Diagnostic monitoring of drivetrain in a 5 MW spar-type floating wind turbine using Hilbert spectral analysis

The objective of this paper is to investigate the frequency-based fault detection of a 5MW spar-type floating wind turbine (WT) gearbox using measurements of the global responses. It is extremely costly to seed managed defects in a real WT gearbox to investigate different fault detection and condition monitoring approaches; using analytical tools, therefore, is one of the promising approaches in this regard. In this study, forces and moments on the main shaft are obtained from the global response analysis using an aero-hydro-servo-elastic code, SIMO-RIFLEX-AeroDyn. Then, they are utilized as inputs to a high-fidelity gearbox model developed using a multi-body simulation software (SIMPACK). The main shaft bearing is one of the critical components since it protects gearbox from axial and radial loads. Six different fault cases with different severity in this bearing are investigated using power spectral density (PSD) of relative axial acceleration of the bearing and nacelle. It is shown that in severe degradation of this bearing the first stage dynamic of the gearbox is dominant in the main shaft vibration signal. Inside the gearbox, the bearings on the high speed side are those often with high probability of failure, thus, one fault case in IMS-B bearing was also considered. Based on the earlier studies, the angular velocity error function is considered as residual for this fault. The Hilbert transform is used to determine the envelope of this residual. Information on the amplitude of this residual properly indicates damage in this bearing

Damage identification in structural health monitoring: a brief review from its implementation to the Use of data-driven applications

The damage identification process provides relevant information about the current state of a structure under inspection, and it can be approached from two different points of view. The first approach uses data-driven algorithms, which are usually associated with the collection of data using sensors. Data are subsequently processed and analyzed. The second approach uses models to analyze information about the structure. In the latter case, the overall performance of the approach is associated with the accuracy of the model and the information that is used to define it. Although both approaches are widely used, data-driven algorithms are preferred in most cases because they afford the ability to analyze data acquired from sensors and to provide a real-time solution for decision making; however, these approaches involve high-performance processors due to the high computational cost. As a contribution to the researchers working with data-driven algorithms and applications, this work presents a brief review of data-driven algorithms for damage identification in structural health-monitoring applications. This review covers damage detection, localization, classification, extension, and prognosis, as well as the development of smart structures. The literature is systematically reviewed according to the natural steps of a structural health-monitoring system. This review also includes information on the types of sensors used as well as on the development of data-driven algorithms for damage identification.Peer ReviewedPostprint (published version

Computer-Aided System for Wind Turbine Data Analysis

Context: The current work on wind turbine failure detection focuses on researching suitable signal processing algorithms and developing efficient diagnosis algorithms. The laboratory research would involve large and complex data, and it can be a daunting task. Aims: To develop a Computer-Aided system for assisting experts to conduct an efficient laboratory research on wind turbine data analysis. System is expected to provide data visualization, data manipulation, massive data processing and wind turbine failure detection. Method: 50G off-line SCADA data and 4 confident diagnosis algorithms were used in this project. Apart from the instructions from supervisor, this project also gained help from two experts from Engineering Department. Java and Microsoft SQL database were used to develop the system. Results: Data visualization provided 6 different charting solutions and together with robust user interactions. 4 failure diagnosis solutions and data manipulations were provided in the system. In addition, dedicated database server and Matlab API with Java RMI were used to resolve the massive data processing problem. Conclusions: Almost all of the deliverables were completed. Friendly GUI and useful functionalities make user feel more comfortable. The final product does enable experts to conduct an efficient laboratory research. The end of this project also gave some potential extensions of the system

Diagnosis of Combination Faults in a Planetary Gearbox using a Modulation Signal Bispectrum based Sideband Estimator

This paper presents a novel method for diagnosing combination faults in planetary gearboxes. Vibration signals measured on the gearbox housing exhibit complicated characteristics because of multiple modulations of concurrent excitation sources, signal paths and noise. To separate these modulations accurately, a modulation signal bispectrum based sideband estimator (MSB-SE) developed recently is used to achieve a sparse representation for the complicated signal contents, which allows effective enhancement of various sidebands for accurate diagnostic information. Applying the proposed method to diagnose an industrial planetary gearbox which coexists both bearing faults and gear faults shows that the different severities of the faults can be separated reliably under different load conditions, confirming the superior performance of this MSB-SE based diagnosis scheme

De-risking Integrated Full Electric Propulsion (IFEP) vessels using advanced modelling and simulation techniques

