STABILITY ANALYSIS AND VOLTAGE-SAG MITIGATION OF POWER SYSTEM IN OFFSHORE OIL RIG PLATFORM Autor:WU DI DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE

Fig A.2 Proposed DVR Design Simulink Configuration in Power System


STABILITY ANALYSIS AND VOLTAGE-SAG MITIGATION OF POWER SYSTEM IN OFFSHORE OIL RIG PLATFORM

WU DI B. Eng. (Hons.), NUS

A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF ENGINEERING 
DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
 NATIONAL UNIVERSITY OF SINGAPORE 2011 

SUMMARY Today’s semi-submersible offshore oil rig platform uses variable-speed induction motors for station—keeping during drilling and sailing. During drilling, the platform needs to be maintained within its intended location to prevent interruption of operation and damage to the drills. Thus, it is crucially important that the induction-motor drive and the power supply feeding the drive are stable. This master thesis aims at analyzing and proposing analytical solutions to these two issues. The main contributions of the thesis are: For the first time, a Matlab Simulink model is built to simulate the detailed dynamics of the induction-motor drive in offshore oil-rig platform. The model and parameters used for the drive are verified by on-site tests of the Keppel FELS motors. Genetic algorithm is developed to the small-signal model of the induction-motor drive to identify, within the full range of speed and load, the instability region of the induction motor fed from ideal variable-frequency supply or a converter. The source of instability is also investigated from the two different supply configurations of the induction-motor drive. It is shown by eigenvalue analysis that instability exists in the induction motor itself but not in the other parts of the drive i.e. the converter supplying the motor. Accordingly, speed feedback comprising a proportional regulator is added to the drive to eliminate the instability region intrinsic to the induction motor plotted using genetic algorithm Voltage sag is known to be the most common disturbance in offshore power system, which has led to blackout in severe cases. A new design of dynamic voltage restorer (DVR) is modeled in Simulink, which deals with the influence of voltage sag on the induction-motor drive within strict harmonic limits imposed by marine standards. The new design outperforms the conventional DVR design by effectively increasing the accuracy of voltage compensation and significantly reducing the level of total voltage harmonic distortion.

 LINK ORIGINAL
http://scholarbank.nus.sg/handle/10635/27925

Direct download link
http://scholarbank.nus.sg/bitstream/handle/10635/27925/Wu%20Di.pdf?sequence=1

Design and Optimization of HF Transformers for High Power DC-DC Applications Mohammadamin Bahmani - Division of Electric Power Engineering Department of Energy and Environment Chalmers University of Technology Goteborg, Sweden 2014

Thesis for The Degree of Licentiate of Engineering 

 Design and Optimization of HF Transformers for High Power DC-DC Applications 
Mohammadamin Bahmani 
 Division of Electric Power Engineering Department of Energy and Environment 
Chalmers University of Technology Goteborg, Sweden 2014 

 Abstract
 Increasing the operational frequency is the most common solution to achieve higher power densities, since the weight and volume of the magnetic part, the bulkiest element in power electronics converters, are then decreased. This solution is well established in low power high frequency applications, while in the recent decade, the possibility of utilizing high frequency at higher power and voltage levels has generated wide interest as well. This work proposes a design and optimization methodology of a high power high frequency transformer accounting for the tuned leakage inductance of the transformer, as well as high isolation requirements, particularly in DC offshore application where a converter module should withstand the MVDC or HVDC link voltage. To achieve this goal, several models were proposed and developed in order to accurately characterize such a transformer. One of these models is a so called pseudo-empirical expression derived from a rigourous regression algorithm based on an extensive 2D finite element simulation scenario, resulting in an accurate analytical expression with an average unsigned deviation of 0.51% and the extreme deviations not higher than 9%. Moreover, using the energy method, an analytical expression to precisely calculate the leakage inductance of high power density magnetic components is proposed. In addition, using the proposed modification of the Steinmetz equation for core loss calculations, general expressions are derived and presented for a rectangular waveform with its associated duty cycle and rise time. Applying the proposed design methodology, in which all the aforementioned models are implemented on a 1 MW case study transformer, indicates that such a transformer can achieve a power density of about 22 kW/L and the efficiencies as high as 99.74%. Moreover, with respect to the isolation requirements, desired leakage inductance and the magnetic material used, a critical operating frequency can be found above which the transformer does not benefit from volume reduction anymore. Keywords High Power High Frequency Transformer, Isolation Requirements, Leakage Inductance.

