Grid connection of offshore wind farm based DFIG with low frequency AC transmission system

Abstract

This paper uses a simulation to investigate the feasibility of applying low frequency AC (LFAC) transmission technology to connect large offshore wind farms to the onshore power system. Compared to the conventional AC transmission system with a power frequency of 50 or 60 Hz, the LFAC system can transfer more power through longer distance and with lower investment costs than the HVDC solution. Firstly, the characteristics of power cable operation at low frequency are discussed. Then a grid connection of an offshore wind farm based on a doubly fed induction generator (DFIG) through LFAC is studied. The simulation results show that there are no difficulties for the wind farm based DFIG when it operates at low frequency. Moreover, the reactive power control at the line side of DFIG can be applied to improve the operation of the cable.