G. Delvecchio

A study for optimizing the number of subareas in the Maxwell's method

This paper aims at reducing the number of subareas needed for studying a large grounding grid by the Maxwells subareas method. This is possible by resorting both to the similarity between grounding electrodes and to an exhaustive study of the formulas for calculating the voltage coefficients.

A Genetic Algorithm Method for Determining the Maximum Touch Voltage Generated by a Grounding System

The Authors suggest a new method for quickly determining the maximum touch voltage generated by a grounding system leaking a known current. The touch voltages in the points of the soil surface are calculated by the Maxwell’s subareas method and the search for the maximum touch voltage is carried out by an ad hoc genetic program which is based both on the “one-point crossover” technique and on a mutation having a pre-arranged probability rate. The method has been successfully tested on some grounding systems.

A fast evolutionary‐deterministic algorithm to study multimodal current fields under safety level constraints

Purpose – This paper aims to design an algorithm able to locate all the possible dangerous areas generated by the leaking of a fault current in a grounding system (i.e. the areas where the limits of the technical standards are not respected) and thus locate, inside each area, the point which takes locally the maximum value of touch voltage. Design/methodology/approach – A fast evolutionary-deterministic algorithm to solve constrained multimodal optimization problems is proposed. The algorithm is composed by three algorithmic blocks: a Quasi Genetic Algorithm to find a population of feasible solutions, a Fitness Sharing Selection to choose a subpopulation of feasible and fitter solutions having high diversity, a Hooke-Jeeves Algorithm to find all the global and local feasible maxima. Findings – The proposed algorithm has been successfully applied to various current field (i.e. to many shapes of grounding grids) problems to find the dangerous values of touch voltages generated by various grounding systems having any shape and it has turned out to be fast and reliable. Originality/value – For this kind of problems, in fact, there is a lack, in literature, of multimodal optimization methods under safety constraints and the application of classical methods (e.g. genetic algorithms or deterministic methods) would be often inadequate since these methods are made so as to converge towards a single maximum point and so they unavoidably lose the information related to all the other possible maxima. On the contrary, a good application of the proposed allows the overcoming of these limits.

Two Cascade Genetic Algorithms to Optimize Unequally Spaced Grounding Grids with Rods

In this paper the authors examine the optimization of the design of unequally spaced grounding grids equipped with rods. To this end, the genetic algorithms method proposed optimizes both the grounding grid cost and the maximum touch voltage it generates. The method has been successfully applied to a real case

Road Lighting Installation Design to Optimize Energy Use by Genetic Algorithms

In this paper the authors suggest a software based on the genetic algorithms to optimize the design of a road lighting installation so as to reduce the use of the energy per year. The method has been applied to a real case

A Method for Studying the Current Field Generated by Interconnected Grounding Systems

In this paper the Authors propose a method for analyzing the current field generated by interconnected grounding systems, with any shape and extension. The method is absolutely general and allows to study the field both in the event of a single line to ground fault (LGF) in one of the interconnected grounding systems and in case of simultaneous line to ground faults in different grounding systems, interconnected to each other. Moreover, this method allows to analyze the grounding systems connected to each other by leaking conductors, as well as to analyze the effects of the faults on metal structures in contact with the soil, such as water pipelines or railway tracks.

A “quasi‐genetic” algorithm for searching the dangerous areas generated by a grounding system

Sets out a method for determining the dangerous areas on the soil surface. The touch voltages are calculated by a Maxwells subareas program. The search for the areas in which the touch voltages are dangerous is performed by a suitably modified genetic algorithm. The fitness is redefined so that the genetic algorithm does not lead directly to the only optimum solution, but to a certain number of solutions having pre‐arranged “goodness” characteristics. The algorithm has been called “quasi‐genetic” algorithm and has been successfully applied to various grounding systems.

A New Method for Optimizing the Designing of Grounding Grids

In the various designing steps of a grounding grid, the grids are gradually chosen by the designer according to his experience. A method for choosing, in a quite automatic way, the various grids and so for speeding up the designing process is given in this paper. The method is based on the determination of the maximum touch voltages, these being calculated by resorting to a genetic algorithm carried out by the Authors. Moreover, the building cost of the grounding grid is optimized thanks to the “Traveling Salesman” algorithm.

A hierarchical evolutionary algorithm with noisy fitness in structural optimization problems

The authors propose a hierarchical evolutionary algorithm (HEA) to solve structural optimization problems. The HEA is composed by a lower level evolutionary algorithm (LLEA) and a higher level evolutionary algorithm (HLEA). The HEA has been applied to the design of grounding grids for electrical safety. A compact representation to describe the topology of the grounding grid is proposed. An analysis of the decision space is carried out and its restriction is obtained according to some considerations on the physical meaning of the individuals. Due to the algorithmic structure and the specific class of problems under study, the fitness function of the HLEA is noisy. A statistical approach to analyze the behavior and the reliability of the fitness function is done by applying the limit theorems of the probability theory. The comparison with the other method of grounding grid design shows the validity and the efficiency of the HEA.

Some geometrical and evolutionary procedures for optimizing the calculation times of 3D current fields by the finite element method

Purpose – As well known, in the finite element method, the calculation and the location of the elements of the matrix C of the coefficients requires a lot of calculation times and memory employment especially for 3D problems. Besides, once the matrix C is properly filled, the solution of the system of linear equations is computationally expensive.Design/methodology/approach – The paper consists of two parts. In the first part, to quickly calculate and store only the non‐null terms of the matrix of the system, a geometrical analysis on three‐dimensional domains has been carried out. The second part of the paper deals with the solution of the system of linear equations and proposes a procedure for increasing the solution speed: the traditional method of the conjugate gradient is hybridized with an adequate genetic algorithm (Genetic Conjugate Gradient).Findings – The proposed geometrical procedure allows us to calculate the non‐null terms and their location within the matrix C by simple recursive formulas. ...