Analysis of thermal instability test methodologies for synchronous generator rotors
- Singh, A.N., Doorsamy, W., Cronje, W.A.
- Authors: Singh, A.N. , Doorsamy, W. , Cronje, W.A.
- Date: 2017
- Subjects: Thermal instability testing , Synchronous generator rotors , Infrared thermography
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/218775 , uj:21818 , Citation: Singh, A.N., Doorsamy, W. & Cronje, W.A. 2017. Analysis of thermal instability test methodologies for synchronous generator rotors.
- Description: Abstract: Thermal instability testing (TIT) is utilised by service providers as a final proving test during the construction, repair and overhaul of large turbo-generator rotors. This test is typically performed using two methodologies – i.e. current injection and friction/windage methods – to evaluate the thermal sensitivity of the generator rotor. Although these methods are distinctly different – service providers/OEMS worldwide show no preference towards a methodology and there is no substantiating evidence or international standards which provide insight into which method is most suitable. This paper investigates these two methods of TIT for synchronous generator rotors. A specialised experimental configuration utilising infrared thermography is used analyse the thermal behaviour a synchronous generator rotor under different test conditions. Experimental results indicate that there are substantial differences in the behaviour of the rotor under the two different methodologies and that an augmented test methodology is required to improve TIT.
- Full Text:
- Authors: Singh, A.N. , Doorsamy, W. , Cronje, W.A.
- Date: 2017
- Subjects: Thermal instability testing , Synchronous generator rotors , Infrared thermography
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/218775 , uj:21818 , Citation: Singh, A.N., Doorsamy, W. & Cronje, W.A. 2017. Analysis of thermal instability test methodologies for synchronous generator rotors.
- Description: Abstract: Thermal instability testing (TIT) is utilised by service providers as a final proving test during the construction, repair and overhaul of large turbo-generator rotors. This test is typically performed using two methodologies – i.e. current injection and friction/windage methods – to evaluate the thermal sensitivity of the generator rotor. Although these methods are distinctly different – service providers/OEMS worldwide show no preference towards a methodology and there is no substantiating evidence or international standards which provide insight into which method is most suitable. This paper investigates these two methods of TIT for synchronous generator rotors. A specialised experimental configuration utilising infrared thermography is used analyse the thermal behaviour a synchronous generator rotor under different test conditions. Experimental results indicate that there are substantial differences in the behaviour of the rotor under the two different methodologies and that an augmented test methodology is required to improve TIT.
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Evaluation of rotor design parameters for minimising torque ripple on a synchronous reluctance machine using multifactor ANOVA
- Authors: Muteba, M. , Doorsamy, W.
- Date: 2017
- Subjects: Synchronous reluctance machines , Rotors - Design and construction , Analysis of variance , Finite element method
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/219393 , uj:21895 , Citation: Muteba, M. & Doorsamy, W. 2017. Evaluation of rotor design parameters for minimising torque ripple on a synchronous reluctance machine using multifactor ANOVA.
- Description: Abstract: This paper presents a method for evaluating, both qualitatively and quantitatively, the effects of specific rotor design parameters on the performance of a synchronous reluctance machine. The method uses multi-factor experimental design, with Analysis of Variance (ANOVA), and Finite Element Analysis (FEA) to determine the optimal rotor design parameter according to a specific objective. Using this method, two factors - rotor flux barrier pitch angle and barrier width - are selected at simultaneously varied levels for assessment with the aim of minimising the response variable, which is, the torque ripple. Results from the investigation show that the influence of the rotor flux barrier pitch angle on the torque ripple is more statistically significant than the influence of the barrier width. However, the effect of the barrier width on the actual torque is more significant.
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- Authors: Muteba, M. , Doorsamy, W.
- Date: 2017
- Subjects: Synchronous reluctance machines , Rotors - Design and construction , Analysis of variance , Finite element method
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/219393 , uj:21895 , Citation: Muteba, M. & Doorsamy, W. 2017. Evaluation of rotor design parameters for minimising torque ripple on a synchronous reluctance machine using multifactor ANOVA.
