摘要
基于电网换相换流器的高压直流输电故障后的动态恢复过程与交直流系统间的无功交换强相关,持续的无功交换过程往往伴随着换相电压持续波动,进而可能引发后续换相失败。基于此,提出采用闭环反馈控制的无功控制方法以降低后续换相失败的风险。首先,利用实时仿真分析了采用典型低压限流(VDCOL)控制的直流系统故障恢复过程与无功交换的关系。其次,利用交直流系统的无功功率特性方程以及隐函数存在定理,分析了直流电流分别与无功交换和关断角之间的微增量关系,并据此提出无功反馈控制结构。然后,提出了用来替代VDCOL的直流电流实时计算方法,该方法同时考虑了无功交换平衡和定关断角二维约束,并通过闭环控制抑制了干扰偏差,控制精度更高。最后,仿真结果表明,所提方法可以减小直流系统发生后续换相失败的概率,改善系统的恢复性能。
The dynamic recovery process after line commutated converter based high voltage direct current(LCC-HVDC)transmission failure is heavily dependent on the reactive power exchange between AC and DC power grids.The continuous reactive power exchange process is often accompanied by continuous commutation voltage fluctuations,which may cause subsequent commutation failure(SCF).To deal with this issue,this paper proposes a reactive power control method using close-loop feedback control to mitigate the SCF risk.Firstly,the real-time simulation is used to analyze the relationship between the fault recovery process and the reactive power exchange for the DC system using typical voltage dependent current order limitation(VDCOL)control.Then,using the reactive power characteristic equation of the AC/DC system and the existence theorem of the implicit function,the micro-incremental relationship between the DC current and the reactive power exchange or extinction angle is analyzed,and the reactive power feedback control structure is proposed accordingly.Furthermore,a real-time DC current computation method instead of VDCOL is proposed.This method considers the two-dimensional constraints of the reactive power exchange balance and the constant extinction angle,and suppresses the interference deviation through closed-loop control to achieve higher control accuracy.Finally,the simulation results prove that the proposed method can reduce the probability of the SCF in the DC system and improve the system recovery performance.
作者
汪家铭
徐谦
戴攀
王冠中
沈广进
辛焕海
WANG Jiaming;XU Qian;DAI Pan;WANG Guanzhong;SHEN Guangjin;XIN Huanhai(College of Electrical Engineering,Zhejiang University,Hangzhou 310027,China;Economic Research Institute of State Grid Zhejiang Electric Power Co.,Ltd.,Hangzhou 310006,China)
出处
《电力系统自动化》
EI
CSCD
北大核心
2021年第12期101-108,共8页
Automation of Electric Power Systems
基金
国网浙江省电力有限公司科技项目“基于动态负荷特性改造的特高压直流多馈入系统连续换相失败防御协调规划研究,5211JY180017”资助。
关键词
高压直流输电
交流故障恢复
无功反馈控制
后续换相失败
闭环控制
high-voltage direct current(HVDC)transmission
AC fault recovery
reactive power feedback control
subsequent commutation failure
closed-loop control
