电力系统电磁转矩系数的性质及其计算方法

Character of Electric Torque Coefficients in Power System and Its Computation

为了揭示电磁转矩系数的实质,证明了用电磁转矩系数表达电磁转矩只是某种近似,还证明了将单机系统的电磁转矩定义推广于多机系统,其前提条件是所研究的机组相对于惯性中心COI(center of inertia)只有1个运动模式;基于状态空间模型,提出了单机、2机和2机群的电磁转矩系数的定义,给出了理论计算方法。在多机情形下,针对某一模式将系统视为2个机群,通过广域测量系统得到局部系统COI的转速和功角、各发电机电磁功率,从而不需等值运算而转化为等值2机,并测辨其电磁转矩系数。算例分析表明,所提出的电磁转矩系数的理论计算和辨识方法是有效的,二者能够相互印证。

In order to investigate the essence of electrical torque coefficients,it is proved that the equation between active power and electric torque based on two coefficients is not satisfied completely and electric torque method lead to a simplified path of accurate power system model essentially.If the electric torque definition of single machine is applied to multi-machine system,the given machine must be dominated by only one oscillation mode on the center of inertia（COI）.This paper also presents electric toque definition and calculating method which can be used for single machine system,two-machine system,and two-area system.In large power system,a two-area system is defined in term of certain mode and its electric torque coefficient can be computed with measured signals（e.g.speed,angle based on partial COI and active power） from wide area measurement system（WAMS）.A four-machine system case showed that the methodology proposed can be utilized to identify the coefficient of electric torques.