Instantaneous phase tracking in power networks by demodulation

A technique for instantaneous monitoring of phase angles during transients in power networks is presented. The proposed algorithm is based on demodulation and subsequent filtering of the measured signal, which allows very accurate tracking of transient phase angles (within 1 degree). The simplicity of this method and its performance make it an excellent candidate for real-time implementation. A number of simulated scenarios are presented to demonstrate the performance of the algorithm on signals which represent transient conditions in power networks. The technique maintains accuracy within the required tolerances of 1 degree while placing relatively moderate computational burden on the measurement hardware. The maximum error of the phase angle estimates occurs at the very beginning of the transient and dies out relatively quickly in all the simulated situations, which implies that better than required accuracy may be expected.