bluuebunny/crossref_metadata_2025 huggingface dataset:
Implement of STEM education in Vietnamese high school: unit of acid-base reagent from purple cabbage
Authors: Duc Nguyen Mau , Linh Nguyễn Quang , Yuenyong Chokchai
Published: October 2019

This study aimed to clarify implement of STEM education in Vietnamese high school in the unit of acid-base reagent from purple cabbage. Methodology regarded experimental design. The samples included 84 students of experimental class grade 11 of 4 high schools: 02 schools in Hanoi are Hai Ba Trung high school and Van Lang high school; 02 schools in Thai Nguyen are Thai Nguyen high school and Gang Thep high school, in the term of 2017-2018. The intervention of STEM topic of acid-base reagent from purple cabbage was organized for the samples. Students’ problem solving capacity in learning about the STEM topic of acid-base reagent from purple cabbage will be evaluated through their performance on conducted activities. Students’ problem solving capacity score was compared between before and after impacts. The findings showed that the students’ performances on conducted activities revealed their problem-solving capacity. The findings will clarify 1) summary of students’ problem-solving capacity comparing between before and after intervention, and 2) the development level of students’ problem-solving capacity. It found that average score of problem solving capacity of experimental class before impacts = 2.47. And, average score of problem solving capacity of experimental class after impacts = 3.13. The scores of the criteria for assessing the environmental impact of the experimental class after impact are always greater than before the impact, the value of p < 0.05, the level of ES effect is 0.78. The value of ES indicates that the experimental results have a moderate effect.
Situation of organizing STEM activities in Vietnamese Schools
Authors: Duc Nguyen Mau , Linh Nguyễn Quang , Yuenyong Chokchai
Published: October 2019

This study aimed to clarify situation of organizing STEM activites in Vietnamese schools. Methodology regarded the survey research and document analysis The study aimed to clarify 1) situation of organizing STEM activities in Vietnamese schools, 2) Existing ideas of problem-solving capacity as STEM education evaluation framework, and 3) developing framework of STEM education orientation. Samples inclued total of 58 teachers and 628 students of these schools: Hai Ba Trung high school, Nguyen Tat Thanh high school and Van Lang high school in Hanoi; Thai Nguyen high school, Dong Hy high school, Gang Thep high school, Luong Ngoc Quyen high school, Luu Nhan Chu high school, Dai Tu high school in Thai Nguyen and other nearby high schools. The findings revealed that some of teachers’ awarenss on STEM activities including STEM, STEM education, STEM festival, and STEM club. And, Low teachers’ awareness on STEM activities included STEM occupation, STEM resources, and robotics competition. The reality of developing problem-solving capacity in schools was provided in small frequency. It found that the the Ministry of Education and Training (Vietnam, 2018) provided some ideas of problem-solving capacity as STEM education evaluation framework. And, the MOET framework and literatures suggested an STEM Process of teaching Science according to STEM education orientation.
Realistic mathematics education (RME) and didactical situations in mathematics (DSM) in the context of education reform in Vietnam
Authors: Trung Nguyen Tien , Thao Trinh Phuong , Trung Tran
Published: October 2019

Mathematics Education plays a key role in the ongoing education reform in Vietnam, which commenced with the renewal of the curriculum and textbooks (from primary to secondary and high schools). In the world, Didactical Situations in Mathematics and The Realistic Mathematics Education have been widely and effectively applied in the Netherlands, America, France, Indonesia, etc. This article presents some cultural characteristics of Mathematics Education in Vietnam and the results of initial research on these two theories, providing some models of teaching situations and examples for pilot implementation, initial survey the ability to apply Didactical Situations in Mathematics in Vietnam, providing some suggestions for the renovation of Mathematics curriculum and textbooks in Vietnam at present.
The needs assessment of internal supervision of teachers in the department sciences and mathematics of Khon Kaen University demonstration secondary school (Suksasat)
Authors: Marwiang Metta
Published: October 2019

The research procedures in the study of the needs assessment of internal supervision of secondary school teachers in the department sciences and mathematics of Khon Kaen University Demonstration School (Suksasat) consisted of three following steps: 1) to identify the concept to study the actual and desired model of internal supervision in six dimensions; including (i) internal supervision planning, (ii) direct support for teachers, (iii) group-working skill development, (iv) professional development, (v) curriculum development, and (vi) learning assessment and evaluation, 2) to investigate the actual and desired model of internal supervision of secondary school teachers in the department sciences and mathematics of Khon Kaen University Demonstration School (Suksasat) in all dimensions. The result showed that the overall actual internal supervision was in a high level (

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=
3
.
6
4

, S.D. = 1.09) while the desired internal supervision was in a strongly high level (

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=
4
.
7
8

, S.D. = 0.49). Therefore, the needs assessment of internal supervision of secondary school teachers of Khon Kaen University Demonstration School (Suksasat) in all dimensions. The results indicated that the participants need internal supervision with the between 0.29 and 0.34, and with the overall of 0.30. The was found at the highest (0.34) when the direct support for teachers was independently considered.
Compose the topic of integration to foster the competency of integrating natural science knowledge for students of Can Tho University’s Physics Pedagogy with Webquest_method
Authors: Tran Thu K. T.
Published: October 2019

