Design and Analysis of Electric Powertrains for Offshore Drilling Applications

Doktorgradsavhandling ved Institutt for ingeniørvitenskap, Universitetet i Agder, 2016The global energy market is challenged with an ever increasing need for resources to meet the growing demands for electric power, transportation fuels, etc. Although we witness the expansion of the renewable energy industry, it is still the fossil fuels, with oil and gas dominating the scene of global energy supply sector, that provide majority of worldwide power generation.However, many of the easily accessible hydrocarbon reserves are depleted which requires from the producers of drilling equipment to focus on cost-effective operations and technology to compete in a challenging market. Particularly high level of activity is observed in both industry and academia in the field of electrical actuation systems of drilling machines, as control methods of alternating current (AC) motor drives have become an industrially mature technology over the past few decades. In addition, state-of-the-art AC motors manufacturing processes allow to conform to the strict requirements for safe operation of electrical equipment in explosive atmospheres. These two main reasons made electric actuation systems a tough competitor to hydraulic powertrains used traditionally by the industry. However, optimal design of induction motor drives and systematic analysis of factors associated with operation in harsh offshore conditions are still considered as a major challenge. In this thesis, effective methods for design and analysis of induction motor drives are proposed, including aspects of optimization and simulation-based engineering. The first part of the thesis is devoted to studying methods for modeling, control, and identification of induction machines operating in offshore drilling equipment with the focus to improve their reliability, extend lifetime, and avoid faults and damage, whereas the second part introduces more general approaches to the optimal selection of components of electric drivetrains and to the improvement of the existing dimensioning guidelines. A multidisciplinary approach to design of actuation systems is explored in this thesis by studying the areas of motion control, condition monitoring, and thermal modeling of electric powertrains with an aspiration to reach the level of design sophistication which goes beyond what is currently considered an industrial standard. We present a technique to reproduce operation of a full-scale offshore drilling machine on a scaled-down experimental setup to estimate the mechanical load that the designed powertrain must overcome to meet the specification requirements. The same laboratory setup is used to verify the accuracy of the estimation and control method of an induction motor drive based on the extended Kalman filter (EKF) to confirm that the sensorless control techniques can reduce the number of data acquisition devices in offshore machines, and thus decrease their failure rate without negatively affecting their functionality. To address the challenge of condition monitoring of induction motor drives, we propose a technique to assess the expected lifetime of electric drivetrain components when subjected to the desired duty cycles by comparing the effects of a few popular motion control signals on the cumulative damage and vibrations. As a result, the information about the influence of a given control strategy on drivetrain lifecycle is made available early in the design stage which can significantly affect the choice of the optimal powertrain components. The results show that some of the techniques that have a well-proven track record in other industries can be successfully applied to solve challenges associated with operation of offshore drilling machines. One of the most essential contributions of this thesis, optimal selection of drivetrain components, is based on formulating the drivetrain dimensioning problem as a mixed integer optimization program. The components of powertrain that satisfy the design constraints and are as cost-effective as possible are found to be the global optimum, contrary to the functionality offered by some commercially available drivetrain sizing software products. Another important drawback of the dimensioning procedures recommended by the motor drives manufacturers is the inability to assess if the permissible temperature limits given in the standards do not become violated when the actuation system experiences overloads different than these tabulated in the catalogs. Hence, the second most significant contribution is to propose a method to monitor thermal performance of induction motor drives that is based exclusively on publicly available catalog data and allows for evaluating whether the standard thermal performance limits are violated or not under arbitrary load conditions and at any ambient temperature. Both these solutions can effectively enrich the industrially accepted dimensioning procedures to satisfy the level of conservatism that is demanded by the offshore drilling business but, at the same time, provide improved efficiency and flexibility of the product design process and guarantee optimality (quantitatively, not qualitatively, measurable) of the final solution. An attractive direction for additional development is to further integrate knowledge from different fields relevant to electric powertrains to enable design of tailored solutions without compromising on their cost and performance

