摘要
直流变压器在直流配电网中应用广泛,双有源桥(dual active bridge,DAB)作为其核心元件,在输出直流侧发生短路故障时会导致DAB内部开关管过流闭锁,降低了系统的故障穿越能力,同时对系统的故障恢复造成不良影响。对此,该文提出针对双有源桥低压侧双极短路后不闭锁的故障穿越方法,以提高系统的暂态可控性。通过在双有源桥内部的高频变压器副边串联电感,同时调节故障期间的移相比,增加了故障期间的可控性,减小开关管的电流应力,限制输出侧故障电流。上述方法使得DAB在故障期间能提供稳定的电气量特征,有利于直流配电网的故障识别和故障恢复。基于PSCAD/EMTDC软件对20k V/750V的直流变压器进行仿真,仿真结果验证了所提方法的正确性。
DC transformers are widely used in DC distribution networks,and the dual active bridge(DAB),as its core component,may cause overcurrent blocking of the internal switching tubes of the DAB when a short-circuit fault occurs on the output DC side.Such blocking reduces the fault ride-through capability of the system and adversely affects the fault recovery of the system.In this paper,we propose a fault ride-through method for the dual active bridge without latching after a bipolar short circuit on the low voltage side to improve the transient controllability of the system.By connecting inductors in series on the secondary side of the high-frequency transformer inside the dual active bridge,the shift compared to the fault period is regulated,increasing the controllability of the system during the fault.The current stress of the switching tubes is reduced,and the output-side fault current is limited.The above method enables the DAB to provide stable electrical quantity characteristics during faults,which facilitates the fault identification and fault recovery in the DC distribution networks.Simulations based on the PSCAD/EMTDC software are performed for a 20 k V/750 V DC transformer,and the simulation results verify the correctness of the proposed method.
作者
郑涛
朴勇
郭勇帆
杨乐
ZHENG Tao;PIAO Yong;GUO Yongfan;YANG Le(State Key Laboratory of Alternate Electrical Power System With Renewable Energy Source(North China Electric Power University),Changping District,Beijing 102206,China)
出处
《电网技术》
EI
CSCD
北大核心
2022年第8期3115-3122,共8页
Power System Technology
基金
国家电网公司科技项目(新能源电力系统超高速保护新原理及样机研制,SGNXDK00DWJS200189)。
关键词
直流变压器
双有源桥
故障穿越
无闭锁
DC transformer
dual active bridges
fault ride-through
no lockout
