Design And Research Of Standard Metering Device Of 60ka Heavy Direct Current

Heavy direct current (DC) has a wide range of application including 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.10-107). 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.This thesis introduced the hardware design of the whole standard metering device of 60KA heavy direct current, including magnetic modulator, feedback winding loop and bias winding loop.Attention was paid to the feedback winding loop, including filtering link, AC amplifying link, phase sensitive demodulation, DC amplifying link and power amplifying link.Meanwhile, it also talked about the design of bias winding loop, including power amplifying link, ripple suppressing circuit, and the power resource which provide power to the bias winding loop.After introducing the hardware design, this thesis also made deep analysis of the key technologies of the linear high power amplifier used in the bias winding loop. It described the problems of limitations of voltage and current, and the maximum dissipation power of linear high power amplifier. This thesis also talked about the selection of the linear high power amplifier of the bias winding loop in the last step.After making a preliminary seletion of the type of the linear high power amplifier, we got the thermal resistance and corresponding temperature rise when the device is operated by calculating the maximum dissipation power.,and set proper radiator and fan.Then it is verified that linear high power amplifier BUT34 can operate in safe operation area (SOA), and second breakdown will not happen.At last, This thesis discussed the essential protection measures when the linear high power amplifier is operating, including selecting proper current-limiting resistance, and protecting diodes between the input terminal and output terminal of the linear high power amplifier.The system can be verified that it can keep dynamic stability when oprating by the tool of Matlab/Simulink, and have a high presicion which can meet the demand of hardware design of the standard metering device of 60KA heavy direct current.