- Description: Abstract: This paper presents a method for evaluating, both qualitatively and quantitatively, the effects of specific rotor design parameters on the performance of a synchronous reluctance machine. The method uses multi-factor experimental design, with Analysis of Variance (ANOVA), and Finite Element Analysis (FEA) to determine the optimal rotor design parameter according to a specific objective. Using this method, two factors - rotor flux barrier pitch angle and barrier width - are selected at simultaneously varied levels for assessment with the aim of minimising the response variable, which is, the torque ripple. Results from the investigation show that the influence of the rotor flux barrier pitch angle on the torque ripple is more statistically significant than the influence of the barrier width. However, the effect of the barrier width on the actual torque is more significant.
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Investigation into effects of a novel rotor cut-off design for synchronous reluctance machines
- Doorsamy, W., Muteba, M., Twala, B., Nicolae, Dan-Valentin
- Authors: Doorsamy, W. , Muteba, M. , Twala, B. , Nicolae, Dan-Valentin
- Date: 2017
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/237805 , uj:24371 , Citation: Doorsamy, W. et al. 2017. Investigation into effects of a novel rotor cut-off design for synchronous reluctance machines.
- Description: Abstract: This paper presents an investigation into the effects of a novel rotor cut-off design on the performance of a synchronous reluctance machine. The rotor design consists of a sinusoidal lamination shape in the axial direction thereby varying the magnetic flux in the q-axis direction and reducing torque harmonics due to slotting effects. The presented study uses single-factor experimental design, with Analysis of Variance (ANOVA), and Finite Element Analysis (FEA) to quantitatively and qualitatively assess the effects of the rotor cut-off on the torque, torque ripple, saliency, power factor and efficiency of the machine. Results of the investigation indicate that although variation in the rotor cut-off design significantly reduces the torque ripple, the effects on the average output torque, saliency, power factor of the machine are relatively insignificant. Index Terms—Synchronous Reluctance Machine; Rotor Design; ANOVA; FEA.
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- Authors: Doorsamy, W. , Muteba, M. , Twala, B. , Nicolae, Dan-Valentin
- Date: 2017
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/237805 , uj:24371 , Citation: Doorsamy, W. et al. 2017. Investigation into effects of a novel rotor cut-off design for synchronous reluctance machines.
- Description: Abstract: This paper presents an investigation into the effects of a novel rotor cut-off design on the performance of a synchronous reluctance machine. The rotor design consists of a sinusoidal lamination shape in the axial direction thereby varying the magnetic flux in the q-axis direction and reducing torque harmonics due to slotting effects. The presented study uses single-factor experimental design, with Analysis of Variance (ANOVA), and Finite Element Analysis (FEA) to quantitatively and qualitatively assess the effects of the rotor cut-off on the torque, torque ripple, saliency, power factor and efficiency of the machine. Results of the investigation indicate that although variation in the rotor cut-off design significantly reduces the torque ripple, the effects on the average output torque, saliency, power factor of the machine are relatively insignificant. Index Terms—Synchronous Reluctance Machine; Rotor Design; ANOVA; FEA.
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Investigation of thermal instability testing on synchronous generator rotors using an experimental direct mapping method
- Singh, A. Narain, Cronje, W. A., Doorsamy, W.
- Authors: Singh, A. Narain , Cronje, W. A. , Doorsamy, W.
- Date: 2017
- Subjects: Thermal instability testing , Turbogenerator , Infrared thermography
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/237711 , uj:24359 , Citation: Singh, A.N., Cronje, W.A. & Doorsamy, W. 2017. Investigation of thermal instability testing on synchronous generator rotors using an experimental direct mapping method.
- Description: Abstract: Utilities employ Thermal instability testing (TIT) for final acceptance testing after the construction and refurbishment of turbogenerator rotors. This type of testing is performed through two methodologies namely current injection and friction/windage in order to assess the thermal sensitivity of the machine’s rotor. Although there are distinct differences between the two methods, no apparent preference is shown by service providers/OEMS globally. There is also no definitive evidence or standards that offer a comparison of the two methods and suitability assessment thereof. The presented research investigates these two methods of TIT for a synchronous generator rotor. An experimental setup with infrared thermography is employed to investigate the thermal behaviour of the machine’s rotor for each of the test methods. Experimental results show that the thermal behavior of the generator rotor is significantly different for each methodology. It is also shown in this paper that contemporary TIT practice requires an augmented test methodology.
