计及LVRT撬棒电路的双馈感应风电机组动态等值

Dynamical Equivalence to DFIGs Considering LVRT Crowbar Circuit

低电压穿越LVRT(low-voltage ride-through)的同时电机结构发生变化,机组差异使撬棒动作不一致,给传统等值方法带来难度,且效果不佳。考虑到风电场对大电网的影响主要关注其出口动态特性,为改善计及LVRT时风电场的等值效果,从其出口特性着手,忽略内部结构,等效整个风电场。通过Prony算法分析风电场出口电压、电流的振荡模式,定义表征各模式影响程度的能量比,以此为依据提取主要模式等效风电场出口特性,并与依据模式的幅值和衰减因子提取的主要模式对比,前者提取的主要模式更为精确,且减小了对模型阶数的要求。仿真结果表明该算法得到的等值模型在计及LVRT时是合理有效的。

The motor structure is changing when low voltage ride through （LVRT） occurs. The inconsistent crowbar ac- tion due to the difference between units brings difficulty to the traditional equivalence method, and its equivalence ef- fect is poor. The impact of wind farm on large power grid is mostly related to the dynamic characteristics of its export. In order to improve the equivalence considering LVRT, in this paper, an equivalent model of wind farm is established from the perspective of export characteristics while ignoring its internal structure. The oscillation modes of voltage and current at the wind farm export are analyzed using Prony algorithm. The major oscillation modes are selected to simulate export characteristics by defining the energy ratio, which represents the degree of influence. The effect is compared with that by analyzing amplitude and attenuation of oscillation modes, indicating that this method is more accurate and it reduces the requirement of model order. The rationality and validity of the equivalent model is verified by simulation considering LVRT.