电流互感器的误差分析与工程计算

电流互感器的正确传变,是继电保护装置正确工作的前提,工程实际中经常需要对电流互感器误差作定量的评估或确切的计算。通过对电流互感器稳态误差特性做物理与数学上的分析,可知电流互感器稳态误差主要来自其励磁阻抗的非线性。建立了以非线性方程组描述的电流互感器误差数学模型,在此基础上对电流互感器误差计算、伏安特性曲线绘制、10%误差特性曲线的绘制以及在给定的短路电流下允许最大负荷阻抗的计算等作了原理与方法上的研究与探讨。上述工作可以通过计算机完成,文中结合工程应用介绍了使用Matlab软件的电流互感器误差特性计算机解法。

Error analysis and engineering calculation of current transformer

Proper transform of CT(Current Transformer) is the precondition for the proper operation of protective relays.Quantitative evaluation or exact calculation of CT error is always necessary.Based on the physical and mathematical analysis,the static error of CT is found mainly from the nonlinearity of its exciting impedance.Mathematical model of CT error is represented by nonlinear equations,based on which,the CT error calculation,volt-ampere characteristic curve drawing and 10 % error characteristic curve drawing,permitted maximal load impedance calculation with given short-circuit current are discussed in principle and methodology.All these can be done with computer.Combined with an engineering application,the computer solution using Matlab is introduced.