Analysis of Electromagnetic Transient Overvoltages of PV Systems Considering Frequency Dependence of Grounding System

Photovoltaic (PV) systems are susceptible to lightning strikes. In this paper, a new accurate and efficient electromagnetic transient (EMT) model of grounding systems (GSs) is presented. The proposed approach considers the impact of frequency-dependent (FD) modeling of GSs on the overvoltage values in PV systems in time domain analysis. The proposed wide-band model is significantly accurate for various types of GSs (single-port and multi-port GSs) and models the frequency dependence of the soil electrical parameters based on experimental data (conductivity and relative permittivity). The proposed model can be implemented in time domain without any GS impedance matrix inversion, so it has less complexity compared to previous approaches. Most of the existing studies suffer from low accuracy in the PV system modeling during lightning transients because of neglecting the effects of the mounting system, metal frame, and mutual coupling, which are considered in the present work. The results demonstrate that the PV factors and frequency dependence of soil have a great effect on the PV system overvoltages. The proposed model offers improved accuracy by covering the entire frequency range of interest. Additionally, it takes into account the mounting system, metal frame, and mutual coupling in EMT analysis.