Partial Power Processing DC Current Source for The Loop Resistance Measurement in Gas Insulated Switchgear

For gas insulated switchgear (GIS), the loop resistance is a good indicator of the health status, which can be measured with dc voltage drop method. Usually, large dc current is demanded for the measurement due to the small loop resistance, and hence a bulky power electronics converter is needed. Aiming to obtain high power density and low cost, this paper proposes a partial power processing dc current source as a substitution for the conventional one. Because only part of the power is transferred through the converter and the rest is directly delivered from the input to the output, the power ratings of active/passive components are much decreased in the proposed scheme. Therefore, it is very attractive for the condition monitoring of GIS. In the paper, a practical partial power processing dc current source based on the current-fed full-bridge converter is firstly proposed. Afterwards, its operational principle, performance characteristics and design considerations are analyzed in detail to achieve a comprehensive understanding. Finally, the corresponding simulation results with 24V input and IOOOA output current are also demonstrated to verify the effectiveness and advantages of the proposed solution.