Mitigation of Harmonic Voltage Amplification in Offshore Wind Power Plants by Wind Turbines with Embedded Active Filters

In this paper, active filters are embedded in the gridconnected converter control of Type-IV wind turbines to reduce harmonic voltage amplification in offshore wind power plants (WPPs). The Extra Element Theorem is employed to tune the active filters and determine the stability margin of the augmented WPP-grid system through a low-entropy expression. Active filter tunings that satisfactorily reduce harmonic voltage amplification yet provide sufficient stability margin in the augmented system are identified. A running example is performed on a 270MW offshore WPP comprised of 3MW wind turbines implemented in real-time simulation as hardware-in-the-loop. Both converter and grid voltage harmonics are suppressed at WPP buses to below the stipulated planning levels.