双馈风力发电系统故障特性及保护方案构建

针对双馈电机励磁方式的特点,本文分析了电网发生故障时定子短路电流呈现的"多态"故障特征,论述了故障点距离、Crowbar保护动作门槛值以及励磁逆变器控制系数等因素对双馈电机短路电流特性的影响,并进行了仿真验证。基于以上研究结果,从提高双馈电机故障穿越能力的角度出发,提出了一套适用在风电场并网节点处的新型复合式电流—电压保护方案。通过对传统电流保护的改进和构建低电压穿越运行特性的电压保护,使其能够适应双馈电机的故障特征,满足风场联络线上故障的可靠切除及配电系统内故障时风电场的低压穿越运行,对实现含双馈风电机组的电网稳定及故障后的快速恢复具有重要意义。

Research on Fault Characteristic and Grid Connecting-Point Protection Scheme for Wind Power Generation With Doubly-Fed Induction Generator

This paper discusses how the fault locations,action of crowbar protection and the proportional and integral coefficient of rotor side inverter affect the magnitude and decay time of doubly-fed induction generator(DFIG)’s short-circuit current.The simulation indicates the "multi-waveform" fault characteristics of DFIG current fed into the grid,which is due to the multi rotor exciting models.Based on this,a grid connecting-point protection scheme for wind farm is proposed.The scheme is composed of advanced current protection and low voltage protections,which can not only reliably remove the fault happened on the tie line,but also ensure the wind farm to operate under fault condition.The proposed protection scheme is of great significance to realizing the reliable operation and fast fault restoration of the grid with high penetration wind generators.