大规模双馈风电场次同步谐振的分析与抑制

已有的运行经验表明,风电场接入含有固定串补的系统时,存在诱发次同步谐振(SSR)的风险.因此,有必要对风电场发生SSR现象的机理做深入分析,以便提出相应的抑制措施.文中首先根据国内某地区风电场的实际参数建立了应用于SSR分析的等值模型,通过仿真呈现了该模型发生SSR的情形;然后,利用特征值法分析了风速、并网风力发电机台数以及双馈感应发电机(DFIG)控制参数等对系统SSR频率和阻尼特性的影响;并进一步推导了等值模型用于SSR分析的等效电路,详细分析了风速、发电机台数和DFIG控制参数等影响SSR特性的机理;综合所有的分析指出,风电场的SSR现象与轴系扭振无关,是一种特殊的电气谐振.最后,提出了抑制风电场SSR的方案,并通过仿真和特征值分析进行了验证.

Analysis and Mitigation of SSR Problems in Large-scale Wind Farms with Doubly-fed Wind Turbines

The existing operation experiences indicate that subsynchronous resonance (SSR) may occur in wind farms which are connected to series compensated systems. Hence, it is necessary to analyze the mechanism of SSR in wind farms, which will contribute to the solutions. Firstly, an equivalent system model for the analysis of SSR is established based on the real parameters of a wind farm in China. The SSR phenomenon of this model is presented by time domain simulation. The impacts on SSR from the factors such as wind speed, number of generators, and control parameters of doubly-fed induction generators (DFIGs) are checked using eigenvalue analysis. An equivalent circuit is deduced for the mechanism analysis of SSR. Based on this circuit, the mechanism of SSR impacts from aforementioned factors are analyzed in details. Considering all the analysis, it is pointed out that the SSR phenomenon of wind farms is a special electrical resonance, and nothing to do with the generator shaft. Solutions of SSR in wind farm are also proposed and are verified by simulations and eigenvalue analysis.