An Online Monitoring Method for DC Busbar Electrolytic Capacitor Bank Based on Optimized Rogowski Coil Current Sampling

Distributed energy storage systems (DESSs) are now widely used in new energy generation technologies. In order to ensure the reliable and safe operation of the energy storage system, it is necessary to carry out online monitoring of its key connecting unit, the dc stacked busbar electrolytic capacitor bank. This article proposes a design method for an online monitoring system of electrolytic capacitor banks based on optimized Rogowski coil current sampling. Extracting the ripple current and ripple voltage of the electrolytic capacitor under high frequency in real time, so as to calculate the value of equivalent series resistance (ESR) of the capacitor, and realize the online monitoring of the working condition of the capacitor. First, in view of the high sampling accuracy requirements of electrolytic capacitor ripple current, the comprehensive consideration of the Rogowski coil winding turns and linewidth generated by its own impedance and self-inductance on the coil measurement accuracy, optimized the design of a high-precision, small-size, strong anti-jamming ability of printed circuit board (PCB) Rogowski coil, and connected two pieces of coils in series with opposite direction of winding to improve the current sampling accuracy of the coil. Then, based on this, the monitoring circuit devices, including embedded current sensor, ripple voltage sampling module, temperature measurement module, and self-power supply module, are designed. The lower computer processor and the upper computer display are designed by software to display the key values of capacitance and carry out reliability evaluation. Finally, the feasibility of the designed monitoring system is verified by experiments. Finally, the feasibility of the designed monitoring system is verified by experiments.