| 引用本文: | 吴大立,尹项根,张哲,鲍凯朋.基于负序电流判别的变压器差动保护零序电流自动补偿方法[J].电力自动化设备,2007,27(2):28-31 |
| .Zero-sequence current automatic compensation of transformer differential protection based on negative-sequence current[J].Electric Power Automation Equipment,2007,27(2):28-31 |
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| 摘要: |
| 对于星形/三角形(Y/d)连接组的变压器,形成差动量一般采用2种转角方式:Y侧电流移相转角(Y→d)和d侧电流移相转角(d→Y)以实现二次电流的幅值和相位校正.为了避免中性点直接接地侧外部单相接地短路时差动保护误动,2种转角方式都消去了差动电流中的零序分量,但因此降低了差动保护反应内部单相接地短路和匝间短路的灵敏度.直接利用中性点零序电流对差动电流进行自动补偿可以兼顾区内外接地短路时保护的可靠性与灵敏度,但实际上由于三相电流互感器(TA)与中性点零序TA的不同型问题,也可能导致差动保护的误动.研究表明,充分利用变压器各侧负序电流在区内外接地短路时的不同相位特征,可以对差动电流进行零序电流的自动补偿,既提高了区外接地短路时保护的可靠性,又保证了区内接地短路时保护的灵敏度不会降低.该方法无需增加额外的零序TA二次接线,也避免了零序TA极性校验问题. |
| 关键词: 变压器保护 差动保护 零序电流 相位校正 |
| DOI： |
| 分类号:TM772 |
| 基金项目: |
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| Zero-sequence current automatic compensation of transformer differential protection based on negative-sequence current |
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WU Da-li YIN Xiang-gen ZHANG Zhe BAO Kai-peng
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| Abstract: |
| For power transformer with Y/d connection,two current compensation methods of Y d and d Y are usually used in differential protection to revise magnitude and phase angle.Both methods remove the zero-sequence component of differential currents to avoid protection misoperation during external single-phase earthing fault at neutral point solid ground side,but lower its sensitivity for internal single-phase earthing fault and inter-turn fault.Direct using neutral point zero-sequence current to automatically compensate differential current may coordinate protection reliability and sensitivity for both internal and external earthing faults,but the type difference between three-phase current transformers and neutral point current transformer may cause protection misoperation.The analysis shows that,the negative-sequence currents at different transformer sides have differential phase features during external and internal earthing faults,which may be used to automatically compensate differential current,ensuring protection reliability during external earthing fault,and increasing protection sensitivity during internal earthing fault.Moreover,the neutral point current transformer and its polarity check are not involved in the method. |
| Key words: transformer protection differential protection zero- sequence current phase adjustment |