 LINK ORIGINAL  THESIS COMPLETE
http://publications.lib.chalmers.se/publication/195670-design-and-optimization-of-hf-transformers-for-high-power-dc-dc-applications

Direct download link
http://publications.lib.chalmers.se/records/fulltext/195670/195670.pdf

LED lighting control driver design and development of the 12V‐12W class using the voltage controlled ring oscillator Ki-Soo Kwon -Department of Electronic Engineering Graduate School Yeungnam University SOUTH KOREA

M. S. Thesis
 LED lighting control driver design and development of the 12V‐12W class using the voltage controlled ring oscillator- Ki-Soo Kwon
Department of Electronic Engineering Graduate School Yeungnam University (Advised by Professor Young-suk Suh)

전압제어 링 발진기를 이용한
12V-12W급 LED 조명제어 구동회로

설계 및 개발

Abstract
This paper presents a Pulse Width Modulation (PWM) controller and circuits for the high power LED (Light Emitting Diode) driver. The controller is available for the remote control through four major operation modes of ON, OFF, Emergency and Power saving using the serial communication M. S. Thesis LED lighting control driver design and development of the 12V‐12W class using the voltage controlled ring oscillator Ki-Soo Kwon Department of Electronic Engineering Graduate School Yeungnam University (Advised by Professor Young-suk Suh) Abstract This paper presents a Pulse Width Modulation (PWM) controller and circuits for the high power LED (Light Emitting Diode) driver. The controller is available for the remote control through four major operation modes of ON, OFF, Emergency and Power saving using the serial communication The entire driver circuits use a DC‐DC converter such a Boost topology with dimming, current, thermal control and communication functions for hallway lighting and automobile applications. According to the type and power of LED, a driver IC has already been developed and is produced. This driver IC makes the constant current and constant voltage available. However, if the LED driver allows delicate dimming control and thermal dissipation through allowance of LED off time, PWM control is needed. Therefore, a MCU (Microcontroller unit) for the PWM control as well as a driver IC for driving LEDs is needed. If this operation is embedded at this driver IC, the expense can be reduced. The LED controller integrated circuit (IC) was designed, simulated and fabricated in 0.35μm Magnachip/Hynix.

DR. Slobodan Cuk - Group POWER ELECTRONICS INSTITUTE

Prof Gustavo Castelo Branco, Prof Slobodan Cuk e Prof Armando Cavero Miranda -Brazilian Power Electronics Conference -Cobep/Spec - 2015 -FORTALEZA-CEARÁ-BRASIL

  DR. Slobodan Cuk 

I am Yugoslav/Serbian who came to United States as an immigrant on flight from Belgrade, Yugoslavia on February 29, 1972 sponsored by NASA. NASA first supported at Santa Clara my MS thesis: “Stability Investigations of the Spinning Skylab” and my 2-year doctorate at Caltech from Sept. 1974 to Dec. 1976. This latter work is now part of the new Vol. 4: “State Space Averaging and Cuk converters”. Vol.1 and Vol. 4 are now combined into a 624-page 40-th anniversary paperback edition while Vol.2 and vol. 3 are combined into 631-page paperback. Kindle editions are also available now individually and as four volume bundle. 1. teslaco.com 2. YouTube.com/c/slobodancukTESLAco 3. Amazon.com/author/slobodancuk 4. linkedin.com/groups/7045487. 5. cuk@teslaco.com; 6. Linkedin.com/in/slobodancuk. Many generations of engineers used these books to get into emerging Power Electronics field and more than 4,000 used them as textbooks in courses I presented. One of my 35 PhD students, now professor, endorsed these books on Amazon with: “This Power Electronics Series is a record of a Big Bang in the History of Power Electronics!” The combined vol.1 and vol.4 paperback and my past research work led me to conclude that a critical re-evaluation is badly needed of the conventional buck, boost, flyback, forward, bridge-type, LLC and other converters which dominated industry for the last 60 years! This is now addressed in the upcoming volume 5! The time has now also come for their replacement by new Power Electronics System Technology based on three new Resonant/PWM type switching methods, related host of novel converter topologies and new magnetics structures I introduced in last 6 years via patents, articles and presentations! They and my contemporary column with articles on teslaco.com home page are slated for upcoming Volume 6 of this series! A well respected Power Electronics expert recently commented to his LinkedIn group: “You should all read everything that Dr. Ćuk has ever written!”.

LINK
https://www.amazon.com/Slobodan-Cuk/e/B00IYCSWQ0

HIGHER MATHEMATICS- SHIPACHEV- Высшая математика. Шипачев В.С.

LINK RUSSIAN VERSION
http://www.mediafire.com/file/o5ryy2rflxnbaxg/SHIPACHEV_HIGHER_MATHEMATICS.pdf