Quasi Z-Source AC-AC converter system connected in series With Dynamic Voltage Restorer(DVR) capability Jun-Hyun Eom - Department of Electrical Engineering Graduate, School Chonnam National University-SOUTH KOREA

동적전압보상 기능을 갖는 출력이 직렬 결합된 Quasi Z-소스 AC-AC 컨버터
 Quasi Z-Source AC-AC converter system connected in series With Dynamic Voltage Restorer(DVR) capability Jun-Hyun Eom
 Department of Electrical Engineering Graduate, School Chonnam National University (Supervised by Professor Young-Cheol Lim)

(Abstract)
 Recently, different with the conventional load, the present load devices such as computers, Automated production equipments, precision electronic devices are very sensitive to the power quality. These load devices sensitive to the power quality are increasing sharply and people are paying more and more attention to the AC-AC power conversion devices like instantaneous voltage-compensators, phase-shifters, electronic transformer which are installed in the side of power system or consumers. Similarly, the AC chopper, PWM AC-AC converter, matrix converter and Z-Source AC-AC converter also belong to the AC-AC power conversion devices referred above. among these devices, due to the latest research method, the Z-Source AC-AC converter has quite simply structure and control method and is possible to boost output voltage in phase and boost or buck output voltage out of phase with respect to input voltage.

Nevertheless, since the Z-Source AC-AC converter operates in DCM (Discontinuous Current Mode), stress of the elements is bigger compared with the case of CCM(Continuous Current Mode) and it's very disadvantageous viewed from the waveform. It is probable to solve the problems referred above by Quasi Z-Source AC-AC converter. However, the operation of buck mode is impossible, even though it's possible to boost or buck the output voltage out of phase and boost the output voltage in phase.

In this study, a single-phase quasi Z-source AC-AC converters with a series connection of the output terminals is proposed. The proposed system has configuration that the input terminals of two quasi Z-source AC-AC converters are connected in parallel and its output terminals are connected in series. for output of in-phase buck mode with respect to the input ,the intersection switching control is presented and the current flow in both of the out phase mode and in phase mode and the output voltage's forming process was shown.

In addition, a DVR(Dynamic Voltage Restorer) though using a single-phase quasi Z-source AC-AC converter connected with the output terminals in series is proposed. In general, among the problems which cause the lower quality, the Voltage Swell or Voltage Sag could be the major one which brings great influence to the consumers with high frequency and sensitive load. The Voltage Swell which is the increasement of the supply voltage's magnitude in duration of 0.5∼30[cycles] while the voltage magnitude is 1.1∼1.8[p.u] of nominal voltage and the Voltage Sag which is the drop of the supply voltage's magnitude in duration of 0.5∼30[cycles] while the voltage magnitude is 1.1∼1.8[p.u] of nominal voltage can lead to the accidents happening in most of the nearby distribution circuits. Such Voltage Swell or Voltage Sag causes the misoperation or suspension of work and bring about Nevertheless, since the Z-Source AC-AC converter operates in DCM (Discontinuous Current Mode), stress of the elements is bigger compared with the case of CCM(Continuous Current Mode) and it's very disadvantageous viewed from the waveform.

It is probable to solve the problems referred above by Quasi Z-Source AC-AC converter. However, the operation of buck mode is impossible, even though it's possible to boost or buck the output voltage out of phase and boost the output voltage in phase.
In this study, a single-phase quasi Z-source AC-AC converters with a series connection of the output terminals is proposed.

LINK ORIGINAL EN LA WEB
http://ocean.kisti.re.kr/downfile/volume/kipe/JRJJC3/2013/v18n4/JRJJC3_2013_v18n4_322.pdf

AMORPHOUS METAL CORES IN MEDIUM FREQUENCY POWER TRANSFORMER - Morteza Razaz Department of Electronic and Electrical Engineering University of Salford - England

AMORPHOUS METAL CORES IN MEDIUM FREQUENCY POWER TRANSFORMER
 Thesis submitted to the University of Salford for the degree of Doctor of Philosophy by Morteza Razaz Department of Electronic and Electrical Engineering University of Salford Salford M5 4WT England

 LINK
http://usir.salford.ac.uk/14782/1/308481.pdf

The Design of LLC Resonant Converter for Wireless Power Transfer Inverter-- Seong-JinLim Department of Electrical Engineering Graduate School of Mokpo National University

