DC Component-based Differential Pilot Relaying Scheme for Half-wave Transmission Lines

To optimize the power system operation, different regional grids are usually interconnected with the help of long transmission lines (TLs). Sometimes, depending upon the geographical position, renewable energy sources (like hydro energy plants) have been integrated with the utility grid using long TLs. However, transmitting power over a long distance is not preferred as it creates operational and economic issues. A half-wave transmission line (HTL) is proposed in 1940 to cope with such problems. HTL is very long compared to conventionally used TLs, making the dynamics of HTL completely different during normal and abnormal conditions. The conventional protection schemes find limitations in the case of HTL with these abrupt dynamics. This paper proposes a DC component-based differential pilot relaying system capable of fault discrimination and classification. Moreover, the performance of the presented method is scrutinized under different scenarios, such as variation of fault location and inception angle/time, CT saturation error, evolving faults, cross-country faults, and found to be reliable and precise. All the results have been simulated and validated using PSCAD/EMTDC software.