Instantaneous line-frequency measurement under nonstationary situations

Design and Implementation of a High Accuracy Sampling Wattmeter under Non-sinusoidal and Time Varying Environments

“…This paper proposes a simple but efficient digital signal processing algorithm for on-line accurate estimation of -------RectwngMar -lTraplza1--a I fundamental frequency of the system. At first, the distorted voltage signal is filtered to its fundamental component using suitable digital band-pass filter (BPF) and then processed statistically, as presented in [21 ], [22] to obtain fundamental frequency information. The theoretical basis of fundamental frequency estimation algorithm has been described below.…”

“…In this situation a small error due to noise or rounding could have a large effect. To overcome this problem, a computationally efficient algorithm has been developed in [21], [22] from theory of statistics.…”

“…Hence, considering expected value and variance of r(n), the following expression has been obtained [21], [22] (VF (n-m-1))(VF (n-M)+VF (n-m-2)) r(n) =~2 Z (VF (n -rn -i))2 (8) where A is the number of consecutive estimations. a) Design ofBand-pass Filter In fundamental frequency measurement algorithm, BPF has been utilized to extract fundamental frequency component from non-sinusoidal voltage signal.…”

“…After executing the developed software, DSPs calculates and displays active power as described in Section III. CT Non-sinusoidal Nonlinear Source LIa i(t)=35.11sin ct+30' -3.912sin 3cot-90°) +1.416sin(5wt +150 )-0.729sin(7wt +300) +0.446sin(9t -90') -0.303 sin (llot + 1500) (22) The signal fundamental frequency has been varied in the range 48 Hz to 51 Hz in steps of 0.5 Hz, but the sampling frequency remains constant at 3 kHz. The variation of maximum percentage error of fundamental frequency estimation algorithm with respect to variation of frequency has been shown in Fig.…”