Adaptive Sensorless Control of PMSGs-Based Offshore Wind Farm and VSC-HVdc Stations

This paper proposes sensorless control strategies for an offshore wind farm (OWF) and voltage source converter high voltage direct current (VSC-HVdc) stations. The extended Kalman filter provides an estimation of the speeds and rotor positions of permanent magnet synchronous generators (PMSGs) of OWF, the dc voltage at dc-bus and the dc voltages of the both VSC-HVdc stations. The OWF, composed of 150 variable speed wind turbines based on PMSGs, is considered in this paper, where each generator is connected in series by its own ac-dc converter to dc-bus. Only one dc-ac inverter converts the dc-bus voltage to a proper ac voltage of wind farm ac-bus. The HVdc transmission system based on a three-level neutral point clamped VSC is used for the interconnection between the OWF and the onshore grid via two dc cables. Detailed modeling and control strategies are developed for each individual component of the system. Simulation results show the effectiveness of the proposed method to manage the desired HVdc system operation.