换相失败故障下的高比例新能源送端系统暂态电压-频率动态耦合机理分析OA

[Objective]Aiming at the new challenge of unclear transient voltage and system frequency operation risks faced by sending-end power systems with a high proportion of renewable energy after commutation failure,this paper reveals the dynamic coupling mechanism between transient voltage and frequency at the sending end.This study provides a theoretical foundation for the stable operation of sending-end systems with high-penetration renewable energy.[Methods]A simulation model of a sending-end system with a high proportion of renewable energy is established based on DIgSILENT/PowerFactory.First,the dynamic coupling law of active power transmission and reactive power consumption of the rectifier during commutation failure is analyzed.Based thereon,the impact of renewable energy fault ride-through characteristics on the imbalanced power of the sending-end system is investigated.Second,considering the influence of the changing renewable energy grid-connected proportion on the system inertia constant and node short-circuit capacity,the dynamic coupling law of transient voltage-frequency,with transient voltage as the conduction path,is revealed.[Results]As the system strength gradually decreases with the increase of renewable energy output,the fault coupling characteristics of"low voltage-high frequency"and"high voltage-high frequency"at the sending end after commutation failure become increasingly severe.It is verified that low-voltage ride-through of renewable energy helps suppress frequency rise,although the recovery process of low-voltage ride-through is unfavorable for the frequency to recover from high frequency to power frequency,while high-voltage ride-through is beneficial for frequency recovery.[Conclusions]This paper reveals the voltage-frequency fault coupling characteristics of sending-end systems with a high proportion of renewable energy,where transient voltage acts as the conduction path after commutation failure.Furthermore,an outlook and analysis on suppression technologies for transient voltage-frequency operation risks in such systems are provided.