Overview Runtime Lirary
E-Screen was developed as an advanced power system screening platform designed to support and streamline EMT study workflows. E-Screen is primarily used ahead of detailed electromagnetic time- domain simulations.
E-Screen was developed as an advanced power system screening platform designed to support and
streamline EMT study workflows. E-Screen is primarily used ahead of detailed electromagnetic time-
domain simulations to identify:
- Critical network scenarios, including base cases, contingencies, operating conditions, and weak system pockets
- Critical dynamic devices to be included for EMT studies
- Appropriate study area to be modeled in detailed for EMT studies (boundary selection)
- Sub-Synchronous oscillation risks and their root causes
- Small-signal instability risks and contributing elements. In addition, E-Screen can also be used to generate:
- Frequency-dependent network equivalents (FDNE)
- Harmonic polygons and amplification factor.
All these screening studies are primarily performed using standard power flow data, which is typically
readily available within utility and system planning environments. For enhanced screening accuracy,
additional inputs — such as dynamic data (.dyr file), frequency response characteristics of black-boxed
IBR models can also be incorporated.
E-Screen consists of three primary modules, each incorporating a range of screening matrices designedto streamline and refine the EMT study workflow. The key modules and their associated screeningmatrices are outlined below.
Single-Frequency Screening
- Network short circuit ratio (NSCR) and interaction factors
- Electrical proximity (Y12)
- Impedance split (Zr)
- Combined short circuit ratio (CSCR)
- Weighted short circuit ratio (WSCR)
Multi-Frequency Screening
- Network frequency scans
- Comparison of frequency scan results based on network sizes and topologies
- Frequency dependant network equivalent (FDNE)
- Harmonic polygon
- Harmonic amplification factor
- Unit interaction factor (UIF) and radiality factor (RF)
Sub-Synchronous (SS) Screening
- SSR analysis: calculations of synchronous machine damping
- SSCI analysis: calculation of net damping at system resonances
- SSFR analysis: calculation of resonance movement across critical frequencies
- Eigenvalue analysis: calculation of unstable modes and participation factors In addition to the individual matrices described above, the EMT study area can also be determined as a combined feature. This approach utilizes the parameters listed below to define a more accurate and representative study boundary for EMT analyses.
- Interaction factors (from NSCR)
- Electrical proximity (Y12)
- Network frequency profiles
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.Add your main body content here.
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.Add your main body content here.
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.Add your main body content here.
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.Add your main body content here.
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.
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.
