Abstract

In this paper is proposed an optimal geometrical shape for a DC electromagnet by combining the design of experiments (DOE) and 2-D FEM. The optimization prob-lem takes into account four geometrical parameters (the coil shape ratio, the support thickness ratio, the support height ratio and the support top ratio) and consists in maximiza-tion of the acting force related to the largest air-gap, pre-serving the global dimensions of the device (the external radius, the height of carcass, the height of plunger with sup-port) and the cross-section of the winding. Before optimiza-tion, the technique of screening was applied to verify the influence of the four geometrical parameters on the acting force. The experiments were performed by numerical tool FEMM in relation to the LUA language. The acting force was computed by Maxwel Stress Tensor principle. Best in-fluence was observed for all the four parameters, especially for the support top ratio, with 99% confidence. The method by zooms without computation of models was applied to increase with 21.20% the acting force related to the air-gap of 41 mm. The cost of this improvement is the reduction of electromagnetic force for lower air-gaps which can be com-pensated by eliminating the economy resistor in this range.

Abstract

The paper is focused on physical phenomena that degrade the effectiveness of the energy transfer in electrical systems when voltages and currents are nonsinusoidal and asymmetrical. The Currents’ Physical Components (CPC) – based power theory provides fundamentals for the analysis of the electric energy flow. This analysis identifies seven distinctive physical phenomena that affect this flow. Accord-ing to the CPC concept, seven current components are asso-ciated with these phenomena. Only one of them contributes to the useful transfer of the energy. Remaining six compo-nents only degrade the effectiveness of this transfer. They could be reduced by various compensators and the CPC-based power theory provides fundamentals for their synthe-sis and control. The results presented in the paper are valid for electrical systems of any complexity, meaning for single- and for three-phase systems and for any loads, meaning for linear and for nonlinear loads.

Content

CPC−Founded Clarification of Decline of the Effectiveness of the Energy Transfer in Power Systems – Leszek S. Czarnecki

Optimal Shape of DC Electromagnet – Alin-Iulian Dolan

Testing a Filtering and Regeneration System on a Recuperative Stand – Alexandru Bitoleanu, Mihaela Popescu and Vlad Constantin Suru

DC-Traction Substation with Improved Power Quality and Regeneration Capability – Mihaela Popescu, Alexandru Bitoleanu, Constantin Vlad Suru, and Mircea Dobriceanu

Static Force Characteristic and Thermal Field for a Plunger-Type AC Electromagnet – Ioan C. Popa, Alin-Iulian Dolan, Constantin Florin Ocoleanu

Diminishing the Computational Burden when Analyzing Electrical Signals with Long Wavelet Filters – Ileana-Diana Nicolae, Petre-Marian Nicolae, Ionuţ Daniel Smărăndescu

Hybrid Systems Modeling Approach with Petri Nets – Mircea  Adrian Drighiciu

Estimation of Certain Power in Single-phase Network and DC Circuits – Constantin Daniel Oancea

Dynamic State of Low Power Asynchronous Motors in Direct-on-Line Starting – Ion Vlad, Aurel Campeanu, Sorin Enache, Monica-Adela Enache

Aspects Regarding Operation of Power Supply System of Cars – Sorin Enache, Aurel Campeanu, Ion Vlad and Monica-Adela Enache

Design Optimization of an Asynchronous Motor Used in Light Railway Traction – Presură Raluca-Cristina, Nicolae Marian-Ştefan, Vlad Ion, Nicolae Petre-Marian

Contributions to the Development of Complementary Equipment for the Romanian Anti-Hail System – Gheorghe Manolea, Laurentiu Alboteanu, Sorin Stepan

Analysis of Crimped Connections Heat Transfer Coefficient Using Experimental and Numerical Determinations – Constantin Florin Ocoleanu, Ioan C. Popa

Modelling and Synthesis of Printed Circuit Boards Testing Systems based on Timed Hard Petri Nets – Sudacevschi Viorica, Ababii Victor, Calugari Dmitri, Bordian Dimitrie

Concerning the Automatic Computation of the Electrical Stresses in the High Voltage Substations during the Transient Regimes – Maria Brojboiu, Virginia Ivanov

Analyzing Signals from a Primary Winding of a Locomotive Transformer with Three Types of Wavelet-Based Transforms – Ileana-Diana Nicolae, Radu-Florin Marinescu, Petre-Marian Nicolae  and Diana-Cristina Marinescu

