Application of Instantaneous Power Spectral Representation for the Active Power Measurement

Nowadays active power refers to the power quality parameters. That’s why, measurement of active power parameters is required in power quality measuring instruments. This paper describes a technique for active power measurement which apply a discrete Fourier transform of instantaneous power. The conveniences and drawbacks of this measurement method are considered in comparison with the accumulation of instantaneous power method and the application of low-pass filtration method. Analytical expressions are obtained that make it possible to estimate the active power measurement error caused by “spectrum leakage” effect for one-harmonic and polyharmonic measured signals situations. Approaches to reducing the methodological measurement error without significant changes of the original measurement algorithm are considered. Methods for decreasing the active power measurement error as a result of finite frequency deviation are proposed. The metrological and implementation features of discrete Fourier transform implementation for solving problem are considered. The simulation model is performed by the implementation of the Goertzel algorithm. With the application of a simulation model, performed by Simulink package, the accuracy and credibility of the obtained analytical formulas are estimated.