增强型死区大小对单机简化系统超低频频率振荡的非光滑分岔影响研究  

Influence of the Enhanced Dead Zone on the Non-smooth Bifurcation ofUltra-low Frequency Oscillations in Single Machine Simplified Systems

作　　者：薛安成 王嘉伟 刘晓博 XUE Ancheng;WANG Jiawei;LIU Xiaobo(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Source(North China Electric Power University),Changping District,Beijing 102206,China)

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),北京市昌平区102206

出　　处：《中国电机工程学报》2021年第18期6160-6168,共9页Proceedings of the CSEE

基　　金：国家重点研发计划项目(2017YFB0902000)。

摘　　要：实际系统中发生了多次与调速系统相关的超低频频率振荡(ultra-low frequency oscillation,ULFO)事故,含增强型死区(阶跃型死区)的电力系统是分段光滑但向量场不连续的Filippov系统,其振荡机理和影响因素复杂。针对含增强型死区的单机水电系统,结合Filippov系统的非光滑分岔理论,分析典型死区下系统对扰动负荷参数的边界穿越型平衡点分岔和跨边界的非光滑极限环分岔特性。结果表明,切换型超低频频率振荡出现对应2种Filippov系统非光滑分岔:第1类为伴随稳定结点型平衡点消失(变为边界上伪平衡点)时,出现稳定非光滑极限环的类Hopf分岔,即对应发生无平衡点的切换型振荡;第2类对应着轨线发生C型非光滑分岔,此时,系统从无平衡点(或存在伪平衡点)变为稳定焦结点型平衡点,但系统轨线收敛到一个大范围的稳定非光滑极限环,即对应系统发生有稳定平衡点的切换型振荡。进一步,分析了不同死区大小(非光滑系统结构变化)对上述2种类型的非光滑分岔的影响,结果表明,增大死区一定程度上能增加系统忍受负荷扰动的能力,有利于系统稳定。Ultra-low frequency oscillations(ULFOs)related to the governor system have occurred in the actual system.The power system with enhanced dead zone(step dead zone)is a piecewise smooth discontinuous system(Filippov system),and its oscillation mechanism and influencing factors are complex.For the single hydropower system with enhanced dead zone,the non-smooth bifurcation theory was used to analyze the system bifurcation characteristics of the border-crossing equilibrium and non-smooth limit cycle of load parameter under typical dead zone size.The results show that the appearance of switching-type ULFO(ST-ULFO)corresponds to two types of non-smooth bifurcation of Filippov system,the first was the Hopf-like bifurcation with the stable node disappearing(becoming a pseudo-equilibrium on the boundary),which corresponds to the occurrence of ST-ULFO without equilibrium.The second was corresponding to the C-bifurcation on the trajectory.In this case,the system changed from no equilibrium(or a pseudo-equilibrium)to a stable focal equilibrium,but the system trajectory converged to a large-scale stable non-smooth limit cycle,which corresponded to the occurrence of ST-ULFO with a stable equilibrium.Furthermore,the effects of different deadband sizes(changes in non-smooth system structure)on the above two types of non-smooth bifurcations were analyzed.The results show that increasing the deadband can improve the system's ability to withstand load disturbance to a certain extent,which may be beneficial to the system stability.

关 键 词：超低频频率振荡 Filippov系统 增强型死区 类Hopf非光滑分岔 C分岔 

分 类 号：TM712[电气工程—电力系统及自动化]