Description integrated science competency of physics education students is important work. Lecturers may be evaluating their students based on level of integrated science competency description table exactly. The paper presents result about structure and expression competency model integration science and give examples of integrated teaching to students through the X-rays topic to develop their skills and knowledge.
STEM education project-Based and Robotic Learning Activities impacting on creativity and Attitude of grade 11 Students in Khon Kaen Wittayayon School.
Authors: Pinasa Siwa , Srisook Luksanawadee
Published: October 2019

This research aims to 1) To study the creativity abilities of the students who have been provided with the STEM education project-based learning and Robotic activities. 2) To study the effects of the STEM education project-based learning and Robotic activities on the students’ attitudes. The target group was the Grade 11 students of Khon Kaen Wittayayon School. The study was conducted in the first semester of the academic year 2017. The 92 students were selected by purposive sampling. Research instruments included 9 lesson plans STEM approach, Evaluate creativity, attitudes questionnaire. The result found that 1. The creativity of the students in the STEM education Project-Based Learning and Robotic Activities was highest level in the Fluency (average 26.80, SD = 2.56) and Flexibility (average 25.04, SD = 2.72). At the high level in the Initiatives (average = 23.82, SD = 2.04), and thoughtfulness (average = 21.78, SD = 2.42) 2. The attitude of glade 11 Students After Learning STEM education Project-Based Learning and Robotic Activities was all high Level
Design Framework of Constructivist Mobile Application Learning Environment to Foster Creative Thinking on Basic Photography Skill for High School Students
Authors: Kwanman Thanaban , Samat Charuni
Published: October 2019

This research study aimed to synthesize theoretical framework and designing of constructivist mobile application learning environment to foster creative thinking on basic photography skill for high school students. The target group consisted of 3 expert reviewers for content, mobile application and learning environment designing. Research methodology is developmental research; developmental research consisted of 3 processes: (1) designing process, (2) developing process, (3) evaluate process. The procedures were as follows: (1) to examine and analyze the principles and theories, (2) to synthesize theoretical framework, and (3) to synthesize designing framework. The result revealed that: 1) to synthesize theoretical framework comprise of 6 components as following that. Contextual base, Psychological base, Pedagogies base, Creative Thinking base and Technologies and media base. 2) To synthesize design framework of mobile application learning environment to foster creative thinking of 6 components i.e., (1) Problem base, (2) Resource, (3) Creative Thinking Photo Lab, (4) Collaboration, (5) Coaching, (6) Scaffolding. The efficiency of this learning environment was evaluated by expert review. It was found that the learning environment is appropriate on 3 aspects: content, mobile application learning design, and learning environment design..
Examining existing ideas about sustainable leadership of private school science principals
Authors: Agsonsua Pha , Kositpimanwech Ekkarad , Yuenyong Chokchai
Published: October 2019

The objectives of this research were: to examine existing ideas about sustainable leadership of private school science principals in jurisdiction of Khon Kaen Provincial Education Office. The quantitative data of population were the private school principals and teachers working in private schools under jurisdiction of Khon Kaen Provincial Education Office from 127 principals, 2,425 school teachers, total of 2552 persons. The samples were 92 school principals selected by Purposive Sampling, and 331 teachers selected by Simple Random Sampling. The research instruments included 5 Level Rating Scale, the content validity was 0.84, and the Reliability of total issue was 0.96. Data were analyzed by using the computer program to calculate the frequency, percentage, and standard deviation. The research findings found that the sustainable leadership of private school administrators under jurisdiction of Khon Kaen Provincial Education Office, in all, was at “High” level. The mean values were ranked in order from high to low as follows: 1) the in-depth body of knowledge, 2) the steadfast standpoint and far reaching stretch, 3) the breadth, comprehesiseness and balance 4) the construction of cooperative network and 5) the various techniques for success and goal achievement. The study may have implications for professional development of administrators’ sustainable leadership in private science school.
Tri-Patterns of Community Network for Carbon Emission Reduction in Thai-Isan Urban
Authors: Chamaratana T , Knippenberg L W J , De Jong E B P , Prabnok P , Phatchaney K , Dasri R
Published: October 2019

