A novel transient control strategy for VSC-HVDC connecting offshore wind power plant

This paper proposes a novel steady-state and transient management scheme for voltage source converter based high voltage direct current (VSC-HVDC) connecting permanent magnet synchronous generator (PMSG)-based offshore wind power plant (WPP). The proposed control arrangement aims to fully utilize the HVDC converters´ normal loading capabilities during steady-state operation. Furthermore, it targets the employment of the available converters´ overloading capabilities to enhance the fault ride through (FRT) performance during faults. The positive and negative sequence components are controlled to 1) neutralize dc-link voltage ripples due to asymmetrical grid faults, 2) inject reactive current support for the grid voltage, and 3) deliver the maximum possible active power during different faults. Novel mathematical and time-variant representations of the positive and negative sequence components are introduced to adapt the converter current limits for full utilization of the converter limit. Comprehensive simulation studies using PSCAD/EMTDC are presented to verify the functioning of the proposed control strategy.