基于二极管分散整流的风电机组中压直流汇集直接送出系统OACSTPCD

The medium-voltage DC(MVDC)collection and DC transmission systems of wind turbines based on distributed diode rectifiers do not require offshore booster stations and offshore converter stations,and have outstanding economic advantages for medium-to-long-distance and medium-scale offshore wind power.Aiming at its unique transmission current ripple problem,a multi-unit dynamic phase-shifting reference frame(DPSRF)is established and voltage vector control oriented to the d-axis of the DPSRF coordinate system is proposed to interleave the rectification current vectors and output current ripple of the distributed diode rectifiers.The staggered distribution of output current ripple effectively reduces DC transmission current and voltage ripple.Considering the influence of the dynamic phase shift angle in the ripple interleaving algorithm,a small-signal state-space model of the wind turbine grid-side converter is established,and the weak damping link of the system is identified based on the characteristic root analysis,and a stabilization control strategy is proposed.Taking advantage of the system's potential to avoid DC circuit breakers,a fault location strategy based on the disturbance injection is formulated,and the relay protection logic and turbine operation sequence are used to realize fault localization and isolation of multiple fault locations in the DC internal network without a communication system.Finally,PSCAD simulation and RT-LAB-based hardware-in-the-loop experiments verify the effectiveness of the proposed control and protection strategy.