Complex multi-domain engineering systems, where for example mechanical and thermal (sub)systems are connected to each other in some way, have increasingly become a vital part of our society. An example of such a system is the Integrated Full Electric Propulsion (IFEP) concept for the marine shipping industry. With this IFEP concept, as opposed to the more conventional marine power system, the power for the ship's propulsion and ship's services is provided by a common power plant. This offers advantages including fuel efficiency and design flexibility. However, due to its system complexity and capital costs, it is important that the overall dynamic behaviour of these systems can be predicted in the early stages of the design. Predicting the overall system behaviour can be obtained by employing an integrated end-to-end model, which combines detailed models of for example the mechanical and electrical (sub)systems. This allows for example ship designers to investigate disturbances and the primary and higher order responses across the system. However, present existing simulation tools do not easily facilitate such employment of a holistic approach. In this thesis the focus is on how advanced modelling and simulation techniques can be used to de-risk the design and in-service of complex IFEP systems. The state-of-the-art modelling and simulation techniques as well as the IFEP application area are considered. An integrated-model of an IFEP vessel was developed under the EPSRC collaborative AMEPS (Advanced Marine Electric Propulsion System) research project, which forms a major part of this thesis. In order to reduce the computational burden, due to a wide variety of time constants in the IFEP system, a multi-rate simulation technique was proposed. It was demonstrated that a reduction in simulation execution time between 10-15 times can be achieved. However, it was conceptually argued that multi-rate simulation could introduce errors, which propagates itself across the system thereby provoking potential unrealistic responses from other subsystems. Several case studies were conducted based on this model, which shows that such an integrated end-to-end model may be a valuable decision-support tool for de-risking the design and in-service phases of IFEP vessels. For example, it was demonstrated that a disturbance on the propeller could provoke a saturation of the gas turbine governor. Different power system architectures were proposed for IFEP power systems such as radial and hybrid AC/DC. For this thesis, an initial study was conducted to assess the relationship between the type of power system architecture and the vessel survivability. For this assessment an existing vessel survivability theory was further developed into a quantitative method. It was concluded that based on a comparative short circuit study and the proposed survivability method that the IFEP-hybrid AC/DC architecture offers the best vessel survivability.Complex multi-domain engineering systems, where for example mechanical and thermal (sub)systems are connected to each other in some way, have increasingly become a vital part of our society. An example of such a system is the Integrated Full Electric Propulsion (IFEP) concept for the marine shipping industry. With this IFEP concept, as opposed to the more conventional marine power system, the power for the ship's propulsion and ship's services is provided by a common power plant. This offers advantages including fuel efficiency and design flexibility. However, due to its system complexity and capital costs, it is important that the overall dynamic behaviour of these systems can be predicted in the early stages of the design. Predicting the overall system behaviour can be obtained by employing an integrated end-to-end model, which combines detailed models of for example the mechanical and electrical (sub)systems. This allows for example ship designers to investigate disturbances and the primary and higher order responses across the system. However, present existing simulation tools do not easily facilitate such employment of a holistic approach. In this thesis the focus is on how advanced modelling and simulation techniques can be used to de-risk the design and in-service of complex IFEP systems. The state-of-the-art modelling and simulation techniques as well as the IFEP application area are considered. An integrated-model of an IFEP vessel was developed under the EPSRC collaborative AMEPS (Advanced Marine Electric Propulsion System) research project, which forms a major part of this thesis. In order to reduce the computational burden, due to a wide variety of time constants in the IFEP system, a multi-rate simulation technique was proposed. It was demonstrated that a reduction in simulation execution time between 10-15 times can be achieved. However, it was conceptually argued that multi-rate simulation could introduce errors, which propagates itself across the system thereby provoking potential unrealistic responses from other subsystems. Several case studies were conducted based on this model, which shows that such an integrated end-to-end model may be a valuable decision-support tool for de-risking the design and in-service phases of IFEP vessels. For example, it was demonstrated that a disturbance on the propeller could provoke a saturation of the gas turbine governor. Different power system architectures were proposed for IFEP power systems such as radial and hybrid AC/DC. For this thesis, an initial study was conducted to assess the relationship between the type of power system architecture and the vessel survivability. For this assessment an existing vessel survivability theory was further developed into a quantitative method. It was concluded that based on a comparative short circuit study and the proposed survivability method that the IFEP-hybrid AC/DC architecture offers the best vessel survivability

Marine gas turbine monitoring and diagnostics by simulation and pattern recognition

Several techniques have been developed in the last years for energy conversion and aeronautic propulsion plants monitoring and diagnostics, to ensure non-stop availability and safety, mainly based on machine learning and pattern recognition methods, which need large databases of measures. This paper aims to describe a simulation based monitoring and diagnostic method to overcome the lack of data. An application on a gas turbine powered frigate is shown. A MATLAB-SIMULINK\uae model of the frigate propulsion system has been used to generate a database of different faulty conditions of the plant. A monitoring and diagnostic system, based on Mahalanobis distance and artificial neural networks have been developed. Experimental data measured during the sea trials have been used for model calibration and validation. Test runs of the procedure have been carried out in a number of simulated degradation cases: in all the considered cases, malfunctions have been successfully detected by the developed model

