Anees Mohammed | The University of Manchester (original) (raw)

Papers by Anees Mohammed

Research paper thumbnail of Rotor Condition Monitoring Using Fibre Optic Sensing Technology

The 10th International Conference on Power Electronics, Machines and Drives (PEMD 2020), 2021

Research paper thumbnail of Electrical Machine Permanent Magnets Health Monitoring and Diagnosis Using an Air-Gap Magnetic Sensor

IEEE Sensors Journal, May 15, 2020

this study proposes a magnetic sensor design and application for monitoring the health of rotor m... more this study proposes a magnetic sensor design and application for monitoring the health of rotor magnets in permanent magnet (PM) electrical machines through in-situ observation of the air-gap magnetic flux density. The reported device employs the concept of Fibre Bragg Grating (FBG) strain sensing fusion with magnetostrictive material to deliver a machine stator slot wedge integrated sensor that allows straightforward installation and retrofit with no invasive action to core elements of the machine. The sensing theory, design, prototyping, calibration and installation of the proposed magnetic sensing scheme are detailed in the paper. The sensor was installed into an inverter driven surface mount PM synchronous machine (SPMSM) and its performance for in-situ observation of rotor PM magnetization conditions validated in a range of healthy and demagnetised PM conditions tests. The obtained experimental data demonstrate the reported device's capability to enable recognition of rotor PMs' magnetisation level and thus their health monitoring. Finally, a fault index is proposed and experimentally validated that allows the application of in-situ magnetic sensor measurements for relative quantification of PM demagnetization fault severity.

Research paper thumbnail of Evaluation and Mitigation of Offshore HVDC Valve Hall Magnetic Field Impact on Inspection Quadcopter Propulsion Motors

Research paper thumbnail of Design, Instrumentation and Usage Protocols for Distributed In Situ Thermal Hot Spots Monitoring in Electric Coils using FBG Sensor Multiplexing

Journal of Visualized Experiments, Mar 8, 2020

Random wound coils are a key operational element of most electric apparatus in modern industrial ... more Random wound coils are a key operational element of most electric apparatus in modern industrial systems, including low voltage electric machines. One of the major current bottlenecks in improved exploitation of electrical devices is the high sensitivity of their wound components to in-service thermal stress. The application of conventional thermal sensing methods (e.g., thermocouples, resistance temperature detectors) for thermal condition monitoring of current carrying random wound coils can impose considerable operational limitations due to sensor size, EMI sensitivity and the existence of electrically conductive material in their construction. Another substantial limitation exists in distributed sensing applications and is caused by what is often a considerable length and volume of conventional sensor wiring leads. This paper reports the design of a fiber optic FBG sensing system intended for enabling real-time distributed internal thermal condition monitoring within random wound coils. The procedure of random wound coil instrumentation with the FBG sensing system is reported in a case study on an IEEE standard wound coil representative of those utilized in electrical machines. The reported work also presents and discusses important practical and technical aspects of FBG sensing system implementation and application, including the FBG array geometry design, sensing head and fiber packaging, the sensor array installation and calibration procedure and the use of a commercial interrogation system for obtaining thermal measurements. Finally, the in situ multiplexed FBG sensing system thermal monitoring performance is demonstrated in representative static and dynamic thermal conditions.

Research paper thumbnail of In-Situ Thermal and Mechanical Fibre Optic Sensing for In-Service Electric Machinery Bearing Condition Monitoring

2019 IEEE International Electric Machines & Drives Conference (IEMDC)

Research paper thumbnail of Fiber Optic Fiber Bragg Grating Sensing for Monitoring and Testing of Electric Machinery: Current State of the Art and Outlook

Machines

This paper presents a review of the recent trends and the current state of the art in the applica... more This paper presents a review of the recent trends and the current state of the art in the application of fiber optic fiber Bragg gratings (FBG) sensing technology to condition the monitoring (CM) and testing of practical electric machinery and the associated power equipment. FBG technology has received considerable interest in this field in recent years, with research demonstrating that the flexible, multi-physical, and electromagnetic interference (EMI) immune in situ sensing of a multitude of physical measurands of CM interest is possible and cannot be obtained through conventional sensing means. The unique FBG sensing ability has the potential to unlock many of the electric machine CM and design validation restrictions imposed by the limitations of conventional sensing techniques but needs further research to attain wider adoption. This paper first presents the fundamental principles of FBG sensing. This is followed by a description of recent FBG sensing techniques proposed for e...

