The Operation and Maintenance Model for Cost Estimation of an Offshore Wind Farm-BY Jae-Hee Park-A THESIS FOR THE DEGREE OF MASTER OF ENGINEERING -JEJU NATIONAL UNIVERSITY

The Operation and Maintenance Model for Cost Estimation of an Offshore Wind Farm

GRADUATE SCHOOL JEJU NATIONAL UNIVERSITY Jae-Hee Park

A THESIS FOR THE DEGREE OF MASTER OF ENGINEERING

Abstract

Several European countries have defined targets to install and to operate offshore wind energy and according to these targets more than 40 GW offshore wind power is expected for the year 2020. Republic of Korea has also defined targets to install and operate offshore wind energy as part of its renewable energy goals. According to its targets, more than 2.5 GW offshore wind power is expected to be installed across Jeju island region and the west side of mainland by the year 2020. So the required effort for operation and maintenance of offshore wind farms will be enormous, also a thorough and appropriate plan of maintenance during the lifetime of these offshore wind turbines is essential for an economical exploitation. The aim of this thesis is to develop operation and maintenance model for an offshore wind farm in Rep. of Korea considering regional marine situation. The model should include both preventive and corrective maintenance plans which needs basic concept of wind energy, wind turbine, and maintenance strategies. The model should be based on real time metrological data, geographic data, generic wind turbine data, equipment data, spare parts and repair data. A 10 minute time series of wind speed data in public water surfaces of Daejeong-eup and 1 hourly time series of Marado significant wave height data in 2010 are used for metrological data. Equipment data is based on vessels of the operating offshore wind farm in the North Sea. Spare parts are modeled from commercial wind turbine components contribution and costs. To define repair data, there are various categories and step to determine the sequence of maintenance phases, and the corresponding amount of work, required equipment and time to organize an each maintenance phase. The operation and maintenance costs are estimated for one year in order to verify the model. A plan of operation and maintenance is set up for offshore wind farm in Jeju Island, Rep. of Korea. The results show that availability of Jeju wind farm is around 90 %. The sum of revenue losses and the total costs of repair is estimated to be approximately 27 % of generation cost which includes 11 % of the total generation cost due to limited equipment usage and 9 % of the total generation cost due to revenue losses for one year in the offshore wind farm. The proposed model can be used for the analysis of different aspects that include overall contributions and costs of operation and maintenance and to make an operation and maintenance support organization and plan for offshore wind farm in Rep. of Korea.

LINK:http://www.mediafire.com/file/7sxzk17rt7yfj04/The_Operation_and_Maintenance_Model_for_Cost_Estimation_of_an_Offshore_Wind_Farm.pdf/file

RELIABILITY AND AVAILABILITY ANALYSIS OF UNINTERRUPTIBLE POWER SUPPLY (UPS) SYSTEM CONFIGURATIONS

RELIABILITY AND AVAILABILITY ANALYSIS OF

UNINTERRUPTIBLE POWER SUPPLY (UPS)

SYSTEM CONFIGURATIONS

A DISSERTATION

SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE

AWARD OF THE DEGREE OF MASTER OF TECHNOLOGY

IN ELECTRICAL ENGINEERING (CONTROL SYSTEM)

BY:

DEEPAK SHARMA

NATIONAL INSTITUTE OF TECHNOLOGY KURUKSHETRA

There are many configurations of UPS. The configurations which are considered for estimating and analyzing the reliability, its parameter and availability in this dissertation work are classified into two groups i.e. Group I and Group II which are as follow

Group I

1. Online UPS with Bypass

2. Online UPS without Bypass

3. Offline UPS

4. Line-Interactive UPS (Buck/Boost)

5. Line-Interactive UPS (Ferroresonant)

Group II

1. Capacity (N) System

2. Isolated Redundant System

3. Parallel Redundant (N+1) System

4. Distributed Redundant System

5. System Plus System "2(N+1)" Redundant System

 

Análise experimental da qualidade da energia de uma microrrede fotovoltaica com back-up Becker, Luís Rodrigo-PROGRAMA PÓS-GRADUAÇÃO EM ENGENHARIA MECANICA-UNISINOS

Análise experimental da qualidade da energia de uma microrrede fotovoltaica com back-up Luís Rodrigo Becker-PROGRAMA PÓS-GRADUAÇÃO EM ENGENHARIA MECANICA-UNISINOS

Dissertação de Mestrado-UNIVERSIDADE DO VALE DO RIO DOS SINOS

Orientador: Dias, João Batista

Resumo:

