LI Chunyan, HUANG Huimin, ZHAO Chenxi, et al. Improved protection method for modular multilevel converter-based DC transformers using DC modulation ratio compensation[J]. Power System Protection and Control, 2026, 54(20).
LI Chunyan, HUANG Huimin, ZHAO Chenxi, et al. Improved protection method for modular multilevel converter-based DC transformers using DC modulation ratio compensation[J]. Power System Protection and Control, 2026, 54(20).DOI: 10.19783/j.cnki.pspc.260288.
基于直流调制比补偿的模块化多电平换流器型直流变压器改进保护方法
摘要
采用负压控制实现模块化多电平换流器型高压直流变压器(modular multilevel converter based high voltage direct current transformer
The application of negative-voltage control for fault ride-through (FRT) of modular multilevel converter-based high-voltage direct-current transformers (M-HVDCTs) may cause misoperation of conventional DC current derivative protection and reduce the sensitivity of leakage current protection. To address these issues
an improved protection method based on DC modulation ratio compensation is proposed for M-HVDCTs. First
the DC fault characteristics of M-HVDCTs are analyzed
and the necessity of adopting negative-voltage-control-based FRT strategy is demonstrated. Then
the influence law of FRT control on fault current characteristics is investigated
revealing that the polarity reversal of the DC current derivative and the reduction of leakage current under FRT conditions degrade the reliability and sensitivity of conventional protection. Subsequently
a compensation method based on the DC modulation ratio is proposed to correct the characteristics of the current derivative and leakage current
thereby restoring the effectiveness of the protection criteria. Finally
a DC system based on an M-HVDCT is established in the PSCAD/EMTDC platform to verify the performance of the improved protection method under FRT conditions. The results demonstrate that the proposed method eliminates the adverse effects of FRT control on conventional protection
improves protection reliability and sensitivity
requires no additional hardware
and features simple implementation and high reliability.
关键词
Keywords
references
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