直流偏磁与剩磁对计量用TA误差影响的研究

Study on the Influence of DC Bias and Remnant Flux on Error of Measuring Current Transformer

直流偏磁与剩磁的存在会改变计量用电流互感器(TA)在铁心磁化曲线上的工作点,直接影响电能计量与测量的准确性。提出了一种基于三参数正弦曲线拟合算法的比差、角差测量方法,并通过试验分析了直流偏磁与剩磁对计量用TA误差特性的影响。试验数据表明,直流偏磁与剩磁都会使比差和角差向着不同的方向增大,而且当直流偏磁与剩磁同方向同时存在时,误差将会远远超过规定的限值,导致电能计量与测量的结果出现较大偏差。

DC bias and remnant flux will change the measuring eurrent transformer （TA） working point in the core magnetization curve and have a direct impact on the accuracy of electric energy metering and measurement. An error measurement method based on the algorithm for three-parameter least squares fit to sine wave is put forward and the influence of DC bias and remnant flux on error characteristics of TA is also investigated through experiments. The experimental data shows that DC bias and remnant flux will increase the ratio error and phase displacement in opposite directions and the ratio and phase displacement will be far more than the limit value when they are exist in same direction at the same time . This will seriously affect the transmission accuracy of TA.