直流偏磁对测量用CT影响及补偿方法的研究
申路，裴东锋，未超，姜艳丰
（国网邯郸供电公司，河北 邯郸 056000）
摘 要：直流偏磁会改变测量用电流互感器(CT) 的传变特性，直接影响电能计量与测量的准确性。分析了直流偏磁的产生机理，根据测量用CT 的等效电路建立起仿真电路，研究了直流偏磁对测量用CT比差、角差及励磁电流的影响。结果表明直流偏磁的存在会使比差、角差向着不同方向增大，并会引起励磁电流增大、波形正负半周不对称、偶次谐波增加，严重影响CT 的传变精度。提出了一种减少测量用CT 计量与测量误差的补偿方法，仿真验证了该方法的有效性。
关键词：测量用电流互感器；直流偏磁；励磁电流；比差；角差；补偿
中图分类号：TM452 文献标识码：A 文章编号：1007-3175(2017)03-0023-05
Research on Influence of Direct Current Magnetic Bias on Measuring Current Transformer and
Its Compensation Measures
SHEN Lu, PEI Dong-feng, WEI Chao, JIANG Yan-feng
（State Grid Handan Electric Power Supply Company, Handan 056000, China）
Abstract: Direct current (DC) bias will change the current transformer (CT) transfer characteristics and has a direct impact on the accuracy of electric energy metering and measurement. Analysis was made to the formation mechanisms of direct current magnetic bias. This paper established the simulation circuit according to the equivalent circuit of measuring CT and researched the influence of DC magnetic bias on ratio error, phase displacement and exciting current of measuring CT. The results show that DC magnetic bias will increase the ratio error and phase displacement in opposite directions, making the exciting current increase, the waveforms plus or minus semi-cycle asymmetry, a lot of evenorder harmonics generate, which seriously affects the transmission transformer accuracy of CT. A kind of compensation method was proposed to reduce measuring CT computation and measuring errors. The simulation verifies the validity of this method.
Key words: measuring current transformer; direct current bias; exciting current; ratio error; phase displacement; compensation
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