Electronic Current Transducer Based On Rogowski Coil

For a long time, current transformers (CTs) are important components for current measurement and relaying protection in power system. When traditional electromagnetic type CTs are used for measurement and protection, the problems of their magnetic path saturation always disturb people. With the development of the computerized and digital technology of measurement and protections devices, the devices don't match with CTs of big output power. Thus electronic current transformers (ETA) based on Rogowski coil with the advantages of small output power, simple construction and ideal linearity attract people's attention and come into extensive research. From basic concept of CT, this paper introduces the principle of traditional electromagnetic type CT and new developing tendency for current measurement, and compares ETA based on Rogowski coil with traditional electromagnetic type CT and LPCT to emphasize their advantages for measurement and protection. Then this paper analyses the principle that Rogowski coil is used to measure currents, constructs different application models varying from different application occasions and uses several authors' experiment results to verify the validity of theory models. Through optical fiber transmitter system, from high voltage system to low voltage system, this paper adopts TMS320C32 to design hardware circuit, and thus utilizes powerful calculation ability to satisfy the requirements of network, such as level of automation, security, reliability and so on. Because ETA based on Rogowski coil is newly born, the author explores various elements that affect experiment errors and relative problems that affect the design of Rogowski coil and precision increase, and puts forward the methods to solve these problems, such as adopting V/F conversion and active integral amplifier to improve the precision, amplitude-frequency characteristic when measuring big current, the methods of measuring small current, the design of inside insulation construction, interface problems, anti-jamming problems and so on.