Access to EMTP user presentations, webinars, and slide deck presentations.
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7 presentations for arrester:

Author(s): Diego F. Rodríguez - GERS
Type:Technical Presentation
Date: 2021-06-17
TOV for renewable, evaluating three different grounding technologies783
Abstract
Temporary overvoltages (TOV) are oscillatory overvoltages mainly caused by switching or faults, which are of relatively long duration and undamped or slightly damped. Maximum overvoltages under faulte... see mored conditions can require considerable energy magnitudes absorbed by surge arresters.
These energies may overpass maximum limits and lead to equipment damage.
This project presented a study to identify the maximum TOV at the MV equipment of a PV power plant during fault-clearing events. Two methods of TOV suppression are evaluated, including grounding transformers and fast grounding switches under two different configuraions. An electrical model was elaborated in EMTP to perform the simulation of the transient overvoltage due to the un-balanced fault clearance, considering each inverter of the PV plant. The results show that considering no grounding technologies at the feeders, the energy absorption limit is overpassed in the islanded system.
Therefore, a fast grounding switch or a system with grounding technology at each feeder is needed in order to protect the substation equipment.

Author(s): Ilhan Kocar, Polytechnique Montréal
Type:Technical Presentation
Date: 2020-11-20
The validation of field measured switching overvoltages, inclusion of statistical prestrike and corona modeling750
Abstract
<h2 class="title">EMTP USA User Conference 2019 </h2> <p class="tagline"><b>The validation of field measured... see more switching overvoltages, inclusion of statistical prestrike and corona modeling</b></p> <p id="text-intro">This presentation is on the simulation of switching overvoltages on transmission lines with trapped charge, validation of EMTP line models, modeling of prestrike in statistical simulation studies and discussion of necessary simulation practices by means of validations with field tests. On transmission lines where switching surges are not mitigated with closing resistors and/or surge arresters, high-speed reclosing on a line with trapped charge will produce high overvoltages that have been measured above 3 pu. Careful simulations of these switching events using available Electromagnetic Transient (EMT) programs consistently produce significantly higher voltages than the measurements. It is demonstrated that the transient voltage waveforms can be reproduced very well using frequency-dependent line models, but the magnitude of the maximum overvoltage is significantly overestimated unless the effect of corona is considered. In principle, once a line model is validated, it is possible to proceed with statistical simulation phase to identify the worst-case overvoltage, which is of utmost importance for transmission line and substation related issues such as the evaluation of minimum approach distance and clearance practices. However, before proceeding with statistical simulation phase, it is also necessary to tune the prestrike model in EMTP. In this presentation, we also discuss how to benefit from field tests to fine tune the generic prestrike model in EMTP and then how to proceed with statistical simulation studies while taking corona into account in an efficient manner.</p>