Phasor Based Zero Crossing Detection of the Mains Fundamental

An algorithm to locate the rising edge zero crossings of the mains fundamental while working in the frequency domain is presented and evaluated. Working in the frequency domain allows easy compensation of the effects of the coupling between the measurement equipment and the power line. Using a modified Discrete Fourier Transform with a raised cosine filter kernel greatly increases frequency selectivity of the generated phasors, especially when measuring noncyclic signals. Zero crossings are located from the gradient of the phase of the mains fundamental and collected as points in time as well as sample indices.