中文摘要：

针对结构复杂的串补输电系统的外网采用何种方法等值及等值后系统保留多大规模这一问题,基于现有的对次同步谐振模式在电网中的传递特性的认识,提出了一种适用于次同步谐振研究的电力系统外网等值方法。根据短路等效阻抗及等值前系统平衡运行状态,确定外网等值参数,并结合次同步谐振研究结果的参数敏感性对等值参数进行适当处理。以系统频率阻抗作为评价指标确定外网合适的等值规模。该方法简单方便,易于实现,适用于结构复杂的串补输电系统的次同步谐振评估分析。通过南方电网的应用算例验证得出,采用该方法进行外网多点等值时等值参数的简化处理及等值规模的判定方法对次同步谐振研究结果的影响很小,从而说明了该方法的有效性。

英文摘要：

Aiming at the problem that how to realize the equivalence of a complex-structured series compensated transmission system and what the system scale should be after the equivalence,based on the transfer characteristics of subsynchronous resonance （SSR）modes in electrical network,a power system external network equivalent method for SSR studies is proposed.The equivalent parameters of external network are obtained based on short-circuit equivalent impedances and the system equilibrating state before equivalence,and then the parameters are appropriately manipulated according to parametric sensitivity of SSR results.Using system frequency impedance as the evaluation index,the equivalent scale fitting for external network can be determined.The proposed method is easy to use and applicable to SSR studies of complex-structured series compensated transmission systems.With the application of the method in China Southern Power Grid,it is proved that simplification of equivalent parameters and determination of equivalent scale exerts little influence on SSR analysis results,thus the validity of the method is illustrated.