励磁系统动态增益对凸极发电机暂态稳定的影响

Effect of Dynamic Gain of Excitation System on Transient Stability of Salient Pole Generator

由于励磁系统动态增益对凸极发电机动态稳定性有显著影响,为改善电力系统阻尼,多需要调整该动态增益,进而配置电力系统稳定器。但在动态增益对发电机暂态稳定的影响方面,存在某些模糊认识,妨碍了相关工作的开展。文中首先分析了发电机暂态稳定与同步转矩的关系,将研究励磁控制系统动态增益对暂态稳定的影响转化为研究对同步转矩的影响,以便于数学推导。然后,对励磁控制系统动态增益影响凸极发电机同步转矩的机理进行了推导和算例计算,继之以单机系统、两机系统和实际系统仿真。计算和仿真结果表明,励磁系统动态增益在正常范围内变化时,对凸极发电机暂态稳定的影响很小,可以忽略。当为了改善电力系统阻尼而在正常范围内调整励磁控制系统动态增益时,不会对凸极发电机暂态稳定带来明显影响。

Because the dynamic gain of excitation system has significant impact on the dynamic stability of the salient pole generator,in order to improve the power system damping,it is often necessary to adjust the dynamic gain and deploy the power system stabilizer(PSS).However,there are some vague understandings for the influence of dynamic gain on generator transient stability,which hinders the development of related work.First,the relationship between transient stability and synchronous torque of the generator is analyzed,and the influence study of dynamic gain of excitation control system on transient stability is transformed into the influence study on synchronous torque for mathematical derivation.Then,the mechanism of dynamic gain of the excitation control system affecting synchronous torque of the salient pole generator is deduced and calculated,followed by the simulation of single-machine,two-machine and actual systems.The results of calculation and simulation show that when the dynamic gain of the excitation system changes in a normal range,its influence on transient stability of the salient pole generator is very small and can be neglected.When the dynamic gain of the excitation control system is adjusted in the normal range to improve the power system damping,the transient stability of the salient pole generator will not be significantly affected.