双馈风力发电机组低电压穿越技术分析

Analysis on Low Voltage Ride Through of DFIG for Wind Power Generation

摘要:

当系统中风电装机容量比例较大时，系统故障导致电压跌落后，风电场切除会严重影响系统运行的稳定性，这就要求风电机组具有低电压穿越(Low Voltage Ride Through, LVRT)能力，保证系统发生故障后风电机组不间断并网运行。分析了双馈风电机组的LVRT原理和基于转子撬棒保护(crowbar protection)的LVRT控制策略，在PSCAD/EMTDC中建立双馈风电机组的模型及其LVRT的控制模型，分析了有无撬棒保护对转子电流的影响，得出有撬棒保护对故障时转子电流起到衰减作用，既保护了变流器，又减少了故障电流对风电机组的冲击。

Abstract: System faults may result in voltage dip due to large proportion wind power in the system. And the system stability is influenced severely when wind farms exit. So the low voltage ride through (LVRT) characteristic of wind turbines is necessary to keep wind turbine units connected to the grid after system failure. This paper analyzes the prin- ciple of LVRT in doubly fed induction generators (DFIG) and control strategy of LVRT based on rotor crowbar protec- tion, and builds the DFIG and LVRT model in the software PSCAD/EMTDC. Analyzing the inputing or not of crowbar protection on the influence of rotor current, it is concluded that crowbar protection makes the rotor current attenuation affect on fault, protection of the inverter, and reduces the fault current of the impact of wind turbines.