An Efficient Protection Scheme for VSC-HVDC System with Modified Bridge Limiter Controller

Voltage source converter-high voltage direct current (VSC-HVDC) system is susceptible to disturbances. This is because of the antiparallel diodes of VSC which allow current flow as well as discharge of DC capacitors. The DC protective devices are also not mature enough till date to protect such a system. In order to protect the VSC-HVDC system, this work proposes an efficient approach based on a modified bridge limiter controller. The proposed technique applies appropriate limiting resistance during contingencies only whereas almost zero impact is observed during normal conditions as the controller bypasses the limiting resistance. Real-time digital simulator (RTDS) has been adopted to simulate the system and its controller. The implemented results show that the proposed method is capable to tackle voltage fluctuation, real power oscillation, and line fault current during contingencies. The numerical results show that 60% voltage fluctuation reduction and 71.4% power oscillation damping are obtained with the proposed approach. A comparative study with the existing method in the literature further guarantees the suitability of this protection scheme.