Harmonic Resonance Interactions in HVDC-Connected Offshore Wind Power Plants.

A large number of power converters in HVDC-connected OWPPs may cause instabilities due to converter control interactions. This paper analyzes the impact that harmonic resonances have on the stability of OWPPs connected through HVDC. Converters and offshore ac grid of a detailed OWPP are represented with an impedance-based model, which is used to identify harmonic resonant frequencies and assess stability. The positive-net-damping criterion is used to evaluate stability considering contribution of all OWPP elements. Active damping is implemented as a virtual resistance to reduce the instability caused by the harmonic resonances. Examples of virtual resistance application are validated with time domain simulations in PSCAD/EMTDC. [ABSTRACT FROM AUTHOR]