Research paper thumbnail of Characterisation of FBG based Magnetic Field Sensor Response Sensitivity to Excitation Orientation for Rotating Electric Machine Applications

2019 8th Mediterranean Conference on Embedded Computing (MECO), 2019

This paper reports an experimental study aimed at characterising the response of an in-situ fibre... more This paper reports an experimental study aimed at characterising the response of an in-situ fibre optic fibre Bragg grating / magnetostrictive flux sensor when exposed to excitation in orientations aligned with and perpendicular to its optimal performance axes. The study is aimed at improving the understanding of the potential for non-invasive in-situ application of this sensing technology in devices with confined geometries which impose restrictions on possible magnetic excitation axis alignment with that of the sensor, such as those encountered in rotating electric machinery.

Research paper thumbnail of The Operation of UAV Propulsion Motors in the Presence of High External Magnetic Fields

Robotics, 2021

The operation and maintenance of converter stations (also known as valve halls) in high voltage D... more The operation and maintenance of converter stations (also known as valve halls) in high voltage DC (HVDC) grids is a key element in long-term, reliable and stable operation, especially in inherently adverse offshore environments. However, the nature of the electromagnetic field environment inside HVDC valve halls presents a challenge for the operation of traditional off-shelf inspection robots. In this paper, the impact of the external magnetic field on the operation of an inspection UAV’s propulsion motors is assessed. An experimental method is proposed to simulate the maximum magnetic field interference to off-shelf UAV motors, which can be used to identify their suitability for use in HVDC valve halls inspection robots. The paper’s experimental results compare the performance of direct torque control and field-oriented control algorithms for propulsion motors under the influence of external magnetic flux. Under the influence of a 177 mT external magnetic field, it was found that ...

Research paper thumbnail of Fibre optic monitoring of induction machine frame strain as a diagnostic tool

2017 IEEE International Electric Machines and Drives Conference (IEMDC), 2017

Research paper thumbnail of FBG sensing for hot spot thermal monitoring in electric machinery random wound components

2016 XXII International Conference on Electrical Machines (ICEM), 2016

His research interests are in electrical machines, drives and condition monitoring. Siniša Djurov... more His research interests are in electrical machines, drives and condition monitoring. Siniša Djurović recieved his Dipl. Ing. degree from University of Montenegro in 2002 and his Ph.D. degree from University of Manchester in 2007. Dr. Djurović is currently a Lecturer in the School of Electrical and Electronic Engineering at The University of Manchester, UK. His research interests are in the area of modelling, design, application and condition monitoring of electrical machines and drives. Alexander C. Smith received the B.Sc.Eng.

Research paper thumbnail of Response Time Characterisation of a Fibre Bragg Grating Humidity Sensor for Power Conversion Device Applications

2020 9th Mediterranean Conference on Embedded Computing (MECO), 2020

As electric machines and other power conversion devices continue to replace conventional pneumati... more As electric machines and other power conversion devices continue to replace conventional pneumatic and hydraulic systems, the need to monitor these and the environmental conditions under which they operate becomes more significant. Humidity ingress in electrical machines is particularly important as humidity in the windings can cause degradation and failure in operating conditions, particularly in those machines that do not operate on a continuous duty cycle. With this in mind, this research aims to explore novel methods of monitoring humidity using state of the art Fibre Bragg Grating Sensors, particularly on their time response to determine their suitability for electric machine applications.

Research paper thumbnail of An End-to-End, Real-Time Solution for Condition Monitoring of Wind Turbine Generators

Energies, 2020

Data-driven wind generator condition monitoring systems largely rely on multi-stage processing in... more Data-driven wind generator condition monitoring systems largely rely on multi-stage processing involving feature selection and extraction followed by supervised learning. These stages require expert analysis, are potentially error-prone and do not generalize well between applications. In this paper, we introduce a collection of end-to-end Convolutional Neural Networks for advanced condition monitoring of wind turbine generators. End-to-end models have the benefit of utilizing raw, unstructured signals to make predictions about the parameters of interest. This feature makes it easier to scale an existing collection of models to new predictive tasks (e.g., new failure types) since feature extracting steps are not required. These automated models achieve low Mean Squared Errors in predicting the generator operational state (40.85 for Speed and 0.0018 for Load) and high accuracy in diagnosing rotor demagnetization failures (99.67%) by utilizing only raw current signals. We show how to c...

