Research And Design Of A New Electronic Current Transducer Primary Converter

Because of no saturation under fault current conditions and high level of insulation, Electronic Current Transformer (ECT) has been considered as the appropriate substitute of the traditional electromagnetic current transformer. However, the unsolved problems are in the way to ECT's practicality up to the present time. The major reasons are the influencing factors, such as ambient temperature and electro -magnetic interference, which decrease the measurement precision and stability of ECT and baffle its application in power industry. This thesis focuses researches on electronic current transformer's sensor technology.Being a foundation of electronic current transformer, the principles of ECT current sensor based on Faraday mageto-optical effect and Rogowski coil are investigated and described. The ECT's basic construction and present research situati -on are summarized, including the unsolved major problems existing in electronic current transformer's sensor technology.The ECT's structure was analyzed. Based on knowledge of electromagnetic theory and electromagnetic field analysis software, the ECT's principle of working, sensing and anti-interference, as well as related anti-interference measures, stable and transient performance, were discussed in details. Because the mutual inductance coefficient is an important parameter to measurement performance, theoretical analysis is derived for the mutual inductance's calculation, systematically and in details. The ECT's mathematical model was established. Through detailed and theoretical analysis, the calculations of the ECT's structure parameters, such as internal resistance, self-inductance, were presented. The new ECT's stable and transient performances were also considered and analyzed. Theoretical analysis shows that the new type of current transformer can meet the requirements and achieve high-precision measurements. To further improve the new ECT's performance, the impact factors on performance, as well as corresponding measures, were analyzed. To improve the overall performance of the PCB spiral air coil, the structural optimization was used for the new Electronic Current Sensor. The structure of the primary conductor was adjusted for the different requirements, such as utility for protecting and measuring devices. A preliminary design optimization was also adopted in the integration circuit. By the above performance analysis and optimization, a prototype and a complete integration circuit were made and tested, theoretical calculation analysis and simulation were also presented. Theory analysis and experiment data indicate that the principle of this new type current transducer is correct. The ECT is simple in structure, accurate in measurement; and has good linearity, strong anti-interference ability, fast transient response. This new type ECT can be used in different voltage classes, and be worth promoting in the future.