Predictors of successful iatrogenic pseudoaneurysm compression dressing repair

Background: Complications to femoral artery puncture may result in formation of a pseudoaneurysm (PSA). We investigated whether PSA obliteration may be achieved by compression dressing repair (CDR) and sought to determine the predictors of successful CDR. Methods: Sixty two patients (30 male, mean age 61.0 ± 12.8) with femoral PSAs due to cardiac catheterization were included in the study. In all patients, duplex ultrasound followed by CDR was performed to evaluate PSA morphology and flow velocities in the PSA neck. Results: Forty six (74.2%) patients did not respond to CDR. Predictors of successful CDR were forward [0.18 (0.07-0.47), p = 0.0004] and reverse [0.08 (0.02-0.33), p = 0.0006] flow velocities in the PSA neck. The forward velocity was identified as an independent predictor of CDR outcome (p = 0.02). Conclusions: Compression dressing repair may serve as an alternative method of femoral pseudoaneurysm management in patients with low forward and reverse velocities of the flow in pseudoaneurysm neck. The forward velocity is an independent predictor of compression dressing repair result. (Cardiol J 2010; 17, 2: 179-183

Cardiac rupture risk estimation in patients with acute myocardial infarction treated with percutaneous coronary intervention

Background: Cardiac rupture (CR) is a common cause of death following acute myocardial infarction (AMI). Despite improvements in AMI treatment, the frequency of CR remains considerable and in most cases leads to death. The aim of the study was to define the independent prognostic CR risk factors of AMI in patients treated with percutaneous coronary intervention (PCI). Methods: A total of 4,200 AMI patients treated by PCI were studied retrospectively. Two hundred and seventy patients who had died of AMI were examined. In all cases CR was confirmed in post-mortem examination. Results: Cardiac rupture occurred in 49 patients (18.1%). In the CR group, 24.4% patients received thrombolysis and 22.6% in the non-CR group (p = NS). The following characteristics were associated with a higher rate of CR in univariable analysis: age (70.3 &#177; 3.2 vs. 65.2 &#177; &#177; 9.9; p < 0.001), female (75.0% vs. 60.2%; p < 0.001), prior cardiac event and absence of myocardial infarction history (61.2% vs. 40.2%; p < 0.05 and 14.2% vs. 33.4%; p < 0.05), presence of QS complex in first ECG (75.5% vs. 52.0%, p < 0.05) and multiple coronary heart disease (75.5% vs. 61.5%, p < 0.05), and long time from onset of symptoms to thrombolysis and to PCI (8.1 &#177; 2.8 vs. 4.7 &#177; 2.3 hours, p < 0.001 and 9.0 &#177; 5.5 vs. 4.5 &#177; 3.2 hours, p < 0.001). In the multivariable analysis, independent predictors of CR were: age (OR: 1.1; 95% CI: 1.02-1.19; p = 0.01); female gender (OR: 0.2; 95% CI: 0.07-0.52; p = 0.001); time from onset of symptoms to PCI (OR: 1.15; 95% CI: 1.07-1.47; p = 0.003). Conclusions: Old age, female gender and long time from onset of symptoms to AMI treatment (independent of previous fibrinolysis) are independent factors of CR in PCI patients. (Cardiol J 2007; 14: 538-543)

Ocena ryzyka pęknięcia serca u pacjentów z ostrym zawałem serca poddanych przezskórnej interwencji wieńcowej