Research paper thumbnail of Real-time insulation lifetime monitoring for motor windings

2016 XXII International Conference on Electrical Machines (ICEM), 2016

This paper investigates the development and implementation of a real-time thermal ageing model fo... more This paper investigates the development and implementation of a real-time thermal ageing model for polymer-based electrical wire insulation using the classical Arrhenius relationship for chemical reaction rates. The paper presents the theoretical development and implementation of the method for predicting the insulation lifetime based on realtime temperature measurements using fibre-optic sensors embedded inside copper-wound coils. The performance of the presented lifetime model in delivering consistent results for winding insulation lifetime predictions is then assessed and validated using real-time steady-state and transient thermal experiments on a wound test coil mounted into a purpose built motorette test rig.

Research paper thumbnail of Electric Machine Bearing Health Monitoring and Ball Fault Detection by Simultaneous Thermo-Mechanical Fibre Optic Sensing

IEEE Transactions on Energy Conversion, 2021

This article reports the use of fiber Bragg grating (FBG) sensors for electric machines' in-servi... more This article reports the use of fiber Bragg grating (FBG) sensors for electric machines' in-service bearing condition monitoring. The proposed method enables simultaneous extraction of thermal and mechanical information on the bearing operational status for health monitoring and fault diagnosis purposes. The work first reports the instrumentation, calibration and the measurements interpretation methods of an FBG array sensor fitted to the drive-end bearing of an operating inverter driven induction motor. Experimental tests are then undertaken on a purpose build test rig to evaluate the proposed in-situ sensing scheme's performance under healthy and faulted bearing conditions. The results demonstrate that the measurements acquired by individual FBG sensors fitted in the bearing architecture contain concurrent thermal and mechanical information, which can be clearly differentiated to enable understanding of the examined motor bearing's thermal only and mechanical only operating conditions. Furthermore the in-situ measurements obtained in fault conditions are shown to contain clearly defined time and frequency domains fault signatures, which can enable unambiguous fault diagnosis and trending.

Research paper thumbnail of Manifestation of Partial Demagnetisation Fault Induced Unbalanced Magnetic Pull Effects in the Stator Current and Torque of Surface-Mounted PM Machines

The 10th International Conference on Power Electronics, Machines and Drives (PEMD 2020), 2021

Research paper thumbnail of Distributed Thermal Monitoring of Wind Turbine Power Electronic Modules Using FBG Sensing Technology

IEEE Sensors Journal, 2020

This paper reports a distributed thermal monitoring scheme for power electronic modules (PEMs) in... more This paper reports a distributed thermal monitoring scheme for power electronic modules (PEMs) in wind turbine converters. The sensing system is based on utilizing electrically non-conductive and electromagnetic interference immune fiber Bragg Grating (FBG) sensing technology embedded in the PEM baseplate. The design and implementation features of the proposed scheme are presented first. The scheme is then applied in a commercial PEM operating within an inverter bridge, equipped also with a conventional distributed thermal monitoring system using a multiple point thermo-couple (TC) sensor suite. A range of tests are performed to evaluate the performance of the FBG distributed thermal monitoring system and correlate it to TC measurements under steady-state and transient operating conditions representative of PEM operation in an actual wind turbine application. It is shown that the proposed FBG monitoring system can offer practical operational improvements in establishment of distributed thermal sensing schemes for wind turbine PEM.

Research paper thumbnail of Double Fed Induction Generator Shaft Misalignment Monitoring by FBG Frame Strain Sensing

IEEE Sensors Journal, 2020

This study explores the potential for using FBG strain sensing to enable recognition of the shaft... more This study explores the potential for using FBG strain sensing to enable recognition of the shaft misalignment condition in electric machine drivetrains through observation of machine frame distributed relative strain. The sensing principles, design and installation methods of the proposed technique are detailed in the paper. The scheme was applied on a purpose built wind turbine generator representative laboratory test rig and its performance evaluated in an extensive experimental study involving a range of healthy and misaligned shaft operating conditions. The obtained experimental data demonstrate the reported method's capability to enable recognition of generator shaft misalignment conditions and thus its health monitoring. Finally, it is shown that the thermal variation of the generator frame structure inherent to its operation, combined with the FBG sensor intrinsic thermo-mechanical cross sensitivity, has no detrimental impact on the fidelity and usability of the observed strain measurements. Index Terms-Electric machines, FBG sensors, misalignment monitoring, strain sensing, wind turbine generators. I. INTRODUCTION O FFSHORE wind generation is increasingly seen as a dominant factor in decarbonizing our power supply and is set to become the largest source of electricity in the European Union by 2040 [1]. With wind turbines (WTs) growing in size and power capacity to exploit the higher and more consistent wind resource offshore, their exposure to harsh ambient conditions in remote offshore locations creates challenges for operation and maintenance (O&M): access is often limited and maintenance costly due to complicated repair infrastructure requirements imposed by the device location and scale. The development of WT in-service monitoring techniques that can assist maintenance decisions is thus of considerable importance as it can improve availability and reduce the high O&M cost [2]-this is currently estimated

