About E-Tran
Users of electromagnetic transients (EMT) simulation programs (such as PSCAD/EMtdC) often face difficulties in obtaining data and developing cases suitable for their studies. Many utilities have the data available for their entire system in loadflow programs, but a great deal of effort is required to re-enter the network data for use in EMT programs.
There are three common challenges:
Translation of circuit/network data (differences in PU systems, data entry, etc.)
The generation of network equivalents
Initialization of machines, generators or sources in large inter-connected networks
The Electranix Corporation was founded by experienced power system engineers Dennis Woodford and Garth Irwin who now offer consulting services specializing in loadflow, stability and EMT studies.
They developed the E-TRAN translator to automate the processes that were repeated for each new study performed for their customers. E-TRAN not only saves considerable time and effort, but it bestows confidence in the study results.
Direct translation of Power System Data into PSCAD
Auto-Routing and Graphical Representation
Formation of Network Equivalents
Initialization of Machines, Generators and Sources
E-TRAN Runtime Library for PSCAD
Sanity Check and Data Verification
Compatible with PSCAD V4.6 and V5
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Example 1
The first image shows a portion of a network near a bipolar HVDC converter station The circuit is loaded in PSCAD V4 and was directly generated by E-TRAN from a PSS/E .raw input file. (Click on the image to download a higher resolution picture.)
The original circuit was more than 18,000 busses, but, for this example, E-TRAN directly translated only 1 bus away (which resulted in a 15 bus circuit) from the HVDC bus and formed a network equivalent of the remaining circuit.
The second image shows the equivalent network on a sub-page. The voltage magnitude and phase angle of the equivalent sources are automatically calculated to match the power flow of the solved loadflow. Note the multi-port equivalent is valid for steady state as well as for open/short circuit conditions.
E-TRAN converted the circuit, using only the PSS/E .raw file, directly into a PSCAD Version 4 .psc file in three phase Single Line Diagram (SLD) format.
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Example 2
The first image shows a portion of a small network at a 345 kV bus. The circuit is loaded in PSCAD V4 and was directly generated by E-TRAN from a PSS/E .raw input file.
E-TRAN directly translated only 2 busses away from the main bus (which resulted in a 15 bus circuit) and formed a network equivalent of the remaining circuit.
The second image shows the equivalent network on a sub-page. Note that the interface busses are at different voltage levels and a transformer is automatically used for the off-diagonal branches instead of a pi section transmission line.
E-TRAN creates a log file which contains details of the conversion process and numerical output of the system admittance matrices. The log file for this small system is in the file “Example2.txt”.
In this case the entire circuit was only 160 busses, so it could have easily been translated and run in PSCAD without the need for any network equivalent.
Frequently Asked Questions
Currently, versions 23-26, 29, 30, 31, 32, 33, and 34 are supported.
E-TRAN can generate three-phase Single Line Diagram (SLD) circuit .psc or .pscx files for PSCAD V4.2, and x4.6.
Check that the .raw file being used is “solved” and has the updated loadflow solution saved in it. Also check that fundamental frequency behaviour of any models in the E-TRAN Substitution Library match that of the standard E-TRAN components (If you turn off the Substitution Library, does the solution then match?). Finally, check DC links to see if they are operating correctly. The DC link controls may have to be adjusted to work in very weak systems (If you use the “Infinite Bus” option in the DC link component, does the loadflow then match?
Detailed EMT models (such as transformers with saturation, frequency dependent transmission lines) are essential for any meaningful study (especially for over-voltage, harmonic studies?). E-TRAN supports a Substitution Library which allows a user to enter the detailed model data maintaining/managing the data in a PSCAD library and will automatically use the detailed data if it is available. The fundamental frequency impedances from the loadflow file are used to generate multi-port network equivalents, and, to determine the steady state powerflow. The powerflow is used to initialize all machines, sources, generators or any device. E-TRAN will automatically modify the initial condition information of machines found in the Substitution Library (which in turn will initialize any exciter, governor, multi-mass system), and in general can provide initial conditions for any device. This means E-TRAN can directly generate a circuit ready for EMT studies, complete with frequency dependent lines, detailed generator/exciter/governor models, detailed HVDC/SVC/FACTS devices etc. providing that the user has entered this data once in a library.
The PSCAD Master library models performs RMS or instantaneous PQ measurement (for example, the sum of VA.IA + VB.IB + VC.IC etc.), which includes the effect of all sequence components and the effect of harmonics. The E-TRAN PQ measurements devices (or voltage measurements) measure the +ve sequence, fundamental frequency quantities (used in loadflow programs), not the instantaneous or RMS quantities. This effect is particularly obvious at locations where there are significant harmonics (such as near a commutating model of a DC link). If the instantaneous quantities being measured are sinusoidal, distortion free and balanced (i.e., only +ve sequence), the results should match.
You can visit http://www.electranix.com/software or you can send e-mail to the Electranix Corporation.
You can visit http://www.PSCAD.com or you can send e-mail to the PSCAD Support team at support@PSCAD.com . PSCAD is developed and supported by the Manitoba HVDC Research Centre Inc (http://www.hvdc.ca).
The E-TRAN program is always under development. Future releases will translate transient stability data in addition to the loadflow data and will form dynamic equivalents. These will include the effects of machine inertia and controls in the network equivalents. We also plan to support additional input formats (in addition to the PSS/E .raw format). If you have any ideas or suggestions for improvements to E-TRAN, please send them to us.