In 2014 more people lived in urban areas than in rural areas. In the energy sector that is the highest proportion of all carbon emission sectors, urban area release carbon 71-76% of global carbon emission. The first priority solution for solving climate change is carbon emission reduction in urban areas. The low carbon city is an area base management to meet the target of city carbon emission reduction. One of means for develop the carbon emission behavior in everyday life of the people is collaborative action in form of networking. The social network is the one of major concept for urban study. It used to focus in individual behavior, but now extended to study group of urban people as community network. The objective of this research was to study the pattern of community network for carbon emission reduction in Urban of Northeastern Thailand as Khon Kaen city. Data were collected via in-depth interviews as well as by participatory and non-participatory observations with 24 key informants who were the community heads and members from 4 communities in Khon Kaen city. Data analyses were content analysis with ATLAS.ti program and social network analyzed by UCI-net program. The results of the study indicated that there are three patterns of community network for carbon emission reduction in Khon Kaen city; One-center network, Dual-center network, and Full network.
Developing the Garbage Problem in Iligan City STEM Education Lesson Through Team Teaching
Authors: Mordeno Ivy Claire , Sabac Algin Michael , Roullo Angel Jane , Bendong Hazel Dwight , Buan Amelia , Yuenyong Chokchai
Published: October 2019

The paper will clarify the learning activities which provide through Sutaphan nad Yuenyong [11] context based STEM education learning approach. This approach consists of 7 stages including (1) Identification of social issues, (2) Identification of potential solution, (3) Need for knowledge, (4) Decision-making, (5) Development of prototype or product, (6) Test and evaluation of the solution, and (7) Socialization and completion decision stage. This will be implemented using team teaching approach by the Earth Science, Physics, Chemistry, and Biology teachers. Identification of social issues, the earth science teacher raises the social issue about the garbage problem affecting the residents of Brgys. Bonbonon and Digkilaan, Iligan City, Philippines. Students may answer that the probable source could be the leachate from the sanitary landfill and from there the teacher will put the problem causes problem to the people in the locality where the landfill is located and to the City’s tourism as well. Identification of potential solution, the Earth Science teacher facilitates the class discussion about thinking of possible solutions to help solve the problem on garbage in Iligan City. The need for knowledge stage, the input of the scientific knowledge necessary for the learners’ decision in designing their prototype or product in solving the problem on garbage in Iligan City will be done separately in Physics, Chemistry, and Biology class. Physics teacher may provide scientific inquiry about force and compression to help the students design a prototype of a garbage/trash compactor. Chemistry teacher may provide learning activities about classification of mixtures according to particle size helps the students think of a design for a water treatment process. Biology teacher may provide learning activities related to macroinvertebrates and a bioindicator of the water quality of the streams/rivers. The decision making stage, lets the students decide on how they are going to make the required prototype for Physics, Chemistry and Biology aspect as possible solutions to the problem. The development of prototype or product stage, students are given enough time to create the compactor, water treatment process and the poster-infographic about macroinvertebrates. Test and evaluation of the solution stage, students will apply their knowledge related to their prototype or product for test and evaluation of the solution. The socialization and completion decision stage, the students’ will have an exhibit of their output. The paper will discuss how to provide students chance to applying STEM knowledge through these activities.
Students’ Performance in Context – Based Lessons in Mathematics Classroom
Authors: Jackaria Potchong M. , Buan Amelia , Yuenyong Chokchai
Published: October 2019

This study aimed at developing contextualized lesson plans integrating writing in mathematics using the pupil’s mother tongue. It also aimed at determining pupil’s improvement in the writing math activities for a period of one month. A Grade 3 class with 31 pupils was purposively selected because of its heterogeneous composition. Using a comparative-descriptive design, this study utilized both quantitative and qualitative data from pupils’ weekly writing outputs, pretest, posttest and transcripts of classroom observations and interviews. Five lesson plans were developed using the backward curriculum design based on the K to 12 curriculum standard. The data revealed that the pupils made significant improvement in their writing math performance irrespective of ability group. However, the high-performing pupils made significant learning gains compared to the developing pupils. In-depth analysis of outputs showed improvements in pupils’ writing mathematics skills. Most pupils organized their ideas even after the question prompts have been removed on the last week of implementation. This study claimed that the use of scaffolding, contextualization, and mother tongue helped pupils in their writing and improved mathematical reasoning.
Linear Equations in Two Variables STEM Education Learning Activities: Developing the Household Power Consumption Calculator App
Authors: Ebal Crispin D. , Luga Mary Joy F. , Flores Maria Rebecca O. , Zabala Dante Joma P. , Buan Amelia T. , Yuenyong Chokchai
Published: October 2019

The lesson was developed with the collaboration of experienced teachers through brainstorming and small-group conference. Social issue about electric consumption usage and rate were identified as part of the lesson. The content and skills to be learned in this lesson aligned to the K-12 curriculum. The topics identified were linear equation in two variables for mathematics and renewable and nonrenewable sources of energy for science. In this unit, students develop a prototype of a mobile application that calculates actual household electric consumption. The application aims to help household units to closely monitor their electric consumption in order to lessen the said consumption and to promote household budget savings. The outcome of this lesson contributes to globe’s quest to fight against climate change and global warming since electric consumption of households will be lessened. The paper may has implication for STEM education.
STEM education program: manufacturing mixture of phosphate and potash fertilizer straws and waste of animal bones
Authors: Duc Nguyen Mau , Ninh Tran Trung , Toan Ngo Thi , Hai Kieu Thi , Yuenyong Chokchai
Published: October 2019

