GPS synchronized digital current differential protection for transmission lines

This paper describes a newly developed digital current differential protection for transmission lines. The proposed protection is different from existing ones in two aspects: one is using GPS time information to implement synchronized sampling at all terminals of the protected line. Another is the application of new differential algorithm based on fault component instantaneous value. To evaluate the performance of the protection, both the EMTP simulation study on the new algorithm and the dynamic simulation test on the prototype of the protection are conducted. The test results have proved the correctness of the new algorithm and the feasibility of the protection scheme. This paper starts with brief introduction to overall scheme of the protection, then focuses on describing the principles of GPS based synchronized sampling and new differential algorithm. The simulation results are also presented. [Copyright &y& Elsevier]