The Siemens PSS/E data format is a widely used for power system simulation. PSS/E uses a variety of plain-text files to store data for different actions. The RAW format (with file extension .raw) is used to store the steady-state data for power flow analysis, and the DYR format (with extension .dyr) is used to store the parameters of dynamic devices for transient simulation.

RAW Compatibility#

ANDES supports PSS/E RAW in versions 32 and 33. Newer versions of raw files can store PSS/E settings along with the system data, but such feature is not yet supported in ANDES. Also, manually edited raw files can confuse the parser in ANDES. Following manual edits, it is strongly recommended to load the data into PSS/E and save the case as a v33 RAW file.

ANDES supports most power flow models in PSS/E. It needs to be recognized that the power flow models in PSS/E is is a larger set compared with those in ANDES. For example, switched shunts in PSS/E are converted to fixed ones, not all three-winding transformer flags are supported, and HVDC devices are not yet converted. This is not an exhaustive list, but all of them are advanced models.

We welcome contributions but please also reach out to us if you need to arrange the development of such models.

DYR Compatibility#

Fortunately, the DYR format does not have different versions yet. ANDES support reading parameters from DYR files for models that have been implemented in ANDES. Owing to the descriptive modeling framework, we implement the identical model so that parameters can be without conversion. If a dyr file contains models that are not recognized by ANDES, an error will be thrown. One needs to manually remove those unsupported models to load.

Like RAW files, manually edited DYR files can often be understood by PSS/E but may confuse the ANDES parser. We also recommend to load and re-save the file using PSS/E.

Loading files#

In the command line, PSS/E files can be loaded with

andes run kundur.raw --addfile kundur.dyr

where --addfile or -a is used to specify the optional DYR file. For now, DYR files can only be added to a RAW file. We will allow different formats to be mixed in the future.

Likewise, one can convert PSS/E files to ANDES xlsx:

andes run kundur.raw --addfile kundur.dyr -c

This will convert all models in the RAW and DYR files. If only the RAW file is provided, only power flow models will be converted. One cannot easily append those in a DYR file to an existing xlx file yet.

To load PSS/E files into a scripting environment, see Example - "Working with Data".

Creating disturbances#

Instead of converting raw and dyr to xlsx before adding disturbances, one can edit the .dyr file with a planin-text editor (such as Notepad) and append lines customized for ANDES models. This is for advanced users after referring to andes/io/psse-dyr.yaml, at the end of which one can find the format of Toggle:

# === Custom Models ===
        - model
        - dev
        - t

To define two Toggles in the .dyr file, one can append lines to the end of the file using, for example,

Line   'Toggle'  Line_2  1 /
Line   'Toggle'  Line_2  1.1 /

which is separated by spaces and ended with a slash. The second parameter is fixed to the model name quoted by a pair of single quotation marks, and the others correspond to the fields defined in the above inputs. Each entry is properly terminated with a forward slash.

Mapping dyr to ANDES models#

ANDES supporting parsing PSS/E dynamic files in the format of .dyr. Support new dynamic models can be added by editing the input and output conversion definition file in andes/io/psse-dyr.yaml, which is in the standard YAML format. To add support for a new dynamic model, it is recommended to start with an existing model of similar functionality.

Consider a GENCLS entry in a dyr file. The entry looks like

1 'GENCLS' 1    13.0000  0.000000  /

where the fields are in the order of bus index, model name, generator index on the bus, inertia (H) and damping coefficient (D).

The input-output conversion definition for GENCLS is as follows

    destination: GENCLS
        - BUS
        - ID
        - H
        - D
                bus: BUS
                subidx: ID
                src: u
                idx: gen
                src: Sn
                idx: gen
                src: Vn
                idx: BUS
                src: ra
                idx: gen
                src: xs
                idx: gen
        u: u
        bus: BUS
        gen: gen
        Sn: Sn
        Vn: Vn
        D: D
        M: "GENCLS.H; lambda x: 2 * x"
        ra: ra
        xd1: xs

It begins with a base-level definition of the model name to be parsed from the dyr file, namely, GENCLS. Five directives can be defined for each model: destination, inputs, outputs, find and get. Note that find and get are optional, but the other three are mandatory.

  • destination is ANDES model to which the original PSS/E model will be converted. In this case, the ANDES model have the same name GENCLS.

  • inputs is a list of the parameter names for the PSS/E data. Arbitrary names can be used, but it is recommended to use the same notation following the PSS/E manual.

  • outputs is a dictionary where the keys are the ANDES model parameter and the values are the input parameter or lambda functions that processes the inputs (see notes below).

  • find is a dictionary with the keys being the temporary parameter name to store the idx of external devices and the values being the criteria to locate the devices. In the example above, GENCLS will try to find the idx of StaticGen with bus == BUS and the subidx == ID, where BUS and ID are from the dyr file.

  • get is a dictionary with each key being a temporary parameter name for storing an external parameter and each value being the criteria to find the external parameter. In the example above, a temporary parameter u is the u parameter of StaticGen whose idx == gen. Note that gen is the idx of StaticGen retrieved in the above find section.

For the inputs section, one will need to skip the model name because for any model, the second field is always the model name. That is why for GENCLS below, we only list four input parameters.

1 'GENCLS' 1    13.0000  0.000000  /

For the outputs section, the order can be arbitrary, but it is recommended to follow the input order as much as possible for maintainability. In particular, the right-hand-side of the outputs can be either an input parameter name or an anonymous expression that processes the input parameters. For the example of GENCLS, since ANDES internally uses the parameter of M = 2H, the input H needs to be multiplied by 2. It is done by the following

M: "GENCLS.H; lambda x: 2 * x"

where the left-hand-side is the output parameter name (destination ANDES model parameter name), and the right-hand-side is arguments and the lambda function separated by semi-colon, all in a pair of double quotation marks. Multiple arguments are accepted and should be separated by comma. Arguments can come from the same model or another model. In the case of the same model, the model name can be neglected, namely, by writing M: "H; lambda x: 2 * x".