Calin Munteanu

A general applicable model for AC predictive and mitigation techniques for pipeline networks influenced by HV power lines

This paper presents a recently developed simulation software tool for ac predictive and mitigation techniques for pipeline networks influenced by high-voltage (HV) power lines. The software can deal with any configuration (no limitation on number of pipes, transmission lines, bonds, groundings, coating, and soil resistivity) and is very user friendly and robust since a general applicable algorithm is used to calculate the induced electromagnetic force (EMF), eliminating the need for a subdivision of the pipelines in sections parallel or not to the transmission line(s). With the calculated values for the EMF, the induced voltages and currents are then obtained by solving the well-known transmission-line model using a numerical technique that allows to specify the pipeline parameters (diameter, coating, soil resistivity, ...) for each individual section of the pipeline. In this paper, simulation results will be presented and compared with available theoretical test cases. It will be demonstrated that the calculated values for the induced EMF and the induced voltage and current are in perfect agreement with these theoretical test cases. In addition, it will be proven that commonly used formulas for the induced EMF need to be handled with care, especially when the distance between the transmission line and the pipeline becomes bigger.

Electric and Magnetic Field Distribution inside High and Very High Voltage Substations

The paper emphasize the results of the first systematic electromagnetic field measurements performed in high and very high voltage substations belonging to the Romanian national power grid in order to face the requirements of the EU documents regarding the human exposure to the electromagnetic fields. In the first part of the paper, the experimental field measurement results from a recently rehabilitated 400/220 kV substation belonging to the Romanian Transport and System Operator (TSO) Company are presented. It follows the experimental field measurement results from two 110/20/10 kV electricity distribution substations. The high intensity field zones are highlighted and the highest field value found is compared with the exposure limits given by the actual legislation. In the second part of the paper theoretical field computation methods are approached following two main reasons: to validate the experimental results and to prove their efficiency in evaluating the electromagnetic field values in the neighbourhood of the power devices from complex systems such as the substations. The final conclusions of the study performed and the actions proposed to be taken in practice finish the paper.

Multi‐terminal resistances optimal design using spline boundary elements and genetic algorithms

This paper proposes a method for multi‐terminal resistor optimal design based on a stochastic optimization algorithm coupled with a high accuracy boundary element method numerical analysis module using spline boundary elements. The aim of the optimization process is to find out the optimal shape of the resistor so that the values of the partial resistances between its terminals can be globally reduced. In the first part of the paper, a short introduction to the boundary element method formulation using spline interpolation of the boundary unknowns is performed. Then, the genetic algorithm optimization method is briefly described, emphasising the numerical implementation particularities related to the actual application. In the second part of the paper, three numerical examples are proposed and the final conclusions are outlined.

Technologies to increase HF losses in planar structures and their limitations

Planar structures are often used in our days due to advantages like lower profile, lower leakage inductances and better thermal management. Although highly used components like power transformers, power inductors and EMI filters are built using this technique, planar structures must be improved because planar structure technology also has disadvantages like large footprint area, increased parasitic capacitance and low window utilization factor. In order to increase the efficiency of planar EMI filters, the equivalent parasitic capacitance (EPC) and the equivalent series inductance (ESL) must be eliminated and high frequency (HF) losses must be increased. This paper presents a study of technologies that can be used to increase HF losses in a planar structure and the parameters that affect the structures behavior.

Minimization of the equivalent parallel capacitance in planar magnetic EMI filters

The magnetic planar technology is nowadays an attractive solution for designing the electrical devices due to its efficiency at high frequencies and its mechanical robustness. On the other hand, the general trend of reducing the dimensions of the integrated structures one inherently leads to the increase of their structural parasitic effects. In this light, the paper proposes a new method for the minimization of the equivalent parallel capacitance (EPC) of these structures based on optimal design. The paper describes the optimization algorithm developed by the authors designed to determine the optimal placement of the structures conductor routes that minimize the structural inter-winding capacitance. In the first part of the paper the theoretical background is presented while in the second part the optimization algorithm validation and the usage of the OptimCond package for complex planar magnetic integrated structures are outlined, followed by the final conclusions.

