Transmission side protection performance with Type-IV wind turbine system integration

The converter controls of the full-converter based Type-IV wind turbine system (WTS) limits the fault current contribution to about 1.1-1.2 per unit (pu). Further, these fault currents are balanced even for unbalanced faults. The absence of significant fault current magnitudes and the lack of negative and zero sequence components in the fault currents poses challenges to the protection of power systems that interconnect wind turbines. This paper first presents the design of the controls of the grid-side voltage sourced converter (VSC) with an averaged non-switching model and a transmission interconnection through a step-up transformer. Faults are placed on the transmission system and fault currents and voltages are measured at relay location and converted to COMTRADE format. These are played back to a simulated relay to analyze the performance of distance elements and the protection elements that supervise them when the fault current is supplied by the grid side converter.