Detection for power grid harmonics based on theory of modified quasi resonant filter

To meet the requirements of the real-time and accurate reference resource in grid harmonics elimination, when the main advantages and disadvantages of quasi resonant filter detection have been analyzed, a modified harmonic detection method is proposed. This method proved the accuracy and shortened the time of power grid harmonic detection by the way of enlarging the cut-off frequency of a quasi-resonant filter and adding an attenuation part and a PLL. What´s more, the algorithm is simulated in a digital way. The simulation experiment results prove that this method is reasonable and efficient.