Injected Harmonic Impedance Measurement Method Considering Background Harmonic and Noise

The selection of the size of the injected harmonic signal is important for the impedance measurement accuracy and normal operation of the system. The system noise and background harmonic interfere greatly with the limitation of the injected harmonic signal amplitude. The noise of the Lee-HVDC converter station and the system background harmonic are analysed, the upper limit of impedance measurement error is preset to 2%. The threshold value of the injected harmonic voltage when considering the noise and the system background harmonic is calculated by changing the system impedance parameters. The threshold selection method is used to find the system harmonic impedance, and polynomial The threshold selection method is used to find the system harmonic impedance and reduce the overall error of the measured harmonic. Through Matlab/Simulink simulation analysis and verification, it is demonstrated that the proposed method can effectively weaken the influence of noise and background harmonic on the harmonic impedance measurement accuracy.