A fast estimation method for unbalanced three-phase systems

Phasorestimation is an important task in many monitoring and control applications in power systems. Fast Fourier transform(FFT) and Park transform are the most common methods to calculate voltage and current phasorsin three-phase systems. Park transform has a small delay but could not work in unbalanced conditions. FFT works well in unbalanced systems but introduces a delay of at least one fundamental cycle. In this paper a new method is presented to calculate magnitude and angle of each phase using Park transform. The delay of phasorestimation is half a cycle and it works well in unbalanced conditions. Several simulations are performed in PSCAD/EMTDC environment to prove the feasibility of this new method.