Research On Saturation Characteristic Of Current Transformer And Its Influence Factors

The current transformer converts high current to small current by the core material Ampere-turns ratio. It is mainly used in two aspects, one is used for current measurement in power system, achieving current monitoring and electrical energy metering and charging; another is used for sampling the running current when the power system is abnormal, then supporting protection system could response timely and make effective protection action. The over-current, load change and non-periodic component influence all will cause the current transformer error increase and even saturation, resulting in transformed current waveform defect. For the energy metering and charging, the defect waveform will result in large economic loss whether it is electricity grid or high electricity company; for the power system protection, it will lead to the protection system fail, resulting in partial paralysis of power network, and even large scale power outage, causing a tremendous impact on industrial and agricultural production and living electricity. I work in Tianjin metrology institute, which is responsible for current transformers legally compulsory verification in highest public measurement standards in Tianjin and provincial current transformer, in order to ensure value transfer accurate and reliable, type evaluation comprehensive and effective, it is important to research and analysis current transformer saturation characteristic.This paper started with analyzing the current transformer structure and error sources, studied the impact of the error Influence quantity on the saturation characteristics, and analyzed the current transformer saturation characteristics in different states. Finally, the theoretical analysis of the steady-state saturation was verified in the process of laboratory tests, and transient saturation process was simulated by PSCAD / EMTDC software when current transformer was short circuit.The issue analyzed current transformer saturation component in theory and explored the impact of different parameters on measurement error and saturation levels in the form of test and simulation, providing data support for researching on current transformer saturation. It not only promoted law measurement and type evaluation in our institute, but also provided technical assistance for current transformer manufacturer and user.