Study of resonance issues between DFIG-based offshore wind farm and HVDC transmission

摘要

Wide-frequency range of resonances can occur in HVDC-connected DFIG-based offshore wind farm (OWF), thus induce large harmonic distortion or endanger system stability. Previous studies usually treat OWF as a single machine system without considering the switching states of individual wind turbines and collecting cables, or ignore the converter responses to wind speed variation and generation control order. In this paper, such factors are included in the modelling of OWF. Their impacts on resonance frequency, amplification level and the occurrence of negative damping are analyzed applying the resonance mode analysis method. Harmonic stability and power quality issues are demonstrated for the frequency range from several Hz to a few kHz. Simulations in MATLAB/Simulink validate the analytical results. Additionally, resonance damping strategies are discussed regarding the identified resonances in widely spread frequencies.