대전력용 차단기 내의 EMC Filter 개발에 관한 연구 = A Study on Development of EMC Filter in the High Power Breaker -Graduate School of Korea Maritime University

Abstract 
 Recently, as the number of usage of various electronic devices increases rapidly, the demand for the power is also growing very much Therefore, to supply electricity of high quality steadily and minimize the power loss, the voltage of power transmission and distribution is getting higher and higher to the maximum, and the demand for heavy electric machines such as high power transformer, instrument transformer, and breaker, is also increasing[I]. The heavy electric machines includes all of machines and tools to transfer the electricity generated from the power plants to houses or factories. It must be insulated well in the high voltage, and do its functions properly even in the extreme working conditions. Therefore, in this dissertation, the EMC filter in the high power breaker, one of the heavy electric machine, was suggested as a countermeasure for conductive noises. And the suggested EMC filter in the high power breaker was attenuated 25 - 70 dB in the range of 10 MHz 1.5 GHz When the EFT of 4 kV in the level 4 of IEC 61000-4-4 was induced, it was soon suppressed to 600 V, and the filter was also verified its excellence by satisfying the level 4 of IEC 61000-4-4. Hence, the best feature of it was to prevent the leakage of electromagnetic noise by enhancing immunity of houses or factory machines. Go forward the suggested EMC filter can be applicable not even for electronic • information devices, but also electronic • control devices as the very innovative countermeasu- re, namely, the range of its application can be expected very broad.

New Software Package for Teaching and Learning the Basics of Photovoltaic System Sizing - SEBASTIEN JACQUES, SEBASTIEN BISSEY University of Tours (France) Polytech Tours, Electronics and Energy Department

Abstract: This paper describes an innovative and highly modular software tool named PVLab and developed by the GREMAN laboratory in collaboration with Polytech Tours from the University of Tours (France). This simulation package assists the designer in the sizing of PV (photovoltaic) installations. PVLab has a high level of flexibility, allowing its physical models and databases (e.g., meteorological data) to be modified according to the user’s needs. This is made possible through the use of expertise applied to all of the computing steps, and to the MATLAB development environment. The user’s ability to control the source code itself will allow much greater progress to be made in the field of renewable energy applications than with PVsyst, which is currently the commercial reference. All of these features come together to make PVLab the perfect tool for modernizing higher education, in particular with regard to students’ competencies. Since recent years, the higher education landscape has been undergoing considerable change as a result of technological innovations and new pedagogical approaches [1], [2], [3]. The Bologna Declaration and Lisbon Strategy in Europe are the clearest examples of international commitment to reform and modernization of university education [4], [5]. The degree and qualifications obtained, in terms of workload, level and learning outcomes are major pillars of the Bologna Process [6]. The competency-based management has been developed to increase the readability and comparability of European higher education degrees worldwide [7], [8]. This approach also supports the employability of higher education graduates [9]. Indeed, they are expected to be fully operational in an international context upon completion of their studies. About 100 Engineering Schools in France have already started the process at the moment. This movement should speed up with the Engineering Education Commission (CTI) guidelines. The Polytechnic Engineering School of the University of Tours (Polytech Tours, France) has just initiated the continuous skills development. The Electronics engineers to design and to have an in-depth understanding of electronic systems, has recently set up new pedagogical tools to achieve the education system modernization target. With regard to the education of photovoltaic (PV) applications in particular, recent researches have focused attention on students’ investment to give them the methods, tools, skills, and understanding since they could potentially be involved in the design, sizing, and installation of PV systems within an efficient industrial context [10], [11]. As the use of photovoltaics expands, with more and more commercial and residential users investing on solar energy systems around the globe, there is a growing demand for software that can be used for the design, simulation, data analysis, and troubleshooting of PV systems, from the preliminary assessment of energy efficiency and cost-effectiveness to the development of the project documentation. For many years, PVsyst has been accepted as a reference by architects, engineers, teachers and researchers, especially as a result of its easy-to-use, and accuracy of electrical energy production estimation thanks to its extensive PV- component, and meteorological databases [12]. However, using this kind of software package, it is not possible to modify the electrical, optical and thermal models, nor the internal databases (i.e., PV modules, inverters, and meteorological databases) [13]. A major question is whether existing commercial PV software, such as PVsyst, are sufficient to accurate forecast the efficiency of a PV plant taking into consideration all technical and environmental requirements.

LINK ORIGINAL
http://www.wseas.org/multimedia/journals/education/2015/a245810-157.pdf