Research And Design Of Small Current Electronic Current Transformer

With the rapid development of the national economy,the State Grid has higher and higher requirements on the voltage level and the capacity demand of the power system is increasing.Electromagnetic current transformer has exposed some serious shortcomings in the use process,which can not meet the requirements of power system to the direction of integration,digitization and intelligence.Therefore,some scholars have researched an electronic current transformer.It has the characteristics of high linearity,high precision,wide measurement range and good insulation.However,there are still some unsolved problems,such as low sensitivity and low accuracy in the measurement of small current.This paper studies these problems.Based on the research of electromagnetic theory,optoelectronic technology and signal processing technology,a novel electronic current transformer based on Rogowsi coil is proposed.Firstly,the design of Rogowski coil was researched,including the measurement principle of Rogowski coil,the analysis of two working states,the design principle,the optimization of coil structure and parameters,and the analysis of errors in the measurement process.Secondly,in the power part,the double guarantee scheme was choosed to ensure the stable power supply.A kind of current transformer was designed in the way of on-line acquiring-energy.In addition,in order to ensure the service life of the laser,the improved fuzzy PID algorithm was utilized to control the stable output power of the laser.Finally,the signal processing part includes following,amplifying,integrating,filtering,ADC and so on.The correctness and feasibility of current transformer design were verified by test.The power frequency test of 0 ～ 100 A small current was carried on the coil,and the average sensitivity of the coil is 0.592mv/a,which shows that it has high sensitivity,and there is a linear relationship between the actual output and input of the coil.The accuracy of the coil was verified by measuring the power frequency current.The measurement result showed that the current transformer can meet the requirements of 0.2 power frequency current measurement.Figure36;Table3;Reference 52...