Research On Transfer Characteristics Of Electronic Transformer Measuring Link

Because of characteristics of large dynamic range, strong anti-interference data transmission capability, high accuracy, good linearity type, the electronic transformer plays an important role in measurement and replay protection for modern power systems.The paper analyzes three common electronic transformers in recent years including Rogowski coil electronic current transformers, low-power electronic current transformers and FOCT all-optical current transformer. Based on the elaboration on structure and measuring principle of three electronic transformers, the paper studies and compares the sensing part and analog signal processing part of three electronic current transformers under different application conditions. The corresponding mathematical models of transmission characteristics are derived and the conditions of use for different modeling methods are also discussed. The paper further studies error impacts and transfer characteristics of three electronic current transformers. The impacts of electromagnetic parameters of electronic current transformers on the transfer characteristics are also studied.The paper introduces and analyzes quantitatively several common distortion waveforms in grid including high harmonic current, inter-harmonic current and impulse current. The further study on the distortion waveform distribution models of three electronic current transformers is also made. To analyze the influence of electronic current transformers structure parameters on the overall distribution model, the Simulink tool is used.Finally, in order to analyze three different electronic current transformers’ applicability in different situations, the characteristics of three different electronic current transformers are compared. The simulation results show that low-power electronic current transformers have a good linear response and large dynamic measuring range on unsaturated state, which makes low-power electronic current transformers have a good measurement on distortion waveform and most widely used. The measurement of Rogowski coil electronic current transformers on higher harmonic current has obvious attenuation and phase shift, which can be improved by optimizing structure parameters. The measurement of FOCT all-optical current transformer on common distortion waveforms is distortionless basically under ideal situations.