Abstract

The paper presents some considerations related to the radiated emissions from automotive area of interest. Firstly the equipment used for tests dedicated to radiated emissions is presented. Afterward some considerations on the test equipment, used in a semianechoic chamber are made. Characteristics of the horn antenna used to accomplish tests dedicated to radiated emissions within the range 0.8…1.6 GHz, along with some aspects related to design and simulation are also presented. The analysis of the electric field in the antenna and respectively of the electric field distribution in the remote field area was performed for three different frequencies (1.2GHz, 1.4GHz, 1.6GHz). Tests conditions are also described. Discussions are made with respect to the recorded data. The results of tests concerning the radiated emissions for a board display are presented, both for the horizontal and respectively vertical polarizations. Tests were made firstly for the initial hardware structure and problems related to the vertical polarization were noticed. Measures to improve the display operation are analyzed. Results of tests after the application of improvement measures are presented. Conclusions related to the improvement of the board display operation are deduced.

Abstract

This paper is concerned with the design of the power control system for a single-phase voltage source inverter feeding a parallel resonant induction heating load and the analyse of its energetic performances. The control of the inverter output current, meaning the active component of the current through the induction coil when the control frequency is equal or slightly exceeds the resonant frequency, is achieved by a Proportional-Integral-Derivative controller tuned in accordance with the Modulus Optimum criterion in Kessler variant. The control system response, in terms of the rms current at the inverter output when a prescribed step current is applied, shows that the dynamic and static performances are very good. In the second part, the paper presents the energetic performances of a proposed system for drying of current transformer from 110 kV Ciungetu power station. First, based on the actual technical solution and experimental recording of voltage and current, the equivalent parameters of the load circuit have been determined. In the proposed solution, the drying process is based on an induction heating system that contains a halfcontrolled rectifier and a voltage source inverter that operates with resonant load. The energetic performances have been determined in order to ensure zero-current switching of the inverter.

Abstract

This paper focuses on the frequency splitting and bifurcation phenomena that appear in the wireless power transfer systems. These two phenomena are analyzed for different possible configurations of the magnetically coupled circuits of the system, through electric circuit methods and mathematical calculus. Considering two printed spiral coils with similar geometrical properties, the study started with a calculus of the splitting frequency. It was made for the series-series connection, but also for series-parallel, parallelseries and parallel-parallel connections. The graphical representations of the load voltage as function of the frequency revealed that this phenomenon is visible only for the series-series and series-parallel connections; even if one or two peaks appear in all cases they are not directly connected to the frequency splitting phenomena, respectively to the spitting factor. The bifurcation phenomenon is analyzed starting from the bifurcation equation defined for the input admittance of the wireless power transfer system. The four types of configurations are analyzed from the graphical representations of the imaginary part of the admittance as function of the frequency. Because an important factor in the frequency splitting and bifurcation phenomena appearance is the ratio between the input resistance and the load resistance, in the last part of the paper the splitting coupling factor as function of the input resistance – load resistance ratio is depicted. The paper brings new contributions in the field through a comparative study on the frequency splitting and bifurcation phenomena for all the four types of configuration of the wireless power transfer systems. Through mathematical calculations, formulas for estimating the frequency (angular frequency) of occurrence of each phenomenon are obtained. The results are validated by comparative simulations related to a system of identical spiral coupled coils. The results of the analysis were commented comparatively and some conclusions could be drawn.

Abstract

This paper is focused on the transformation of a classical DC-traction substation with twelve-pulse uncontrolled rectifier into an active traction substation by adding a dedicated system for active filtering and regeneration called SISFREG. The connection of SISFREG to the ACside is performed in the primary of the traction transformer via a passive coupling filter and a recovery transformer, whereas an active separating circuit ensures the connection to the DC-traction line. The new functions added to the DCtraction substation lead to the increasing the energy efficiency of the whole system in both traction and braking regimes of the vehicles’ traction motors. The control of the current provided by the shunt active filter, which is the main component of SISFREG, is achieved in indirect mode, by means of the current upstream the point of common coupling. In the generation of the set current, the concepts of the Fryze-Buchholz-Depenbrock theory are implemented. Thus, an active current is always imposed at the power supply side and the current control loop guarantees almost sinusoidal current and global unity power factor. A complex Simulink model of the whole system, including facilities for energetic analysis, has been developed and the simulation results show good performances in both steady-state and dynamic regimes.

