E-TRAN - Translator for Power System Simulation

• Translation of circuit/network data (differences in PU systems, data entry...).
• The generation of network equivalents.
• Initialization of machine, generators or sources in large inter-connected networks.

• Direct translation of Power System Data into PSCAD: E-TRAN allows a user to select a network (or a portion of the network) and will perform an exact translation of the data into PSCAD.
• Auto-Routing and Graphical Representation: E-TRAN will directly create PSCAD .psc files, complete with correct data for all busses, loads, DC links, switched shunt devices, br/anches, generators, transformers, phase shifters (etc..) all correctly drawn and graphically interconnected. Drawings are grouped by location and voltage level, and can be created for a complete network or a portion of a network.
• Formation of Network Equivalents: The user identifies a portion of the network for a direct translation into PSCAD models (ie the "kept" network), and E-TRAN creates a network equivalent of the rest of the network based on the available fundamental frequency impedance and powerflow information. The equivalent is a multi-port (which means that the representation will be correct for steady state as well as for open circuit and short circuit conditions) and contains Thevenin voltage sources (to match PQ flow and represent generation in the equivalent network). The equivalents are generated based on the +ve sequence data entered in PSS/E .raw files, and includes the effect of -ve and 0 sequence data (if .seq files are available).
• Initialization of Machines, Generators and Sources: The bus voltages and angles and PQ loadflow information (from the solved load flow input file) are used to directly initialize sources/generators in PSCAD (and to initialize non-linear loads etc..). The initialization information can be used in simple voltage source representations of generators, or can be used to initialize detailed machines, governors, exciters, multi-mass systems etc.. The resulting simulation in PSCAD will exactly match the solved load flow results for any circuit and complex systems with any number of machines can be initialized without startup oscillations.
• E-TRAN Runtime library for PSCAD: E-TRAN includes a freely downloadable runtime library for use in PSCAD. The E-TRAN library contains all models used in loadflow programs (including load models, sources, transmission lines, transformers, phase shifters etc..) and has data entry based on the same Per Unit system and data entry standards as used in loadflow programs. PSCAD cases generated with E-TRAN can be freely distributed to other users without license fees! (see E-TRAN Runtime library for PSCAD below).
• Substitution library: If a user has more detailed data available (for example geometrical data for transmission lines suitable for a frequency dependent line model or a detailed core representation of a transformer with saturation data entered etc) then the user can maintain this data in a Substitution library and E-TRAN can directly write out this data instead of the simple RXB data.
• Sanity Check and Data Verification: E-TRAN generates extensive warnings and error messages when it reads in PSS/E .raw input files. This will inform the user of areas of mis-matched voltage levels, inconsistencies in the entry of data.. The result messages are output to the E-TRAN log file.

• Auto-routing: The algorithm used to automatically generate the circuit layout (in PSCAD) based purely on busses and connection information (from the PSS/E.raw file) is based on Graph Theory.
• Matching the Loadflow in PSCAD: The E-TRAN library for PSCAD contains models which mirror the functionality of the device models contained in PSS/E (constant PQ loads for example..). The E-TRAN program translates the results into PSCAD, and then the PSCAD differential equation solver is used during the run. The resulting solution will match the PSS/E loadflow results to about 3 or 4 decimal points everywhere in the system.
• Initialization of Generators/Machines: The best method to initialize a large system in PSCAD is to set the initial voltage magnitude, phase angle, and PQ flow into machine/generator models, and then start each machine as a fixed frequency source. after a few cycles the ac system in the simulation will reach the correct loadflow, at which point the machines electrical and mechanical systems can be initialized for a "bumpless" start. The transfer of all necessary initial condition information into PSCAD is automated by E-TRAN.
• Network Equivalents: E-TRAN generates a complex admittance (Y) for the entire system (this can be > 50,000 busses!). It then calculates the PQ mismatch of the entire system (to see if the input .raw file is solved) and de-composes using LDU sparse decomposition techniques (to generate network equivalents).
• Download Chapter 9 from the E-TRAN User's Manual (E-TRAN_Chap9_Theory.pdf) for more information..

• Please see examples.htm for examples of circuits translated by E-TRAN.
  

• Transformers (including impedance correction factors)
• Phase Shifters (leading or lagging)
• DC link (Back-Back and Point-Point, including built-in or external controls)
• Loads (constant PQ, current, impedance and RLC)
• Switched Shunt devices
• Simple transmission lines (PI section)
• Generator (simple source based on R,X source impedance)
• Measurement Components (fundamental frequency RMS V, PQ etc.. with online animated viewing)

All models accept the identical data as required in PSS/E (ie RXB in Per Unit, Voltages in L-L, kV, RMS, 3 phase MVa...) and have been tested against the steady state results generated by PSS/E (see Theory->Matching the Loadflow).