Temperature-Based Overload Evaluation in Low-Voltage Distribution Lines Considering PVs and EVs: Model Validation and Simulations

As photovoltaic systems (PVs) and electric vehicles (EVs) are introduced in residential houses, overloads of low-voltage distribution lines have become a significant problem. A promising approach to address this problem is temperature-based overload evaluation, which is expected to take place under variation in current and various weather conditions. In this study, we developed a thermal equivalent circuit model to evaluate the line conductor temperature of low-voltage distribution overhead cables. The thermal equivalent circuit model was verified by simulation using rated current and experimental results from an actual 600-V XLPE cable. Moreover, assuming EV charging load on a distribution line, the time constant of the step response can be evaluated as approximately 7 min for the aforementioned cable. Finally, using the proposed thermal equivalent circuit model, the low-voltage cable conductor temperature was evaluated under a line current presenting high fluctuations due to the high penetration of PVs.