Abstract

The paper deals with the evaluation of the Root Mean Square (RMS) indices of signals with linearly variable magnitude by using Wavelet Packet Transform (WPT) and Fast Fourier Transform (FFT). Firstly there is presented a synthesis of employed techniques and previous results of the authors with respect to synthetically generated singleharmonic signals. The signals had linearly decreasing/increasing magnitude M. M varies according to a constant slope G. The studied absolute difference between the final and initial values of M belongs to the set {2,5, 5, 7.5 and 10}% from the initial M. Results of the RMS evaluation by using both FFT and WPT in a single harmonic approach are recalled, focusing on the maximum absolute values of percent relative errors. New studies are presented now, firstly considering randomly generated synthetic multiharmonic signals. Three cases are considered, corresponding to harmonic orders belonging to 3 distinct ranges: 3…9, 31…39 and respectively 3…40. The errors associated to the use of FFT and WPT are evaluated for them. Two real multi-harmonic signals are afterward analyzed. Small differences were noticed between the values yielded by FFT and WPT for the total RMS as compared to those computed with Riemann sums. The differences between the RMS yielded by FFT and WPT are also evaluated and discussed.

Abstract

The reactive power flows affect voltages, losses and transmission capacities. Thus MVAR flows are a matter of increasing concern for the grid operators and the Romanian Regulatory Authority for Energy has established their importance into a specific Order. The latest corresponding regulation for Romania allows the grid operator to exonerate of payment those injections of reactive which affect in a positive manner positively the voltages in the network. Such exemption is difficult to apply since the influence of MVARs on voltages is locational and time dependent. This paper deals with the assessment of reactive powers related to network users for payment and compensation purposes. The drawbacks are evaluated and compared with the benefits for voltage regulation, according to Romanian regulations. Theoretical skills are combined into one organic methodology, and an in-house software package for reactive power assessment is built. This is based on sensitivities of voltage, loss and transmission capacity to reactive injections into nodes. A case study consisting of a real 110kV network of about 2000 nodes was adopted. The survey was conducted for 6000 hours and outlines voltage to sink’s MVARs. The results were used to evaluate the opportunities to compensate and/or to discharge payments the MVARs with positive contribution to voltage regulation. This paper proposes a sensitivity based analysis for a real 110kV network.

Abstract

The paper deals with a preparatory research stage for controlling the air pressure inside a small tank by various characteristics and algorithms. Basic elements both for the hardware design and for the software support are presented. The experimental platform brings together parallel solutions: a microcontroller board using a PICTM 16F877 chip from Microchip and an industrial controller from HoneywellTM. The functionality of the platform will be tested in this stage by the on-line commutation of the control characteristics IN (pressure error) – OUT (PWM control for the air pump). A set for the available characteristics of the controller is stored in software. For a fast design with simulation and debugging capabilities, the author used FlowcodeTM of Matrix Technology Solutions – an Integrated Development Environment with a Very High Level Programming Language. Future research works are intended for some fuzzy control algorithms that could adapt and optimize the control accordingly the dynamic of the process. The main components of the platform are, besides the controllers mentioned above, an industrial pressure sensor, a compressor, the pressurized container and some standard pneumatic devices for a safe operation. Both the hardware and the software design are made so that besides the research aims, the platform could be a flexible and multi – purpose didactic tool for the students.

Abstract

Abstract – This paper presents a model of a Surface Permanent Magnet Synchronous Motor which can be used in a faulty case and a torque ripple control approach developed to be applied if the faulty case is detected. Two faulty cases are considered for study, the first consider an asymmetry between the stator phases of the motor created by unbalanced number of turns and the second a short circuit between the stator windings of the motor. Proposed torque ripple control use a phasor approach to provides the current reference for stator asymmetry and an injection of an inverse current for stator short circuit fault in order to decrease the motor torque ripple. The torque control has been implemented using a model of surface permanent magnet synchronous motor based on the dynamic equations. Simulation and experimental results highlight the link between the faulty and the torque ripple and show the possibility to decrease in this case the torque ripples by changing a balanced sinusoidal current reference by unbalanced one. In practical tests the impact of the unbalanced system of currents in the torque variation is studied using an analysis of vibratory harmonic measured at twice of the supply frequency.

Abstract

It is shown in this paper that the Conservative Power Theory (CPT) describes power properties of electrical circuits in a way which has a strong analogy to this description in terms of Budeanu’s power theory which misinterprets the power phenomena in such circuits. Also, similarly as Budeanu’s power theory, the CPT does not create right fundamentals for the power factor improvement by reactive compensation. Moreover, Budeanu’s power theory is no less “conservative” than the Conservative Power Theory, thus both theories can be referred to as conservative ones.

