A demodulation based technique for accurate estimation of real-time single-phase grid voltage fundamental parameters

This paper proposes a simple technique for accurate, robust and fast estimation of real-time single-phase grid voltage fundamental amplitude and frequency under distorted grid conditions. A frequency adaptive oscillator tuned at around second harmonic is combined with a conventional demodulation based technique. The proposed oscillator can reduce the negative effects caused by the oscillations at around second harmonic which is generated by the demodulation of fundamental component. The proposed technique improves the fundamental voltage amplitude and frequency estimation accuracy significantly as compared to the conventional demodulation based technique. Moreover, the integration of the proposed oscillator with the demodulation based technique does not affect the dynamic response of the estimated fundamental voltage amplitude and frequency. Real-time experimental results are presented to verify the performance of the proposed technique.