Fault Analysis and Protection Solution for DC Transmission Lines of Solar Farms Using Superconducting Fault Current Limiters

Achieving carbon neutrality is one of the important goals for many developed and developing countries worldwide. One method to reduce carbon emissions and reach carbon neutrality is the extensive utilization of renewable energy sources (RES). Even though there are significant benefits of the high penetration of RESs to the electrical grid, there are some challenges: the losses in the AC transmission lines. With the current improvement of power electronics devices, the DC transmission lines can be more viable technically and economically for various reasons. To name a few, DC transmission lines do not suffer from the skin effect. Also, corona losses are significantly lower in the case of DC systems. However, DC transmission line faults pose a protection challenge due to the lack of zero-crossing points, which erupt high fault magnitudes with a short rise time. Coupled with the fact that existing DC circuit breakers have long operation times of up to 4 msec. In this paper, superconducting fault current limiters (SFCL) are proposed to be used as a protection solution for the DC transmission line of the solar farm. The SFCL can reduce the fault currents and support the protection system during fault scenarios. A community solar farm, DC transmission lines, rectifiers, inverters, and SFCLs have been modeled in MATLAB/Smilunk to carry out the fault analysis in the DC transmission lines and test the performance of the SFCL model during fault scenarios.