Damping Control of HVDC Links to Mitigate Controller Interaction with Resonances of the Offshore Wind Farm

This paper deals with the harmonic instability problem in offshore wind farms caused by the interaction of HVDC controller with the resonance frequencies of the grid. Due to the HVDC filters, transformers and long submarine cables wind farms have natural resonances, which are close to the operating frequency of the HVDC converter. Even through the grid resonances exhibit inherent damping, the converter control may amplify the oscillations resulting in harmonic instability. Therefore, the converter control has to be designed properly taking into account all possible operating conditions and grid topologies. In this paper a new damping control approach is presented that is using the dq components of the current for modulating the converter output voltage. The parameters of the damping controller are estimated by the heuristic optimization algorithm MVMO simultaneously for three different disturbance scenarios. Simulation results in the time domain demonstrate the effectiveness of the proposed method. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.