Limit in microgrid network size with respect to fault detection and clearing capability - A simulation study of the Arholma Microgrid
(2025) In CODEN:LUTEDX/TEIE EIEM01 20251Industrial Electrical Engineering and Automation
- Abstract
- To minimize the number of households affected by power outages during faults in the distribution grid, microgrids can be utilized to disconnect from the main grid and supply power locally. When disconnected from the main grid, these systems operate in \textit{island mode} and must remain self-sufficient for a few hours. However, for a fault occurrence within an islanded microgrid, traditional protection devices may malfunction due to the reduced fault current contribution from inverter-interfaced distributed energy resources (IIDERs). This thesis investigates the limitations in microgrid size required to ensure sufficient fault detection and clearing during island operation.
Using a simulation model of a real microgrid with customers... (More) - To minimize the number of households affected by power outages during faults in the distribution grid, microgrids can be utilized to disconnect from the main grid and supply power locally. When disconnected from the main grid, these systems operate in \textit{island mode} and must remain self-sufficient for a few hours. However, for a fault occurrence within an islanded microgrid, traditional protection devices may malfunction due to the reduced fault current contribution from inverter-interfaced distributed energy resources (IIDERs). This thesis investigates the limitations in microgrid size required to ensure sufficient fault detection and clearing during island operation.
Using a simulation model of a real microgrid with customers called the Arholma microgrid, the thesis explores how microgrid topology and design influence protection system performance. The study examines system grounding, fault types, and inverter behavior. Through various case simulations, the thesis evaluates multiple scenarios involving network expansion, inverter limitations, and reduced protection device availability.
Results show that constraints on fault detection differ by voltage level: zero-sequence capacitance accumulation limits the medium voltage (MV) grid size, while rising impedance constrains the low voltage (LV) network size. Current-limited IIDERs also cause discrepancies between theoretical and actual fault current contributions. The thesis concludes that while selective fault clearing is challenging, simplified protection relying only on the MV level relays and circuit breakers is viable within certain design boundaries, and a relationship between inverter size and system impedance may serve as a useful benchmark for future microgrid planning. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9201274
- author
- Thunholm, Axel LU and Molin, Jonathan LU
- supervisor
- organization
- alternative title
- Begränsningar i storlek av ett mikronät med hänsyn till feldetektering och felbortkoppling
- course
- EIEM01 20251
- year
- 2025
- type
- H3 - Professional qualifications (4 Years - )
- subject
- keywords
- microgrid, inverter, grid-forming inverter (GFMI), inverter-interfaced distributed energy resource (IIDER), protection, fault detection, fault clearing, relay, low voltage circuit breaker (LVCB)
- publication/series
- CODEN:LUTEDX/TEIE
- report number
- 5534
- language
- English
- id
- 9201274
- date added to LUP
- 2025-06-19 12:22:00
- date last changed
- 2025-06-19 12:22:00
@misc{9201274,
abstract = {{To minimize the number of households affected by power outages during faults in the distribution grid, microgrids can be utilized to disconnect from the main grid and supply power locally. When disconnected from the main grid, these systems operate in \textit{island mode} and must remain self-sufficient for a few hours. However, for a fault occurrence within an islanded microgrid, traditional protection devices may malfunction due to the reduced fault current contribution from inverter-interfaced distributed energy resources (IIDERs). This thesis investigates the limitations in microgrid size required to ensure sufficient fault detection and clearing during island operation.
Using a simulation model of a real microgrid with customers called the Arholma microgrid, the thesis explores how microgrid topology and design influence protection system performance. The study examines system grounding, fault types, and inverter behavior. Through various case simulations, the thesis evaluates multiple scenarios involving network expansion, inverter limitations, and reduced protection device availability.
Results show that constraints on fault detection differ by voltage level: zero-sequence capacitance accumulation limits the medium voltage (MV) grid size, while rising impedance constrains the low voltage (LV) network size. Current-limited IIDERs also cause discrepancies between theoretical and actual fault current contributions. The thesis concludes that while selective fault clearing is challenging, simplified protection relying only on the MV level relays and circuit breakers is viable within certain design boundaries, and a relationship between inverter size and system impedance may serve as a useful benchmark for future microgrid planning.}},
author = {{Thunholm, Axel and Molin, Jonathan}},
language = {{eng}},
note = {{Student Paper}},
series = {{CODEN:LUTEDX/TEIE}},
title = {{Limit in microgrid network size with respect to fault detection and clearing capability - A simulation study of the Arholma Microgrid}},
year = {{2025}},
}