High frequency directional-based protection scheme for transmission lines emanating from large scale wind farms

Penetration of large-scale renewables has changed the fault current characteristics, degrading reliability of the transmission line traditional protection system. This paper presents a high frequency directional-based protection scheme for transmission lines connecting large scale wind farms to the high voltage grid. The proposed protection mitigates the negative influence of the wind farm response to faults on the fundamental frequency phasors by using the high frequency components generated during the fault. The proposed protection scheme is applied to the relays at both sides of the protected transmission line independently. Therefore, each relay utilizes its locally measured voltage and current signals. Then, the relays share their individual decisions to obtain the final decision using the proposed operation logic. In addition, the proposed protection scheme does not require a compensation algorithm for the line capacitive current. An assessment study is conducted on the PSCAD/EMTDC software considering different fault types including cross-country and evolving faults, fault locations, fault resistance values up to 500 ohm, line lengths up to 200 km, and output power of the wind farm. The simulation results emphasize the dependability and security of the proposed protection scheme at different test conditions.