PSS®E

PSS®E software from Siemens provides analysis functions for power system networks in steady-state and dynamic conditions. PSS®E uses different types of files to exchange data about the network. One of them is the RAW file (power flow data file). A PSS®E RAW file contains a collection of unprocessed data that specifies a Bus/Branch network model for the establishment of a power flow working case.

The RAW file has multiple groups of records (data blocks), with each group containing a particular type of data needed in power flow. The last record of each data block is a record specifying a value of zero to indicate the end of the category.

Each record in a data block contains a set of data items separated by a comma or one or more blanks where alphanumeric attributes must be enclosed in single quotes. As many of the data items specified in the RAW file have a default value only the specific information needed should be defined in the record.

In PSS®E version 35 a new RAWX file format (Extensible Power Flow Data File) based on JSON has been introduced. It will be the standard text-based data format for PSS®E power flow data exchange. The RAWX files contain two types of data objects: Parameter Sets and Data Tables. A Parameter Set has an array with field names and a single array with field values. A Data Table has an array with field names an and array of records, each record being an array of field values. The field names array indicates the order and subset of fields for which data is provided in the data arrays.

A minimum network model is included as an example in version 35 of both formats RAW and RAWX.

 0,      100.0, 35, 0, 0, 60.00       / October 27, 2020 18:37:53
 PSS(R)E Minimum RAW Case

0 / END OF SYSTEM-WIDE DATA, BEGIN BUS DATA
    1,'Slack-Bus   ', 138.0000,3
    2,'Load-Bus    ', 138.0000,1
0 / END OF BUS DATA, BEGIN LOAD DATA
    2,'1 ',1,,,   40.000,    15.000
0 / END OF LOAD DATA, BEGIN FIXED SHUNT DATA
0 / END OF FIXED SHUNT DATA, BEGIN GENERATOR DATA
    1,'1 ',   40.350,   10.870
0 / END OF GENERATOR DATA, BEGIN BRANCH DATA
    1,     2,'1 ', 0.01938, 0.05917,0.05280
0 / END OF BRANCH DATA, BEGIN SYSTEM SWITCHING DEVICE DATA
0 / END OF SYSTEM SWITCHING DEVICE DATA, BEGIN TRANSFORMER DATA
0 / END OF TRANSFORMER DATA, BEGIN AREA DATA
0 / END OF AREA DATA, BEGIN TWO-TERMINAL DC DATA
0 / END OF TWO-TERMINAL DC DATA, BEGIN VOLTAGE SOURCE CONVERTER DATA
0 / END OF VOLTAGE SOURCE CONVERTER DATA, BEGIN IMPEDANCE CORRECTION DATA
0 / END OF IMPEDANCE CORRECTION DATA, BEGIN MULTI-TERMINAL DC DATA
0 / END OF MULTI-TERMINAL DC DATA, BEGIN MULTI-SECTION LINE DATA
0 / END OF MULTI-SECTION LINE DATA, BEGIN ZONE DATA
0 / END OF ZONE DATA, BEGIN INTER-AREA TRANSFER DATA
0 / END OF INTER-AREA TRANSFER DATA, BEGIN OWNER DATA
0 / END OF OWNER DATA, BEGIN FACTS CONTROL DEVICE DATA
0 / END OF FACTS CONTROL DEVICE DATA, BEGIN SWITCHED SHUNT DATA
0 / END OF SWITCHED SHUNT DATA, BEGIN GNE DEVICE DATA
0 / END OF GNE DEVICE DATA, BEGIN INDUCTION MACHINE DATA
0 / END OF INDUCTION MACHINE DATA, BEGIN SUBSTATION DATA
0 / END OF SUBSTATION DATA
Q
{
     "network":{
         "caseid":{
             "fields":["ic", "sbase", "rev", "xfrrat", "nxfrat", "basfrq", "title1"],
             "data":[0, 100.00, 35, 0, 0, 60.00, "PSS(R)E Minimum RAWX Case"]
         },
         "bus":{
             "fields":["ibus", "name", "baskv", "ide"],
             "data":[
                 [1, "Slack-Bus", 138.0, 3],
                 [2, "Load-Bus", 138.0 1]
             ]
         },
         "load":{
             "fields":["ibus", "loadid", "stat", "pl", "ql"],
             "data":[
                 [2, "1", 1, 40.0, 15.0]
             ]
         },
         "generator":{
             "fields":["ibus", "machid", "pg", "qg"],
             "data":[
                 [1, "1", "40.35", "10.87"]
             ]
         },
         "acline":{
             "fields":["ibus", "jbus", "ckt", "rpu", "xpu", "bpu"],
             "data":[
                 [1, 2, "1", 0.01938, 0.05917, 0.05280]
             ]
         }
    }
}