Research paper thumbnail of Electrical Machine Permanent Magnets Health Monitoring and Diagnosis Using an Air-Gap Magnetic Sensor

IEEE Sensors Journal, 2020

this study proposes a magnetic sensor design and application for monitoring the health of rotor m... more this study proposes a magnetic sensor design and application for monitoring the health of rotor magnets in permanent magnet (PM) electrical machines through in-situ observation of the air-gap magnetic flux density. The reported device employs the concept of Fibre Bragg Grating (FBG) strain sensing fusion with magnetostrictive material to deliver a machine stator slot wedge integrated sensor that allows straightforward installation and retrofit with no invasive action to core elements of the machine. The sensing theory, design, prototyping, calibration and installation of the proposed magnetic sensing scheme are detailed in the paper. The sensor was installed into an inverter driven surface mount PM synchronous machine (SPMSM) and its performance for in-situ observation of rotor PM magnetization conditions validated in a range of healthy and demagnetised PM conditions tests. The obtained experimental data demonstrate the reported device's capability to enable recognition of rotor PMs' magnetisation level and thus their health monitoring. Finally, a fault index is proposed and experimentally validated that allows the application of in-situ magnetic sensor measurements for relative quantification of PM demagnetization fault severity.

Research paper thumbnail of FBG Thermal Sensing Ring Scheme for Stator Winding Condition Monitoring in PMSMs

IEEE Transactions on Transportation Electrification, 2019

This article proposes a random wound stator winding thermal monitoring scheme for permanent-magne... more This article proposes a random wound stator winding thermal monitoring scheme for permanent-magnet synchronous motors (PMSMs) utilizing an end-winding embedded, ring-shaped, fiber Bragg grating (FBG) thermal sensing array. The scheme enables in situ measurement of winding distributed thermal conditions, which is key to their effective health diagnosis and protection. It is designed to provide a thermal sensing point per each individual end-winding coil-end span and thus enable monitoring of the entire winding structure. This was achieved by utilizing FBG thermal sensing multiplexing in a ring-shaped sensor array inserted into the end-winding assembly to ensure desired in situ placement of separate sensing elements. The scheme was implemented on an inverter-driven PMSM and its performance examined in tests under healthy and faulted winding conditions. The results demonstrate the capability of effective monitoring of healthy windings distributed thermal status and that of unambiguous identification of localized overheating originating from winding fault, providing monitoring functionality that is largely unattainable by conventional thermal sensing techniques. Finally, the proposed scheme also enables straightforward advanced graphical visualization of the windings' thermal status and, hence, a more effective diagnostic interpretation of thermal data to extract knowledge on locations of increased thermal stress. Index Terms-Fiber Bragg grating (FBG) technology, localized temperature monitoring, end-winding, permanent-magnet synchronous motor (PMSM), thermal monitoring, winding fault. NOMENCLATURE PMSM Permanent-magnet synchronous motor. FBG Fiber Bragg grating. ITSCF Interturn short-circuit fault. 2-D TSR 2-D thermal sensing ring. DE-winding Drive end winding. PEEK Polyetheretherketone. C x Thermal cycles, x is a cycle number. FS, HS, and LS Full, half, and low speeds. FL, HL, and NL Full, half, and no loads. xT Number of shorted turns.

Research paper thumbnail of Feasibility study of embedded FBG thermal sensing use for monitoring electrical fault-induced thermal excitation in random wound coils

The Journal of Engineering, 2019

This paper reports an experimental feasibility study of the potential for using Fibre Bragg Grati... more This paper reports an experimental feasibility study of the potential for using Fibre Bragg Grating (FBG) thermal sensing technology for electrical fault detection in random wound coils. The study is performed on prototype test coils housed in a purpose built steel core section. The FBG thermal sensors are embedded between copper conductors in multiple positions within the coil structure and in close proximity of the known hot spots of interest. The examined coils are designed to enable emulation of hot spots representative of those that would be expected at the outset of winding fault events. A series of experiments were separately conducted in order to characterise the potential of coil internal thermal stress monitoring to provide recognition of a developing winding fault. To this end, winding fault scenarios with different severity levels of inter-turn fault are experimentally examined. The reported findings demonstrate the potential of the proposed in-situ thermal sensing scheme to enable monitoring and recognition of coil internal thermal stress induced at various stages of emulated electrical fault.

