Transformer inrush current mitigation techniques for grid-forming inverters dominated grids

Abdulrahman Alassi, Khaled Ahmed, Agusti Egea Alvarez, Colin Foote

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
80 Downloads (Pure)


The use of inverters-based resources (IBRs) is rising rapidly in power networks due to increased renewable energy penetration. This requires revisiting of classical network operation standards. For instance, high transformer energization inrush current has been studied extensively under the classical network paradigm. Whereas this paper investigates transformers' energization techniques in the context of inverters dominated grids, where inverters with limited short-circuit current are expected to utilize their grid-forming capabilities for black-start. Common transformer energization techniques such as controlled switching and soft energization are first analyzed with a new perspective aiming to assess their feasibility when used with grid-forming inverters and existing network assets. Parameters influencing soft energization voltage ramp-up time (Tramp) are investigated, and a new Tramp estimation framework for transformer energization from IBRs is introduced. Due to the variability of available point-on-wave circuit breakers (CBs) in distribution networks, controlled energization using single-pole and three-pole CBs is investigated for various configurations and their application limits are identified. A comprehensive case study is then presented using a test network with multiple transformers to benchmark the performance and requirements of each technique when the network is energized from an IBR, followed by a set of practical recommendations.
Original languageEnglish
Pages (from-to)1610 - 1620
JournalIEEE Transactions on Power Delivery
Issue number3
Early online date2 Nov 2022
Publication statusPublished - Jun 2023


  • black-start
  • transformers energization
  • inrush current
  • controlled switching
  • soft energization


Dive into the research topics of 'Transformer inrush current mitigation techniques for grid-forming inverters dominated grids'. Together they form a unique fingerprint.

Cite this