同步发电机整流系统的稳定性分析

Stability analysis of synchronous generator-rectifier system

同步发电机整流带反电动势负载时,当系统参数不匹配,在一定工况下,可能出现低频振荡。为了消除低频振荡,基于系统的特征方程、利用R ou th判据推导出小扰动稳定判据,对特征根和系统的等效阻抗进行了计算和分析。系统出现低频振荡是由于系统负的等效阻抗导致自激和Hop f分叉。当系统的总阻抗为零,且有一对共轭的特征虚根时,低频振荡出现。仿真证实了理论分析。给出在转子的交轴上增设一短路绕组和增大交轴阻尼绕组的时间常数等几种解决低频振荡的措施。

For some operating conditions, a synchronous generator with a rectifier and back-EMF load maybe exhibit low-frequency oscillations when the system parameters do not match. To eliminate the low-frequency oscillations, a stability criterion for small disturbances was derived using the Routh criteria based on the characteristic system equation with the characteristic roots and equivalent impedances of the system calculated and analyzed. The low-frequency oscillations of the system were due to the negative equivalent system impedance which results in self-excitation and Hopf bifurcation. The low-frequency oscillations occur when the equivalent system impedance is zero and an imaginary conjugate pair of eigenvalues appears. Simulations verified the theoretical analysis, Several measures are given to eliminate the oscillations such as installing a short-circuited quadrature-axis winding on the rotor and increasing the quadrature-axis damper winding time constant.