Research paper thumbnail of Rotor Condition Monitoring Using Fibre Optic Sensing Technology

The 10th International Conference on Power Electronics, Machines and Drives (PEMD 2020), 2021

Research paper thumbnail of Electrical Machine Permanent Magnets Health Monitoring and Diagnosis Using an Air-Gap Magnetic Sensor

IEEE Sensors Journal, May 15, 2020

this study proposes a magnetic sensor design and application for monitoring the health of rotor m... more this study proposes a magnetic sensor design and application for monitoring the health of rotor magnets in permanent magnet (PM) electrical machines through in-situ observation of the air-gap magnetic flux density. The reported device employs the concept of Fibre Bragg Grating (FBG) strain sensing fusion with magnetostrictive material to deliver a machine stator slot wedge integrated sensor that allows straightforward installation and retrofit with no invasive action to core elements of the machine. The sensing theory, design, prototyping, calibration and installation of the proposed magnetic sensing scheme are detailed in the paper. The sensor was installed into an inverter driven surface mount PM synchronous machine (SPMSM) and its performance for in-situ observation of rotor PM magnetization conditions validated in a range of healthy and demagnetised PM conditions tests. The obtained experimental data demonstrate the reported device's capability to enable recognition of rotor PMs' magnetisation level and thus their health monitoring. Finally, a fault index is proposed and experimentally validated that allows the application of in-situ magnetic sensor measurements for relative quantification of PM demagnetization fault severity.

Research paper thumbnail of Evaluation and Mitigation of Offshore HVDC Valve Hall Magnetic Field Impact on Inspection Quadcopter Propulsion Motors

Research paper thumbnail of Design, Instrumentation and Usage Protocols for Distributed In Situ Thermal Hot Spots Monitoring in Electric Coils using FBG Sensor Multiplexing

Journal of Visualized Experiments, Mar 8, 2020

Random wound coils are a key operational element of most electric apparatus in modern industrial ... more Random wound coils are a key operational element of most electric apparatus in modern industrial systems, including low voltage electric machines. One of the major current bottlenecks in improved exploitation of electrical devices is the high sensitivity of their wound components to in-service thermal stress. The application of conventional thermal sensing methods (e.g., thermocouples, resistance temperature detectors) for thermal condition monitoring of current carrying random wound coils can impose considerable operational limitations due to sensor size, EMI sensitivity and the existence of electrically conductive material in their construction. Another substantial limitation exists in distributed sensing applications and is caused by what is often a considerable length and volume of conventional sensor wiring leads. This paper reports the design of a fiber optic FBG sensing system intended for enabling real-time distributed internal thermal condition monitoring within random wound coils. The procedure of random wound coil instrumentation with the FBG sensing system is reported in a case study on an IEEE standard wound coil representative of those utilized in electrical machines. The reported work also presents and discusses important practical and technical aspects of FBG sensing system implementation and application, including the FBG array geometry design, sensing head and fiber packaging, the sensor array installation and calibration procedure and the use of a commercial interrogation system for obtaining thermal measurements. Finally, the in situ multiplexed FBG sensing system thermal monitoring performance is demonstrated in representative static and dynamic thermal conditions.

Research paper thumbnail of In-Situ Thermal and Mechanical Fibre Optic Sensing for In-Service Electric Machinery Bearing Condition Monitoring

2019 IEEE International Electric Machines & Drives Conference (IEMDC)

Research paper thumbnail of Fiber Optic Fiber Bragg Grating Sensing for Monitoring and Testing of Electric Machinery: Current State of the Art and Outlook

Machines

This paper presents a review of the recent trends and the current state of the art in the applica... more This paper presents a review of the recent trends and the current state of the art in the application of fiber optic fiber Bragg gratings (FBG) sensing technology to condition the monitoring (CM) and testing of practical electric machinery and the associated power equipment. FBG technology has received considerable interest in this field in recent years, with research demonstrating that the flexible, multi-physical, and electromagnetic interference (EMI) immune in situ sensing of a multitude of physical measurands of CM interest is possible and cannot be obtained through conventional sensing means. The unique FBG sensing ability has the potential to unlock many of the electric machine CM and design validation restrictions imposed by the limitations of conventional sensing techniques but needs further research to attain wider adoption. This paper first presents the fundamental principles of FBG sensing. This is followed by a description of recent FBG sensing techniques proposed for e...

