Performance Assessment of Grounding System for Large-Scale Grid-Connected-Photovoltaic System Using the PEEC-MTL Hybrid Model

Abstract

This article proposes an efficient and refined simulation method combining partial-element-equivalent-circuit (PEEC) and multiple-transmission-line (MTL) model considering the effects of lossy ground to develop a large-scale grid-connected photovoltaic (PV) system. The concentrated complex wire-conductor structure, such as PV panels, dc line of PV, grounding grids, and power distribution towers, are modeled using PEEC, while the long-distance transmission lines, such as buried cables and overhead lines are modeled with MTL. Both the ac side and dc side of the system are simulated synchronously, and the influence of the ac system on the dc system, including surge protecting device (SPD) installation, and grounding configurations are discussed. It is noted that a direct lightning strike on the dc side poses a significant threat to the system. However, when considering the connection to the ac system, the risk of lightning-caused overvoltage is mitigated. Moreover, this overvoltage reduces as the number of PV panels increases. For safe operation, it is essential to incorporate grounding at both ends of the cable enclosure and establish equipotential bonding among various grounding electrodes.