VSC-HVDC System Stability Augmentation with Bridge Type Fault Current Limiter

Voltage source converter high voltage DC (VSC-HVDC) system has number of advantages over traditional line commutated converter HVDC (LCC-HVDC). However, VSC-HVDC system is exposed to high current due to faults having great negative effect on converters. In order to limit fault current to relatively low level, bridge type fault current limiter (BFCL) for VSC-HVDC system has been proposed in this study. Fault current limiters are placed with the AC gird sides of VSC-HVDC system. Real and reactive power controller for the VSC-HVDC has been developed based on current control mode. Symmetrical as well as unsymmetrical faults are applied to evaluate the effectiveness of proposed BFCL controller in order to limit the fault current and improve system stability. Simulations are carried out with real time digital simulator (RTDS) to validate the efficacy of the proposed BFCL solution. The results show the potential of the proposed scheme to limit the fault current and improve greatly the system performance.