On the Choice of System Strength Metrics for the Allocation and Sizing of Synchronous Condensers in Power Grids
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Date
2025
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Publisher
IEEE
Abstract
The integration of high levels of inverter-based generation (IBG) into power grids requires
meticulous planning, especially as IBGs lack the inherent short-circuit capacity of conventional generators,
potentially weakening system strength. To mitigate this, synchronous condensers (SCs) are deployed
in weak areas to enhance fault current and voltage support. Traditional SC allocation methods use the
short-circuit ratio (SCR) as a key metric, but this may not account for control interactions in grids with
significant IBG penetration. This study compares two approaches for optimizing SC placement and sizing:
SCR-based and network-response short-circuit ratio (NRSCR)-based, a metric that captures dynamic IBG
interactions. Applying a genetic algorithm (GA) to the Nigerian power grid as a case study, the SCR-based
approach identified two critical points of interconnection (PoIs) requiring 68 MVA of SC capacity, while
the NRSCR-based method identified four PoIs, requiring a total of 674 MVA. Although the NRSCR-based
method significantly improved system performance during faults—offering faster voltage recovery post-fault
and higher fault current contributions—it resulted in a cost increase of approximately 7 times. This highlights
the trade-off between cost and performance, underscoring the need for utilities to balance economic and
technical considerations when deploying SCs in IBG-dominated grids.
Description
Keywords
Control interactions, synchronous condensers, inverter-based generation, system strength, short-circuit ratio.