Connection of Offshore Wind Farm to Onshore Using Diode-Rectifier-Based HVDC Platform

An improved maximum power point tracking (MPPT) strategy for PMSG based wind power plant with diodes-based uncontrolled rectifier HVDC transmission system is proposed. The generator side VSC is arranged to control the DC link voltage of the back-to-back converter. The control of offshore AC grid side VSC can operate on neither voltage control model nor current control mode. The MPPT is applied using the hard limitation which give order of the inner current. Due to the power losses in the back-to-back system, deviation from the actual optimal power curve happens. The improved MPPT considers the power losses, and improves the efficiency. Furthermore, an optimized DC link voltage of back-to-back system is proposed to improve the efficient of the wind energy conversion system. The proposed control method is carried out in PSCAD/EMTDC, and the simulation results shows its satisfactory performance.