摘要
随着中国交直流混联电网的快速发展,弱送端系统特征日益显著,构网型与跟网型变流器混合送出模式电压支撑优势显著,但直流故障受扰过程中系统功率动态交互过程尚不明晰。为此,首先分析常规跟网型变流器经基于电网换相换流器的高压直流输电(line commutated converter based high voltage direct current,LCC-HVDC)送出系统的局限性,阐明电压弱支撑下其在换相失败(commutation failure,CF)后易出现功率振荡,从而加深故障程度,导致后续换相失败的发生;其次,理论分析常规构网型变流器电流分配系数调控极限对应的电气量相量关系,揭示换相失败过程中构网型变流器存在电流限幅控制延迟退出的情况,进而造成暂态过电压抑制效果欠佳甚至进一步导致后续换相失败的发生。最后,提出换相失败时间尺度下的改进电流限幅故障穿越控制,并基于PSCAD/EMTDC平台,验证相关理论分析及控制策略的正确性和有效性。
With the rapid development of China's AC/DC hybrid power grid,the characteristics of weak transmission end systems are becoming increasingly prominent.The voltage support advantages of grid forming and grid following new energy hybrid transmission modes are significant.However,the dynamic interaction process of system power during DC fault disturbance is not yet clear.Therefore,this article first analyzes the limitations of conventional grid following converters sent out through line commutated converter based high voltage direct current(LCC-HVDC).It is revealed that under weak voltage support,power oscillations are prone to occur and thus deepen the fault depth after commutation failure(CF),leading to subsequent commutation failures.Secondly,this paper theoretically analyses the phase-volume relationship of electrical quantities corresponding to the regulation limit of the current distribution coefficient of conventional grid forming converters.It is also revealed that there is a delayed withdrawal of current limit control in the process of commutation failure in grid forming converters,which results in a poor inhibition of transient overvoltage and even leads to the occurrence of subsequent phase-change failure.Finally,the improved current limiting fault ride-through control under the time scale of commutation failure is proposed,and the correctness and effectiveness of the relevant theoretical analysis and control strategy are verified based on the PSCAD/EMTDC simulation platform.
作者
王彤
韩梓畅
王潇桐
王增平
刘崇茹
WANG Tong;HAN Zichang;WANG Xiaotong;WANG Zengping;LIU Chongru(State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University),Changping District,Beijing 102206,China)
出处
《中国电机工程学报》
北大核心
2025年第23期9239-9253,I0014,共16页
PROCEEDINGS OF THE CHINESE SOCIETY FOR ELECTRICAL ENGINEERING
基金
国家重点研发计划项目(2022YFB2402704)。
