Author(s): Aboutaleb Haddadi
Type:Technical Presentation
Date: 2021-09-02

Ground Fault Overvoltage with Inverter-Based Distributed Energy Resources841

Abstract
A Ground Fault Overvoltage (GFO) can occur in situations where an ungrounded transmission line and associated ungrounded transmission equipment is energized from distribution connected Distributed En... see moreergy Resource (DER) during a transmission single-phase-to-ground (SLG) fault. The condition could result in 1.73 pu overvoltage on phase to ground connected equipment which will be sustained until the DER ceases to energize the substation distribution transformer. Transmission equipment on the isolated circuit will be subjected to the above phase to ground overvoltage, also if there is frequency shift, the isolating transmission circuit breakers could potentially see up to 2.73 pu phase to ground overvoltage. Such an overvoltage can cause damage to customer or utility equipment and must be avoided. GFO concerns are already becoming a barrier to large-scale DER deployment either by posing low hosting capacity or by necessitating installation of costly mitigation equipment. Utilities need to study GFO risks and identify low-cost mitigation options to enable large-scale DER deployment. Given the fundamental differences in mechanisms and phenomena driving a GFO under DERs, classical GFO analysis methods do not apply to inverters, and advanced simulation methods and tools are required.


This presentation highlights EPRI’s work on GFO analysis, concerns, and evaluation of mitigation options using EMTP. The objective is to determine if or when high DER penetration presents a GFO problem and how to prioritize the mitigation and equipment evaluation. This includes evaluating the impact lightning arresters can have in reducing or clamping the overvoltage, the application and performance of high voltage substation overvoltage protection, and DER on-board voltage/frequency protection. The presentation further provides modeling recommendations for such a study using EMTP. As DER deployment increases, utilities will need to perform similar analysis to identify potential overvoltage risks and develop low-cost mitigation methods. This work provides a basis for such a study.

Tag(s): gfov, tov, ibr, DER, inverter, islanding, load rejection, inverter based resources

Author(s): Aboutaleb Haddadi
Type:Technical Presentation
Date: 2020-12-14

Geomagnetic Disturbance Simulation Studies: Recent Developments and Challenges761

Abstract
<p>This presentation studies how to perform a GMD study in EMTP in compliance with the NERC requirements.<p></p>
Overview: - GMD Disturbance - TPL-007 - ... see moreGMD Simulation studies - Existing Methods - GMD Simulation in EMTP - Transformer Model - Transmission Line Model - Load Model - Machine Model - Substation Grounding Resistance - Modeling Details
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Author(s): Aboutaleb Haddadi, Polytechnique Montréal & Afshin Rezaei-Zarei, York University
Type:Technical Presentation
Date: 2020-11-20

Geomagnetic disturbance simulation studies: recent developments and challenges738

Abstract
<h6 class="text-black" style="padding-bottom: 30px; padding-top: 30px; text-align: justify;">Speaker: <strong>Aboutaleb Haddadi</... see morestrong>, <em>Polytechnique Montréal</em></h6> <p class="text-black">Inverter-based resources have much more complex fault current characteristics compared to conventional synchronous generators. Hence, legacy protective relays set under the assumption of a conventional power system with predominantly synchronous generation, may misoperate under high level of renewables.<br><br> This presentation first investigates the impact of wind generation on the performance of negative-sequence-based protection. In many applications, wind generators are designed to suppress negative sequence current partially or entirely. Negative sequence current suppression control may result in the misoperation of protection schemes whose operation relies on the assumption of negative sequence quantities being present in substantial levels during unbalanced faulted conditions. The impact of wind generation on negative-sequence overcurrent and negative-sequence-based directional elements is investigated in this work.<br> In addition, the impact of renewable resources on the performance of power swing protection is investigated. Case studies with examples of Power Swing Blocking (PSB) and Out-of-Step Tripping (OST) elements misoperation under wind generation will be presented.</p>