Improvement of Fault Tolerance in HVDC Transmission System Based on Hybrid Multilevel VSC

In this paper suggest a different technology of High Voltage dc (HVDC) transmission system created on fusion multilevel voltage source converter (VSC) along with cascaded H-bridge cells on ac side. This paper suggested that HVDC system have capability to regulate both reactive and active power by using VSC systems, ability to protect the converter equipment’s against over voltages and over currents, ability to generate the power without any support from the grid in case of system collapse and the special feature has the ability for current limiting capability in case of dc side faults.In addition to, it offers special features such as larger reactive and active power capability for smaller foot print by using modular multilevel VSC in HVDC converters. This paper evaluates its active evaluation under steady state and network adjustments and finding its response in case of pole to pole dc fault and three phase- ground ac fault. Fuzzy logic controller (FLC) is used to improve the response in case of dc and ac side faults and the simulation results are shown in MATLAB SIMULINK model.