Research On Nonlinear Characteristics Of Current Transformer And Impact On Energy Metering

With the development of science and technology and the development of the society,the power system has been greatly developed,and the smart grid has been well applied.Electric energy metering as a means of connecting power supply,power generation and electricity is the main factor to promote the development of smart grid.In today's electric energy metering system,power meter and the error of current transformer is inevitable,so the circuit components and power calculation method are optimized,affecting as much as possible the calculation of power and reduce the error.Based on the research of current transformer error of each theory,characteristics of its frequency characteristics,transmission is studied,which makes the nonlinear characteristic of current transformer the degree of effect on the calculation of power were quantified.Firstly,the corresponding theory of current transformer and the error,and the phase characteristics of current transformer are studied based on the non periodic component.The results show that the phase error of current transformer will increase with the increase of number of non periodic component,until it reaches the saturated state.Secondly,the frequency characteristic of the current transformer is studied through the combination of theory and experiment.The results show that the current transformer has a good linear relationship when the frequency range is close to 300 Hz,and the frequency characteristics of the current transformer can be improved to some extent by the change of the two side coil and the excitation impedance.Finally,the influence of external constant magnetic field on the transmission characteristics of the transformer is studied by adding a constant magnetic field outside the current transformer.The results show that with the increase of the magnetic induction intensity of the external magnetic field,the error of the current transformer will increase,which will affect the accuracy of the power calculation.Through these studies,the corresponding methods to reduce the measurement error of electric energy are summarized and analyzed.