大型风电场中不同位置的风机对次同步谐振特性影响程度的比较分析

Comparative Study of the Impact on Subsynchronous Resonance Characteristics From the Different Location of Wind Generators in a Large Wind Farm

针对双馈风机串补系统的次同步谐振问题,现有文献大都将整个风电场等效为单台风机进行研究,而忽略不同位置风机的风速、输出功率及其间线电缆参数对系统次同步特性的影响。该文将整个风电场划分为两个子风电场,分别等效为一台风机,建立两机串补系统模型,然后分别改变每台风机的转速、输出功率和电缆参数,比较对整个系统次同步特性的影响程度。结果表明:在同样风速条件下,不同位置的风机,对系统的次同步特性影响程度不同,离汇流母线近端的风机对系统稳定性的影响大于远端的风机。当整个风电场的输出功率给定,两子风电场输出容量配置比例不同,系统表现出的次同步特性不同,远端风电场输出功率越高系统稳定性越好。风机与汇流变母线之间的输电线路阻抗越大,系统的稳定性越强。

In addressing the subsynchronous resonance （SSR） issue associated with series-compensated wind farms, most of the literatures use a single wind turbine generator （WTG） to represent the entire wind farm, without considering the impact on SSR characteristics from the wind speed, output power of WTGs at different locations and the parameters of cables connecting those WTGs. This paper divided the entire wind farm into two sub wind farms and used an aggregated DFIG to represent each sub wind farm. The small-signal model of the series-compensated two-WTG system was built and then the SSR characteristics under different wind speed, output power and cable impedance were investigated. It is found that the location of WTGS has great influence on SSR characteristics when the wind speed is fixed. The WTGs near the collecting bus have relatively greater impact than those far from the collecting bus. If the generation produced by the whole wind farm is fixed, the higher percentage the far-end WTGs account for, the more stable the system becomes. Generally, when the impedance of the line connecting the WTGs and the collecting bus is increased, the stability of SSR will be improved.