用于离岸风场高压直流输电的并网型多电平拓扑研究

摘要

This paper presents a topology to connect HVDC offshore wind farm into the grid; the offshore part consists of five units,and each one contains permanent magnet synchronous generator (PMSG) connected to a three-level neutral point clamped converter (3 L-NPC) which works as a rectifier to control the generator speed by using a maximum power point tracking (MPPT) control.The offshore platform consists of a half bridge connected in series to balance the voltage between units and to collect the voltage in order to get the desired DC voltage.The HVDC cable will be used to transfer power from the offshore side to the onshore side.A modular multilevel converter (MMC) is used in the onshore side to convert the voltage from DC to AC voltage and to connect the offshore wind farm into the Grid.%提出一种新型的风力发电变换器拓扑结构.可用于离岸型海上风电场,并可采用高压直流输电的方式接入电网.其中,离岸部分包括5个单元结构,每一个单元结构均由一个永磁同步电机(permanent magnet synchronous generators,PMSG)和一个三电平中点钳位(3-level neutral point clamped,3L-NPC)变换器组成,通过最大功率点跟踪(maximum power point tracking,MPPT)算法控制3L-NPC变换器,进而控制PMSG运行速度.离岸平台由半桥结构串联组成,用于平衡各离岸单元电压并控制总体直流侧电压为给定值.超高压直流电缆将被用于离岸侧和岸侧的功率传输.在岸侧,采用一种模块化多电平变换器(modular multilevel converter,MMC)实现直流到交流的逆变,并将系统接入电网.