Saturated Iron Core Superconductor and Thyristor based DC Fault Current Limiter for HB-MMC

Abstract

Last three decades have witnessed exponential growth in necessities of limiting DC fault current and instant restoration of High Voltage DC power systems. In this paper, Half Bridge Modular Multilevel Converter (HB-MMC) has been investigated for DC fault current. Half Bridge Modular Multilevel Converter is unable to clear DC fault current due its free-wheeling diodes, therefore it is indispensible to confine DC fault current. For limiting DC fault current and instant restoration of system, Thyristor based DC fault current limiter and Saturated Iron Core Superconductor fault current limiter (SI-SFCL) is analyzed with Hybrid DC Circuit Breaker (HDCCB). The Thyristor based fault current limiter consists of thyristor, resistor and an inductor. SI-SFCL consists of primary, secondary and superconducting coil. The Thyristor based DC fault current Limiter confine fault current to 2.5 kA from 14 kA which show 82% suppression of DC fault current, while SI-SFCL confine fault current to 3.5 kA from 14 kA which shows 75% suppression of DC fault current. The restoration time achieved from TB-FCL with HDCCB is 28 ms and from SI-SFCL with HDCCB is 140 ms. A PSCAD/EMTDC is used to design and simulate HB-MMC, SI-SFCL, TB-FCL and HDCCB.