STEM educational orientation program is one interdisciplinary approaching way during study which consists of academic terms with principle characteristics combines with lectures in real life. Joining in STEM educational orientation program, students will have practical experience, thus they have opportunities to develop their capabilities including ability to apply knowledge and skills (AAK&S), help students to improve study skills and methods such as planning, analyzing, summarizing information, suggest creative solutions; encourage motivation, benefits and study activities. Based on the foundation of utilizing STEM educational orientation program in teaching, it can be a direction to develop student’s capabilities. In this study, the author instructed students to research “Manufacturing mixture of phosphate and potash fertilizer from straws and waste of animal bones” following STEM educational orientation program in improving abilities and applying Chemistry knowledge to life for the student. The result shows STEM system could handle the theoretical weight situation, help students shape and develop core competencies, specialized Chemistry and especially, the ability to apply knowledge and skills in a systematic and solid manner.
Developing Ellipse Properties Learning Unit with Computer Assisted Learning through GeoGebra software for Thai High School Students
Authors: Setthaphongsakorn Suphanat , Yuenyong Chokchai
Published: October 2019

This study aimed to clarify the developing ellipse properties learning with computer assisted learning through GeoGebra software for Thai high school students. Participants include 40 Grade 10 students who were studying in Khon Kaen University Demonstration secondary school, academic year of 2016. Methodology regarded qualitative research. The intervention of Geometry with GeoGebra was provided for semester. The paper will explain how the GeoGebra will be provided for the opportunity students to construct and dynamically visualize geometric figures. GeoGebra builds a dynamic ellipse to show the characteristic of the points that form the ellipse. And, students may find the relation between two points on the ellipse by using GeoGebra. The unit provide students to generate their representation to explain ellipse definition and properties when they on tasks with the GeoGebra.
Integrating Nature Conservation and Biodiversity Education in Teaching in General schools in Vietnam
Authors: Oai Le Thanh , Thanh Hoi Phan Thi
Published: October 2019

Conservation of nature and biodiversity is the responsibility of the whole society, of all management agencies and of individuals, each of whom needs to be aware of their roles and actions that contribute to nature and biodiversity conservation. The education of nature and biodiversity conservation for school students contributes to creating responsible citizens in the future. On the basis of analyzing a number of key concepts such as nature and biodiversity conservation; general analysis of the situation of biodiversity in Vietnam and degradation, in this article, we introduce some integrated methods, teaching methods and techniques to integrate nature and biodiversity conservation education into teaching in secondary schools in Vietnam which contributes to the development of knowledge and skills on nature and biodiversity conservation for secondary school students.
Current Situation of Problem Solving Ability Development for Chemistry Teaching at High Schools of Lao PDR
Authors: Volayuth Khongvilay , Ninh Tran Trung , Yuenyong Chokchai
Published: October 2019

Education in the Lao People’s Democratic Republic (Lao PDR) plays an important role in the development of national construction and defense. Among subjects at High schools, Chemistry is one in the field of natural science with many applications. However, nowadays, despite many achievements, the reality of teaching chemistry at High school has showed a lot of inadequacies. This article addresses some of the problems in the development of problem solving ability in chemistry-teaching at high schools in the Lao People’s Democratic Republic.
Developing the innovative inquiry-based lesson plan through lesson study
Authors: Canalita Everlita E. , Buan Amelia T. , Amboayan Nikki B. , Mindalano Jabber I.
Published: October 2019

This study aims to develop an innovative inquiry-based lesson plan through lesson study (LS) [2]. LS is considered as an updated professional development which aims at improving the teaching process and students’ learning [16]. The lesson plan makes use of 7E learning cycle [5] embedded with inquiry activities that transform an ordinary classroom setting into an active student-centered learning environment [8]. The lesson model includes the following stages (1) Elicit, (2) Engage, (3) Explore, (4) Explain, (5) Elaborate, (6) Evaluate and (7) Extend. The research lesson made by the lesson study (LS) team was innovated gradually every after each implementation cycle. Revisions were done based on observations such as students’ responses, teacher-student interaction or student-student interaction depending on how students view the lesson and how the group activity work smoothly. The innovative lesson plan has refined three times, based on the needs of the students. It is also evident in the implementation that students’ learning and motivation are dependent on the scaffolding questions and the ability of the teacher to connect relationships that would help students contextualized the concepts in real life experiences.
Development of Mathematics Collaborative Problem-Solving Skills Scale
Authors: Medina Joneil B. , Buan Amelia T. , Mendoza Josie Vic D. , Liwanag Grace P.
Published: October 2019

