Algorithms for Determining the Parameters of Synchrophasor for the Standard of Vector Electrical Power Quantities

The article addresses the challenge of metrological support for phasor measurement unit. It provides an overview of signal processing algorithms designed to calculate parameters of synchronized voltage and current vectors in electrical networks: magnitude, phase, instantaneous frequency, and rate of frequency change. Two algorithms developed and investigated by the authors are presented. The first algorithm follows the structure recommended by international standards for phasor measurement units. It is based on shifting the spectrum of the signal’s fundamental harmonic to a low frequency and extracting the informative signal using a digital low-pass filter. The authors use a specially designed bank of filters in the algorithm, which are dynamically selected depending on the frequency of the fundamental harmonic of the input signal. The second algorithm proposed by the authors is a parametric algorithm applied to an extended signal model that includes, in addition to sinusoidal, linearly frequency-modulated (chirp) components. The mathematical method for obtaining the optimal estimate of the synchrophasor parameters, corresponding to decomposing the signal into a basis of linear frequency-modulated signals, is described. The advantages and limitations of the developed algorithms for application in reference standards and measuring instruments are examined, and practical recommendations for their use are provided. The presented algorithms have been implemented in the software of the State Primary Standard for Electrical Power Quantities.