Impact of VSC Converter Topology on Fault Characteristics in HVDC Transmission Systems

摘要

This work presents the outcome of a comprehensive study that assesses the transient behaviour of two high voltage direct current (HVDC) networks with similar structures but using different converter topologies, termed two-level and half-bridge (HB) modular multilevel converter (MMC). To quantify the impact of converter topology on DC current characteristics a detailed comparative study is undertaken in which the responses of the two HVDC network transients during dc side faults are evaluated. The behaviour of the HVDC systems during a permanent pole-to-pole and pole-to-ground faults are analysed considering a range of fault resistances, fault positions along the line, and operational conditions as a prerequisite. Fast Fourier Transform (FFT) has been conducted analysing di/dt for both converter architecture and fault types taking into consideration sampling frequency of 96 kHz in compliance with IEC-61869 and IEC-61850:9-2 for DC-side voltages and currents.