Collaborative Problem Solving (CPS) is one of the most critical and necessary skills in education and workplace; hence, its assessment is a necessary subject of research. CPS assessment tools must be crafted to establish the effectiveness of the pedagogies to CPS development. Therefore, to address these gaps, this study developed a Likert scale called Mathematics Collaborative Problem Solving Skills (MaCoPSS) Scale. The scale development followed the process: (1) item generation, (2) item evaluation, (3) try-outs, (4) Exploratory Analysis, (5) final evaluation. Open-ended questionnaires were administered to 273 respondents. After analysis, 551 statements were produced as initial item pool. The items are evaluated and only 59 of them are used for the draft scale for the try-outs. The scale was administered to 648 students for the try-outs and responses were cleaned then subjected to Exploratory Factor Analysis (EFA). Two factors, namely social skills (SS) and problem-solving skills (PSS) were extracted. To establish internal consistency, the factors are correlated to one another (r=0.708), and factor to total raw score (TRS) correlations are highly correlated: SS-TRS (r=0.955) and PSS-TRS (r=0.894). The final scale consists of 27 SS and 17 PSS items. The overall reliability coefficient of the scale is α=0.941. The resulting scale is considered valid and reliable.
Explicit Nature of Science in the STS Contact Lens “Big Eyes” Unit
Authors: Attapan Nonglak , Yuenyong Chokchai
Published: October 2019

This paper aimed to explain Grade 11 students’ view of nature of science (NOS) in the STS contact lens “big eyes” unit and explicit NOS. The STS contact lens “big eyes” provided students to learn about refraction, thin lens, eyes and vision through science technology and society (STS) approach and learning activities of explicit NOS. Participants included 15 Grade 11 students who study in Kaewsadet school, Kalasin, 2nd semester, academic year of 2011. Students’ views of NOS were interpreted through students’ responses in learning activities of explicit NOS, participant observation, journal writing, and interviewing. Students’ responses were categorized regarding 8 aspects of NOS. These 8 aspects included (1) scientific knowledge demands evidences; (2) tentativeness of scientific knowledge; (3) laws and theories; (4) scientific methods (no universal scientific method); (5) subjective in that science is a human endeavor and investigations are conducted within the context of particular theoretical frameworks; (6) partly the product of inference, imagination, and creativity; (7) socially and culturally embedded (can be influenced by contextual factors outside of the scientific community); and (8) developed from a combination of observation and inferences. The paper will discuss students’ views of NOS that were showed in explicit NOS activities of the STS contact lens “big eyes unit. This paper has implications for enhancing students’ understanding of NOS in Thailand
Teachers as Makers: The Key Provision of Teacher Preparations for STEM Education
Authors: Chamrat Suthida
Published: October 2019

This study explores how learning activities based on maker concepts prepared pre-service teachers entering the STEM Education pipeline. 25 pre-service science teachers from the faculty of education at Chiang Mai University enrolled in an Independent Study in Science Teaching course. The course was called “Integrating maker concepts and STEM Education.” The course sought to integrate existing science objectives with maker concepts and activities. Pre-service teachers were divided into 8 groups. Each group had to write and present a proposal, develop their instruments/Makings, try it out in schools, submit full reports, present and review peers’ final reports, attend a regional STEM festival where they participated in poster presentations. Using the collected data from a shared Google Drive, Video recordings, interviews, and extended activities, the findings indicated that STEM concepts and practices could be conveyed to pre-service teachers by instilling the maker mindset. From the 8 groups, 3 themes emerged: research in science education, science project, and STEM Education which consisted of 1, 1 and 6 projects, respectively. The creation of artefacts or Makings required scientific and mathematical concepts, empirical testing, and technological design. These enabled pre-service teachers to understand and practice teaching and learning in the STEM field. Event case study was employed as research methodology. Details of 8 pre-service teacher projects and 5 assertions of research findings are described.
Mooring System Design for the 10MW Triple Spar Floating Wind Turbine at a 180 m Sea Depth Location
Authors: Azcona José , Vittori Felipe
Published: October 2019

This works presents a methodology for the design of a mooring system for the Triple Spar floating wind turbine that supports the INNWIND 10MW wind turbine. The mooring system keeps the platform at the desired location and avoids the drift caused by wind, currents and nonlinear hydrodynamics. A semi-taut mooring system configuration, combining steel chain and polyester is chosen to reduce the cost. The basic configuration is defined using static equations and provides a smooth relationship between the restoring force and the displacement, to prevent snap loads. A dynamic analysis for the environmental conditions of the Gulf of Maine is performed to verify the performance of the design. The tensions on the lines are well below the maximum breaking limit for the different materials. Nevertheless, the chain weight can not be decreased as it provides the required mooring system stiffness. It has been verified that the polyester segment does not contact the seabed that could potentially damage it. The dynamic analysis also shows that the anchors do not experience vertical forces and the lines do not impact the platform heave plates. A complete load analysis must be performed to fully validate the proposed design.
Effect of wind flow direction on the loads at wind farm
Authors: Kazacoks Romans , Amos Lindsey , Leithead Prof William
Published: October 2019

