基于主导模式的风电并网小扰动稳定模型等值研究

大规模风电基地通过联络线接入电网,使得风电并网小扰动稳定问题更加突出,建立对应的小扰动稳定分析的数学模型并有效等值是稳定性分析的基础.详细分析推导了双馈风电机组轴系系统、变桨系统和发电机模型,建立其小扰动稳定分析状态方程.基于主导模式,推导采用最优线性组合理论的等值模型计算方法,获得阶次降低后的等值模型表达式.实例中以降阶前后状态变量动态特性的拟合度论证等效模型的准确性,结果表明合理选择主导模式可以有效利用最优线性组合法获得等值模型.

A Study on Small Signla Stability Model in Wind Power Grid based on Dominant Mode

Large-scale wind parks gain access to grids via tie lines,which renders the small signals of wind power grid integration more unstable.The underlying principle for stability analysis is to build a mathematical model for analyzing small signals and to provide effective equivalents. This paper presents a detailed analysis and deduction of doubly fed induction generator unit shaft system,a pitch system,and a generator model.A state equation of stability is thus given. Based on the dominant mode,equivalent model calculation method is deduced using optimal linear combination theory,which enables to obtain equivalent model expression after the order is reduced.The accuracy of the model is proved by the fitting degree of dynamic characteristics before and after the order reduction.The results show that equivalent model for the dominant mode can be obtained by applying optimal linear combination method.