跟构网换流器并联的海上DRU低频交流送出方案

LFAC TRANSMISSION SCHEME OF OFFSHORE DRU IN PARALLEL WITH GFL CONVERTER AND GFM CONVERTER

基于不可控整流单元(DRU)的风电低频交流送出系统不具备功率返送的能力,需采用构网型换流器实现海上风电场的自组网。同时考虑传统跟网型换流器所具备的快速功率响应能力对海上风力发电带来的正面影响,以六相永磁同步电机构成的风电机组作为研究对象,阐明在风电机组内,采用两种控制策略的换流器并联经DRU低频交流送出系统的拓扑结构和运行特性。分别设计风电机组网侧换流器的构网型控制策略与跟网型控制策略,并在此基础上探讨两组网侧换流器之间的功率不平衡问题,进一步设计环流抑制策略,实现风电功率经DRU送出。通过搭建Simulink仿真模型和RT-LAB半实物仿真系统验证方案的可行性。

The offshore wind power low-frequency AC transmission system based on uncontrollable rectifier units(DRU)lacks the capability of power feedback,necessitating the use of grid-forming converters to enable self-networking of offshore wind farms.At the same time,considering the positive impact of the fast power response capability inherent in traditional grid-following converters on offshore wind power generation,this study uses a wind turbine unit composed of a six-phase permanent magnet synchronous generator as the research object.It elucidates the topological structure and operational characteristics of using parallel converters with two control strategies in the wind turbine unit,transmitting power through the DRU low-frequency AC system.The grid-forming control strategy and grid-following control strategy for the wind turbine's grid-side converter are respectively designed.On this basis,the issue of power imbalance between the two grid-side converters is discussed,and a circulation suppression strategy is further developed to enable the transmission of wind power through the DRU.The feasibility of the proposed scheme is verified by constructing a Simulink simulation model and RT-LAB hardware-in-the-loop simulation system.