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2019-01-21 10:22:10 -0500 answered a question ImportError: No module named psspy

Do a quick sanity check. Open PSSE explore, and then type

import psspy

into the Python command line. If you don't get an error message in the Output Bar, then there's some problem linking everything up externally.

2019-01-21 08:59:20 -0500 answered a question How to convert PSCAD model to PSS/E model ?

In PSS/E, there is the HVDCPL1 model, based on Siemens HVDC Plus technology, which is MMC-HVDC.

This model is available in v34.2 of PSS/E; I can't confirm if it is in earlier versions.

Your challenge is to fit your PSCAD model to the HVDCPL1 model parameters - caveat utilitor!

2019-01-18 02:12:56 -0500 commented answer Help with compiling FORTRAN Models

Use IF(MIDTRM) RETURN and remove all references to the DLTCHG parameter, and your model should compile and run correctly in dynamic simulations in v33.

2019-01-16 02:19:28 -0500 commented answer Help with compiling FORTRAN Models

As far as I am aware, DLTCHG is only relevant for extended term simulations. You should be able to use a statement like IF(MIDTRM) RETURN to avoid extended term simulations, which you are most likely not interested in. User-defined modelling is not very well documented in PSSE.

2019-01-15 11:36:55 -0500 answered a question Help with compiling FORTRAN Models

DLTCHG is the flag for a variable step size in an extended term simulation. The line of code that you posted is saying that the model execution should end if you select extended term simulation mode with a fixed time step. Are you intending to use extended term simulation mode with a variable time step? That would be MIDTRM=1 and DLTCHG=1. If not, then you can remove all references to DLTCHG in your code, and try a compile in v33. You won't lose any relevant functionality.

2018-12-21 02:10:32 -0500 commented question PV and WTG Step Change

Why don't you try that and find out if it works?

2018-12-19 10:51:39 -0500 answered a question PSSE, python, dynamic run

Look in the PSSE "Example Directory", which on my PC is here.

C:\Program Files (x86)\PTI\PSSE34\EXAMPLE

The "dyntools_demo.py" file shows you the code for running PSSE simulations from Python and plotting results.

That and the PSSE API manual should give you a head start.

2018-12-13 02:24:38 -0500 commented question UDM with vars and states equal to zero during dynamic simulation

It's very difficult to debug code without actually seeing the code!

2018-12-10 07:21:28 -0500 answered a question .sav file with psse34

I presume you are talking about the *.sav file format? There are several versions of PSSE34, and the files might not be backwards compatible. For example. if you have v34.2 installed, and someone gives you a sav file that was created using v34.4, then you might not be able to open it. I would advise you to "go back to the source" and find out what version of PSSE was used to create the sav file that you cannot open.

2018-12-05 11:35:17 -0500 commented answer IEEE 118 Bus System in PSSE

https://file.io/g03YRa Try again. This is a once-off download, then the online file is deleted.

2018-12-05 03:52:23 -0500 commented answer IEEE 118 Bus System in PSSE

I found a v33 RAW file at the University of Illinois website. I converted this to v32, and you can download that from here. https://file.io/dnMCdX

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2018-12-03 09:01:56 -0500 answered a question IEEE 118 Bus System in PSSE

If you post the RAW file here then I can import it into PSSE and then export it to v32 format, and post that for you.

2018-11-23 10:56:22 -0500 commented question PLBVFU1 Playback model

I was assuming that it was available in v33, based on the original question. Clearly that was incorrect.

2018-11-23 04:21:04 -0500 answered a question Prony Analysis

As far as I am aware, there is no built-in Prony analysis tool in PSSE. You can use Python to extract the results from a dynamic simulation. Then, you can either search for and download a Python package that does Prony analysis, or write the Python code yourself.

2018-11-23 04:14:15 -0500 commented question PLBVFU1 Playback model

I don't have v34.0.0 installed, but PLBVFU1 is available in 34.2.0 and 34.3.1, and you say that it is available in v33, so I would be surprised if it is not available in v34.0.0.

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2018-10-26 01:40:49 -0500 answered a question Plotting a CON Parameter

Thanks for your help, I got it working.

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2018-10-22 07:45:38 -0500 commented question Overwriting OUTX Files

Version 34.2.0

2018-10-21 03:36:44 -0500 asked a question Overwriting OUTX Files

Hello All,

I am using PSSE Dyanmics. I have run a simulation, and there is an OUTX file in memory ("V Change 5.outx").

