Abstract

A major problem with the increased penetration of electric vehicles is the preparation of the power supply system to accommodate the increasing number of charging stations. Possible problems include exceeding the rated power of distribution equipment and electrical systems components, changing the voltage profile and altering the quality parameters of electricity. In these scenarios it is important for the grid operators to have an accurate information on present grid status, as well as the effects of EVs charging facilities interaction with the hosting grid. This knowledge will help the operators to more efficiently manage their grids while the e-mobility is expanding. This paper addresses issues related to the challenges of large-scale implementation of electric vehicles in Romania and especially their estimated impact on the power quality in current distribution networks. The authors present some of the results of a monitoring and analysis study of the power quality parameters in the coupling buses of some electric vehicle models during their charging cycle. The results of the study are included in a database used as a reference for a larger project aimed at developing intelligent solutions for PQ-based control of load units.

Abstract

In this paper, using LabVIEW graphical pro-gramming environment and the portable reconfigurable input/output (RIO) device from National Instruments (myRIO-1900), the concept of virtual instrumentation is implemented. Thus, it is created a hardware and software system that is used to study the nickel and titanium shape memory alloy (NiTi SMA) strip during bending under the influence of electric current. The SMA strip is caught in cantilever mode (fixed at one end only). For this study, the following quantities are measured: the deformation of the strip (using a created electronic transducer around an oper-ational amplifier and a piezoelectric effect sensor), the volt-age applied to its ends and the current flowing through it (with LEM transducers). The evolution of the electrical re-sistance as well as the bending of the SMA band at different values of the electric current, during and due to the heating process is reported using this system. The values of the measured quantities are presented in graphical and numeri-cal form. Thus, the evolution on time intervals of the order of seconds can be followed with precision with the help of horizontal and vertical cursors, respectively. Amplitude values can also be accurately determined. The results ob-tained with the proposed system are useful in practical ap-plications of cantilever SMA strip for development of sim-ple, more compact and reliable actuators or sensors.

Abstract

Recently, metamaterials have attracted considerable attention due to their feasibility and multiple applications. As man-made artificial structures, metamate-rials possess properties that are not yet highlighted in the natural world, such as perfect lensing, negative refraction, and backward propagation. These properties are obtained by the proper design of the structure of metamaterials, with the periodic arrangement of unit cells, ”meta-atoms”, which have dimensions below the order of magnitude of the inci-dent wavelength, at which resonance processes can be estab-lished. Thus, the electric and magnetic response of the met-amaterial can be flexibly tailored to meet the desired macro-scopic properties, in terms of effective electric permittivity and magnetic permeability. In this paper, a review of the state of research and development of metamaterials is made, highlighting the new challenges and ways to improve and to apply these new synthetic structures in electromagnetics and optics. There are analyzed the processes and structures of metamaterials used in various applications. Based on the actual researches, new classification of metamaterials with the criterion of the capabilities and flexibilities in controlling electromagnetic waves is described and analyzed.

Abstract

The parameters of transmission lines, as a rule, are determined by reference data, but during the operation, it might vary essentially from the actual data. There are noted the reasons for the parameters’ modification. This paper explains the opportunity of parameter identification based on the synchronized measurements during the operation of the transmission line. The methods of parameter identification can be classified by various criteria. The diagram of classification was elaborated for the first time. Transmission lines can be represented in the form of quadripole and the Т- and П-forms equivalent schemes, so, applying only the current and voltage synchronized measurement on both ends it is possible to obtain passive parameters of the line. There are presented final formula of six most effective methods for parameter identification of the transmission lines. All analyzed methods were verified with the models of real transmission line. There were compared the results of all proposed methods: the relative errors of calculation for all mentioned methods are less than 1%. The obtained results show the high accuracy of parameter identification for the proposed methods. The influence of measurement errors upon the values of parameters’ results was analyzed in this work. The main contribution of this paper lies in the classification of the methods of transmission line parameters identification and in the research of influence of measurement errors on the results of the parameter identification for transmission lines.

