The protection principle and engineering application of double-circuit transmission lines in China

The characteristics of double-circuit transmission lines protection are expatiated. Main protection principles and protection configuration schemes of real operating double-circuit transmission lines in China are introduced. Based on the summarize of protection schemes and engineering experiences, the analysis of tripping reasons and measures of wrong trip incidents of the double-circuit transmission lines, which voltages levels range from 110 kV to 500 kV in China, are discussed. The preferential protection principles and the pivotal issues which should be emphasized on are proposed in the paper. The digital protection technology and its engineering application are surveyed also.