Research paper thumbnail of Characterisation of FBG based Magnetic Field Sensor Response Sensitivity to Excitation Orientation for Rotating Electric Machine Applications

2019 8th Mediterranean Conference on Embedded Computing (MECO), 2019

This paper reports an experimental study aimed at characterising the response of an in-situ fibre... more This paper reports an experimental study aimed at characterising the response of an in-situ fibre optic fibre Bragg grating / magnetostrictive flux sensor when exposed to excitation in orientations aligned with and perpendicular to its optimal performance axes. The study is aimed at improving the understanding of the potential for non-invasive in-situ application of this sensing technology in devices with confined geometries which impose restrictions on possible magnetic excitation axis alignment with that of the sensor, such as those encountered in rotating electric machinery.

Research paper thumbnail of The Operation of UAV Propulsion Motors in the Presence of High External Magnetic Fields

Robotics, 2021

The operation and maintenance of converter stations (also known as valve halls) in high voltage D... more The operation and maintenance of converter stations (also known as valve halls) in high voltage DC (HVDC) grids is a key element in long-term, reliable and stable operation, especially in inherently adverse offshore environments. However, the nature of the electromagnetic field environment inside HVDC valve halls presents a challenge for the operation of traditional off-shelf inspection robots. In this paper, the impact of the external magnetic field on the operation of an inspection UAV’s propulsion motors is assessed. An experimental method is proposed to simulate the maximum magnetic field interference to off-shelf UAV motors, which can be used to identify their suitability for use in HVDC valve halls inspection robots. The paper’s experimental results compare the performance of direct torque control and field-oriented control algorithms for propulsion motors under the influence of external magnetic flux. Under the influence of a 177 mT external magnetic field, it was found that ...

Research paper thumbnail of Fibre optic monitoring of induction machine frame strain as a diagnostic tool

2017 IEEE International Electric Machines and Drives Conference (IEMDC), 2017

Research paper thumbnail of FBG sensing for hot spot thermal monitoring in electric machinery random wound components

2016 XXII International Conference on Electrical Machines (ICEM), 2016

His research interests are in electrical machines, drives and condition monitoring. Siniša Djurov... more His research interests are in electrical machines, drives and condition monitoring. Siniša Djurović recieved his Dipl. Ing. degree from University of Montenegro in 2002 and his Ph.D. degree from University of Manchester in 2007. Dr. Djurović is currently a Lecturer in the School of Electrical and Electronic Engineering at The University of Manchester, UK. His research interests are in the area of modelling, design, application and condition monitoring of electrical machines and drives. Alexander C. Smith received the B.Sc.Eng.

Research paper thumbnail of Response Time Characterisation of a Fibre Bragg Grating Humidity Sensor for Power Conversion Device Applications

2020 9th Mediterranean Conference on Embedded Computing (MECO), 2020

As electric machines and other power conversion devices continue to replace conventional pneumati... more As electric machines and other power conversion devices continue to replace conventional pneumatic and hydraulic systems, the need to monitor these and the environmental conditions under which they operate becomes more significant. Humidity ingress in electrical machines is particularly important as humidity in the windings can cause degradation and failure in operating conditions, particularly in those machines that do not operate on a continuous duty cycle. With this in mind, this research aims to explore novel methods of monitoring humidity using state of the art Fibre Bragg Grating Sensors, particularly on their time response to determine their suitability for electric machine applications.

Research paper thumbnail of An End-to-End, Real-Time Solution for Condition Monitoring of Wind Turbine Generators

Energies, 2020

Data-driven wind generator condition monitoring systems largely rely on multi-stage processing in... more Data-driven wind generator condition monitoring systems largely rely on multi-stage processing involving feature selection and extraction followed by supervised learning. These stages require expert analysis, are potentially error-prone and do not generalize well between applications. In this paper, we introduce a collection of end-to-end Convolutional Neural Networks for advanced condition monitoring of wind turbine generators. End-to-end models have the benefit of utilizing raw, unstructured signals to make predictions about the parameters of interest. This feature makes it easier to scale an existing collection of models to new predictive tasks (e.g., new failure types) since feature extracting steps are not required. These automated models achieve low Mean Squared Errors in predicting the generator operational state (40.85 for Speed and 0.0018 for Load) and high accuracy in diagnosing rotor demagnetization failures (99.67%) by utilizing only raw current signals. We show how to c...

