Design And Implementation Of Co-Operative Control Strategy For Hybrid AC/DC Microgrids

This thesis is mainly divided in two major sections: 1) Modelling and control of AC microgrid, DC microgrid, Hybrid AC/DC microgrid using distributed co-operative control, and 2) Development of a four bus laboratory prototype of an AC microgrid system. At first, a distributed cooperative control (DCC) for a DC microgrid considering the state-of-charge (SoC) of the batteries in a typical plug-in-electric-vehicle (PEV) is developed. In DC microgrids, this methodology is developed to assist the load sharing amongst the distributed generation units (DGs), according to their ratings with improved voltage regulation. Subsequently, a DCC based control algorithm for AC microgrid is also investigated to improve the performance of AC microgrid in terms of power sharing among the DGs, voltage regulation and frequency deviation. The results validate the advantages of the proposed methodology as compared to traditional droop control of AC microgrid. The DCC-based control methodology for AC microgrid and DC microgrid are further expanded to develop a DCC-based power management algorithm for hybrid AC/DC microgrid. The developed algorithm for hybrid microgrid controls the power flow through the interfacing converter (IC) between the AC and DC microgrids. This will facilitate the power sharing between the DGs according to their power ratings. Moreover, it enables the fixed scheduled power delivery at different operating conditions, while maintaining good voltage regulation and improved frequency profile. The second section provides a detailed explanation and step-by-step design and development of an AC/DC microgrid testbed. Controllers for the three-phase inverters are designed and tested on different generation units along with their corresponding inductor-capacitor-inductor (LCL) filters to eliminate the switching frequency harmonics. Electric power distribution line models are developed to form the microgrid network topology. Voltage and current sensors are placed in the proper positions to achieve a full visibility over the microgrid. A running average filter (RAF) based enhanced phase-locked-loop (EPLL) is designed and implemented to extract frequency and phase angle information. A PLL-based synchronizing scheme is also developed to synchronize the DGs to the microgrid. The developed laboratory prototype runs on dSpace platform for real time data acquisition, communication and controller implementation

TDP2は、前立腺上皮細胞においてアンドロゲンによるゲノム不安定性を抑制する

付記する学位プログラム名: 充実した健康長寿社会を築く総合医療開発リーダー育成プログラム京都大学新制・課程博士博士(医学)甲第23090号医博第4717号新制||医||1050(附属図書館)京都大学大学院医学研究科医学専攻(主査)教授 篠原 隆司, 教授 小川 修, 教授 溝脇 尚志学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDFA

Feedback Linearized Controller Design and Switching Frequency Sensitivity Analysis of Distributed Generators

The conventional power system undergoes a massive change owing to the penetration of distributed generators into distribution networks and the standalone operation of microgrids. The characteristics of distributed generators largely depend on power electronic interfaces that are not matched with conventional synchronous machine-based generation systems. The changing behaviours of the distribution side of the electrical network continue to provide new challenges to power system design and operation engineers. To overcome such issues, the design of high-performance controllers plays a crucial role. In addition, investigation of the dynamic behaviours of the power electronic interfaces, including switching frequency is essential, which is the critical characteristic of the distributed generators. The first contribution of this dissertation is the design of a robust nonlinear controller to enhance the transient stability of distributed generators. In this work, the feedback linearization technique is used to linearize the standalone solar photovoltaic including battery energy storage, grid-connected fuel cell, and grid-connected solar photovoltaic including battery energy storage systems. Robust H_\infty mixed-sensitivity loop-shaping controllers are designed to stabilize the linearized part of the nonlinear feedback linearized control laws. The proposed robust H_\infty controller for the feedback linearized control scheme provides several benefits over the existing feedback linearization that is stabilized by the conventional PI controller. The second and unique contribution of this thesis is the developed single-input two-output feedback linearized control scheme based on the conventional single- input single-output feedback linearization approach. The third contribution of this dissertation is single-input two-output controller design for the islanded DC, AC, and hybrid DC/AC microgrids to enhance the voltage stability and minimize the circulating current among parallel-connected distributed generators. The fourth and final contribution of this work is the developed multi-frequency averaging based dynamic phasor model of a standalone, grid-connected, and two-stage distributed photovoltaic generators. The developed dynamic phasor models are provided with switching frequency-dependent characteristics, showing the switching frequency effect on the distributed generators. This contribution provides the idea of a suitable switching frequency range for power electronic interfaces

Modeling Friction Losses in the Water-Assisted Pipeline Transportation of Heavy Oil

In the lubricated pipe flow (LPF) of heavy oils, a water annulus acts as a lubricant and separates the viscous oil from the pipe wall. The steady state position of the annular water layer is in the high shear region. Significantly, lower pumping energy input is required than if the viscous oil was transported alone. An important challenge to the general application of LPF technology is the lack of a reliable model to predict frictional pressure losses. Although a number of models have been proposed to date, most of these models are highly system specific. Developing a reliable model to predict pressure losses in LPF is an open challenge to the research community. The current chapter introduces the concept of water lubrication in transporting heavy oils and discusses the methodologies available for modeling the pressure drops. It also includes brief descriptions of most important pressure loss models, their limitations, and the scope of future works

