Sharing용 ESS의 누설전류 발생 메커니즘 및 모델링에 관한 연구

Abstract

Contrary to a stationary ESS, a sharing ESS is movable and ought to be interconnected with distribution systems at many different locations, which means the reliability of safety for personnel and ESS facilities is essentially required. Especially, the leakage-current due to insulation degradation of customer facilities and load-unbalance may adversely influence batteries in sharing ESS depending on the grounding system of customers. Therefore, this paper presents mechanisms of the leakage-current occurrence by load-unbalance, insulation degradation of secondary lines and facilities, and stray-capacitance of IGBT in PCS of sharing ESS. And also, a modeling of the proposed mechanism is performed using PSCAD/EMTDC software to evaluate the characteristics of leakage-current in accordance with the causes of occurrence. As a result of the simulation with parameter analysis based on the above-mentioned modeling, it is found that the magnitude of leakage-current caused by switching operation of PCS is dependent on stray-capacitance of IGBT and is confirmed that inflow of leakage-current to batteries is occurred. Moreover, it is validated that the sharing ESS can be potentially influenced by the leakage-current inflow due to the unbalanced-load and insulation degradation at customer side, depending on the resistance ratio of cases of battery and PCS in sharing ESS.