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- Authors: Singh, A. Narain , Cronje, W. A. , Doorsamy, W.
- Date: 2017
- Subjects: Thermal instability testing , Turbogenerator , Infrared thermography
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/237711 , uj:24359 , Citation: Singh, A.N., Cronje, W.A. & Doorsamy, W. 2017. Investigation of thermal instability testing on synchronous generator rotors using an experimental direct mapping method.
- Description: Abstract: Utilities employ Thermal instability testing (TIT) for final acceptance testing after the construction and refurbishment of turbogenerator rotors. This type of testing is performed through two methodologies namely current injection and friction/windage in order to assess the thermal sensitivity of the machine’s rotor. Although there are distinct differences between the two methods, no apparent preference is shown by service providers/OEMS globally. There is also no definitive evidence or standards that offer a comparison of the two methods and suitability assessment thereof. The presented research investigates these two methods of TIT for a synchronous generator rotor. An experimental setup with infrared thermography is employed to investigate the thermal behaviour of the machine’s rotor for each of the test methods. Experimental results show that the thermal behavior of the generator rotor is significantly different for each methodology. It is also shown in this paper that contemporary TIT practice requires an augmented test methodology.
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On-line monitoring of metal-oxide surge arresters using improved equivalent model with evolutionary optimisation algorithm
- Authors: Doorsamy, W. , Bokoro, P.
- Date: 2017
- Subjects: Surge arresters , Resistive current extraction , Evolutionary optimisation
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/237719 , uj:24360 , Citation: Doorsamy, W. & Bokoro, P. 2017. On-line monitoring of metal-oxide surge arresters using improved equivalent model with evolutionary optimisation algorithm.
- Description: Abstract: A resistive-current extraction algorithm to assist with on-line monitoring of surge arresters is proposed in this paper. The algorithm is based on the improved equivalent model for surge arresters and combines evolutionary optimisation with the base-frequency approximating method. A genetic algorithm is used to obtain the optimal capacitance such that the phase shift between the base-components of the branch voltage and current is minimised thereby yielding a good approximation of the resistive current. In this paper, the algorithm is implemented and tested using Matlab/Simulink. Results indicate that the proposed algorithm is able to efficiently and accurately obtain the resistive component of the leakage current, using the improved equivalent model, under both ideal and distorted supply conditions.
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- Authors: Doorsamy, W. , Bokoro, P.
- Date: 2017
- Subjects: Surge arresters , Resistive current extraction , Evolutionary optimisation
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/237719 , uj:24360 , Citation: Doorsamy, W. & Bokoro, P. 2017. On-line monitoring of metal-oxide surge arresters using improved equivalent model with evolutionary optimisation algorithm.
- Description: Abstract: A resistive-current extraction algorithm to assist with on-line monitoring of surge arresters is proposed in this paper. The algorithm is based on the improved equivalent model for surge arresters and combines evolutionary optimisation with the base-frequency approximating method. A genetic algorithm is used to obtain the optimal capacitance such that the phase shift between the base-components of the branch voltage and current is minimised thereby yielding a good approximation of the resistive current. In this paper, the algorithm is implemented and tested using Matlab/Simulink. Results indicate that the proposed algorithm is able to efficiently and accurately obtain the resistive component of the leakage current, using the improved equivalent model, under both ideal and distorted supply conditions.
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A review of current signature analysis for condition monitoring of wound rotor induction generator and fault diagnosis techniques
- Authors: Swana, E.F. , Doorsamy, W.
- Date: 2018
- Subjects: Condition monitoring , Current signature analysis , Intelligent fault diagnosis
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/290446 , uj:31531 , Citation: Swana, E.F. & Doorsamy, W. 2018. A review of current signature analysis for condition monitoring of wound rotor induction generator and fault diagnosis techniques.
