ZHENG Tao,GUO Xingchao,HU Xin,et al.Fault inrush current generation mechanism of inverter-side converter transformer and its influence on differential protection[J].Electric Power Automation Equipment,2019,39(09):39-45.
ZHENG Tao,GUO Xingchao,HU Xin,et al.Fault inrush current generation mechanism of inverter-side converter transformer and its influence on differential protection[J].Electric Power Automation Equipment,2019,39(09):39-45.DOI: 10.16081/j.epae.201909015.
Fault inrush current generation mechanism of inverter-side converter transformer and its influence on differential protection
Since fault inrush current of converter transformer may be initiated by the grounding fault at valve side of inverter side of UHVDC system,the difference of valve bridge on-off condition with fault at converter bridge of different voltage levels and at different times is discussed,the fault current characteristics at valve side after commutation failure are analyzed,and the generation mechanism and characteristics of fault inrush current at inverter side are described. On this basis,the operation characteristics of conver-ter transformer differential protection considering the influence of fault inrush current are analyzed. Research results show that the fault inrush current may cause mal-block of differential protection at the transition of out-zone fault to in-zone fault of converter transformer,aiming at this problem,a novel solution scheme to prevent mal-block of differential protection is proposed according to the characteristics of polarity reversal of valve side DC component when fault occurs. Simulative results on PSCAD/EMTDC verify the correctness of theoretical analysis.
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