Abstract

This paper describes a wireless remote control designed for the positioning system of the launching pad of anti-hail missiles used by the Romanian Anti-Hail System. The remote control operates in the ISM band of 2,4 GHz and was successfully tested on a simplified, small size, experimental model of the actual launch ramp. The remote control allows the operator to position the launch ramp on two axes, azimuth, and elevation, and fire the missiles, using momentary push buttons. A 16×2 characters LCD display indicates the current position of the ramp, and the presence and the type of the anti-hail missiles loaded on the ramp. The remote control was built using Arduino microcontrol-lers and radio frequency transceivers and uses two separate one-way transmitter-receiver radio channels. The simplified experimental model of the launch ramp features the main functional characteristics of the actual ramp and was de-signed and built for the purpose of testing the remote con-trol, due to no access to the actual ramp, along with the in-tention of using it to train the Local Unit operating person-nel during the off-season time. When designing and building the remote control and the experimental model of the ramp it was taken into consideration an easy implementation on the actual ramp, with minimal modifications.

Abstract

Helmholtz coils (HC) are used in order to generate and control uniform magnetic fields for a variety of re-search applications. They can be easily constructed and their fields can be easily calculated. This makes them espe-cially useful in calibrating magnetic field sensors. Such a calibration system with large Helmholtz coils (1x1m) can be found in ICMET Institute, designed to operate only at a frequency of 50 Hz. There has recently been a request for the calibration of several measuring sensors operating at frequencies up to 10 kHz used in industrial applications such as induction hardening of metal parts. The paper aims to determine the conditions under which this low frequency HC system can be used at frequencies at least 100 times higher. The first part of the paper describes a theoretical analysis on the volume confining the space where the mag-netic field components have a predetermined deviation (a 2% threshold) from the center of the HC system followed by a comparison with a 3D FEM simulation and measurement of HC field. The second part describes the identification of the HC parameters at higher frequencies and the resonant methods used to achieve the excitation power required at these frequencies.

Identification and Sensorless Control Using Embedded System of PMSM Based on FOC Strategy and Power Factor Correction – Claudiu-Ionel Nicola, Marcel Nicola

Determining Idle Running and Short-Circuit Operating Characteristics of an Asynchronous Traction Motor – Raluca-Cristina Presură (Nicolae), Marian-Ştefan Nicolae, Sorin Enache, Ion Vlad

On the Thermographic Analysis and Thermal Resistance Estimation of the Capacitor-Run Single-Phase Induction Motors – Adrian Dănilă, Radu Mihai Campeanu

Deploying Renewable Energy Sources and Energy Storage Systems to Achieve Energy Security in the R. of Moldova – Ion Comendant, Iulia Prepeliţă, Lilia Turcuman

Sensorless Adaptive and Predictive Control of PMSM Based on FOC Strategy – Marcel Nicola, Claudiu-Ionel Nicola

Harmonics Based Clustering Patterns Featured by the Final Nodes of a WPT tree – Lucian Cristian Scărlătescu, Ileana-Diana Nicolae, Petre-Marian Nicolae, Marian Ştefan Nicolae, Anca Purcaru

Operational Aspects of an Auxiliary Converter Used in Railway Applications – Radu Florin Marinescu, Adrian Hurezeanu, Petre Marian Nicolae, Diana-Cristina Marinescu

Rehabilitation of Wastewater Treatment Plant Gardabani – Moldovan Artiom, Ilie Nucă

Modified Petri Nets for Hybrid Systems Modeling – a Case Study – Mircea Adrian Drighiciu, Daniel Cristian Cismaru

Achievement of Current Pulses of High Amplitude Using a Voltage Pulse Generator – Ion Pătru, Marcel Nicola, Maria Cristina Nitu

Tuning the PID Controller to the Model of Object with Inertia Second Order According to the Maximum Stability Degree Method with Iteration – Bartolomeu Izvoreanu, Irina Cojuhari, Ion Fiodorov, Adrian Secrieru

Contributions Regarding the Modernization of the Anti-Hail Rocket Launcher Monitoring System – Gheorghe Manolea, Ionel Laurenţiu Alboteanu, Alexandru Novac, Constantin Şulea Iorgulescu, Sorin Stepan

A Cost-Effective Smart Irrigation System For Water Reduction – Constantin-Florin Ocoleanu, Adrian-Mihai Nechita

Determination of the Dielectric Stresses that Appear in the Windings of aLlightning Impulse Autotransformer – Maria Cristina Nitu, Marcel Nicola

Comparison between Fuzzy Controller and Classical Methods for Determining the Degree of Polymerization – Maria Cristina Nitu, Ancuţa-Mihaela Aciu, Claudiu-Ionel Nicola

Parameter Identification of Transformers and Transmission Lines Based on PMU Measurements –Ecaterina Murdid, Ion Stratan

