Research on Interference Harmonic Impedance Measurement Method of Non-characteristic Harmonic Current Injection

The high proportion of new energy sources such as wind power and photovoltaic (PV) connected to the grid, coupled with a large number of nonlinear users entering the grid on a large scale, leads to increasingly prominent power quality problems and stability problems caused by harmonics in the new grid. As a result, accurate system harmonic impedance measurements are an important means of solving some of these problems. A non-characteristic harmonic current injection method is proposed to obtain the harmonic impedance value with high accuracy at each frequency and to confirm the series-parallel resonance points in the system. The simulation results show that the scheme achieves good results in the ideal case, the case containing background noise, and the case containing noise.