Protection and Disturbance Mitigation of Next Generation Shipboard Power Systems

Today, thanks to modern advances mainly in the power electronics field, megawatt-level electric drives and magnetic levitation are being integrated into the marine power grids. These technologies operate based on Direct Current (DC) power which require Alternating Current (AC) to DC conversion within the current grid. Medium-voltage Direct Current (MVDC) and Flywheel Energy Storage Systems (FESS) are the next state-of-the-art technologies that researchers are leaning on to produce, convert, store, and distribute power with improved power quality, reliability, and flexibility. On the other hand, with the extensive integration of high-frequency power electronic converters, system stability analysis and the true system dynamic behaviors assessment following grid disturbances have become a serious concern for system control designs and protection. This dissertation first explores emerging shipboard power distribution topologies such as MVDC networks and FESS operation with charge and discharge dynamics. Furthermore, the important topic of how these systems perform in dynamic conditions with pulsed power load, faults, arc fault and system protection are studied. Secondly, a communication-based fault detection and isolation system controller that improves upon a directional AC overcurrent relay protection system is proposed offering additional protection discrimination between faults and pulsed-power Load (PPL) in MVDC systems. The controller is designed to segregate between system dynamic short-circuit fault and bus current disturbances due to a PPL. Finally, to validate the effectiveness of the proposed protection controller, different bus current disturbances are simulated within a time-domain electromagnetic transient simulation of a shipboard power system including a PPL system operating with different ramp rate profiles, pulse widths, peak powers, and fault locations. This overarching goal of this work is to address some of the critical issues facing the US Navy as warfighter mission requirements increase exponentially and move towards advanced and sophisticated pulsed power load devices such as high energy weapon systems, high energy sensor and radar systems. The analyses and proposed solutions in this dissertation support current shipbuilding industry priorities to improve shipboard power system reliability and de-risk the integration of new power system technologies for next generation naval vessels

CFD Modelling and Simulation of Water Turbines

The design and development of water turbines requires accurate methods for performance prediction. Numerical methods and modelling are becoming increasingly important tools to achieve better designs and more efficient turbines, reducing the time required in physical model testing. This book is focused on applying numerical simulations and models for water turbines to predict tool their performance. In this Special Issue, the different contributions of this book are classified into three state-of-the-art Topics: discussing the modelling of pump-turbines, the simulation of horizontal and vertical axis turbines for hydrokinetic applications and the modelling of hydropower plants. All the contributions to this book demonstrate the importance of the modelling and simulation of water turbines for hydropower energy. This new generation of models and simulations will play a major role in the global energy transition and energy crisis, and, of course, in the mitigation of climate change

Resilience in Floating Offshore Wind Turbines: A Scoping Review

Background With climate change a looming global threat, offshore wind energy is a vital resource, and floating offshore wind turbines (FOWT) are essential to capture its full potential. Unfortunately, high operations and maintenance expenses pose an obstacle to widespread implementation of FOWT. Reducing maintenance needs by limiting FOWT damage or failure in harsh environments will undoubtedly contribute to lowering costs and to improving on-site personnel safety. Resilience, an important concept in the field of risk management, may be instrumental in achieving these goals. Objective The objective of this thesis was to develop a thorough understanding of how resilience is understood and its applications to FOWT design and operation. The following issues were of greatest interest: the degree to which FOWT literature addresses resilience, the various interpretations and definitions of resilience that are employed in FOWT research, and how those definitions of resilience are applied to FOWT. These issues and objectives led to the question this thesis sought to answer, in order to map the knowledge and potential gaps in FOWT resilience research: How is resilience understood and applied in the context of FOWT design and operation? Methodology In order to answer this research question, a scoping review was conducted, in which two databases – ScienceDirect and GreenFILE – were searched for sources that discussed resilience with respect to FOWT. In accordance with the JBI scoping review methodology, a search and screening strategy, including search terms and inclusion criteria, was determined in advance. The multi-stage screening process ensured that all relevant sources were included, and the entire process is described in such a way as to be transparent and repeatable. Results Thirteen sources, consisting of twelve articles and one report, were found to meet the inclusion criteria, and these were thematically analyzed in order to investigate the definitions/interpretations and applications of resilience to FOWT technology. Several trends were discovered among the included sources, including a dominant engineering perspective and a glaring lack of explicit resilience definitions. Despite this lack of definitions, however, several interpretations of resilience were found to be used among the thirteen sources, and these are discussed in depth. Furthermore, the various applications of resilience to FOWT were mapped in order to identify popular topics, and these findings were compared to trends noted elsewhere in the literature. Conclusions The results of this review provide valuable insight into the main interpretations of resilience that are used in relation to FOWT. They also provide a solid foundation for future work and for improvements in FOWT resilience research. Among these are the need for a clear definition of resilience in FOWT studies and the potential benefits that could come from the development of a risk management approach to enhance the strong engineering perspective within the field of FOWT resilience research