P. Molfino - Academia.edu (original) (raw)

Papers by P. Molfino

Research paper thumbnail of On the Measurement of Fields produced by Sea Return Electrodes for HVDC Transmission

2020 International Symposium on Electromagnetic Compatibility - EMC EUROPE, 2020

The use of HVDC transmission is spreading worldwide, for a number of reasons. When return electro... more The use of HVDC transmission is spreading worldwide, for a number of reasons. When return electrodes are used, their compliance with international technical standards and environmental limitations has to be assessed after commissioning, before regular operations can start. While the measurements of the fields produced by ground return electrodes is basically derived by the techniques developed over the years for industrial grounding plants, when sea electrodes are used things are more complex, the instruments and measurement techniques are less common. In this paper, we try to summarize the issues and to describe the relevant techniques than can be used.

Research paper thumbnail of Analysis and design of magnets for linear and disk MHD applications

Research paper thumbnail of A combined FEM-BEM tableau analysis approach for the modelling of moving devices fed by arbitrary lumped parameters electrical circuits

Research paper thumbnail of The two-harmonic reluctance motor: an introduction to a new kind of variable-speed device

Research paper thumbnail of A flexible preprocessor with automatic meshing features for the electromagnetic research analysis package CEDEF

Research paper thumbnail of A modular finite element package for research in electromagnetic analysis developed in a group of italian universities

Research paper thumbnail of Equivalent source methods for 3-D force calculation with nodal and mixed FEM in magnetostatic problems

IEEE Transactions on Magnetics, 2001

In this paper, the application of equivalent source methods for the numerical computation of tota... more In this paper, the application of equivalent source methods for the numerical computation of total and local forces in three-dimensional magnetostatics is proposed. A nodal two-scalar potential formulation and a mixed face-edge formulation are used to solve the field problem and to derive force values, which are then compared to analytical results. The numerical accuracy of the proposed methods, in connection both to the used formulation and to the level of refinement of the mesh, is analyzed and discussed. It is shown that results coming from the mixed solution are more accurate than those obtained with the nodal one.

Research paper thumbnail of Analysis of thermo-electromagnetic stresses in high field tokamak resistive coils

Fusion Engineering and Design, 1989

The problem of the accurate computation of thermo-electromagnetic stresses in a toroidal field co... more The problem of the accurate computation of thermo-electromagnetic stresses in a toroidal field coil for Tokamak machines will be an important task in the design of future high field Tokamak machines. The high value of flux density, and the pulsed current operation of these machines, imply critical working conditions and require a correct modelling of the thermal and electrical diffusion phenomena. In this paper are presented the thermo-electromagnetic model developed for this aim and the results obtained by implementing this mode1 in the code COMPELL. These results are then used to derive input data for the structural analysis code, ANSYS, thus providing the means for a rather detailed analysis of the structure.

Research paper thumbnail of Open problems in computational electromagnetics

Research paper thumbnail of A WWW-based tool for the remote optimization of electromagnetic devices

IEEE Transactions on Magnetics, 2001

ABSTRACT In this paper, a World Wide Web-based tool for the remote definition and analysis of opt... more ABSTRACT In this paper, a World Wide Web-based tool for the remote definition and analysis of optimization problems in electromagnetic design is described. The tool can find effective applications both in advanced teaching and in industrial design activities, thanks to its user-friendliness. The architecture of the system and its current implementation, based on commonly available tools, are presented and discussed in detail. Examples of the use of the tool for the design of a magnet to be used in high energy physics experiments and a simple electromagnetic actuator are given

Research paper thumbnail of Technical and compatibility issues in the design of HVDC sea electrodes

International Symposium on Electromagnetic Compatibility - EMC EUROPE, 2012

ABSTRACT The HVDC (High Voltage Direct Current) transmission system, although in use since about ... more ABSTRACT The HVDC (High Voltage Direct Current) transmission system, although in use since about half a century, is gaining new popularity in recent years, as it can allow to transmit very large amounts of power over long distance at reasonable costs. Many plants are being commissioned and many others are in the design phase, both for mainland and submarine links. Ground/sea electrodes are normally used in such applications, either operated on a full time basis, or during partial failures of one pole of bipolar plants. Due to the adverse effects that stray currents dispersed by such electrodes may have in terms of corrosion to nearby structures, and to the growing concern for environmental issues, the design of sea electrode has to be defined with increasing attention. This paper deals with the technologies and with the design criteria that can be adopted to develop satisfactory sea electrodes.

