A new integrated protection scheme for power transmission lines

This paper presents a new protection scheme of integrated all frequency protection. First, a review of the development of transient based protection and integrated protection is given. After a series of protection techniques are introduced, the proposed scheme is stated, which integrates the conventional power frequency protection algorithms and the transient based protection algorithms, and divides the protection algorithms based on power frequency and transient measurement into three groups: the single end protection group, double or multiple end protection group and backup protection group. The single end protection group includes the conventional distance protection techniques based on power frequency measurement and the boundary and positional protection techniques, which are based on high frequency transient measurement, and they are employed to form an instant tripping protection group based on single local end measurement. The double or multiple end protection group consists of the conventional current differential protection and the time synchronizing transient protection based on communication link. The backup protection group consists of conventional directional comparison and transient protections based on polarity comparison techniques. Finally, by integrating all frequency domain protection techniques, an effective solution for the protection of the ultra long length of the half-wave transmission line is present.