Shielding Effectiveness Measurement Using a DTEM Cell – Viorica Voicu, Ion Pătru, Livia-Andreea Dina, Petre-Marian Nicolae, Relu Aipu, Ionuţ Daniel Smărăndescu

Synthesis of the PID Algorithm for Control the Thermal Regime in the 3D Printer – Irina Cojuhari, Bartolomeu Izvoreanu, Ion Fiodorov, Dumitru Moraru, Sorin Botnaru

Analysis of Direct Current Motors in Dynamic Regimes Using Numerical Techniques – Ioana-Gabriela Sîrbu and Lucian Mandache

Control of Flow and Pressure in the Cooling Water Circuit of a Thermal Power Plant Using Fuzzy Logic – Radu Cristian Dinu, Cristian Bratu and Daniela Popescu

The Influence of the Output Current Deforming Regime on the Input Current Harmonics for a Three-Phase Rectifier Bridge – Mitică Iustinian Neaca

Theoretical and Practical Aspects Regarding Radiated Emission Testing in Semi-Anechoic Chambers – Livia-Andreea Dina, Viorica Voicu, Petre-Marian Nicolae, and Ionuţ Daniel Smărăndescu

Optimization of the Aerodynamics Airfoils Placed in Supersonic Viscous Flow – Victoriţa Rădulescu

Monitoring System for Reducing the Electric Equipment Stress in Transport and Distribution Lines – Virginia Ivanov, Maria Brojboiu and Sergiu Ivanov

Technical and Economic Analysis of Thermal Energy Storage in the Biomass CHP Plants with ORC Technology – Pavel Atănăsoae, Radu Pentiuc, Crenguţa Bobric, Elena Olariu and Valentin Martin

The Implementation and Validation of a Bidirectional PWM Boost Rectifier Control Algorithm – Ionuţ Deaconu, Constantin Vlad Suru, Mihăiţă Lincă, Cristina Alexandra Preda

Abstract

Today, most of the human activities are computer-controlled with respect to equipments and platforms functionality, quality of the process and people and goods safety. Unlike the specialized platforms, where this feature is already implemented and developed according to the system architecture, in many other applications this function can be achieved by including a simple desktop or laptop and the specific software application in the platform original configuration. These applications can be also very sensitive, in terms of safety, quality and costs, so the whole controlling process must be accurate, stable and robust. One of the main problems that can occur and affect these systems workability is represented by electromagnetic interference (EMI) presence and the complementary issues, especially when the scenario takes place in a hard electromagnetic environment (industrial, military, IT&COM high-density areas etc.). There are some technical approaches to solve this inconvenience, but most are focused to adapt the current equipment configuration, which was intended to work in a specific environment and to provide specific features, to the new place working requirements. Our solution is to develop a self-independent EMI protection system that can be easily adapted to a large range of the IT&COM equipments in order to minimize costs, product performances distortion and overall time implementation.

Abstract

The modern world’s needs of electric and electronic devices and systems lead to a continuously electromagnetic interferences growing in ways that were hard to predict few decades ago, a serious reason to consider the electromagnetic compatibility (EMC) regulations a top priority for the developers and the end-users as well. An important segment of these products is represented by integrated systems, and not only the large scale ones, as a natural consequence of the increased equipments interoperability and versatility. The integrated systems developers are facing many issues regarding EMC products compliance, although the individual components of their systems are fully or partially compliant with the EMC standards and regulations. Practical solution to identify and solve these problems consists in preliminary precompliance tests deployed in specialized EMC laboratories. Unlike the classic EMC tests, the specialized pre-compliance probes enable the developers to improve their products, according to the provided feedback, and to minimize their efforts to reach that goal. Our specialized EMC laboratory has been involved in many testing and evaluation projects for different types of electric and electronic systems compliance characterization. The authors participated in experimentation activities as well as software simulation sfor EMI protection solutions design and realization. The accumlated experience allow us to investigate the associated phenomena related to EMC problems and to find solutions for these inconveniences

