Technical Presentations

EMTP Development Roadmap: New Line/Cable data in EMTP 4.2829

Abstract
1. Brief review of transmission line equations

2. Per unit length parameter
- Traditional line data and cable data
- MoM-SO and Extended TL theory

3. New Line/Cable dat... see morea
- Mask options
- Application examples

Tag(s): EMT simulations, transmission, cable data,

Modeling and evaluation of overvoltage792

Abstract
A case study will be presented demonstrating modeling of overvoltage in a moderately sized system involving medium voltage vacuum breakers, cables and transformers. The focus is on simulating high fre... see morequency overvoltage generated by circuit breaker prestrikes and re-ignitions and evaluating the impacts on transformer insulation.
-Results obtained from a customized breaker TRV model which is capable of controlling the capability of switching high frequency current will be presented.
-The methodology of analyzing severity of overvoltage in the frequency domain was applied in this project. Results and discussions regarding frequency domain analysis will be shared.
-Simulation results regarding typical system configurations with variation of key parameters such as cable lengths, load power factors will be briefly presented.
-Application of EMTP study results in assisting equipment specification, as well as overvoltage mitigation methods including optimizing switching sequences, necessity of snubber circuits will be discussed.
-Case specific strategies to improve simulation speed and work flow with EMTP will be introduced and discussed.

Switching overvoltages studies for Live Working791

Abstract
In order to obtain the distances required to perform live working maintenance on the Uruguayan transmission network under secure conditions, electromagnetic transient (EMT) studies are conducted to ob... see moretain the maximum switching overvoltage that can be found in 500-150 kV transmission network. Two different approaches were considered for these studies. On one hand, a simple approach is used, analyzing line switching transients on simplified two line network models. On the other hand, a detailed approach is considered, analyzing line switching overvoltage transients on a complete network model.


This complete model considers 500 kV and 150 kV overhead lines, 500/150 kV transformers, cables, reactive power shunt compensation, hydraulic and thermal generators. Electromagnetic transient studies and the complete network model are performed in EMTP software. Finally, a comparison between the results obtained considering each approach is performed.

The new frequency dependent line and cable model: Wideband Model760

Abstract
<p>This presentation introduces the new Windband Model, capable of eliminates the modeling problems encountered with the existing ULM approach.</p><p>
Ov... see moreerview: - Time domain Solution o The Wideband (WB) Model coded in Fortran - WB Fitter o Executable, coded in MATLAB o Off line, Frequency Domain (FD) system identification - Implementation Notes with Theoretical Explanations o Follows the code with all necessary mathematical equations
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The new frequency dependent line and cable model: wideband model739

Abstract
<h6 class="text-black" style="padding-bottom: 30px; padding-top: 30px; text-align: justify;">Speaker: <strong>Ilhan Kocar</strong... see more>, <em>Polytechnique Montréal</em></h6> <p class="text-black">The new WB model encapsulates many improvements including state-of-the-art research results. It eliminates the modeling problems encountered with the existing universal line model (ULM) approach.<br> In the new model, there is no limitation on the number of conductors. For symmetric coaxial cable systems with several cables, numerical problems are avoided by using the new cable correction function. The newly added DC correction scheme together with frequency band partitioning ensures high precision both at low frequencies and high frequencies. Frequency partitioning also improves the numerical conditioning of the system of equations. Unrealistic delays are avoided thanks to the new routines for the identification and adjustment of time delays. The delay adjustment is a search routine with boundaries for optimized fitting.<br><br> The state space formulation in time domain is reformulated using a precise discrete integration method. It minimizes the numerical integration and interpolation errors. This allows achieving stable simulations with larger time steps. The object oriented programming approach with vectorized variables and new memory allocation routines significantly improves the simulation speed and use of memory. The new initialization routines allow seamless transition from steady state solution into time domain simulations.</p></div>