For the Ground grid proposal for photovoltaic parks, A groundbreaking improvement in the configuration of grounding grids for protection against direct lightning strikes in photovoltaic parks is proposed. Existing grids in some parks involve two rings of horizontal electrodes connected to metallic structures supporting solar panels. Simulation results illustrate the proposed changes, demonstrating a significant reduction in transient potentials, mainly when introducing a discharge at node 1. The maximum potential value at the discharge node is approximately 24kV, less than half of the previous configuration. Potentials decrease as they penetrate the park, reaching values below 2kV. Given the considerably lower transient peaks, these substantial differences underscore the importance of reinforcing surge protection elements.
FOTOPROT is introduced as a sophisticated technical tool featuring a graphical interface. With robust calculation capabilities, FOTOPROT enables the inputting of crucial data for PV farm design and calculates the necessary mast system for installation protection. The application facilitates a graphical representation of the mast layout and resulting protection areas. Combining calculation and visualization functionalities provides a comprehensive solution for planning and optimizing PV farm protection against adverse events, ensuring efficiency and safety.
The theoretical foundation of FOTOPROT described in this segment is based on the Electrogeometric Model. According to this model, the impact distance of a beam, which is the distance over which the stepped guide is attracted to impact a target, is directly proportional to the charge density of the stepped guide. In addition, the current in the subsequent return discharge is proportionally related to the charge density of the preceding guide, this return current being a measurable parameter.
When protection is implemented using a simple mast, the attraction area is configured as a sphere segment above the earth attraction area, as depicted in Figure 1. In this case, an impact occurs if the discharge passes through this spherical segment.
Figure 1. Attraction area and protection
zone of a single mast.
Figure 2. Rectangular area protected by
four masts.
To protect a rectangular area with dimensions of width (As) and length (Ls), vertical masts and rows of masts covering the designated area are used. In this scenario, the width between two rows of masts (Am) equals the width of the active bar structures, plus twice the minimum distance between the functional parts and the grounded objects, i.e. AS + 2 Sb. The distance between two adjacent masts of the same row (Lm) is illustrated in Figure 2, where four masts are used to protect the area.
To completely protect the rectangle (Ls As), the spheres must cover the entire area, implying that the radius rf circles must overlap without leaving space between them. However, there are other conditions for complete protection. The section below point A in the figure, where the two diagonals intersect, represents the masts' furthest point within the protected area. At this point of interception, which is closest to the ground plane, the height of the area of attraction provided by the mast at point A must be greater than the area of attraction of the ground plane [12].
Computational applications represent an efficient tool to expedite calculations in solving specific problems. GMAT's use in ground grid design and transient potential analysis against atmospheric discharges reveals notable disparities between the installed and proposed models, showcasing a significant decrease in potential values for the suggested grid. FOTOPROT, another noteworthy application, is a specialised calculation tool for determining the necessary mast system to ensure the integral protection of a Photovoltaic Park. Its development is rooted in the Electrogeometric Model, specifically addressing mast protection in defined areas. With its simple interface, this software can graph the results, an essential feature in any design process. Economic considerations should be considered, and it is imperative to thoroughly analyse potential losses associated with the lack of protection in the installation, underscoring the importance of addressing economic aspects in any proposal.
The comprehensive analysis of solar farm protection focuses on overvoltages, grounding systems and lightning protection. An exhaustive literature search on photovoltaic farms provided a solid basis for the analyses and suggestions presented. A detailed analysis of surge protection systems highlighted their effectiveness and technologies and identified challenges posed by grounding systems. An evaluation of the direct lightning protection system revealed the limits of the overall protection of the park area and prompted suggestions for improvement. An optimised grounding network configuration for interconnected circular farms was presented, demonstrating a significant reduction of transient short-circuit potentials. As a practical result, FOTOPROT was developed, an intuitive graphical user interface that allows calculating protection against direct lightning falls on poles and represents a global solution to protect the entire area of a photovoltaic park. This contribution provides significant advances in understanding and improving the safety of solar farms and highlights the importance of implementing effective and efficient solutions in this critical area of electrical engineering.
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