Investigation of harmonic properties of a typical nonlinear load in an AC power-electronics-based micro-grid

A new attempt for investigating the impact of a typical nonlinear load on the AC power-electronics-based micro-grid is presented. For this purpose, the harmonic properties of the three-phase diode-bridge rectifier at the point of common coupling (PCC) are explored, taking into account the effects of the dc side load impedance and ac side grid impedance. Instead of the accurate analytical methods, a method to calculate the harmonic impedance of the nonlinear loads based on measurement and data assessment is proposed from the perspective of simple and practical. Then obtained harmonic impedance of the nonlinear load is applied in the analysis of the impact on the micro-grid, it is found that it will deteriorate the current injection of the grid connected converters (GCC) in the micro-grid. Simulations validate this phenomenon.