基于协同控制的级联型电力电子变压器备用交流短引线故障检测及安全投入方案  

Fault Detection and Safety Investment Scheme of Power Electronic Transformer with Cascaded H-Bridge Backup AC Short Lead Based on Cooperative Control

作　　者：郑涛 郭勇帆 杨毅 Zheng Tao;Guo Yongfan;Yang Yi(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Source North China Electric Power University,Beijing 102206 China)

机构地区：[1]新能源电力系统全国重点实验室(华北电力大学),北京102206

出　　处：《电工技术学报》2025年第8期2668-2678,共11页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金联合基金资助项目(U2166205)。

摘　　要：级联型电力电子变压器(CHB-PET)可实现交直流微电网、储能装置等可再生能源和直流负荷的柔性互联。针对某实际工程中CHB-PET通过互为备用的两条交流短引线接入不同母线段的场景,考虑CHB-PET交流短引线发生故障后,备用短引线需快速投入,以实现CHB-PET供电的快速恢复。但常规方案无法判别备用短引线投入时是否存在故障,存在将故障短引线接入的风险。针对此问题,该文提出一种基于CHB-PET与直流微电网协同控制,并主动注入特征电压以实现短引线安全投入的方案。故障发生后,首先闭锁CHB-PET的输入级以实现故障隔离;其次切换±375 V直流微电网所连接的储能装置为直流电压控制,维持±375 V直流母线电压稳定以及直流微电网负荷等装备的正常运行;然后解锁CHB-PET的输入级并切换为定U/f控制,向备用短引线注入特征电压来检测是否存在故障点,并进一步提出一种计及电流不平衡因子的故障检测方法,减少故障检测所需时间,从而实现备用短引线的快速安全投入;最后,利用PSCAD/EMTDC仿真平台和半实物硬件在环实验平台验证所提出方案的可行性和有效性。Power electronic transformer with cascaded H-bridge(CHB-PET)can realize the flexible interconnection of AC/DC microgrid and renewable energy sources such as energy storage devices and DC loads.In a practical project,CHB-PET is connected to different bus segments through two short leads that are standby for each other.Considering the fault occurring AC side of CHB-PET,the spare short lead needs to be put into operation quickly to realize the rapid recovery of power supply.However,the conventional scheme cannot distinguish whether there is a fault before the spare short lead is put into operation,and there is a risk of connecting the faulty short lead.To solve this problem,this paper proposes a scheme based on the cooperative control of CHB-PET and DC microgrid,which achieves safe input of short leads by actively injecting characteristic voltage.Firstly,CHB is blocked to achieve fault isolation after fault occurring.The energy storage device is switched to DC voltage control mode,maintaining the DC bus voltage and ensuring the normal operation of DC microgrid load and other equipment.Secondly,CHB is unlocked and switched to the U/f control.CHB-PET can inject characteristic voltage into the spare line to detect whether there is a fault point in the line.Furthermore,a fault detection method considering the current imbalance factor is proposed to reduce the time required for fault detection,so as to realize the rapid and safe investment of spare short lead.The verification results on PSCAD/EMTDC simulation platform show that the scheme based on characteristic voltage injection can give accurate detection results when the spare line is fault-free.When three-phase fault,phase-phase fault,double-phase to ground fault and single-phase to ground fault occur in the spare line,the transition resistance of the phase-to-phase fault is 200Ω,and the transition resistance of the ground fault is 300Ω.The proposed scheme can also give accurate detection results.Through the simulation verification and experimental verification of

关 键 词：故障检测 级联型电力电子变压器 主动注入 协同控制 

分 类 号：TM771[电气工程—电力系统及自动化]