Mitigation of Half-Cycle Saturation of Adjacent Transformers during HVDC Monopolar Operation - Part I: Mitigation Principle and Device Design

Ming Yang, DIgvijay Deswal, Francisco De León

Research output: Contribution to journalArticle

Abstract

When HVDC transmission systems operate in the ground return mode, transformers in adjacent ac systems frequently suffer half-cycle saturation. In this two-part paper, an effective mitigation method using power electronic switches is proposed that does not compromise the ability of the protection system to detect fault currents. In Part I, a study is conducted to find the physical performance of the half-cycle saturation and give a technical solution to the inrush-like half-cycle saturated currents. Power electronic switches, opening the neutral connection to ground, are utilized to mitigate the saturation without compromising the reference ground of the transformer. The determination of the switch parameters, switching frequency, and duty cycle is performed. Details of the mitigation transient are studied by comparing simulations and laboratory experiments to validate the efficacy of the proposed power electronic switch for the mitigation of half-cycle saturated currents. In Part II, the influence of the proposed switch on the detection of ground faults is investigated. Proper parameter and operation strategies are selected to effectively detect the ground faults and ensure the fast response of protective relays. The techniques proposed are applicable to mitigate geomagnetically induced current.

Original languageEnglish (US)
Article number8674530
Pages (from-to)2232-2239
Number of pages8
JournalIEEE Transactions on Power Delivery
Volume34
Issue number6
DOIs
StatePublished - Dec 2019

Keywords

  • Geomagnetically induced current (GIC)
  • HVDC
  • half-cycle saturation
  • monopolar operation
  • neutral switching
  • transformers

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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