공동주택에 적용한 계통연계형 태양광발전시스템의 보호방식에 관한 연구 A Study on the Protection Method of the Grid-Connected Photovoltaic Power Generation System Applied to Apartments-GeunYub Lee- Dept. of Electrical Eng. The Graduate School Korea University

 

공동주택에 적용한 계통연계형 태양광발전시스템의 보호방식에 관한 연구

 A Study on the Protection Method of the Grid-Connected Photovoltaic Power Generation System Applied to Apartments

 高麗大學敎工學大學院 電氣工學科 李根燁 2011年 

 A Study on the Protection Method of the Grid-Connected Photovoltaic Power Generation System Applied to Apartments 

BY GeunYub Lee 

Dept. of Electrical Eng. The Graduate School Korea University 

(Supervised by Prof. Gilsoo Jang, Ph.D)

 Abstract 

Global environment problems have emerged rapidly throughout international society since the 1990s. Diverse global environment problems are being raised including global warming, ozone depletion, waste contamination, acid rain, desertification, marine pollution, extinction of species, and radioactive contamination. The root cause of these phenomena is energy consumption. Moreover, around a fourth of the total energy consumption is consumed by buildings. In Korea, buildings consume around 25% of the total energy consumption, and residential buildings consume around 75% of energy consumed by buildings and energy consumption by residential buildings is expected to keep growing along with the rise of economic level. Taking this issue seriously, the Korean government has been supporting investments in research and facilities for energy saving and alternative energy technologies since the 1980s as an effort to secure future energy sources, to solve global environment problems, and to attain sustainable economic growth. Recently, facilities using new and renewable energies are being spread and expanded and people are recognizing particularly the importance of technologies for photovoltaic power generation as an infinite energy source. Considering the current situation of Korea highly dependent on fossil energy, the application of photovoltaic power generation to apartment buildings is desirable not only for the growth of national economy and the stable security of alternative energy resources but also for the conservation of global environment. Nevertheless, there have not been many studies for developing technologies to connect photovoltaic systems to electric companies. It is urgently required to increase stable electric power supply of enhanced reliability and to develop system connection technologies. The installation of photovoltaic systems is steadily increasing as evidenced by the onemillion green home construction project under the government’s active support. If photovoltaic facilities are installed on the slanting roofs of apartment buildings and connected to existing distribution systems, they may have an adverse effect on quality, stability and reliability of electric power and, most of all, may disrupt the protective coordination of systems. The connection of photovoltaic systems to distribution systems means a new change in the conventional concept of electric power system. Thus, this study aimed to analyze the quality of electric power required and expected problems when photovoltaic facilities are connected to distribution systems, to look for solutions for the problems, and ultimately to enhance the performance, stability and reliability of photovoltaic systems and establish technological conditions to be satisfied for connection to distribution systems. First, this study examined how to prevent islanding detection caused by power failure in existing distribution systems during the connected operation of photovoltaic facilities and existing distribution systems and to minimize the loss of human life and properties caused by such accidents. Second, this study analyzed the capacity of photovoltaic facilities connectable to low‐voltage distribution systems based on voltage regulation as a part of research on the capacity of photovoltaic systems connected to existing distribution systems. Third, with regard to the ground system of photovoltaic facilities, this study demonstrated the need of a new evaluation method suitable for DC systems apart from existing AC ones. There will be unexpected problems raised along with the spread of system‐connected photovoltaic facilities. Thus we expect active research to find solutions for problems resulting from connection between photovoltaic facilities and distribution systems and to hasten the stable supply of electric power to consumers through photovoltaic facilities using solar energy.

LINK: http://www.mediafire.com/file/k91e2oag6epy4g7/A+Study+on+the+Protection+Method+of+the+Grid-Connected+Photovoltaic+Power+Generation+System+Applied+to+Apartments.pdf/file

MANUAL DE ENGENHARIA PARA SISTEMAS FOTOVOLTAICOS-JOÃO TAVARES PINTO-MARCO ANTONIO GALDINO-GRUPO DE TRABALHO DE ENERGIA SOLAR-GTES-CEPEL-DTE-CRESESB

 
MANUAL DE ENGENHARIA PARA SISTEMAS FOTOVOLTAICOS-JOÃO TAVARES PINTO-MARCO ANTONIO GALDINO-GRUPO DE TRABALHO DE ENERGIA SOLAR-GTES-CEPEL-DTE-CRESESB

LINK: http://www.mediafire.com/file/nd09taqdktrb39r/Manual_de_Engenharia_FV_2014.pdf/file

Control Architecture for Parallel Inverter in Uninterruptible Power Systems Chi Zhang, Student Member, IEEE, Josep M. Guerrero, Fellow, IEEE, Juan C. Vasquez, Senior Member, IEEE, Ernane A.A. Coelho, Member, IEEE

 

