DC Fault Performance in MTDC System : Active Fault Clearing by FB-MMC

Rayamarakkarveettil Puthanpurayil, Shahariya Rasheed

4. term

Energy Engineering, Master

2025

2025-05-28

64

Abstract: HVDC technology is a key enabler of large, interconnected power grids with high penetration of renewable energy sources. For a DC fault, the fault current behaviour and interruption capability are significantly influenced by the type of converter used. In line-commutated converter HVDC systems, the converters can rapidly interrupt the fault current. In modular multilevel converter-based HVDC systems, especially those using half-bridge submodules, fault current interruption relies on either AC or DC circuit breakers. DC circuit breakers can interrupt the fault current before the converter blocks; however, they are expensive and come with significant technical complexities. AC circuit breakers operate during the free-wheeling diode conduction phase from the AC side, resulting in relatively long fault clearance and system restoration times. This project focuses on utilising the full-bridge submodule configuration of modular multilevel converters with active fault-clearing capabilities in hybrid pointto- point and multi-terminal systems. Instead of passively blocking the fault current, an enhanced control strategy is employed, utilising the full operational range of the full-bridge.

DC fault ; FB MMC ; Active fault clearing ; HB MMC ; MMC ; LCC ; HVDC ; Hybrid HVDC

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