-16 13:10:33 -0600 answered a question How to determine if a generator tripped?

All generator trips during a simulation should be written to log file, if progress window is redirected. Search the file after simulation.

2022-11-16 13:05:34 -0600 commented answer Simulation Crash at Fault Creation

@Pasnos proposal No 2 is better.

2022-11-16 13:02:12 -0600 commented question Is pssarrays model ACCC_SOLUTION valid for V35

Yes, why not?

2022-11-16 12:58:19 -0600 commented answer Having issues with initializing case in 33.4 version.

Your data looks ok. It may be a bug in rev 33.4.

2022-11-16 12:54:45 -0600 commented answer Unperturbed dynamic simulation is not stable.

Maybe a too short time constant in a generator model. Check the time constants in all generator models (GENSAL, GENROU, etc)

2022-11-14 10:43:08 -0600 answered a question Unperturbed dynamic simulation is not stable.

Try to disable all exciter models (or governor models) and see if it makes it stable.

Another method is to enable "Display network convergence monitor" and check dynamic models located at or close to the bus with highest mismatch at the first iteration at each time step.