Monthly Archives: January 2020

Annals of the University of Craiova, Series : Electrical Engineering - 2019

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 MotorsAdrian 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 IterationBartolomeu 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 BuildingsIhsan 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)

Analysis of Load Demand and Economic Assessment Based on Weather Forecasting in Green Buildings


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. images

Modeling of Heat Transfer through Multilayer Walls of a Building, in Stationary and Non-stationary Regimes


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. images

Qualitative Analysis for Faults Diagnosis of a Driving System with Static Converter


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. images

The Influence of the Treatment Mode of the Neutral in the 6-35 kV Networks on the Displacement Voltage in the Quasi-Stationary Regime


Contactless energy transfer 1 has indubitable advantages in modern technique given by the lack of electro-mechanical contacts predisposed to pitting and failure: use in aggressive or explosive (no sparks) environments, application to mechanisms with translation or rotation move-ments (robotics), high efficiency on relatively short distances a.s.o. Recent researches carried out in Romania demonstrate the feasibility of these systems for a wide power range, from a few watts up to tens of kW, suitable for the expansion of the electro-mobility and proliferation of multimedia and mobile communication devices. Such systems impose storing the energy in batteries requiring frequent charging. The concept of high frequency transformer with separable windings, as well as a capacitor with separable electrodes working in near field regime, the use of resonance and magnetic flux concentrators for increasing the transfer efficiency, some practical achievements and also maintaining of electromagnetic compatibility within well-defined limits are presented. The paper aims to draw the attention of users and also of prospective investors on the applications and advantages of these systems and to encourage national partnerships for developing theoretical and applied research in this field. images

Graphical User Interface to Plot the Torque Speed Curves of Multiples Cage Induction Motor


The aim of this paper is to propose an interdisci-plinary approach in study of asynchronous machine with multiple cages rotor. There were two reasons to choose as subject of studying the asynchronous motor with multi-ple/double cages rotor: firstly, because of its large applica-tion in fans and water pumps for various industrial and irrigation systems, as well as in lathe and drilling machines, and secondly, because the theoretical background of this subject is a very complex one. Because the torque-speed curve has a crucial importance in improving the perform-ances of a system, the final results of this study is to propose a Graphical User Interface in Matlab which could be used to calculate the characteristics of an asynchronous motor with multiple /double cages rotor. After a brief introduction about the constraints of systems with multiple cage asyn-chronous motors, paper propose a short review on theoreti-cal background of these machines. The next step will be to underline the designing aspects of the machine and finally to models in Matlab its characteristics. The importance of this work is bringing in attention usual aspects which could be improved by revising in learning process and in new indus-trial technologies. The results of this work could be used to design a virtual laboratory in area of electrical machine. images

Parameter Identification of Transformers and Transmission Lines Based on Synchronized Measurements


The parameters of power transformers and 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 opportu-nity of parameter identification based on the synchronized measurements during the operation of the studied object. The methods of parameter identification can be based on one, two or more measurements. Two-winding power trans-formers and transmission lines can be represented in the form of quadripole, so, applying only the current and volt-age synchronized measurement on both terminals it is pos-sible to obtain parameters of the Г-, Т- and П-forms equiva-lent schemes. There are presented a final and intermediate formula for transformer parameters. Also, there are ob-tained a similar formula for transmission lines. Besides, for transmission lines, there are obtained expressions for the method of the current balance, then for power balance. The last-mentioned methods are based on two samples of meas-urements and haven’t been previously described in any other source. All proposed methods were verified with the models of real transformers and transmission lines. The obtained results show the high accuracy of parameter iden-tification for the proposed methods. For power transform-ers, the influence of load factor upon the values of parame-ters was analyzed. It is worth noting that the most reliable results are obtained from measurements at the load factor β=0.55..0.85. For the model of the 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 main contribution of this paper lies in the explanation of the novel method of quadripole (based on one measurement) for parameter identification of transformers and electric lines. That represents a good advantage over other methods with multiple measurements. images

Comparison between Fuzzy Controller and Classical Methods for Determining the Degree of Polymerization


This paper shows a fuzzy logic-based method for determining the degree of polymerization of the solid insulation of a transformer, taking into account the 2-FAL (2-furfuraldehyde) content. The proposed method generates information on the “health” condition of the transformer, with a high precision degree. The proposed system is based on two fuzzy-type controllers, and for each input/output of them it is defined a type of membership functions, triangle and trapezoid for a better response of analysis. The obtained results were compared to the results got by classical methods applied for the same 2-FAL content. For verifying the precision and accuracy, the proposed method was applied on more than a hundred of samples subjected to verification. images

Determination of the Dielectric Stresses that Appear in the Windings of a Lightning Impulse Autotransformer


This paper presents two methods for determining the dielectric stresses occurring in the tap winding of a lightning pulse autotransformer. The first method is to im-plement the equivalent circuit using the ATP / EMTP pro-gram, and the second method consists in testing the auto-transformer at a low voltage impulse before being put into the tank. The design of the autotransformer was done tak-ing into account the results obtained with ATP/EMTP. This fact allowed the design of the winding structure as well as their location in space to obtain uniformly distributed over-voltages along the axial and radial direction of the coil as-sembly. The results of the laboratory tests performed on the autotransformer, validated the results obtained with ATP / EMTP. images

A Cost-Effective Smart Irrigation System For Water Reduction


A cost-effective solution for water reduction based on a smart irrigation system is presented in this pa-per. The system consists of a microcontroller, moisture sen-sors, relays, solenoid valve and water pump. Depending on the conditions of a specific location (soil condition – wet, dry, etc.) the system can control the amount of used water by modifying some parameters. In this application were considered 2 zones which mean that 2 humidity sensors were used. When the humidity drops below a threshold val-ue on one of the two zones, the corresponding humidity sen-sor transmits the information to the controller, opens the solenoid valve and starts the water pump until the humidity reaches at the preset value. If humidity decreases in the meantime on the other zone the information received from the humidity sensor leads the solenoid valve to open and the pump starts until the desired humidity is attained. When the humidity is over the threshold value, the system is in “stand-by” until the sensors send new information to the microcon-troller and thus the system resumes its operating cycle. In this way various crops can be watered without using a high quantity of water. In addition, a smartphone application was used in order to provide to the user information about the soil condition. In order to implement this solution, a laboratory model was constructed and experimental results were performed to test the performance of the irrigation system. images