Este trabalho apresenta uma análise experimental de uma microrrede fotovoltaica formada por dois subsistemas, um isolado com estocagem e outro conectado à rede. Foi verificado o seu comportamento, sua capacidade no fornecimento de energia para uma carga isolada e rede da concessionária, monitorado a qualidade da energia elétrica entregue à diferentes cargas e rede da concessionária e também quantificado os índices de performance do sistema conectado. O subsistema conectado à rede (SFCR) é formado por um painel de 1080 Wp de silício multicristalino e um inversor c.c./c.a. de 1200 W. O subsistema isolado de back-up (SFI-b) é formado por um painel de 600 Wp de silício monocristalino, controlador de carga, banco de estocagem com baterias chumbo-ácido 24 V / 210 Ah e um inversor off-grid c.c./c.a. de 1000 W. O comportamento e a capacidade do sistema são monitorados durante o atendimento de uma carga, representada por um refrigerador. A qualidade da energia é analisada através de medições de energia ativa, reativa e aparente, fator de potência e geração de correntes harmônicas pelos inversores. O SFI-b é monitorado atendendo diferentes tipos e regimes de cargas. Já o SFCR é monitorado em dias de céu claro, parcialmente encobertos e encobertos. Os índices de performance são calculados em dias de céu claro e parcialmente encoberto ao longo dos seis primeiros meses de 2016. Os resultados demonstram que o SFI-b é capaz de atender a carga de forma confiável, comutando-a automaticamente para a concessionária quando o banco de baterias atinge uma profundidade de descarga pré-definida, enquanto o SFCR injeta a energia produzida na rede da concessionária. Os indicadores de qualidade da energia do inversor do SFI-b mostraram-se adequados, permanecendo dentro dos limites citados na legislação e análogos aos apresentados pela rede da distribuidora local. Já o inversor do SFCR apresentou indicadores de qualidade de energia satisfatórios, também na maior parte do tempo dentro dos limites citados na legislação, exceto nos dias encobertos e períodos de baixa irradiância, constatando-se significativa geração de energia reativa e distorções harmônicas de corrente. Considerando a média entre dias de céu claro e parcialmente encoberto, a eficiência média global do SFCR é de 9,9% e a energia média diária entregue à rede é de 4,7 kWh. Foi verificado que a qualidade da energia produzida pelo SFI-b praticamente independe da irradiância, já o SFCR depende diretamente da irradiância e do nível de carregamento do inversor, na geração de uma energia de qualidade.

LINK NA WEB: http://www.repositorio.jesuita.org.br/handle/UNISINOS/6430

Design and Development of an X-Ray Machine Francisco Piernas Díaz-UNIVERSIDAD DE GRANADA-2019

1 Introduction

The X-Ray analysis has developed constantly over time since Wilhelm R¨ontgen discovered it’s applications. X-Rays are now used not only for simple radiography. Modern algorithms are capable of reconstruct a three dimensional view of the object, allowing us to recover important information about the inside of the object to study, for example, a human body. Ionizing radiations like X-Rays have also been used to discover the structure of the DNA thanks to X-Ray diffractometry. This project aims to explore the technologies of 2D radiography (sections 10 and 11) and 3D tomographic scans (section 12), and for that, a 3D printable machine is designed, built and tested using a long list of software, tools and parts [28]. One of these parts is an improved Zero Voltage Switching (ZVS) Mazzilli driver, optimized for higher frequency (section 2.1.3). The design and testing is done considering safety, as described in section 9. A Geiger counter is used to ensure that the device is safe to operate and that the operator is not exposed. In addition to the device, three programs written in C++ have been developed. The first one is an original implementation of the inverse Radon transform to perform tomographic reconstructions of the data gathered wih the X-Ray machine and it’s explained in appendix A. The second program, found in appendix B, uses an original algorithm for pseudocolor radiography that tries to improve other algorithms that usually saturates the color of the result. The last program is a numerical model of the Mazzilli ZVS transformer driver inside the machine and it provides useful information about the voltages and currents involved depending on some circuit parameters. It’s found in appendix C.

LINK:http://www.mediafire.com/file/ah56thrfymxohj1/Design_and_Development_of_an_X-Ray_Machine%252C_Francisco_Piernas_Diaz.pdf/file

PhD Thesis High Frequency Modeling of Power Transformers under Transients -by Kashif Imdad-Universidad Politécnica de Cataluña

LINK: https://www.tesisenred.net/bitstream/handle/10803/457774/TKI1de1.pdf?sequence=1&isAllowed=y

Abstract

This thesis presents the results related to high frequency modeling of power transformers. First, a 25kVA distribution transformer under lightning surges is tested in the laboratory and its high frequency model is proposed. The transfer function method is used to estimate its parameters. In the second part, an advanced high frequency model of a distribution transformer is introduced. In this research, the dual resonant frequency distribution transformer model introduced by Sabiha and the single resonant frequency distribution transformer model under lightning proposed by Piantini at unloaded conditions are investigated and a modified model is proposed that is capable to work on both, single and dual resonant frequencies. The simulated results of the model are validated with the results of Sabiha and Piantini that have been taken as reference. Simulations have shown that the results of the modified model, such as secondary effective transfer voltages, transferred impedances and transformer loading agree well with the previous models in both, the time and frequency domains. The achieved experimental and simulated objectives of this research are:  Methodology for determining the parameters of a power transformer.  High frequency modeling of a transformer in order to simulate its transient behavior under surges.  Modification of high frequency model for single and dual resonance frequency. The originality and methodology of this research are:  High frequency transformer model is derived by means of the transfer function method. In the literature, the transfer function method has been used in many applications such as the determination of the mechanical deformations or insulation failure of interturn windings of transformers. In this thesis, the parameters of the proposed model are estimated using the transfer function method.  Modification of high frequency model for single/dual resonance frequency using the transfer function method. The transfer function can also be used to determine the state of the transformer. The modification in the developed model using the proposed technique has been validated (by simulations).