This paper investigates the effect of wind flow direction on the fatigue loads on wind turbine within a wind farm, to determine the most critically loaded machines within the wind farm. The fatigue loads are calculated according IEC standards. In this study, the two layouts are considered. Additionally, this paper includes the effect of wind flow direction on the power efficiency of the wind farm for the two layouts. The simulations performed by StrathFarm, which is an in-house developed wind farm modeling tool, for the below and above rated wind speed flow with turbulence. In the regular and installed regular layouts at zeros degree of the prevailing wind flow direction, the spacing among turbines is eight diameters. At 90 degrees of wind flow direction the spacing between turbines is five diameters. The simulations demonstrate that the majority of the maximum fatigue loads occur at the range 40 and 70 degrees for the two layouts. However, there is small number of machines, which are experienced the highest fatigue loads at 90 degrees of wind flow direction. For the two layout the lowest power efficiency occurs at 10 degrees of wind flow direction. The regular layout is experienced same power efficiency at five and eight diameters spacing among turbine in the wind flow direction. The highest power efficiency occurs at wind flow angles, which produce the highest fatigue loads.
Development of coupling module between BHawC aeroelastic software and OrcaFlex for coupled dynamic analysis of floating wind turbines
Authors: Arramounet V , Winter C.E. de , Maljaars N , Girardin S , Robic H
Published: October 2019

Floating Offshore Wind Turbines (FOWTs) dynamic analysis can be quite challenging as it requires to model within the same calculation aerodynamics, hydrodynamics, controller, moorings and structure behaviour. Mooring and anchor design are strongly affecting FOWTs dynamic behaviour. Also, floater structural behaviour can be complex to model in a decoupled finite element analysis software. To do so, Innosea and Siemens Gamesa Renewable Energy developed a coupling between BHawC software and OrcaFlex software. BHawC is a nonlinear aeroelastic tool performing dynamic analysis of wind turbines. OrcaFlex is a generalist offshore marine engineering software that can perform the dynamic analysis of floaters and their mooring system. This paper describes the method and the mathematical background that is used to perform detailed time-domain simulations of a floating wind turbine coupling BHawC and OrcaFlex. The coupling is verified comparing time domain simulations on several load cases for rigid floaters coupled to a turbine with a rigid RNA. This shows a good agreement which confirms the correctness of the coupling.
Operation of aerial inspections vehicles in HVDC environments Part A: Evaluation and mitigation of high electrostatic field impact
Authors: Heggo M , Kabbabe K , Peesapati V , Gardner R , Watson S , Crowther W
Published: October 2019

Offshore high voltage DC (HVDC) wind farms offer a promising solution to growing energy demands in the future. Condition monitoring of substation assets is essential for reliable and resilient operation of electrical networks. Existing condition monitoring techniques for onshore substation and electrical network assets include regular and scheduled on-site visits by trained personnel to substation sites. However, such routine inspection is not a cost-effective solution for offshore sites. In cases where the accessibility to network assets becomes difficult, robotic and autonomous condition monitoring provides a solution. Such a robotic/autonomous solution would need to interact with the surrounding substation environment, without increasing the risk of electrical breakdown and flashovers between different energized components. In Part A of this paper, the effect of high electrostatic fields on an inspection unmanned aerial vehicle (UAV) is analyzed, with respect to: 1) AC corona emissions interference on the UAV, and 2) Air breakdown clearance characteristics. Both simulations and experiment results presented in the paper show the impact of corona emissions interference to both UAV autopilot and actuation sections, which requires a shielding mitigation solution. Also, experiment results show the limited effect of introducing a shielding solution on increasing the flashover risk between valve hall towers.
Operation of aerial inspections vehicles in HVDC environments Part B: Evaluation and mitigation of magnetic field impact
Authors: Heggo M , Mohammed A , Melecio J , Kabbabe K , Tuohy P , Watson S , Djurovic S
Published: October 2019

Using robotic systems to conduct remote inspections of offshore wind farm HVDC converter stations has been proposed as a promising solution to reduce the operation and maintenance (O&M) down-time and costs. However, the nature of the electromagnetic field environment inside HVDC valve halls presents a challenge for the operation of traditional off-shelf inspection robots. High electrostatic interference to inspection unmanned aerial vehicles (UAV) has been studied in Part A of this paper. In Part B, the impact of the external magnetic field on the operation of an inspection quadcopter‘s propulsion motors is assessed. An experimental method is proposed to identify the maximum magnetic field tolerable by off-the-shelf quadcopter motors. The reported method can be used to test commercial off-the-shelf quadcopter motors to identify their suitability for use in HVDC valve halls inspection robots. The paper experimental results show the failure of direct torque control (DTC) algorithm, that is used in quadcopters speed controllers in mitigating the magnetic field impact on motor‘s speed and current consumption.
Wind-wave directional effects on fatigue of bottom-fixed offshore wind turbine
Authors: Sørum S H , Krokstad J R , Amdahl J
Published: October 2019