Numerical optimization of an electrostatic device based on the 3D XFEM and genetic algorithm

The objective of this paper consists in the development, implementation, testing and validation of a new mathematical model based on the eXtended Finite Element Method (XFEM) and Genetic Algorithm (GA) specially designed for modeling the mobile material discontinuities with direct application in optimization of electric structures in 3D space. This new mathematical concept eliminates the conventional use of discrete elements and provides an efficient, stable, accurate and fast calculation scheme, removing the finite elements network re-meshing at each step of optimization.

CAD/CAE modeling of the human exposure to electric field inside a high voltage substation

This paper presents the computer aided design (CAD) and computer aided engineering (CAE) modeling of Cluj-Sud 110 kV high voltage substation in order to examine the influence of substation constructive elements and apparatus (e.g. phase conductors, bypass bus bars, breakers and towers) on the spatial electric field distribution. The substation belongs to FDEE Electrica distributie Transilvania Nord SA. In a first step the detailed three dimensional (3D) CAD models of the substation components are constructed and assembled in the CAD environment SolidWorks. Then the exact 3D coordinates of the terminals are automatically retrieved and the electric field distribution is computed on the 3D CAD model using a CAE software developed. The electric field distribution is represented on horizontal and transversal slices at the 3D CAD model in order to highlight the high intensity field zones and compare them with respect to the actual legislation norms of human exposure.

3D electromagnetic field model for numerical analysis of the electromagnetic interferences between overhead power lines and pipelines

The paper outlines a recently developed numerical computation algorithm set up for the analysis of the electromagnetic interferences generated by the overhead high voltage lines (OHL) on the neighbour pipeline networks. The main advantage of the algorithm proposed is that it can handle applications with unparallel arrangements between OHL and pipelines and therefore the induced potential and current values are more accurately computed than the traditional software packages. For this purpose, an original full 3D electromagnetic field model was developed. The computational module is based on a coupled Finite elements (FEM) — Boundary elements (BEM) numerical analysis technique that is detailed in the first part of the paper. The computation accuracy of the numerical algorithm developed was tested considering simple cases and comparing the numerical results with those obtained using a known software package based on the Transmission Lines Method (TLM). In the second part of the paper an application in the case of a OHL working on normal and fault conditions is outlined. The importance of the magnitude and direction of the currents flowing through the OHL on the induced potentials distribution along the victim pipeline is outlined. The final conclusions end the paper.

Software Package for Multi-Objective Optimal Design of Electromagnetic Devices

Resistive, capacitive and inductive parasitic coupling effects are very important in integrated circuit technology development and must be taken into account in the global circuit analysis and design. These values are seldom possible to be computed analytically because often we deal with complex multi-route layout geometries. Optimizing the placement of the routes inside the integrated design, in accordance with imposed constraints, one may lead to the decrease of the coupling effects. Due to the high number of the design parameters involved, stochastic optimization methods based on Genetic Algorithms (GA) have been previously involved. The first solution proposed consisted in using a basic GA in which a single global fitness function is built up from the partial objectives. The main drawback of this method is that even if the global fitness function decreases during the optimal design process, there are partial objectives that get an important increase. A first trial to eliminate this drawback has been done using the method of objective weighting [TMM03]. The drawback of this method is the fact that it requires some prior knowledge about the partial objectives behaviour in order to proper select the weighting values. This is quite difficult to be done in practice. Therefore the best solution would be to built up an algorithm that takes into account the information from partial objectives behaviour during the optimization process without any prior knowledge and also to take into account the global fitness function behaviour. The solution consists of setting-up a multi-objective optimal design algorithm based on Strength Pareto Evolutionary Algorithms (SPEA). The software package developed based on the above mentioned method, together with a practical application example will be presented in this paper.

A new approach for shape optimization of resistors with complex geometry

This paper presents a new numerical approach for shape optimization of resistors with complex geometry. The aim of this method is to develop a systematic modification of resistor design in combination with the computation of the electric field, in order to optimize some chosen properties like homogenization of the power dissipation on the resistor surface.