Research paper thumbnail of A user-oriented package for computer aided design of high-voltage devices

Research paper thumbnail of A new brushless excitation device for inverter-fed synchronous motors with variable frequency and voltage

Research paper thumbnail of Skin effect coupled magneto-thermal and stress analysis of the toroidal coils of high field resistive tokamaks

Research paper thumbnail of Studio del campo elettromagnetico e delle forze elettrodinamiche per un modello sperimentale di cava avvolgimento statore

Research paper thumbnail of A multiformulation approach to eddy current computation

Research paper thumbnail of Concept Design of a module for reversible HVDC submarine deep-water sea electrodes

Over the last years many HVDC (High Voltage Direct Current) links are being studied, commissioned... more Over the last years many HVDC (High Voltage Direct Current) links are being studied, commissioned and built. Among the constraints, one of the most important is the corrosion risk analysis of surrounding submerged/buried metallic structures. If the coastal area is rich of metallic structures, corrosion risk may be unacceptable, and the electrode must be located at greater distance offshore. As seawater at the selected location may be considerably deep, many issues about maintenance and mechanical resistance must be considered, and related problems must be solved. We developed a modular electrode able to cope efficiently with all such requirements

Research paper thumbnail of Algorithm for the Fast Calculation of Magnetic Fields Generated by Arc-Shaped Conductors With Rectangular Cross Section

IEEE Transactions on Applied Superconductivity, 2014

This paper presents a novel procedure for the fast numerical integration of the magnetic field pr... more This paper presents a novel procedure for the fast numerical integration of the magnetic field produced by arc-shaped conductors, which are characterized by a rectangular cross section. Available procedures are based on the analytical integration of Biot-Savart's law, but most of them exploit the analytical integration along one coordinate and then perform a 2-D numerical integration. In the proposed procedure, the analytical integration was performed along two coordinates, obtaining a 1-D integrand (thus avoiding the use of elliptic integrals), which is very easy to process using a state-of-the-art numerical quadrature library. The result is very satisfactory in terms of high speed and precision, particularly on the conductor surface, and when its cross dimensions are very uneven.

Research paper thumbnail of A statistical investigation on the breakdown strength of liquid helium with IEC and cylindrical electrodes

1982 IEEE International Conference on Electrical Insulation, 1982

To provide data to the designer of high voltage cryogenic apparatuses, a statistical investigatio... more To provide data to the designer of high voltage cryogenic apparatuses, a statistical investigation is performed on the breakdown strength of liquid helium. Tests are performed under as controlled as possible conditions, with gaps in the millimeter range, bath with IEC spherical bowl electrodes and cylindrical electrodes. The gap effect and the influence of test conditions are investigated with IEC electrodes, whereas with cylindrical electrodes is performed an analysis of the area effect. The main statistical parameters of the data test sets are calculated and reported, and the obtained results are discussed.

Research paper thumbnail of On the materials for reversible HVDC sea electrodes: a comparison aimed at their correct selection

2021 AEIT HVDC International Conference (AEIT HVDC)

Over the last years the use of HVDC transmission has been constantly increasing worldwide. Furthe... more Over the last years the use of HVDC transmission has been constantly increasing worldwide. Furthermore, new converters based on IGBT (called VSC converters) are spreading. This fact leads to develop reversible sea electrodes, as the direction of the current may frequently change. In this paper, we would like to clarify the subject, especially examining in detail the materials that can be used to effectively manufacture deep-sea return electrodes that can be operated with minimal or no maintenance over their life.

Research paper thumbnail of On the Measurement of Fields produced by Sea Return Electrodes for HVDC Transmission

2020 International Symposium on Electromagnetic Compatibility - EMC EUROPE, 2020

The use of HVDC transmission is spreading worldwide, for a number of reasons. When return electro... more The use of HVDC transmission is spreading worldwide, for a number of reasons. When return electrodes are used, their compliance with international technical standards and environmental limitations has to be assessed after commissioning, before regular operations can start. While the measurements of the fields produced by ground return electrodes is basically derived by the techniques developed over the years for industrial grounding plants, when sea electrodes are used things are more complex, the instruments and measurement techniques are less common. In this paper, we try to summarize the issues and to describe the relevant techniques than can be used.

