摘要
新能源大规模并网引发的振荡问题近来得到广泛关注。目前,忽略变流器的限幅等非线性特性,在稳态工作点附近线性化得到的小信号模型是研究上述振荡问题的主流方法。然而,在某些条件下,变流器中的限幅环节对振荡特性的影响不可忽视。结合相图分析方法,揭示直驱风机次同步频段振荡的数学机理之一是与限幅相关的非光滑分叉。首先,介绍了与限幅环节有关的非线性非光滑分叉理论。其次,介绍了直驱风机并网系统的限幅环节及其和限幅相关的次同步频段振荡现象。再次,分析了不同限幅环节对次同步频段振荡特性的影响,揭示了定子直流电压限幅环节饱和是导致系统振荡的原因。进一步,分析了短路比对系统振荡特性的影响,揭示了参数变化导致的非光滑分叉现象。最后,分析了交流故障持续时间、接地电阻对振荡的影响,揭示了初值导致的非光滑分叉现象。分析表明,直驱风机并网系统在故障清除后产生的次同步频段振荡,是在足够大的故障冲击下多个限幅环节共同作用产生的,数学上,也对应着相应的动力学系统发生非光滑分叉。
Recently,the oscillations with the interconnection of the large-scale renewable energy have received extensive attention.At present,the small signal model near the stable operation point,which ignores the nonlinear characteristics such as limits of converter,is very popular.In fact,the influence of the limits of the converter on the oscillation characteristics cannot be ignored under certain conditions.This paper reveals that one of the mathematical mechanisms of the subsynchronous band oscillation(SSBO)of the power system interconnected with direct-driven wind turbine is the non-smooth bifurcation related to oscillation limits with the phase portrait analysis.Firstly,the nonlinear non-smooth bifurcation theory related to the limits is introduced.Secondly,the limit links of the power system interconnected with direct-driven wind turbine and the subsynchronous frequency band oscillation phenomenon related to the limits is presented.And then,the influence of different limits on the characteristics of the SSBO is analyzed,and the phenomenon of saturation of the stator DC voltage limit is the main cause of the SSBO is revealed.Furthermore,the characteristics of SSBO with different short circuit ratios(SCRs)are analyzed and the non-smooth bifurcation caused by changing parameters is revealed.Finally,the effect of AC fault duration and grounding resistance on SSBO is analyzed,and the non-smooth bifurcation caused by caused by initial value is revealed.The analysis shows that the SSBO in the power system interconnected with direct-driven wind turbine after the fault cleared is induced by multiple limits with a sufficiently large disturbance,which causes large deviation from the stable equilibrium point.Mathematically,the occurrence of the SSBO is corresponding to the non-smooth bifurcation in the dynamic system.
作者
薛安成
王子哲
付潇宇
王嘉伟
乔登科
XUE Ancheng;WANG Zizhe;FU Xiaoyu;WANG Jiawei;QIAO Dengke(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources,North China Electric Power University,Beijing 102206,China)
出处
《电力系统自动化》
EI
CSCD
北大核心
2020年第7期87-92,共6页
Automation of Electric Power Systems
基金
国家重点研发计划资助项目(2017YFB0902000)
国家自然科学基金资助项目(51477050)。
关键词
直驱风机
限幅环节
非光滑分叉
振荡特性
交流故障
direct-driven wind turbine
limit link
non-smooth bifurcation
oscillation characteristic
AC fault
