Real-time testing of Newton-phaselet method for calculating the power factor of single phase loads

A combination of Newton iterations and phaselet tight frames allows calculating the power factor of a single phase load. In this paper, the real-time implementation and experimental testing of the Newton-phaselet method are presented. The tested method is structured to employ the Newton iterations in order to estimate values for the apparent power S, and to utilize phaselet tight frames to calculate an angle v for the estimated S at each iteration. The estimated S and calculated v at each iteration provide a numerical value for the active power P. This calculated value of P is compared to the measured one in order to determine the required adjustment in S for the next iteration. The Newton-phaselet method is implemented in real time by using a digital signal processing board, where the measured active power is fed as the input. Experimental performances of the Newton-phaselet method are investigated for single phase linear, non-linear, and inverter-fed loads supplied at different frequencies. Test results demonstrate high accuracy, simple implementation, low memory requirements, fast convergence, and negligible sensitivities to harmonic components and supply frequencies.