Research paper thumbnail of Analysis and design of magnets for linear and disk MHD applications

Research paper thumbnail of A combined FEM-BEM tableau analysis approach for the modelling of moving devices fed by arbitrary lumped parameters electrical circuits

Research paper thumbnail of The two-harmonic reluctance motor: an introduction to a new kind of variable-speed device

Research paper thumbnail of A flexible preprocessor with automatic meshing features for the electromagnetic research analysis package CEDEF

Research paper thumbnail of A modular finite element package for research in electromagnetic analysis developed in a group of italian universities

Research paper thumbnail of Equivalent source methods for 3-D force calculation with nodal and mixed FEM in magnetostatic problems

IEEE Transactions on Magnetics, 2001

In this paper, the application of equivalent source methods for the numerical computation of tota... more In this paper, the application of equivalent source methods for the numerical computation of total and local forces in three-dimensional magnetostatics is proposed. A nodal two-scalar potential formulation and a mixed face-edge formulation are used to solve the field problem and to derive force values, which are then compared to analytical results. The numerical accuracy of the proposed methods, in connection both to the used formulation and to the level of refinement of the mesh, is analyzed and discussed. It is shown that results coming from the mixed solution are more accurate than those obtained with the nodal one.

Research paper thumbnail of Analysis of thermo-electromagnetic stresses in high field tokamak resistive coils

Fusion Engineering and Design, 1989

The problem of the accurate computation of thermo-electromagnetic stresses in a toroidal field co... more The problem of the accurate computation of thermo-electromagnetic stresses in a toroidal field coil for Tokamak machines will be an important task in the design of future high field Tokamak machines. The high value of flux density, and the pulsed current operation of these machines, imply critical working conditions and require a correct modelling of the thermal and electrical diffusion phenomena. In this paper are presented the thermo-electromagnetic model developed for this aim and the results obtained by implementing this mode1 in the code COMPELL. These results are then used to derive input data for the structural analysis code, ANSYS, thus providing the means for a rather detailed analysis of the structure.

Research paper thumbnail of Open problems in computational electromagnetics

Research paper thumbnail of A WWW-based tool for the remote optimization of electromagnetic devices

IEEE Transactions on Magnetics, 2001

ABSTRACT In this paper, a World Wide Web-based tool for the remote definition and analysis of opt... more ABSTRACT In this paper, a World Wide Web-based tool for the remote definition and analysis of optimization problems in electromagnetic design is described. The tool can find effective applications both in advanced teaching and in industrial design activities, thanks to its user-friendliness. The architecture of the system and its current implementation, based on commonly available tools, are presented and discussed in detail. Examples of the use of the tool for the design of a magnet to be used in high energy physics experiments and a simple electromagnetic actuator are given

Research paper thumbnail of Technical and compatibility issues in the design of HVDC sea electrodes

International Symposium on Electromagnetic Compatibility - EMC EUROPE, 2012

ABSTRACT The HVDC (High Voltage Direct Current) transmission system, although in use since about ... more ABSTRACT The HVDC (High Voltage Direct Current) transmission system, although in use since about half a century, is gaining new popularity in recent years, as it can allow to transmit very large amounts of power over long distance at reasonable costs. Many plants are being commissioned and many others are in the design phase, both for mainland and submarine links. Ground/sea electrodes are normally used in such applications, either operated on a full time basis, or during partial failures of one pole of bipolar plants. Due to the adverse effects that stray currents dispersed by such electrodes may have in terms of corrosion to nearby structures, and to the growing concern for environmental issues, the design of sea electrode has to be defined with increasing attention. This paper deals with the technologies and with the design criteria that can be adopted to develop satisfactory sea electrodes.

