Comparative Performance of Fault ride through Controller in Modular Multilevel Converter based HVDC Transmission

This paper centres on the performance of PI and hysteresis controllers for AC fault ride through for an MMC VSC - HVDC transmission system. In the simulated MMC converter test system, a 600 MW VSC-HVDC transmission line connects two farms, formed from combined offshore wind turbines and wave converters, to the two onshore AC grids. The model in this study included two 300kV DC submarine cables with a cable length of 100km. In the reported simulation a three-phase to ground fault, a single line to ground fault, a double line to ground fault and a line-to-line fault were applied to the onshore AC network. The simulation results reveal reductions in DC voltage overshoot and transient energy with the PI-based controller (compared to the hysteresis controller) for 3- phase to ground, line to ground and line - to - line to ground faults respectively, with no difference for line-to-line faults.