Research paper thumbnail of Real-time insulation lifetime monitoring for motor windings

2016 XXII International Conference on Electrical Machines (ICEM), 2016

This paper investigates the development and implementation of a real-time thermal ageing model fo... more This paper investigates the development and implementation of a real-time thermal ageing model for polymer-based electrical wire insulation using the classical Arrhenius relationship for chemical reaction rates. The paper presents the theoretical development and implementation of the method for predicting the insulation lifetime based on realtime temperature measurements using fibre-optic sensors embedded inside copper-wound coils. The performance of the presented lifetime model in delivering consistent results for winding insulation lifetime predictions is then assessed and validated using real-time steady-state and transient thermal experiments on a wound test coil mounted into a purpose built motorette test rig.

Research paper thumbnail of Electric Machine Bearing Health Monitoring and Ball Fault Detection by Simultaneous Thermo-Mechanical Fibre Optic Sensing

IEEE Transactions on Energy Conversion, 2021

This article reports the use of fiber Bragg grating (FBG) sensors for electric machines' in-servi... more This article reports the use of fiber Bragg grating (FBG) sensors for electric machines' in-service bearing condition monitoring. The proposed method enables simultaneous extraction of thermal and mechanical information on the bearing operational status for health monitoring and fault diagnosis purposes. The work first reports the instrumentation, calibration and the measurements interpretation methods of an FBG array sensor fitted to the drive-end bearing of an operating inverter driven induction motor. Experimental tests are then undertaken on a purpose build test rig to evaluate the proposed in-situ sensing scheme's performance under healthy and faulted bearing conditions. The results demonstrate that the measurements acquired by individual FBG sensors fitted in the bearing architecture contain concurrent thermal and mechanical information, which can be clearly differentiated to enable understanding of the examined motor bearing's thermal only and mechanical only operating conditions. Furthermore the in-situ measurements obtained in fault conditions are shown to contain clearly defined time and frequency domains fault signatures, which can enable unambiguous fault diagnosis and trending.

Research paper thumbnail of Manifestation of Partial Demagnetisation Fault Induced Unbalanced Magnetic Pull Effects in the Stator Current and Torque of Surface-Mounted PM Machines

The 10th International Conference on Power Electronics, Machines and Drives (PEMD 2020), 2021

Research paper thumbnail of Distributed Thermal Monitoring of Wind Turbine Power Electronic Modules Using FBG Sensing Technology

IEEE Sensors Journal, 2020

This paper reports a distributed thermal monitoring scheme for power electronic modules (PEMs) in... more This paper reports a distributed thermal monitoring scheme for power electronic modules (PEMs) in wind turbine converters. The sensing system is based on utilizing electrically non-conductive and electromagnetic interference immune fiber Bragg Grating (FBG) sensing technology embedded in the PEM baseplate. The design and implementation features of the proposed scheme are presented first. The scheme is then applied in a commercial PEM operating within an inverter bridge, equipped also with a conventional distributed thermal monitoring system using a multiple point thermo-couple (TC) sensor suite. A range of tests are performed to evaluate the performance of the FBG distributed thermal monitoring system and correlate it to TC measurements under steady-state and transient operating conditions representative of PEM operation in an actual wind turbine application. It is shown that the proposed FBG monitoring system can offer practical operational improvements in establishment of distributed thermal sensing schemes for wind turbine PEM.

Research paper thumbnail of Double Fed Induction Generator Shaft Misalignment Monitoring by FBG Frame Strain Sensing

IEEE Sensors Journal, 2020

This study explores the potential for using FBG strain sensing to enable recognition of the shaft... more This study explores the potential for using FBG strain sensing to enable recognition of the shaft misalignment condition in electric machine drivetrains through observation of machine frame distributed relative strain. The sensing principles, design and installation methods of the proposed technique are detailed in the paper. The scheme was applied on a purpose built wind turbine generator representative laboratory test rig and its performance evaluated in an extensive experimental study involving a range of healthy and misaligned shaft operating conditions. The obtained experimental data demonstrate the reported method's capability to enable recognition of generator shaft misalignment conditions and thus its health monitoring. Finally, it is shown that the thermal variation of the generator frame structure inherent to its operation, combined with the FBG sensor intrinsic thermo-mechanical cross sensitivity, has no detrimental impact on the fidelity and usability of the observed strain measurements. Index Terms-Electric machines, FBG sensors, misalignment monitoring, strain sensing, wind turbine generators. I. INTRODUCTION O FFSHORE wind generation is increasingly seen as a dominant factor in decarbonizing our power supply and is set to become the largest source of electricity in the European Union by 2040 [1]. With wind turbines (WTs) growing in size and power capacity to exploit the higher and more consistent wind resource offshore, their exposure to harsh ambient conditions in remote offshore locations creates challenges for operation and maintenance (O&M): access is often limited and maintenance costly due to complicated repair infrastructure requirements imposed by the device location and scale. The development of WT in-service monitoring techniques that can assist maintenance decisions is thus of considerable importance as it can improve availability and reduce the high O&M cost [2]-this is currently estimated