Wstęp: Pęknięcie serca jest częstą przyczyną śmierci pacjentów z ostrym zawałem serca (AMI). Pomimo postępu w leczeniu AMI do pęknięcia serca dochodzi dość często, a powikłanie to w większości przypadków prowadzi do śmierci. Celem tego badania było określenie niezależnych wskaźników predykcyjnych pęknięcia serca w przebiegu AMI u pacjentów poddanych przezskórnej interwencji wieńcowej (PCI). Metody: Zbadano retrospektywnie 4200 pacjentów z AMI leczonych za pomocą PCI. Analizą objęto 217 osób, które zmarły z powodu AMI. We wszystkich przypadkach pęknięcie serca potwierdzono w badaniu pośmiertnym. Wyniki: Pęknięcie serca wystąpiło u 49 pacjentów (18,1%). W grupie osób z pęknięciem serca leczenie trombolityczne zastosowano u 24,4% chorych, w porównaniu z 22,6% pacjentów, u których nie doszło do pęknięcia serca (p = NS). Z większym ryzykiem pęknięcia serca w analizie jednozmiennej wiązały się następujące cechy: wiek (70,3 &#177; 3,2 vs. 65,2 &#177; 9,9 roku; p < 0,001), płeć żeńska (75,0% vs. 60,2%; p < 0,001); wcześniejszy incydent sercowy (61,2% vs. 40,2%; p < 0,05), negatywne wywiady w kierunku uprzednio przebytego zawału (częstość występowania uprzednio przebytego zawału: 14,2% vs. 33,4%; p < 0,05), obecność zespołów QS w pierwszym elektrokardiogramie (75,5% vs. 52,0%; p < 0,05), choroba wielu tętnic wieńcowych (75,5% vs. 61,5%; p < 0,05) oraz długi czas od początku wystąpienia objawów do trombolizy lub PCI (odpowiednio 8,1 &#177; 2,8 vs. 4,7 &#177; 2,3 h, p < 0,001 oraz 9,0 &#177; 5,5 vs. 4,5 &#177; &#177; 3,2 h; p < 0,001). W analizie wielozmiennej niezależnymi wskaźnikami predykcyjnymi pęknięcia serca były: wiek [iloraz szans (OR) 1,1; 95-procentowy przedział ufności (CI) 1,02-1,19; p = 0,01], płeć żeńska (OR 0,2 dla płci męskiej w porównaniu z żeńską; 95% CI 0,07-0,52; p = 0,001) oraz czas od początku objawów do PCI (OR 1,15; 95% CI 1,07-1,47; p = 0,003). Wnioski: Starszy wiek, płeć żeńska i długi czas od początku wystąpienia objawów do leczenia AMI (niezależnie od wcześniejszej trombolizy) są niezależnymi czynnikami ryzyka pęknięcia serca u pacjentów poddawanych PCI. (Folia Cardiologica Excerpta 2008; 3: 79-84)

<Book Review> Yamanoi Kazunori, How does the politics change the social security

WSTĘP. Celem pracy była ocena wpływu otyłości oraz cukrzycy typu 2 na przerost lewej komory serca u pacjentów z nadciśnieniem tętniczym. MATERIAŁ I METODY. Badaniem objęto grupę 554 osób z nadciśnieniem tętniczym (62% mężczyzn, 38% kobiet) oraz 97 osób z nadciśnieniem tętniczym i cukrzycą typu 2 (61% mężczyzn, 39% kobiet). Średni wiek w obu grupach wynosił 53 &#177; 13 lat v. 58 &#177; 8 lat. U wszystkich badanych wykonano echokardiografię, dwukrotny pomiar ciśnienia tętniczego, mierzono obwód talii i bioder oraz określano wskaźnik masy ciała (BMI). WYNIKI. Masa lewej komory (LVM) oraz wskaźnik masy lewej komory serca (LVMI) były istotnie wyższe w grupie osób z nadciśnieniem tętniczym i cukrzycą typu 2 w porównaniu z grupą osób bez cukrzycy, wynosiły one odpowiednio: LVM &#8212; 280,6 &#177; 67,4 g v. 247,3 &#177; 74,8 g, p < 0,0001; LVMI &#8212; 145,2 &#177; 33 g/ /m2 v. 129,9 &#177; 36 g/m2, p < 0,0001. W przypadku osób z nadciśnieniem tętniczym nieobciążonych cukrzycą wykazano dodatnią korelację BMI z LVMI (r = 0,17, p < 0,0001), zarówno wśród mężczyzn, jak i kobiet. W przypadku wskaźnika talia/biodro wykazano dodatnią korelację z LVMI tylko w grupie kobiet (r = 0,26, p < 0,0001). U pacjentów ze współistniejącą cukrzycą typu 2 nie stwierdzono związku BMI oraz wskaźnika talia/biodro z przerostem lewej komory serca. WNIOSKI. Czynnikami zwiększającymi ryzyko przerostu lewej komory serca wśród osób z nadciśnieniem tętniczym są wysoki wskaźnik masy ciała oraz otyłość brzuszna w przypadku kobiet. Pacjenci ze współistniejącą cukrzycą typu 2 cechują się bardziej zaznaczonym przerostem lewej komory serca. (Diabet. Prakt. 2011, tom 12, nr 4, 134&#8211;141)INTRODUCTION. The aim of this study was to assess the influence of obesity and diabetes mellitus on left ventricular hypertrophy in patients with arterial hypertension. MATERIAL AND METHODS. Study population consisted of 554 patients with hypertension (62% men, 38% women), and 97 patients with hypertension and concomitant diabetes mellitus (DM) (61% men, 39% women). The mean age in these two groups was 53 &#177; 13 years v. 58 &#177; 8 years respectively. We performed echocardiography as well as blood pressure (twice) and waist and hip circumference measurements. Body mass index (BMI) was assessed. RESULTS. Left ventricular mass (LVM) and left ventricular mass index (LVMI) were significantly higher in the group with hypertension and concomitant DM than in the group without DM, LVM &#8212; 280.6 &#177; 67.4 g v. 247.3 &#177; 74.8 g, p < 0.0001, LVMI &#8212; 145.2 &#177; 33 g/m2 v. 129.9 &#177; 36 g/m2, p < < 0.0001. In patients with hypertension without DM, BMI positively correlated with LVMI (r = 0.17, p < < 0,0001) in men and in women. Waist/hip ratio positively correlated with LVMI in women (r = 0.26, p < 0.0001). In the group of patients with concomitant DM, BMI and waist/hip ratio didn&#8217;t correlate with left ventricular hypertrophy. CONCLUSIONS. Higher body mass index and abdominal obesity in women are risk factors for left ventricular hypertrophy. Left ventricular hypertrophy is more prevalent in the group with concomitant DM. (Diabet. Prakt. 2011, vol. 12, no 4, 134&#8211;141

