A Method Based on A Supercapacitor Energy Storage System to Overcome the Switching Overvoltage in LVDC Systems with Constant Power Loads

Abstract

Abstract This paper presents a novel method to mitigate the overvoltage transients caused by the circuit breaker operation in the low voltage DC (LVDC) systems. This method is based on using the existing supercapacitor energy storage system (ESS) in the DC grids to limit the switching overvoltage within the standard range. The supercapacitor sizing is performed with considering instability problems of the constant power loads (CPLs) and the boundary between underdamped and overdamped modes. Firstly, a simplified DC system is considered and the analytical expressions are presented to determine the boundary values of the supercapacitor. Effects of the system parameters on the allowable range of the supercapacitor are also discussed. Then, an approach is introduced to determine the boundary values of the supercapacitor for more detailed models of the LVDC systems. This approach applies SimPowerSystems and Control System Toolbox of the MATLAB software. Finally, the effectiveness of the proposed method is verified using simulation.