Content

Professor Aurel CAMPEANU at his 80th anniversary

Professor Grigore CIVIDJIAN at his 80th anniversary

Comparison of the Conservative Power Theory (CPT) with Budeanu’s Power Theory – Leszek S. Czarnecki
Modeling and Torque Ripple Control in Faulty SPMSM – Elmehdi Bahri, Remus Pusca, Raphael Romary, Driss Belkhayat
Digital Control for the Air Pressure with Multi-Characteristics Selection – Dan Mihai
Study of the Reactive Power Side Effects for Tariff and Compensation Purpose at the Transmission Networks’Users – Leonardo Geo Mănescu, Denisa Ruşinaru, Marian Ciontu, Cosmin Buzatu, Eugen Butoarcă, Miron Alba
Evaluating RMS of Linearly Variable Magnitude Waveforms by Using FFT and WPT. Theory and Practice– Ileana-Diana Nicolae, Petre-Marian Nicolae, Diana Cristina Maria, Scărlătescu Lucian
On the Implementation of FBD-Theory Concepts in the Control of Active DC-Traction Substations – Mihaela Popescu, Alexandru Bitoleanu, Mircea Dobriceanu
New Aspects on the Frequency Splitting and Bifurcation Phenomena in Wireless Power Transfer Systems –Mihai Iordache, Andrei Marinescu, Ioana-Gabriela Sîrbu, Lucian Mandache, Dragoş Niculae, Lavinia Iordache
Power Control and Energetic Performances of an Induction Heating System Destined for Drying of Current Transformers – Alexandru Bitoleanu, Mihaela Popescu, Dinu Roxan Doboşeriu
Some Considerations Concerning Radiated Emissions Produced by a Board Display – Petre-Marian Nicolae, Ileana-Diana Nicolae, Relu-Adrian Aipu
Development of a Barrier Structure Actuated by Three Shape Memory Alloy Springs – Sonia Degeratu, Costel Cărămidă, Laurenţiu Alboteanu, Irina Boncea, Daniela Coman, Monica S. Stăicuş, Gabriela Tont
Energetic Analysis of the Drying Process of Cur-rent Transformers from 110 kV Ciungetu Power Station – Dinu Roxan Doboşeriu, Alexandru Bitoleanu, Mihaela Popescu
Improving the Power Quality and Controllability of PV Power Plants for Microgrids Integration – Luminiţa Barote, Corneliu Marinescu, Ioan Şerban, Daniel Munteanu
Simulation and Implementation of Sensorless Control Using Estimators in Electric Drives with HighDynamic – Marcel Nicola, Dumitru Sacerdoţianu, Adrian Hurezeanu
Monitoring and Analysis of the Electrical Parameters for an Industrial Consumer using LabVIEWEnvironment – Claudiu-Ionel Nicola, Viorica Voicu, Sebastian Popescu, Maria Cristina Niţu, Daniela Iovan, Marian Duţă, Alin Benea, Silviu Andreescu
Modeling and Simulation of the Coal Flow Control System for the Longwall Scraper Conveyor – Olimpiu Stoicuţă, Teodor Pană
Design and Simulation of Wireless Power Transfer Systems – Mihai Iordache, George Andronescu, Victor Bucată, Maria-Lavinia Iordache (Bobaru), Marilena Stăculescu, Dragoş Niculae
Small Scale Model of Automatic Barrier Powered by Photovoltaic Panel – Laurenţiu Alboteanu, Gheorghe Manolea, Alexandru Novac
Dynamic Regime Electromagnetic Torque in Brushless Direct Current Motors – Ion Vlad, Sorin Enache, Monica Adela Enache
Enhancing the dynamic frequency of microgrids by means of PV power plants with integrated energy storage – Daniel Munteanu, Ioan Şerban, Corneliu Marinescu, Luminiţa Barote
The Analysis of Magnetic Field Measurements in a Public Access Area – Georgiana Roşu, Octavian Baltag
Comparisons Among p – Channel, n-Channel and Mixed n/p Channel OTFTs – Cristian Ravari, Georgeta Alecu
On the Immunity of Data Acquisition Systems Used in Power Systems – Livia-Andreea Dina, Ileana-DianaNicolae, Petre-Marian Nicolae, Dorina-Mioara Purcaru
Aspects of Behavior Regarding Certain Electronic Equipment Subject to Electrostatic Discharge – Mircea- Emilian Ardeleanu, Paul Nicoleanu
Load Flow Analysis of Unbalanced Distribution Networks using Symmetrical Components Based Software – Denisa Ruşinaru, Leonardo Geo Mănescu, Marian Ciontu, Miron Alba Technical Aspects Regarding Electromagnetic Compatibility Compliance of the Electric and Electronic Integrated Systems – Stoica Dan, Cosereanu Liviu, Enache Mihai, Ploşniţă Albert, Mazăre Petru
Electromagnetic Shielding System for Information and Communication Equipments – Stoica Dan, Cosereanu Liviu, Enache Mihai, Boteanu Adina, Ploşniţă Albert

Annals of the University of Craiova, Series : Electrical Engineering, 2016