Modeling and mitigation of harmonic resonance between wind turbines and the grid

Harmonic resonance can happen in traditional power systems between power factor correction (PFC) capacitors and transformer leakage inductance. In a distribution network with high penetration of renewable generation sources, inverter PWM harmonic currents can be a source of harmonic excitation for system resonance. This paper discusses harmonic resonance problems caused by impedance interactions between the wind inverter and the grid. An impedance-based analysis approach is used to characterize such resonance. Modeling of inverter output impedance directly in the phase domain to enable such analysis is presented. Possible mitigation methods by active damping and grid synchronization design are presented, and their effectiveness demonstrated by simulations and experiments.