ATM suppresses c-Myc overexpression in the mammary epithelium in response to estrogen

ATM遺伝子変異による乳癌発症機構を解明 --HBOC症候群の乳腺特異的発癌機構の解明に貢献--. 京都大学プレスリリース. 2023-02-09.ATM gene mutation carriers are predisposed to estrogen-receptor-positive breast cancer (BC). ATM prevents BC oncogenesis by activating p53 in every cell; however, much remains unknown about tissue-specific oncogenesis after ATM loss. Here, we report that ATM controls the early transcriptional response to estrogens. This response depends on topoisomerase II (TOP2), which generates TOP2-DNA double-strand break (DSB) complexes and rejoins the breaks. When TOP2-mediated ligation fails, ATM facilitates DSB repair. After estrogen exposure, TOP2-dependent DSBs arise at the c-MYC enhancer in human BC cells, and their defective repair changes the activation profile of enhancers and induces the overexpression of many genes, including the c-MYC oncogene. CRISPR/Cas9 cleavage at the enhancer also causes c-MYC overexpression, indicating that this DSB causes c-MYC overexpression. Estrogen treatment induced c-Myc protein overexpression in mammary epithelial cells of ATM-deficient mice. In conclusion, ATM suppresses the c-Myc-driven proliferative effects of estrogens, possibly explaining such tissue-specific oncogenesis

Stability Analysis of Grid-Connected Photovoltaic Systems with Dynamic Phasor Model

The typical layout of power systems is experiencing significant change, due to the high penetration of renewable energy sources (RESs). The ongoing evaluation of power systems is expecting more detailed and accurate mathematical modeling approaches for RESs which are dominated by power electronics. Although modeling techniques based on state–space averaging (SSA) have traditionally been used to mathematically represent the dynamics of power systems, the performance of such a model-based system degrades under high switching frequency. The multi-frequency averaging (MFA)-based higher-index dynamic phasor modeling tool is proposed in this paper, which is entirely new and can provide better estimations of dynamics. Dynamic stability analysis is presented in this paper for the MFA-based higher-index dynamical model of single-stage single-phase (SSSP) grid-connected photovoltaic (PV) systems under different switching frequencies

Business model alignment of small and medium enterprises during crisis : A single case study of a Swedish lifting equipment manufacturing company

To explore critical aspects and analyse factors in the alignment of a business model during thecrisis is the purpose of this study. This study considers only the perspective of small andmedium enterprises on barriers and facilitators of the crisis moment to align with the existingbusiness model. By understanding these factors analysis and its abductive theory approachcan benefit other small and medium enterprises to be sustainable in the present and futurecrises from the critical aspects of this thesis research. It utilizes existing theories todemonstrate a theoretical framework by four factors analysis with the business modelelements, which was created and subsequently tested through a qualitative research strategy.The research design included three different steps of analysis before and during crisissituations. The primary data comprised interviews with a leadership position and topmanagement at each department relevant to the research area from the company as a singlecase study. The locations for the case study selection were based in Halmstad, Sweden. The results of the analysis imply that a number of dimensional changes happened during thecrisis in the case study company. Among these variations, the existing business model takes adifferent way to find out a new arena of opportunity. To sum up, the final frameworkillustrates more on changes factors, the reason of changes, challenges, and facilitators arecoming out, which is definitely the latent innovation in the crisis moment. According to these findings, practical and theoretical implications are presented and examinedin this research paper. The critical implications are that the case company as a category ofsmall and medium enterprise sustained by their acceptance in changes factors like a newcustomer, assortment, product alignment, and new demand creation by a different marketingapproach are really driving the whole potential barriers, no matter in logistics, support,functional layout, and resource allocation, etc. the facilitators of the driven-changes found theway out by crisis risk planning, establishing systems for resource planning and awareness inextensive picture leadership. Additionally, they drive for the new opportunity and areoptimistic in their value proposition and objectives of the company. I also admire that howimportant it is to make the situation calm and result-driven in a crisis situation that everybodyin the company communicates, takes the decision, and expresses the same language when needed.

Factors influencing selection of higher learning institutes: An empirical investigation in Bangladesh

The aim of this paper is to assess the factors that play a significant role while selecting learning institutions service providers. Survey instruments employed on Bangladesh students included demographic background, financial issues, university teaching quality, university facilities, marketing friends and family influence. Data were collected from the students of different institutions in major cities in Bangladesh. This research has applied exploratory factor analysis, confirmatory factor analysis and structural equation modeling for testing the hypotheses. The results reveal that teaching quality in a university is the most important factor. It is hoped that the findings of this study will assist higher learning institutions of Bangladesh to produce and promote buffer education. The findings may also assist vice-chancellors and chairman to make more quality decisions utilize resources more efficiently, thus making changes as to crucial quality attributes of students expectations. Keywords: higher learning institution; teaching quality; marketing; Bangladesh