Research On Temperature Characteristic And Compensation Method Of Embedded Current Transformer

Current transformers are affected by many factors during actual operation,including the length of work and the surrounding environment at work.Changes in the working environment temperature will cause the measurement accuracy of the current transformer to change,resulting in the secondary side of the transformer connection measurement or relay protection device malfunction.This thesis briefly introduces the basic working principle of current transformer,analyzes the main causes of transformer error caused by theoretical knowledge and the related preventive measures.The change of temperature leads to the change of the magnetic permeability of the core of the current transformer,which causes the current transformer to produce the error.At the same time,the change of the temperature will change the resistance of the copper winding and affect the error of the current transformer.Due to the impact of temperature,the secondary side of the integral resistance value will change due to changes in temperature.It can be said that the temperature of the electromagnetic current transformer of this effect is called temperature affect the exact characteristics.In order to compensate for the error of the electromagnetic current transformer caused by the temperature,two kinds of compensation methods based on different methods are introduced in this thesis.The temperature has an important effect on the traditional electromagnetic current transformer.In different ambient temperature,the current transformer core permeability and the secondary winding and integral resistance of the resistance will change to varying degrees,resulting in reduced accuracy of the transformer,resulting in errors,resulting in the secondary side connection Of the relay protection device action is not timely or malfunction or even refused to move.In this thesis,the finite element method is used to simulate the temperature characteristics of the current transformer.Based on the experimental results,the secondary current curve of the electromagnetic current transformer is operated at room temperature and the temperature of the thermostat.And then use the Lagrangian interpolation method to interpolate,fitting out the basic expression of temperature and primary current,and compare with the actual measured value.It is found that with the increase of temperature,the secondary current of the transformer is decreasing,and it is linear in a certain temperature range,and it is in a non-linear working state beyond this temperature range.In addition to the mathematical method of fitting the curve,but also with a positive temperature coefficient of the thermistor in the original transformer integral resistance,through the form of integral circuit to determine the temperature in different temperature thermistor resistance,so that the output The signal is more accurate.There are many ways to carry out temperature compensation.This thesis introduces the Lagrangian interpolation method and the compensation method based on the integral hardware circuit.