| 摘要: |
| 电力系统继电保护装置的动作正确性在很大程度上取决于故障电流转变的准确性。通过电力系统保护用电流互感器等值电路分析了由于激磁电流和铁损的存在造成电流互感器比值差和相角误差产生的原因，研究了传统交流励磁特性测试法、低频电源测试法和直流饱和法的测试方法，并对比了3种方法的优缺点。结合某500 kV变电站电流互感器励磁特性测试实例给出了电流互感器10 % 误差曲线的绘制方法，进行了负载校核，给出了二次负载不满足要求时的改进措施。分析了电流互感器饱和对母线差动保护及线路零序电流保护误动作的影响，得出了应在电流互感器选型及二次负载校核等方面采取措施以减小对保护误动作影响的结论。 |
| 关键词: 励磁特性 低频 饱和 差动保护 |
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LI Bingyu, 郝晓光
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Hebei Electric Power Research Institute，Shijiazhuang 050021，China
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| Abstract: |
| The correct operation of relay protections largely depends on the correct detection of fault current in power system. The factors causing CT ratio and phase errors by excitation current and iron loss are analyzed based on the equivalent circuit of protective CT. Three test methods，traditional AC excitation characteristics test，low-frequency power supply test and DC-saturation test，are studied and compared. Combined with the excitation characteristics test in a 500 kV station，the plotting method of CT 10 % error curve is given，the load is checked out，and the improvement measures are given when the secondary load does not meet the requirements. The influence of CT saturation on bus differential protection and zero -sequence current protection are analyzed. Countermeasures，such as CT type selection and second load checkout，should be taken to lessen the impact on the proper performance of protections. |
| Key words: excitation characteristics low frequency saturation differential protection |