When I try to repeat the simulation, I get this message in the Output Bar.

Insufficient access rights. V Change 5.outx (OpnApplFil/LOPEN)

This message seems to say that I do not have permission to overwrite the contents of the OUTX file, but when I run the simulation the contents of the OUTX file are overwritten, as I can see new/different simulation results in the overwritten file. Note that I have also implemented the following command. ierr = psspy.file_overwrite(1)

I don't know why PSS/E is showing this warning message about insufficient access rights. Does anyone have any thoughts?

Thanks.

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2018-10-21 03:31:04 -0500 commented question Plotting a CON Parameter

Yes, I do have a FORTRAN compiler. What do you suggest? Thanks.

2018-10-19 11:00:04 -0500 asked a question Plotting a CON Parameter

Hello All,

Here's the situation.

With a USRMDL of a STATCOM that I am using (but did not write and do not have the source code for) the voltage setpoint of the STATCOM is a CON parameter. I make changes to this CON parameter and see the response of the STATCOM. I want to plot the STATCOM voltage and the reference voltage on the same graph, to show how the voltage follows the changes in setpoint. However, it seems that I cannot plot the CON parameter. Does anyone know a workaround?

I would like to ask the model writer to include the CON parameter as a VAR, so that I can plot it that way, but this might not happen any time soon.

Perhaps some of you have faced a similar situation. I would appreciate your replies. Thanks.

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2018-09-14 12:12:16 -0500 asked a question Function in excelpy to get the name of a worksheet

Hello readers,

I'm trying to find a function in excelpy that will return the name of a worksheet. I don't think there is one, but please correct me if I am wrong.

I do know that such a function exists in the openpyxl module, but I would prefer to use excelpy if possible.

Thanks.

2018-09-10 07:56:09 -0500 commented answer excelpy reading excel files

I have not used xlrd, but it seems that you can't use it to write data to an Excel file. I have used openpyxl, and it lets you read from and write to Excel. The online Help for openpyxl can be tricky to navigate though.

2018-09-10 06:21:26 -0500 answered a question excelpy reading excel files

Hello Andre, I have shared your frustration with finding out how to read data from an Excel file using excelpy.

The v34.3.1 documentation for excelpy lists the functions, but the alphabetical list goes directly from the "freezepanes" function to the "height" function. For some unknown reason, it does not list the following two (very useful) functions.

 |  get_cell(self, address, sheet=None)
 |      Get value from one cell.
 |  
 |  get_range(self, address, transpose=False, sheet=None)
 |      Get data from cells in the range.
 |      data = get_range(address, ...)
 |      Inputs:
 |      address   - range tuple specified as (topRow, leftCol, bottomRow, rightCol)
 |      transpose - Logical
 |          Excel methods read data row by row and returned as Python list of lists.
 |          transpose = False
 |              Each returned list represents data in a speadsheet row.
 |          transpose = True
 |              Each returned list represents data in a speadsheet column.
 |      Returns:
 |          data = List or List of Lists values.

You can see all of the documentation for the excelpy functions by importing excelpy and then running help(excelpy).

This should save you the hassle of installing additional module(s) to read Excel files. Hopefully PSSE will update their documentation so that more users are not confused as you and me were.

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2018-09-05 05:53:28 -0500 answered a question PSS/E vs E-tran for Network reduction and PSCAD conversion

I have used the second approach with ETRAN and PSCAD.

I had to go 6 buses away from the relevant bus, at which point there was no significant difference compared to the frequency sweep results (Impedance vs Frequency) using the 5 buses away option. Therefore, explicit representation of the network up to 5 buses away from the relevant bus gives sufficient accuracy. In your own study, the answer may be 3, 4, 5 or >5, but the approach should be the same.

You can also consider using the frequency dependent equivalent network element in PSCAD. With this element, you enter the results of the frequency sweep at the relevant bus, do some vector fitting, and then you have an equivalent representation of the external network that is valid for a large range of frequencies.

2018-09-04 07:03:45 -0500 commented question Do you have an example for svc model in PSS/E?

When you say that you used the model of the SVC, which model were you using? Also, what parameters did you use for this SVC model? If you give more details, then your readers will be in a better position to answer your questions.

