基于柔性直流输电的风电场并网故障穿越协调控制策略

A Coordinated Control Strategy for Fault Ride-Through of Wind Farm Integration Based on VSC-HVDC

分析了新型模块化卸荷(dynamic braking resistor,DBR)电路的结构特点与工作特性,并基于模块化卸荷电路控制方法与升频法/降压法,提出一种适用于由双馈感应风电机组与普通异步风电机组构成的混合风电场柔性直流输电并网系统的故障穿越(fault ride-through,FRT)协调控制策略。根据风机实际运行特性与电网规范要求设计升频/降压限值,充分利用风电机组(wind turbine generator,WTG)自身特性降低风场侧出力,配合模块化卸荷电阻可获得更加理想的故障穿越效果,同时进一步降低了系统造价。根据南澳柔性直流输电示范项目实际参数,应用PSCAD/EMTDC电磁暂态仿真软件搭建相应的三端柔性直流输电系统模型验证了所提控制策略的有效性。

This study analyzes the structure property and operating characteristics of modular dynamic braking resistor（DBR） circuits in detail, and proposes a novel coordinated control strategy. This strategy combines modular DBR circuit control method with AC-voltage frequency increase or magnitude reduction method, applying to hybrid wind farms equipped with doubly-fed induction generators（DFIG） and squirrel cage induction generators（SCIG） for fault ride-through（FRT）. To make full use of wind turbine generators＇（WTGs） own performance characteristics, the limits of AC-voltage frequency increase or magnitude reduction at the point of connection of wind farm are designed according to grid code requirements and the operating characteristic of WTGs. Through power reduction of WTGs, further reductions in rated capacity of braking resistor, which may bring lower costs of DBR and better FRT effects, can be achieved. Simulation based on actual parameters from Nanao VSC-HVDC demonstration project and conducted in PSCAD/EMTDC validated the correctness and effectiveness of the proposed coordinated control strategy.