Countermeasures for Mal-operation of Zero-sequence Differential Protection of Converter Transformer Under Inrush Current Condition [涌流工况下换流变压器零序差动保护误动对策]

作者：Weng H.; Guo Y.; Li H.^*; Wan Y.; Li Z.; Huang J.

来源：Automation of Electric Power Systems, 2020, 44(23): 143-149.

DOI：10.7500/AEPS20191216010

• Converter transformer
• Dynamic time warping (DTW) distance
• Magnetizing inrush current
• Recovery inrush current
• Zero-sequence differential protection

Aiming at the case of mal-operation of zero-sequence differential protection for the converter transformer in the high voltage direct current (HVDC) transmission project, this paper analyzes the phenomenon that the neutral-line zero-sequence current has a large amplitude and decays slowly under the recovery inrush current condition caused by removal of external faults and the inrush current condition caused by the energization of unloaded converter transformers, based on the HVDC simulation model using actual engineering parameters. By identifying differences in similarity characteristics between the waveforms of neutral-line zero-sequence current and the self-produced zero-sequence current under inrush current and internal fault conditions, this paper proposes a new criterion of the zero-sequence differential protection for converter transformers, based on the dynamic time warping (DTW) distance of zero-sequence current. The simulation and recorded cases show that the criterion has the same operation performance as the conventional zero-sequence differential protection in aspects of protecting range and transition resistance endurance ability during various internal faults. The false differential current caused by abnormal transmission of current transformers under the inrush current condition can be correctly identified, and the risk of mal-operation of zero-sequence differential protection can be reduced.

• 出版日期2020
• 单位三峡大学