A wavelet-based ultra high speed superimposed voltage directional protection

The superimposed principle is widely used in power system protection since it has lots of advantages. The criteria of ultra high-speed directional protection based on superimposed voltage are proposed in this paper. As the powerful signal process tools, using wavelet to denoise the voltage and current signal can refine the fundamental signal to a great extent. Combining lifting wavelet transform denoise technology with short windows algorithm in fault directional identification is good for characteristic improvement of the proposed protection scheme. The operational characteristic of directional protection using the proposed algorithm under different situation is also simulated in this paper.