Harmonic detection for single-phase circuits based on resampling and feedback theory

A method for digital harmonic detection based on re-sampling and feedback theory is proposed, and a digital harmonic detecting system is designed. According to feedback theory, a filter can be designed to take the direct current Ip (Iq), and ip (iq) before a low-pass filter can be re-sampled based on the re-sampling theory. Through this digital system the harmonic currents in a power system can be detected timely and accurately. The system simulation shows that this filter not only takes advantages of digital filters in accuracy, but also overcomes the bad performance of digital filters in dynamics, and can fellow the measured signal in real time.