A 60kA Dual-Loop Self-Balancing Direct Current Comparator

Heavy direct current (DC) has been wide used in power system, electrolysis industry and many other industries. With the development of the application of heavy direct current, the requirements of the standard metering device of heavy direct current become much stricter. It is more and more eager to develop a new type of standard metering device, which have larger measuring range, higher precision, and stronger anti-interference ability.This thesis is based on the special research project of public welfare industry of general administration of quality supervision, inspection and quarantine——research of standard metering device of heavy direct current(No.200710-107). We proposed the method based on the principle of current comparator including the magnetic modulator after researching several measuring methods of heavy direct current. This device consist of feedback winding loop and bias winding loop, which can get self-balancing by automatic feedback system.First,the thesis introduced the working principle of the whole standard metering device of 60KA heavy direct current, then it introduced the working principle of magnetic modulator and dual-Loop self-Balancing principle of feedback winding loop and bias winding loop. After that,the thesis discussed the hardware design of the whole device ,including magnetic modulator, feedback winding loop and bias winding loop .Attention was paid to the bias winding loop, including the circuit of crude regulation and accurate adjustment, and the power resource which provide power to the bias winding loop.After introducing the working principle and hardware design, this thesis also made deep analysis of the key technologies of the device which we met in debugging the feedback winding loop and the bias winding loop. It discussed the problems of feedback winding loop : How to keep the device stably and reliably running ; How to reduce the zero value; How to keep the stable of zero value; How to improve the S of the device; How to improve the precision of the device. The thesis also talked about the methods how the bias winding loop precise and automatic tracked the measured current.Then this paper introduced the self-calibration methods of the standard metering device. Through comparing with a variety of existing standards system ,and analysis the error and uncertainty of the test data, we can conclude that the device has a high precision which can meet the demand of hardware design of the standard metering device of 60KA heavy direct current.