The current trend for offshore wind energy is that larger turbines are placed on monopile foundations at increasing water depth. This requires larger foundations, increasing the importance of hydrodynamic loading. It is well established that wave loads perpendicular to the wind direction are important for the fatigue damage in monopile foundations. However, this is normally only taken into account considering wind-wave misalignment. In this paper, the effect of assuming short-crested waves in design calculations is considered. The lifetime fatigue damage may increase significantly for hydrodynamically sensitive support structures when modelling the waves as short-crested rather than long-crested. For the turbines in this paper, the fatigue damage increased with up to 80 %. At the same time, the changes in fatigue damage were small for support structures that are less hydrodynamically sensitive. The work performed in this paper shows that the typical design assumption of long-crested waves may be both conservative and non-conservative. This fact is important to be aware of when designing support structures for offshore wind turbines.
Collection Grid Optimization of a Floating Offshore Wind Farm Using Particle Swarm Theory
Authors: Lerch Markus , De-Prada-Gil Mikel , Molins Climent
Published: October 2019

Floating substructures for offshore wind turbines is a promising solution in order to harness the vast wind potential of deep water sites where bottom-fixed turbines are not feasible. The electrical system of large scale floating offshore wind farms will experience the application of new technologies and installation procedures that likely affect the cost-competitiveness. Thus, in this work, an optimization model based on the particle swarm theory is presented that allows optimizing the collection grid of a floating offshore wind farm. The developed model is applied to a study case consisting of a 500MW floating offshore wind farm located at the Golfe de Fos in the Mediterranean Sea. The resulting layout allows to reduce the total cost of the collection grid by more than 6% and to decrease the energy losses by 8% compared to the actual layout. Besides this, a further study analyzes the effect of a quantity discount with a reduced number of power cable cross sections.
Stochastic load effect characterization of floating wind turbine support structures
Authors: Okpokparoro Salem , Sriramula Srinivas
Published: October 2019

Achieving substantial reductions in Levelized Cost of Energy (LCOE) of floating wind turbines (FWTs) requires robust reliability assessment that accounts for inherent design uncertainties. A key aspect of such reliability assessment is the definition of limit states. In this regard, load effects need to be evaluated accurately. This paper presents a computational framework for evaluating load effects on FWT support structures. The computed load effect is subsequently characterized. A high fidelity finite element model of the National Renewable Energy Laboratory (NREL) 5MW reference turbine mounted on the OC3-Hywind spar buoy was developed and validated for this purpose. The loads from fully coupled time domain aero-hydro-servo-elastic simulations are transferred for detailed finite element (FE) load effect computation in Abaqus. Matlab® and Python are used as the computational tools for automating the whole analysis from start to finish. The initial part of this study addresses the amount of run-in-time to be excluded from response statistics. Based on convergence studies carried out, recommendations are made for run-in-time to be excluded from response statistics. The maximum von Mises stress in the tower as a measure of yielding is the load effect investigated in this study.
Piezoelectric Patch Transducers: Can alternative sensors enhance bearing failure prediction?
Authors: Schilling L , Dalhoff P
Published: October 2019

This paper examines the applicability of piezoelectric patch transducers as condition monitoring sensors for the drive train of wind turbines. Three laboratory experiments are conducted to determine the sensor’s temperature stability, sensitivity toward electromagnetic interference and general ability to detect bearing damages. The sensors show little deviation under thermal influence in a tested temperature range between -40 °C and +80 °C. Although they react to electromagnetic interference, the disturbance signal is predominated by the damage signal. Proper shielding is yet recommended to fully eliminate electromagnetic interference. An example of shielding is given through the use of mu-metal. In direct comparison of bearing fault detection capability to a state-of-the-art accelerometer, the patch transducer performs slightly worse in matters of signal-to-noise-ratio. However, when excited by small damage impulses, it yields good signal depth and output. Altogether, the sensor shows fundamental applicability as a condition monitoring sensor in all experiments, though further optimization seems feasible and worthwhile.
Offshore Wind Turbine Loads and Motions in Unstable Atmospheric Conditions
Authors: Putri R M , Obhrai C , Knight J M
Published: October 2019

Even though it is widely known that unstable atmospheric stability conditions can lead to higher turbulence, the use of proper turbulent wind models considering unstable conditions are not often used in the simulation of loads and motions of offshore wind turbines. For this reason, the Højstrup model, which was specifically developed for unstable conditions, is used to simulate a spar-buoy offshore wind turbine (OWT) and investigate the importance of unstable conditions in the design of floating offshore wind turbines. It is found that fatigue damage of a spar-buoy OWT is strongly influenced by unstable conditions, where very unstable condition gives 65% higher fatigue damage than neutral conditions for the tower top torsion, followed by 37% higher for tower base side-side bending and 24% higher for blade root flap-wise mode.
Fatigue sensitivity to foundation modelling in different operational states for the DTU 10MW monopile-based offshore wind turbine
Authors: Katsikogiannis George , Bachynski Erin E. , Page Ana M.
Published: October 2019

