Semnan University Press Journal of Modeling and Simulation in Electrical and Electronics Engineering 2821-0786 6 1 2026 03 01 A Novel Method for Inverter Fault Localization in CSC-HVDC System Using DC Current Component 33 42 10438 10.22075/mseee.2026.39553.1236 EN Fatemeh Fallahi Meybodi Department of Electrical Engineering, Yazd University, Yazd, Iran. Ahmad Mirzaei Department of Electrical Engineering, Yazd University, Yazd, Iran. Hamidreza Toodeji Department of Electrical Engineering, Yazd University, Yazd, Iran. Journal Article 2025 10 31 Internal faults within the current source converter–based high-voltage direct current (CSC-HVDC) systems pose serious threats to system reliability and operational security. While integrated protection and control schemes can effectively clear most temporary faults, permanent faults or failures in the control system require accurate localization to enable targeted isolation procedures. Moreover, recurrent transient faults demand timely diagnostic interventions to prevent equipment degradation. This paper focuses on short circuit faults that occur within the inverter stage of CSC-HVDC systems. Considering the converter control dynamics, arm currents are monitored under both forced-alpha operation and normal operating conditions. A novel diagnostic approach is proposed, in which the DC current component is exploited as a distinctive signature to achieve precise arm-level fault localization. The method is computationally simple, does not require high sampling rates, and identifies the fault location within a maximum of two cycles, allowing for isolation before forced-alpha mode is activated. The proposed technique is validated through detailed simulations of the Hydro-Quebec monopolar CSC-HVDC test system in MATLAB/Simulink, demonstrating its effectiveness and rapid response under various fault scenarios. https://mseee.semnan.ac.ir/article_10438_4e75bf9e719c5f8b978ebd3fa89678d3.pdf