2018-09-03 06:21:54 -0500 answered a question Does Python 3.6 can work with psse

Hello Gary,

As far as I know, the Python modules for PSSE are compiled in v2.X of Python (note how there are numerous *.pyc files in the installation directories). Therefore, I doubt that everything will work correctly in Python v3.X.

2018-08-31 03:04:07 -0500 answered a question How to modulate the governor or exciter of generator in PSS/E for dynamic simulation?

You can write Python code into a loop,where you are running the simulation from one time step to the next, and then changing the value of GREF in accordance with the sine function (which is a function of time of course). It's not a very elegant solution, but at least writing the code into a loop means that it will not be too verbose.

2018-08-17 08:47:42 -0500 commented answer "Library not found (000281)" PSS/E v34.3 & PSS/E v34.4

Check out this discussion also, where some users have had issues when moving models from {v34.2 and lower} to {v.34.3} and higher, or vice versa. https://psspy.org/psse-help-forum/question/3660/user-defined-library-in-psse34-library-not-found/

2018-08-15 02:27:01 -0500 answered a question Why do we convert generators and loads??

In a regular power flow calculation, the generators and loads are represented as sources or sinks of active and reactive power. Take a look at any textbook to see how the equations are structured. In a dynamic simulation, generators are modelled as voltage-controlled current sources. So, you need to convert the generators to current sources before you transition from power flow calculation to dynamic simulation. The load in a regular PSSE power flow calculation has no dependency on terminal voltage or frequency. In a dynamic simulation, you want to consider these dependencies, or at least consider the voltage dependency. To do this, you need to convert the loads to impedances and/or current sources. More information about these processes can be found in the PSSE manuals.

2018-08-15 02:20:37 -0500 answered a question unbalanced fault dynamics

You can use PSSE's short-circuit calculation procedures to get the sequence components of voltage and current due to an unbalanced fault. However, this is a "static" calculation, calculating the sequence components at one instance in time, immediately after the fault. It sounds like you want to do a dynamic simulation, and calculate the sequence components as a function of time, let's say in the 1s following the occurrence of the fault. This is not possible in PSSE dynamics, which considers the positive sequence only. There are other software packages that do provide such a calculation function, but I am wary of mentioning any names here to prevent any accusation of bias.

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2018-07-20 08:00:49 -0500 asked a question Conveting OUTX File to TXT or CSV

Hello all,

Does anyone have any experience converting *.outx files to *.txt (ASCII) or *.csv file formats, which are more easily read by other plotting programs (e.g. Excel). Preferably, I'd like to be able to "batch convert" a number of *.outx files in one sweep.

I was able to batch convert *.out files, but *.outx seems to be a different file format.

Thanks,

James

2018-07-16 04:45:50 -0500 commented answer Short circuit calculation with type 4 wind turbines or PV generator

That's another way of doing it, but you have to replace the generator with a load when you are doing short-circuit calculations. When you want to revert to load flow calculations (where the WTG does voltage control) or dynamic simulations, then you have to swap the models again.

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2018-07-16 03:29:16 -0500 answered a question Short circuit calculation with type 4 wind turbines or PV generator

Generators are typically represented as Thevenin equivalent voltage sources in short-circuit calculations, and not as constant current sources, which is how a Type 4 WTG should be represented. The type 4 WTG will have a short-circuit contribution of approx 1.2pu current for a large range of retained voltages at its terminals (e.g. 0.9pu down to 0pu). When I have needed to represent this type 4 WTG behaviour as accurately as I can then I have written a Python script that adjusts the value of Zsource for the generator until you get the required value of current (1.2pu). This is not ideal, but it works.

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2018-06-28 01:41:25 -0500 answered a question Open circuit test performance of the voltage step exciter

If you know how to execute these commands in PSSE then all you need to do is record a Python script while you execute the commands. The resulting Python script will show you which API functions were used. If you are not sure about the syntax of the functions in the Python file that was generated, you can consult the API Manual. As far as I know, this is the way almost everyone learns how to use Python in PSSE. Record->Execute->Read API Manual.

2018-06-12 09:51:17 -0500 answered a question Initial condition suspect for GAST2A

It is difficult to answer this question without seeing your input data, and replicating your issue from there. If you can send your RAW and DYR files then perhaps I or some of the other forum readers can assist you.

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