Research on High Frequency Distance Protection for Wind Power Grid Connection with Thyristor Controlled Series Compensation

The fault current of the grid-connected wind energy system with Thyristor Controlled Series Compensation (TCSC) exhibits the characteristics of voltage reversal, non-power frequency, and weak feedback, which leads to the risk of rejection of the distance protection of the wind farm over the transmission line. In order to resolve this issue, this paper proposes a distance protection approach utilizing high-frequency(HF) variations. By comparing the scale of the operational HF voltage with the HF voltage in the fault point, the internal and external fault of the reliable area is reliably partitioned. On this basis, the protection of TCSC when installed in different positions is analyzed to verify the scope of protection. This method uses the HF signal generated by voltage dip in the fault point to eliminate the effects of frequency shift, weak supply effect of wind farm, and voltage reversal caused by TCSC. At the same time, due to the small equivalent HF reactance value of TCSC, this method can operate correctly when TCSC is installed anywhere, overcoming the risk of misoperation caused by voltage reversal. Simulation results also prove that this method is feasible.