用于振荡稳定性分析的并网风电场动态等效模型

风电接入引发的电力系统低频振荡、次同步振荡和超同步振荡事件在全球范围内均有发生,合理有效地对风电场进行等效建模,是研究风电场并网系统中此类"振荡稳定性"问题的基础。为此,该文研究了用于振荡稳定性分析的风电场动态等效模型。首先,推导了风电场线性化模型的相似变换,将N机风电场等效为N个单机并网构成的等效子系统。然后,结合等效子系统模型的数学表示形式,分析了可对风电场进行单机等值的理论依据和成立条件;并提出一种可用于振荡分析的风电场动态等效模型。最后,通过仿真算例,验证了所提动态等效模型的有效性。结果表明,该模型可有效反映原风电场的振荡特性,且计算量小、应用简单。

Dynamic Equivalent Model of a Grid-connected Wind Farm for Oscillation Stability Analysis

The events of low-frequency oscillations, subsynchronous oscillations and super-synchronous oscillations induced by wind power integration are reported world-wide and a reasonable and effective equivalent modeling of the wind farm is the basis for researches on these ‘oscillation stability’ issues. In this paper, the dynamic equivalent model of a wind farm for oscillation stability analysis was studied. Firstly, a similarity transformation on the linearized model of a wind farm was derived and a wind farm with N wind turbine generators(WTGs) could be equivalent to N subsystems each of which consisted of a single grid-connected WTG. Secondly, according to the mathematic representations of the equivalent subsystems, theoretical basis and establishing conditions for representing a wind farm by a single-machine equivalent model was analyzed and a dynamic equivalent model of the wind farm for oscillation stability analysis was proposed. Finally, the effectiveness of the dynamic equivalent model proposed was examined by study cases and it was shown that this model could effectively reflect the oscillations of the original wind farm with less computation burden and was easy to use.