Research paper thumbnail of Electrical Machine Permanent Magnets Health Monitoring and Diagnosis Using an Air-Gap Magnetic Sensor

IEEE Sensors Journal, 2020

this study proposes a magnetic sensor design and application for monitoring the health of rotor m... more this study proposes a magnetic sensor design and application for monitoring the health of rotor magnets in permanent magnet (PM) electrical machines through in-situ observation of the air-gap magnetic flux density. The reported device employs the concept of Fibre Bragg Grating (FBG) strain sensing fusion with magnetostrictive material to deliver a machine stator slot wedge integrated sensor that allows straightforward installation and retrofit with no invasive action to core elements of the machine. The sensing theory, design, prototyping, calibration and installation of the proposed magnetic sensing scheme are detailed in the paper. The sensor was installed into an inverter driven surface mount PM synchronous machine (SPMSM) and its performance for in-situ observation of rotor PM magnetization conditions validated in a range of healthy and demagnetised PM conditions tests. The obtained experimental data demonstrate the reported device's capability to enable recognition of rotor PMs' magnetisation level and thus their health monitoring. Finally, a fault index is proposed and experimentally validated that allows the application of in-situ magnetic sensor measurements for relative quantification of PM demagnetization fault severity.

Research paper thumbnail of FBG Thermal Sensing Ring Scheme for Stator Winding Condition Monitoring in PMSMs

IEEE Transactions on Transportation Electrification, 2019

This article proposes a random wound stator winding thermal monitoring scheme for permanent-magne... more This article proposes a random wound stator winding thermal monitoring scheme for permanent-magnet synchronous motors (PMSMs) utilizing an end-winding embedded, ring-shaped, fiber Bragg grating (FBG) thermal sensing array. The scheme enables in situ measurement of winding distributed thermal conditions, which is key to their effective health diagnosis and protection. It is designed to provide a thermal sensing point per each individual end-winding coil-end span and thus enable monitoring of the entire winding structure. This was achieved by utilizing FBG thermal sensing multiplexing in a ring-shaped sensor array inserted into the end-winding assembly to ensure desired in situ placement of separate sensing elements. The scheme was implemented on an inverter-driven PMSM and its performance examined in tests under healthy and faulted winding conditions. The results demonstrate the capability of effective monitoring of healthy windings distributed thermal status and that of unambiguous identification of localized overheating originating from winding fault, providing monitoring functionality that is largely unattainable by conventional thermal sensing techniques. Finally, the proposed scheme also enables straightforward advanced graphical visualization of the windings' thermal status and, hence, a more effective diagnostic interpretation of thermal data to extract knowledge on locations of increased thermal stress. Index Terms-Fiber Bragg grating (FBG) technology, localized temperature monitoring, end-winding, permanent-magnet synchronous motor (PMSM), thermal monitoring, winding fault. NOMENCLATURE PMSM Permanent-magnet synchronous motor. FBG Fiber Bragg grating. ITSCF Interturn short-circuit fault. 2-D TSR 2-D thermal sensing ring. DE-winding Drive end winding. PEEK Polyetheretherketone. C x Thermal cycles, x is a cycle number. FS, HS, and LS Full, half, and low speeds. FL, HL, and NL Full, half, and no loads. xT Number of shorted turns.

Research paper thumbnail of Feasibility study of embedded FBG thermal sensing use for monitoring electrical fault-induced thermal excitation in random wound coils

The Journal of Engineering, 2019

This paper reports an experimental feasibility study of the potential for using Fibre Bragg Grati... more This paper reports an experimental feasibility study of the potential for using Fibre Bragg Grating (FBG) thermal sensing technology for electrical fault detection in random wound coils. The study is performed on prototype test coils housed in a purpose built steel core section. The FBG thermal sensors are embedded between copper conductors in multiple positions within the coil structure and in close proximity of the known hot spots of interest. The examined coils are designed to enable emulation of hot spots representative of those that would be expected at the outset of winding fault events. A series of experiments were separately conducted in order to characterise the potential of coil internal thermal stress monitoring to provide recognition of a developing winding fault. To this end, winding fault scenarios with different severity levels of inter-turn fault are experimentally examined. The reported findings demonstrate the potential of the proposed in-situ thermal sensing scheme to enable monitoring and recognition of coil internal thermal stress induced at various stages of emulated electrical fault.