Abstract— In this paper, a control strategy for the parallel operation of three-phase inverters forming an online uninterruptible power system (UPS) is presented. The UPS system consists of a cluster of paralleled inverters with LC filters directly connected to an AC critical bus and an AC/DC forming a DC bus. The proposed control scheme comprises two layers: (i) a local layer that contains a “reactive power-to-phase droop” in order to synchronize the phase angle of each inverter and a virtual resistance loop that guarantees equal power sharing among inverters; and (ii) a central controller that guarantees synchronization with an external real/fictitious utility, and critical bus voltage amplitude restoration. Improved transient and steady-state frequency, active, reactive and harmonic power sharing, and global phase-locked loop resynchronization capability are achieved. Detailed system topology and control architecture are presented in this paper. Further, a mathematical model was derived in order to analyze critical parameters effects on system stability. The proposed control approach has been validated by means of experimental results obtained for several case-study scenarios. Index Terms— UPS system; parallel inverters; voltage restoration; droop control; virtual impedance

LINK:https://vbn.aau.dk/files/219215517/Zhang_Chi_trans_manu_doublecol.pdf

Updating and Customizing an industrial UPS HMI-A Master's Thesis Submitted to the Faculty of the Escola Tècnica d'Enginyeria de Telecomunicació de Barcelona Universitat Politècnica de Catalunya by Ali Ahmadi

 Abstract 

Uninterruptable Power Supply or UPS is one of the key parts of industries nowadays. Importance of it has risen because of the increasing demand for more stable power supply for Electronics and Electrical systems each year, especially in the field of IT and Data Servers. During these years, with improving Electrical products, Human Machine Interface became part of most electrical products and UPS is no exception. These days, UPS has a graphical display which according to the application of UPS, its design and abilities is different. HMI design for UPS has challenges, as instance: design according to the application, efficiency of design, preventing bugs, graphical design and etc. During this project, our plan is designing a new generation of Salicru HMI with the capability of adopting with old version Industrial UPS which manufactured by partner companies and also this HMI use for Salicru new generation UPS, Cube 4.

LINK: https://upcommons.upc.edu/bitstream/handle/2117/165610/TFM_Ali Ahmadi-Final Version.pdf

Optimal Design Method of the LLC resonant converter using the hybrid current balancing circuit for LED lighting -Author Jin-Gu Kim Department of Electrical & Medical Convergent Engineering Graduate School, Kangwon National University South Korea.

 

Optimal Design Method of the LLC resonant converter using the hybrid current balancing circuit for LED lighting  Author Jin-Gu Kim

 Department of Electrical & Medical Convergent Engineering Graduate School, Kangwon National University South Korea.

Abstract 

In this thesis, a novel hybrid current balancing circuit and an optimum design of LLC resonant converter for driving a current balancing circuit are proposed. 

First of all, the hybrid current balancing circuit was proposed for compensating current deviation among LED strings. LEDs have been widely used in lighting, automobiles, and airplanes owing to their excellent light output characteristics and long lifespan. Though LEDs are manufactured under the same process, variations in impurity concentrations cause electrical deviation among LEDs. This electrical deviation results in current unbalance of LED strings. The resulting current unbalance does not only reduce the life time of the LED but also cause non-uniform luminance of LEDs connected in parallel. The LED driving circuit is researched to solve the above problems. In this thesis, a novel hybrid current balancing circuit with a Y-type current balancing transformer and a voltage doubler rectifier circuit was proposed for the compensation of 6 LED strings with a simple structure.

 Secondly, the Optimal design method of LLC resonant converter for driving hybrid current balancing circuit was proposed. The difference between the proposed optimal design method of LLC resonant converter and conventional design method can be divided into three categories.

 First of all, when designing transformer with leakage inductance(Lr ) and magnetizing inductance(Lm), unwanted leakage inductance of secondary side (Lr2) which cause error in the process of measuring the leakage inductance (Lr ) with instrument occurs. This design error could be reduced by taking into account the leakage inductance of secondary side(Lr2). 

Secondly, in general, the voltage gain characteristic curve is applied to design LLC resonant converter. in this thesis, the current gain characteristic curve was applied to the design process which is suitable for LED that is non-linear load and necessary to be controlled to a constant current. 

Lastly, the equivalent circuit of LED was applied to the design process. Normally, a resistive load which has linear load characteristic is used for designing the LLC resonant converter. However, in this thesis, the equivalent circuit of LED which includes a voltage source, a resistor and a diode could be obtained by using the linear approximation method. This circuit was then applied to the design process for reducing design error. 

Experimental results are presented to verify the performance of the proposed hybrid current balancing circuit and the optimal design method of the LLC resonant converter. The LED maximum current error rate which was 19.57% was reduced to 4.5% by Y-type current balancing transformer. Also, the validity of the proposed optimal design method of the LLC resonant converter was verified by comparing it with the conventional design method. An 150W prototype was implemented and used for the performance verification of the hybrid current balancing circuit and the LLC resonant converter.

LINK: http://www.mediafire.com/file/sfzdhsuo3y91zod/file