Graphical User Interface to Plot the Torque Speed Curves of Multiples Cage Induction Motor –Gabriela Dana Petropol Şerb, Ion Petropol Şerb

The Influence of the Treatment Mode of the Neutral in the 6-35 kV Networks on the Displacement Voltage in the Quasi-stationary Regime – Ina Dobrea

Qualitative Analysis for Faults Diagnosis of a Driving System with Static Converter – Virginia Ivanov, Maria Brojboiu, Sergiu Ivanov

Numerical Modeling of Heat Transfer Through Multilayer Walls of a Building, in Stationary and Non-stationary Regimes – Ioana-Gabriela Sîrbu, Radu-Cristian Dinu, Dan-Gabriel Stănescu

Analysis of Load Demand and Economic Assessment Based on Weather Forecasting in Green Buildings – Ihsan Mizher Baht, Petre Marian Nicolae, Marian Ştefan Nicolae, Ileana Diana Nicolae

ANNALS OF THE UNIVERSITY OF CRAIOVA – Electrical Engieneering Series, no. 43, vol. 43, Issue 1, 2019 (click to download)

Abstract

This1 study is concerned with the efficient integra-tion of the power management system from a microgrid with the power generation by using renewable resources and the green buildings concept. The software BIM was em-ployed in order to study the effects of climate and other external factors on energy consumptions and related costs. Two sites, highly different with respect to the climate condi-tions and cost of electric power (Bagdad from Iraq and Craiova from Romania) were addressed in order to evaluate the volume of CO2 emissions and respectively the effective-ness of power generation by using solar and wind energies. Two identical weather forecast buildings from the same sites were also studied. The results of studies over the monthly power consumptions structures for one year were discussed. The conclusions of an analysis concerned with the perform-ances (power consumption and costs) for 3 scenarios (with BIM, without BIM and respectively “high performance”) were presented as well. A study on the cost efficiency of photovoltaic cells arrays in different contexts was made, addressing the same geographic locations. General aspects of the influence of environment conditions (solar irradiance and temperature) over the performances of the studied PV array were approached for this aim. The seasonal Pay Back indices were evaluated for both locations, concluding that for any of them the use of the solar energy represents a cost effective solution for a “green” power supply.

Abstract

In order to perform the calculations regarding the energy efficiency of a building, one of the stages is to deter-mine the thermal resistance of the building elements. This quantity depends on the temperature difference and on the heat flow that crosses them. A possible approach to this calculation is the numerical one, where, depending on the existing or imposed by the regulations environmental condi-tions, these quantities can be accurately determined, whether the materials of these elements are homogeneous or inhomogeneous, linear or nonlinear. In this paper, the calcu-lation method based on the numerical calculation using the finite volumes method is presented. As an example, the study focuses on the analysis of a multilayer exterior wall. The temperature conditions to which it is subjected corre-spond to the normal operating conditions during the winter, as they are provided by the regulations in force in Romania. The stationary case was firstly analyzed, considering the constant ambient temperatures inside and outside the build-ing. Subsequently, a non-stationary thermal field analysis was performed, taking into account the variation in tem-perature over the course of a day, during the winter period. The algebraic equations resulting from the discretization of the problem equations were implemented in a program cre-ated in MATLAB. The obtained results were compared with those offered by a specialized calculation program for the thermal fields, which uses the finite element method, Quick-Field Professional. The calculation of errors proved a good correspondence between the obtained values.

Abstract

Fault Diagnosis for Engineering Systems gives a complete presentation of basic essentials of fault diagnosis, and takes a look at the cutting-edge discipline of intelligent fault diagnosis for condition-based maintenance. The paper presents a defect detection system based on development the tree faults analysis for a power rectifier. The tree fault method is used for quantitative and qualitative analysis of system reliability. For the qualitative analysis of the faults, the tree of faults is developed, based on symptoms, considered to be the most frequent ones during the operation of the power rectifiers. The paper describes the steps of the diagnostics system and the results obtained after the quantitative and qualitative analysis with the tree fault method for the three phase power rectifier. For the quantitative analysis, the reliability of the drive system is determined based on the values of the operating probabilities of the component elements. The reliability of a product can be provided in the design stage, controlled during the manufacturing process, measured during the test and maintained during the operation. The life of a product is influenced by the characteristics of the working environment. Specific information about the product’s working environment includes temperature, vibration strains, chemically or inert aggressive environments, electromagnetic conditions.