Model Predictive Control Approach for Bridge-Type Fault Current Limiter in VSC-HVDC System

Voltage source converter–high-voltage DC (VSC-HVDC) system has number of advantages over traditional line commutated converter 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, this paper proposes model predictive control (MPC)-based bridge-type fault current limiter (BFCL) for VSC-HVDC system. Fault current limiters are placed with the AC grid sides of VSC-HVDC system. Finite control set MPC is developed for the control of VSC-HVDC system along with BFCL. BFCL controller has been developed to insert resistance and reactance during disturbances. Balanced and unbalanced disturbances are applied to evaluate the effectiveness of proposed BFCL controller so as to limit the fault current and augment transient stability. Real-time digital simulator has been used to conduct simulation works. The performance of the proposed MPC-BFCL is compared with that of series dynamic braking resistor (SDBR). Comparative simulation results show that the proposed MPC-BFCL is superior over SDBR in improving dynamic stability of VSC-HVDC system.