Hardware-based simple, fast and accurate measurement of power system frequency using a hybrid system

Abstract

All digital methods developed for frequency measurement suffer from one or more factors such as superimposed noise, non-linear static characteristics, high-order harmonics and slow response because of complex computations. The measurement speed of conventional analogue methods is constant and depends on the input signal frequency. Additionally, as a result of deviated and/or spurious zero-crossings caused by the DC component, noise and high-order harmonics in the AC waveform, it is hard to attain the desired accuracy with conventional analogue methods. In this study, a phase-locked loop and microcontroller-based hybrid frequency measurement method developed by the modification of conventional zero-crossing is presented. The input signal, with harmonics and noise, and the frequency can be measured in a fast and accurate way with the proposed method, whose real-time application is extremely simple; this is demonstrated in a comparable manner to the studies in the literature. The measurement method presented in this study is fast, cheap, reliable, accurate and suitable for real-time applications.