Investigation of vehicle crash modeling techniques: theory and application

Creating a mathematical model of a vehicle crash is a task which involves considerations and analysis of different areas which need to be addressed because of the mathematical complexity of a crash event representation. Therefore, to simplify the analysis and enhance the modeling process, in this work, a brief overview of different vehicle crash modeling methodologies is proposed. The acceleration of a colliding vehicle is measured in its center of gravity—this crash pulse contains detailed information about vehicle behavior throughout a collision. A virtual model of a collision scenario is established in order to provide an additional data set further used to evaluate a suggested approach. Three different approaches are discussed here: lumped parameter modeling of viscoelastic systems, data-based approach taking advantage of neural networks and autoregressive models and wavelet-based method of signal reconstruction. The comparative analysis between each method’s outcomes is performed and reliability of the proposed methodologies and tools is evaluated

Development of lumped-parameter mathematical models for a vehicle localized impact

In this paper, we propose a method of modeling for vehicle crash systems based on viscous and elastic properties of the materials. This paper covers an influence of different arrangement of spring and damper on the models’ response. Differences in simulating vehicle-torigid barrier collision and vehicle-to-pole collision are explained. Comparison of the models obtained from wideband (unfiltered) acceleration and filtered acceleration is done. At the end we propose a model which is suitable for localized collisions simulation

A fuzzy logic approach to modeling a vehicle crash test

This paper presents an application of fuzzy approach to vehicle crash modeling. A typical vehicle to pole collision is described and kinematics of a car involved in this type of crash event is thoroughly characterized. The basics of fuzzy set theory and modeling principles based on fuzzy logic approach are presented. In particular, exceptional attention is paid to explain the methodology of creation of a fuzzy model of a vehicle collision. Furthermore, the simulation results are presented and compared to the original vehicle’s kinematics. It is concluded which factors have influence on the accuracy of the fuzzy model’s output and how they can be adjusted to improve the model’s fidelity

Influence of unloading modes of spring-mass-damper models on vehicle to pole collision simulation results

Our intention, in this brief note, is to investigate what influence the viscoelastic models' unloading properties have on models' accuracy of representing vehicle crash event. Two types of simple spring-mass-damper systems (Kelvin models) such underdamped and critically damped conditions are analyzed. Subsequently, two different unloading scenarios are specified: elastic rebound in which only the damper is an energy dissipating element and plastic collision in which the model's maximum achievable displacement is at the same time its constant deflection at the zero-force level. By comparing models' behavior not only in terms of their time responses but also in terms of their force-deflection characteristics, it is concluded which of them is the most suitable to represent vehicle to pole collision