Abstract

This paper presents the algorithm and the main features of a Matlab (R2014a)-based software conceived by the authors for analysis of the asymmetrical operation of the three-phase distribution networks. The software’s algorithm is based on an iterative procedure of Newton-Raphson type. This algorithm is independently applied on three equivalent sequence networks and includes an equivalent model for the unbalanced loads supplied from the analysed distribution grid. In order to outline the capabilities of this software tool named PFASYM and illustrate the key concepts a comprehensive case study was considered. This one summarizes the results of a three-phase load flow analysis performed for a real representative 110/20 kV distribution network supplying industrial unbalanced loads. The PFASYM’s results are validated by comparison with those generated by a proprietary software package. The analysis methodology used in this illustrative case study and the results generated for different grid configurations could assist the grid operator in conducting the power flow studies of operational areas of interest. This work is part of an overall energy systems modelling and analysis project developed by the authors, in collaboration with the local power distribution operator. This one has as objective to facilitate the understanding of the power flow concepts for the present distribution networks operating in asymmetry conditions and to assist the grid operator in applying optimal mitigation measures.

Abstract

Electrical discharge due to human operators may cause disturbances with very fast variation reaching the sensitive equipment by conduction and radiation and can affect and even destroy them. Therefore, between a human, possible to load electrostatic voltages of 10-15kV ordinal, and an electronic device (computer, laptop, memory stick, etc.), system connected to the grounding, an electrostatic discharge can occur as a result of electric charging (electrification) the person wearing clothes made of synthetic fibers, due to friction with the air. This paper proposes a study of the transient arrangement produced by human electrostatic discharge and the disruptive or destructive effects that may occur. Experimental tests have been performed to determine the degree of immunity to electrostatic discharge (ESD) into the air and through direct contact, in accordance with the regulations in force, in the specialized laboratory of ICMET Craiova, subjecting a memory stick and a wireless Internet connection stick to electrostatic discharge. The results obtained revealed the individualized behavior for each device tested.

Abstract

The paper deals with some tests regarding the immunity for radiated emissions and compliance with international standards for electromagnetic compatibility (EMC) measurements for an industrial data acquisition system (DAS) used in power systems. The behavior of the DAS, when functioning near electromagnetic disturbance sources, is studied. The goal is to test its robustness in similar conditions as those encountered in its normal environment. It is known that multiple factors may affect the accuracy of data acquired by DAS. The Equipment Under Test (EUT), witch in this case is represented by DAS is tested for immunity in a specialized enclosure (GTEM Cell). The immunity based on the analysis of the influences of an electric field with constant magnitude and variable frequency in the range of 80 MHz…1 GHz is studied. After analyzing the initial tests results, partial and, afterwards, full shielding of the EUT’s case is performed in order to remove the EM influence. The tests’ results drive to the conclusion that it is necessary to design and build an enclosure from conductive material for the DAS. After the implementation of the measures, the EUT passed the tests concerning the immunity. The GTEM Cell construction, GTEM model, generation and distribution of electric and magnetic field inside the GTEM Cell, equipment under test (EUT), radiated emission measurement scheme, EMC standards for GTEM Cell, are exposed.

Abstract

Some theoretical approaches of an alternative organic semiconductor device are presented in this work. The Organic transistors are based either on n-type or p-type or mixed p/n overlapped layers. The carrier modulation insides different films is carried out by two gates electrodes, as is usual in the thin film transistor field. This paper introduces some novel aspects for these kinds of organic transistors, selecting a suitable biasing regime. The simulations emphasize a stronger influence on the static characteristics when the superior gate is acted. One of the novelties of this paper concerns the electrical conduction occurrence by two simultaneous channels, in comparison with one volume channel conduction, for different gate voltage regimes. A similar work regime is also encountered in the SOI devices with ultra-thin films that develop a volume channel. The volume channel regime is advantageously when the technology of fabrication of the organic semiconductors on different insulators provides an extremely charged interface, which can degrade the surface currents. Comparisons and applications for both situations – with one volume channel or two accumulation channels – are finally discussed. The vertical n/p junction arose between the upper n-channel and the bottom p-channel, offers novel physical properties and prevented any interaction among channels. The device simulations revealed multiple behaviors, depending on the Top and Bottom Gate voltages, if a positive drain-source voltage is applied.

Abstract

This paper describes a case study referring to the magnetic field measurements performed in a public access area. Compared to the standard limits regarding the human exposure to electromagnetic fields, the measurement results were significantly higher. Based on these results and the scarce data regarding the magnetic field sources in the area, there are discussed several cases of power lines configurations and their corresponding magnetic field levels.