Patent ID: 9478966
Filing Date: 2016-10-25
CPC Classification: H02H,H02J

Claim Text:
1. A protection relay for protection of an electric network, comprising: means for measuring an electric signal in the network; means for converting the measured signal to a frequency domain representation of the measured signal; means for rotating a measuring phasor based on the frequency domain representation, the phase rotation of the measuring phasor being dependent on at least one frequency component present in the measured electric signal; means for generating a rotating reference phasor, the reference phasor being rotated at one of a nominal frequency and a measured frequency of the electric network; means for comparing the phase rotation of the rotating measuring phasor to the phase rotation of the generated rotating reference phasor; and means for launching protection if the comparison of the measuring phasor and the reference phasor fulfils a predetermined criterion.