Application of Optical-fiber Current Differential Protection to TEED LINES

To increase the transmission ability of power load for110 kV transmission lines in southern Xi'an Power Grid,the fiber- optic current differential protection is adopted in Nanbai-Wenbai and NanyanⅢ-Wenyan 110 kV branch line in Xi'an Power Grid. According to the characteristics of the fiber-optic current differential protection and three-terminal fault component current under the circumstances of Teed line fault,the criteria of differential protection for CSC-163T three-terminal fiber-optic current differential protection,which is applied to Teed lines,is analyzed.In the light of the factors influencing the proper actions of current differential protection,including TA saturation and the ratio difference between two ends of TA,the solution is proposed;the connection between the current differential protection device and communication systems is also analyzed.Finally,the application of the CSC-163T device in Xi'an Power Grid is summarized.