Reactive Power Control in All-DC Wind Generation System

This paper introduces a novel reactive power control scheme tailored for a hybrid generator within a wind turbine (WT) system, interfacing with an all-DC wind generation setup. The hybrid generator, featuring a 9-phase dual rotor design with permanent magnet (PM) and wound field (WF) rotors, aims to produce fixed and variable flux, respectively. The machine’s generated power is rectified by a diode rectifier and integrated into a medium voltage DC (MVDC) collector grid. For voltage regulation, DC-DC converters on an offshore substation step up the voltage to a stable high-voltage DC (HVDC) for efficient transmission. The generator WF variable flux can be controlled. The proposed controller governs the injected DC field current to the WF winding of the hybrid generator, managing the machine's total back-EMF, rectified DC voltage at the WT's output, generator's reactive power, and consequently, the power factor. Rigorous simulations validate the efficiency of the proposed controller.