基于多端直流输电的风电并网技术

摘要

以西北电网大规模风场为背景,提出了采用相控换流器的多端直流输电系统（LCC-MTDC）进行大规模风电并网的方法,同时结合西北电网拟建直流输电项目,构建出用于风电并网的多端系统拓扑图并设计了相关器件的参数。在推导出LCC-MTDC数学模型基础上,提出了适用于LCC-MTDC系统的电流裕度控制策略,分析了系统出现扰动时换流器通过控制策略切换而重新恢复稳定运行的原理。PSCAD/EMTDC软件中的仿真结果表明：所提出的控制策略具有良好的控制特性,特别是在故障条件下能有助于系统快速恢复。%This paper is aimed at the application aspect of using line-commutated converter based multi-terminal HVDC（LCC-MTDC） for doubly-fed induction generator（DFIG） based wind farms integration,including the configuration and parameters design in the context of Northwest Grid（NG） in China,combining with practical requirements.The control strategies for the LCC-MTDC are conceived, considering the steady-state and transient respectively.Meanwhile various scenarios such as ac fault on rectifier and inverter sides are simulated to investigate the system performance during disturbance and verify the control strategies in PSCAD/EMTDC.It is proven that the proposed control strategy gives stable operation and is well controlled over the whole operating range.