Research paper thumbnail of A user-oriented package for computer aided design of high-voltage devices

Research paper thumbnail of A new brushless excitation device for inverter-fed synchronous motors with variable frequency and voltage

Research paper thumbnail of Skin effect coupled magneto-thermal and stress analysis of the toroidal coils of high field resistive tokamaks

Research paper thumbnail of Studio del campo elettromagnetico e delle forze elettrodinamiche per un modello sperimentale di cava avvolgimento statore

Research paper thumbnail of A multiformulation approach to eddy current computation

Research paper thumbnail of Concept Design of a module for reversible HVDC submarine deep-water sea electrodes

Over the last years many HVDC (High Voltage Direct Current) links are being studied, commissioned... more Over the last years many HVDC (High Voltage Direct Current) links are being studied, commissioned and built. Among the constraints, one of the most important is the corrosion risk analysis of surrounding submerged/buried metallic structures. If the coastal area is rich of metallic structures, corrosion risk may be unacceptable, and the electrode must be located at greater distance offshore. As seawater at the selected location may be considerably deep, many issues about maintenance and mechanical resistance must be considered, and related problems must be solved. We developed a modular electrode able to cope efficiently with all such requirements

Research paper thumbnail of Algorithm for the Fast Calculation of Magnetic Fields Generated by Arc-Shaped Conductors With Rectangular Cross Section

IEEE Transactions on Applied Superconductivity, 2014

This paper presents a novel procedure for the fast numerical integration of the magnetic field pr... more This paper presents a novel procedure for the fast numerical integration of the magnetic field produced by arc-shaped conductors, which are characterized by a rectangular cross section. Available procedures are based on the analytical integration of Biot-Savart's law, but most of them exploit the analytical integration along one coordinate and then perform a 2-D numerical integration. In the proposed procedure, the analytical integration was performed along two coordinates, obtaining a 1-D integrand (thus avoiding the use of elliptic integrals), which is very easy to process using a state-of-the-art numerical quadrature library. The result is very satisfactory in terms of high speed and precision, particularly on the conductor surface, and when its cross dimensions are very uneven.

Research paper thumbnail of A statistical investigation on the breakdown strength of liquid helium with IEC and cylindrical electrodes

1982 IEEE International Conference on Electrical Insulation, 1982

To provide data to the designer of high voltage cryogenic apparatuses, a statistical investigatio... more To provide data to the designer of high voltage cryogenic apparatuses, a statistical investigation is performed on the breakdown strength of liquid helium. Tests are performed under as controlled as possible conditions, with gaps in the millimeter range, bath with IEC spherical bowl electrodes and cylindrical electrodes. The gap effect and the influence of test conditions are investigated with IEC electrodes, whereas with cylindrical electrodes is performed an analysis of the area effect. The main statistical parameters of the data test sets are calculated and reported, and the obtained results are discussed.

Research paper thumbnail of On the materials for reversible HVDC sea electrodes: a comparison aimed at their correct selection

2021 AEIT HVDC International Conference (AEIT HVDC)

Over the last years the use of HVDC transmission has been constantly increasing worldwide. Furthe... more Over the last years the use of HVDC transmission has been constantly increasing worldwide. Furthermore, new converters based on IGBT (called VSC converters) are spreading. This fact leads to develop reversible sea electrodes, as the direction of the current may frequently change. In this paper, we would like to clarify the subject, especially examining in detail the materials that can be used to effectively manufacture deep-sea return electrodes that can be operated with minimal or no maintenance over their life.

Research paper thumbnail of Technical and compatibility issues in the design of HVDC sea electrodes

The HVDC (High Voltage Direct Current) transmission system, although in use since about half a ce... more The HVDC (High Voltage Direct Current) transmission system, although in use since about half a century, is gaining new popularity in recent years, as it can allow to transmit very large amounts of power over long distance at reasonable costs. Many plants are being commissioned and many others are in the design phase, both for mainland and submarine links. Ground/sea electrodes are normally used in such applications, either operated on a full time basis, or during partial failures of one pole of bipolar plants. Due to the adverse effects that stray currents dispersed by such electrodes may have in terms of corrosion to nearby structures, and to the growing concern for environmental issues, the design of sea electrode has to be defined with increasing attention. This paper deals with the technologies and with the design criteria that can be adopted to develop satisfactory sea electrodes.