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Featured Application: The paper investigates the efficacy of grounding systems in power distribution networks during the transition from overhead to underground network configurations. Through scenario analysis and comparative evaluations, it aims to provide insights for optimal design methodologies, emphasizing safety and techno-economic criteria. Factors such as soil structure, fault current magnitude, and fault clearing times are examined to standardize the design of grounding systems in distribution networks. Designing and installing efficient grounding systems in power distribution networks is considered a complex and crucial task to ensure the reliable operation of power-protective schemes while mitigating hazardous potentials arising from faults, thereby safeguarding both personnel and equipment. This paper aims to offer guidance on designing effective grounding systems in distribution networks by assessing the influence of parameters such as soil structure, fault current magnitude, and fault clearing time. This involves proposing a more precise methodology for calculating hazardous potentials, leveraging software tools like PowerFactory, to accurately determine short-circuit (SC) currents and fault clearing times at specific locations where grounding grids are to be installed. Consequently, Distribution System Operators (DSOs) can design tailored grounding systems that optimize techno-economic considerations without unnecessary over-dimensioning, accounting for the unique characteristics of the Medium-Voltage (MV) Line and soil structure. [ABSTRACT FROM AUTHOR]

In this paper, a methodology has been proposed according to which, after carrying out a set of soil's resistivity measurements, one can compute the parameters of the multilayer earth structure using a genetic algorithm (GA). The results provided by the GA constitute the indispensable data that can be used in circuital or field simulations of grounding systems. The methodology, developed on the base of the PC Opera software package, allows to proceed toward a very efficient simulation of the grounding system and an accurate calculation of potential on the ground's surface. Index Terms--Genetic algorithms (GAs), grounding system, multilayer soil, simulation, soil resistivity measurements.

The aim of this research is to calculate and analyze the harmonic distortion extent caused in weak low-voltage networks due to a possible large-scale installation of the widely spread compact fluorescent lamps (CFLs). The research uses data from laboratory measurements of the produced harmonic currents by CFLs, as well as field measurements of the harmonic content and other characteristic measurements of the electric network of a small Greek island, which is supplied by an autonomous photovoltaic (PV) station. The PV station is also a harmonic generator by itself. This fact combined with other highly nonlinear loads--such as CFLs--causes serious problems at the network power quality as undesirable harmonic components are induced. The whole network is simulated and three scenarios of CFL installation extent are considered, so that the harmonic flow analysis reveals the influence in the power quality. It is examined whether this weak low-voltage electric network is able to keep the total harmonic distortion factor at all nodes under 8%, as more and more CFLs are installed. The conclusions drawn from this analysis are important and must be taken into account in every electric network design. Index Terms--Fluorescent lamps, harmonic analysis, harmonic distortion, photovoltaic power systems, power quality.

The study of the stability of m-dimensional systems is a difficult one especially when m [greater than or equal to] 3. There exist only a few results in the literature and unfortunately, there does not exist any practical criterion. In this brief, the stability of an m-dimensional system is dealt as a minimization problem of the absolute value of its characteristic polynomial over the boundaries of its variables (i.e., on the m unit circles). This minimization problem is solved by using genetic algorithms (GAs). Using GAs we obtain, in general, better results than other methods of minimization (numerical techniques, neural networks, etc.). Numerical examples are presented.

In this paper, we examine a new design method for two-dimensional (2-D) recursive digital filters using genetic algorithms (GAs). The design of the 2-D filter is reduced to a constrained minimization problem the solution of which is achieved by the convergence of an appropriate GA. Theoretical results are illustrated by a numerical example. Also, comparison with the results of some previous design methods is attempted. Index Terms--Constrained optimization, genetic algorithm (GA), multidimensional systems, two-dimensional (2-D) recursive filters, 2-D systems.

In this paper, a solution to the problem of the multidimensional (m-D) polynomial factorization is attempted by using genetic algorithms (GAs). The proposed method is based on an appropriate minimization of the norm of the difference between the original polynomial and its desirable factorized form. Using GAs, we can obtain better results than with other methods of minimization (numerical techniques, neural networks, etc.). The present methodology, which can also be used for every type of m-D factorization, is illustrated by means of a numerical example. Index Terms--Genetic algorithm (GA), multidimensional (m-D) polynomial factorization, multivariate polynomials.

In this paper, the performance of a lightning protection system (LPS) on a grid-connected photovoltaic (PV) park is studied by simulating different scenarios with the use of an appropriate software tool. The aim of this paper is to highlight the importance of an LPS and optimize its design for the protection of equipment and personnel in case of a direct lightning strike. In particular, developed potential due to lightning strikes is examined considering isolated and non-isolated external LPS. Moreover, the effect of the separation distance on the lightning performance of the PV installation is investigated for different soil structures and grounding systems. The extracted results are expected to support the design and implementation of a secure PV park and endorse its uninterrupted operation considering techno-economically balanced protection measures. [ABSTRACT FROM AUTHOR]