Mitigation of commutation faults in HVDC system

To transfer large amount of direct current power having high amplitude voltage over long distance, high voltage direct current (HVDC) transmission system is used. This system was introduced 60 year ago and now it is widely used all over the world. Some examples of HVDC systems are following; Voltage-SourcedConverter (VSC), current commutated converter (CCC) and line commutated converter (LCC) dependent HVDC techniques.VSC method used for multi-terminal Direct Current grid, but line commutated direct current method performs better as compare to VSC in broad distance large amount of power transmission due to its efficiency. When voltage is reduced to 10% to 15% in LCC HVDC system the commutation failure occurs. The LCC HVDC system is having better performance in comparison to others so the analysis is done on this system to mitigate the commutation failure which is very frequent event that occurs in the this system. The DC fault is having less effect on commutation as compare to the AC single and three phase fault. During DC fault only the distortion is occurring which is minimized with the help of DC filter. During AC faults the commutation failure occurs which is minimized using IGBT capacitor circuit. The comparison of systems with and without faults is done and it is concluded that the AC faults are the main reason of commutation failure and mitigation is done using IGBT capacitor circuit.