The importance of foundation modelling for the support-structure fatigue damage estimation of a 10 MW monopile based offshore wind turbine is investigated in different operational states and wind-wave misalignment conditions. Three different models are used: (1) a non-linear elasto-plastic model including hysteretic behaviour effects, (2) a linear elastic model and (3) a non-linear elastic model, using numerical simulations with an aero-hydro-servo-elastic computational tool. Depending on the environmental condition, different dynamic processes dominate the responses. For parked states, deviations between models up to 160% were found. For wind wave-misalignment over 30° in operational cases, differences up to 180% were found for low sea states and 119% for high sea sates. Both nonlinear foundation damping and stiffness formulation have considerable effect on the responses, with hysteretic effects becoming crucial when aerodynamic damping is negligible in the direction of the response. Attention is required when comparing the fatigue damage only at the mudline, as larger variations between the models may occur in the embedded part of the monopile, where the absolute maximum is found.
On Initial Design and Modelling of a 10 MW Medium Speed Drivetrain for Offshore Wind Turbines
Authors: Wang Shuaishuai , Nejad Amir R. , Moan Torgeir
Published: October 2019

This paper presents the initial design and modelling of a medium speed drivetrain for the DTU 10 MW offshore wind turbine. Design basis and criteria of the drivetrain are described. Minimum weight and volume of the drivetrain are chosen as the main design targets. A four-point support, two main bearings and two torque arms, drivetrain configuration is selected in this study. One conventional gearbox layout, two planetary stages and one parallel stage, which is commonly used in large offshore wind turbines is adopted. Four gearbox layout options are provided and compared, and one optimal option is finally selected with holistic considerations of volume and weight as well as load sharing performance principles. Then, a high fidelity drivetrain numerical model for the 10 MW reference turbine is established using multi-body system (MBS) approach. In addition, model comparison is conducted, which shows that drivetrain eigenfrequencies in torsional mode obtained from the numerical model agree well with the values in the DTU report. Finally, future work relating to dynamic response analysis, critical limit states check for the drivetrain model is proposed.
Resonance Characteristics in Offshore Wind Power Plants with 66 kV Collection Grids
Authors: Holdyk A , Kocewiak Ł H
Published: October 2019

This paper presents a study of the influence of doubling the collection grid voltage on the electric resonances in the collection grid of large offshore wind power plants. This was done using wide-band models of most important passive components such as transformers and cables. Wide-band models based on measurements (black box) of transformers were used. Scaling of admittance matrix elements was used in order to adjust the voltage ratio of the measured wind turbine transformers to take into account the doubled voltage at the medium voltage side.

It was shown that doubling the collection grid voltage decreases the main resonance frequency seen at the medium voltage terminal of the wind turbine transformers as well as the offshore substation transformer. The decrease was approximately 25 per cent when doubling the voltage and keeping the same number of turbines in a radial. When the number of turbines was doubled, there was a proportional decrease of the resonance frequency.

Decreasing the main resonance frequency in offshore wind power plants might have an impact on the harmonic and transient behaviour and should therefore be investigated by developers.
The X-Rotor Offshore Wind Turbine Concept
Authors: Leithead William , Camciuc Arthur , Amiri Abbas Kazemi , Carroll James
Published: October 2019

The following paper provides an overview of a novel wind turbine concept known as the X-Rotor Offshore Wind Turbine. The X-Rotor is a new wind turbine concept that aims to reduce the cost of energy from offshore wind. Cost reductions are achieved through reduced capital costs and reduced maintenance costs. The following paper includes results from an early feasibility study completed on the concept. In the feasibility study exemplary designs were created and structural analyses were carried out. Turbine capital costs and maintenance cost of the X-Rotor concept were then roughly estimated. X-Rotor turbine costs and O&M costs were compared to four existing wind turbine types to investigate potential cost savings from the X-Rotor concept. Results show that the X-Rotor has potential to reduce O&M costs by up to 55% and capital costs by up to 32%. The combination of the capital cost and O&M cost savings show potential to reduce the CoE by up to 26%.
Power Losses in Electrical Topologies for a Multi-Rotor Wind Turbine System
Authors: Sunde Ingvar Hinderaker , Torres-Olguin Raymundo E. , Anaya-Lara Olimpo
Published: October 2019

Multi-rotor wind turbine systems are proposed as an additional technology to the future of wind energy, and a way of achieving wind turbines generating 20 MW or more. Research regarding the electrical connections of such a system is lacking, and this is key parts of the system. The controllability and power losses are important factors in the different topology options. In this study, three different electrical topologies are proposed and their controllers are implemented respectively. The systems are fairly simplified. Further, ways to measure the power losses within the power converters are researched, and a way of doing so is implemented on the three systems. The simulations performed on the system show the validity of the controllers as well as the power loss calculation method. In this study, the power losses found in the different topologies in total are quite similar to each other, right above 1%, so it is hard to prefer on of the topologies based on this. However, this serves as a tool that can be adjusted and used on more complex systems, and in this way contribute to finding an optimal electrical collector topology for a multi-rotor wind turbine system.