Import

The import module reads and converts a PSS®E power flow data file to the PowSyBl grid model. The current implementation supports RAW format for versions 33 and 35 and RAWX format for version 35. The import process is performed in three steps:

  • Read input file.
  • Validate input data.
  • Convert input data into PowSyBl grid model.

First, input data is obtained by reading and parsing the input file and as result a PSS®E model is created in memory. This model can be viewed as a set of Java classes where each data block of the PSS®E model is associated with a specific Java class that describes all their attributes or data items. Then, some inconsistency checks are performed on this model. If the validation succeeds the PSS®E model is converted to a PowSyBl grid model.

Options

Parameters for the import can be defined in the configuration file in the import-export-parameters-default-value module.

psse.import.ignore-base-voltage
The psse.import.ignore-base-voltage property is an optional property that defines if the importer should ignore the base voltage information present in the PSS®E file. The default value is false.

Inconsistency checks

-TODO

Conversion

A PSS®E file specifies a Bus/Branch network model where typically there is a bus for each voltage level inside a substation and where substation objects are not explicitly defined. Breakers and switches were traditionally modeled as zero impedance lines with special identifiers. Since version 35 PSS®E supports explicit definition of substation data and switching devices at both system and substation level. However, this information is optional and may not be present in the case.

The PowSyBl grid model establishes the substation as a required container of voltage levels and equipment. The first step in the conversion process assigns a substation for each PSS®E bus, ensuring that all buses at transformer ends are kept in the same substation.

The current conversion does not use explicit PSS®E substation information. Instead, buses are grouped using zero impedance branches and transformers as connectors. A new voltage level is created for each group of buses connected by zero impedance branches, and a new substation is created for the voltage levels connected by transformers. Explicit substations will be supported in future versions, allowing to represent the internal connectivity.

In the PowSyBl grid model all the network components are identified through a global and unique alphanumeric identifier (Id). Optionally, they may receive a name (Name).

For each substation the following attributes are defined:

  • Id following the pattern S<n> where n represents a consecutive integer number starting from 1.

Every voltage level is assigned to its corresponding substation, with attributes:

  • Id following the pattern VL<n> where n represents the minimum PSS®E bus number included inside the voltage level.
  • NominalV Nominal voltage of the voltage level. Equal to 1 if psse.import.ignore-base-voltage property is true. Otherwise, it is assigned to the base voltage of one representative bus inside the voltage level, read from PSS®E field BASKV.
  • TopologyKind Topology level assigned to the network model, always BUS_BREAKER.

The following sections describe in detail how each supported PSS®E data block is converted to PowSyBl network model objects.

Bus Data

There is a one-to-one correspondence between the records of the PSS®E Bus Data block and the buses of the PowSyBl network model. For each record in the Bus Data block a PowSyBl bus is created and assigned to its corresponding voltage level with the following attributes:

  • Id according to the pattern B<n> where n represents the [email protected] bus number (field I in the Bus Data record).
  • Name is copied from PSS®E field NAME.
  • V is obtained from the PSS®E bus voltage magnitude, VM, multiplied by the nominal voltage of the corresponding voltage level.
  • Angle is copied from the PSS®E bus voltage phase angle, VA.

Load Data

-TODO

Fixed Bus Shunt Data

-TODO

Switched Shunt Data

-TODO

Generator Data

-TODO

Non-Transformer Branch Data

-TODO

Transformer Data

-TODO

Slack bus

-TODO

Export

The export of PowSyBl networks to PSS®E format is not yet supported.