- Description: Abstract: The wound-rotor induction generator (WRIG) is commonly used for wind energy application. WRIGs have simple construction, are robust with high starting torque and low starting current. Additionally, WRIGs allow rotor resistance control and can be driven at variable speeds. Despite the relative robustness of WRIGs, these machines still experience a variety of faults in practice. This paper presents an in-depth review of condition monitoring techniques for three-phase wound-rotor induction generators. Various recent research applying current signature analysis as a method of detecting and diagnosing different types of faults on both the stator and rotor of this machine is reviewed. The application of probabilistic and artificial intelligence methods such as Bayesian classification, artificial neural networks and fuzzy logic used for fault diagnosis are also investigated.
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- Authors: Swana, E.F. , Doorsamy, W.
- Date: 2018
- Subjects: Condition monitoring , Current signature analysis , Intelligent fault diagnosis
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/290446 , uj:31531 , Citation: Swana, E.F. & Doorsamy, W. 2018. A review of current signature analysis for condition monitoring of wound rotor induction generator and fault diagnosis techniques.
- Description: Abstract: The wound-rotor induction generator (WRIG) is commonly used for wind energy application. WRIGs have simple construction, are robust with high starting torque and low starting current. Additionally, WRIGs allow rotor resistance control and can be driven at variable speeds. Despite the relative robustness of WRIGs, these machines still experience a variety of faults in practice. This paper presents an in-depth review of condition monitoring techniques for three-phase wound-rotor induction generators. Various recent research applying current signature analysis as a method of detecting and diagnosing different types of faults on both the stator and rotor of this machine is reviewed. The application of probabilistic and artificial intelligence methods such as Bayesian classification, artificial neural networks and fuzzy logic used for fault diagnosis are also investigated.
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A review of research on lightning protection for photovoltaic systems
- Holland, I., Doorsamy, W., Nixon, K.
- Authors: Holland, I. , Doorsamy, W. , Nixon, K.
- Date: 2018
- Subjects: Lightning protection , Photovoltaic systems , Risk assessment
- Language: English
- Type: Conference proceeding
- Identifier: http://hdl.handle.net/10210/290453 , uj:31532 , Citation: Holland, I., Doorsamy, W. & Nixon, K. 2018. A review of research on lightning protection for photovoltaic systems.
- Description: Abstract: The global PV market has grown extensively for small- to large-scale systems. Inevitably, this leads to the increased development of PV technology. PV systems are intrinsically exposed to weather phenomena. One such phenomenon is lightning. Direct and indirect effects of lightning can cause damage to PV systems. However, lightning protection for PV systems is often neglected and existing standards for protection are underdeveloped. In this paper, previous work is analysed to understand the interaction between lightning and PV systems and to ascertain gaps in current knowledge thereof. Investigation of these aspects will ultimately assist in understanding lightning risk, protection system design and aid in the development of lightning protection standards for PV in the renewable energy industry.
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- Authors: Holland, I. , Doorsamy, W. , Nixon, K.
- Date: 2018
- Subjects: Lightning protection , Photovoltaic systems , Risk assessment
- Language: English
- Type: Conference proceeding
- Identifier: http://hdl.handle.net/10210/290453 , uj:31532 , Citation: Holland, I., Doorsamy, W. & Nixon, K. 2018. A review of research on lightning protection for photovoltaic systems.
- Description: Abstract: The global PV market has grown extensively for small- to large-scale systems. Inevitably, this leads to the increased development of PV technology. PV systems are intrinsically exposed to weather phenomena. One such phenomenon is lightning. Direct and indirect effects of lightning can cause damage to PV systems. However, lightning protection for PV systems is often neglected and existing standards for protection are underdeveloped. In this paper, previous work is analysed to understand the interaction between lightning and PV systems and to ascertain gaps in current knowledge thereof. Investigation of these aspects will ultimately assist in understanding lightning risk, protection system design and aid in the development of lightning protection standards for PV in the renewable energy industry.
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Analysis of lightning surge effects on small-scale rooftop photovoltaic systems
- Holland, I., Doorsamy, W., Nixon, K.
- Authors: Holland, I. , Doorsamy, W. , Nixon, K.
- Date: 2018
- Subjects: Lightning protection , Modelling , Photovoltaic systems
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/274102 , uj:29227 , Citation: Holland, I., Doorsamy, W. & Nixon, K. 2018. Analysis of lightning surge effects on small-scale rooftop photovoltaic systems.
- Description: Abstract: Small-scale rooftop PV systems have become an attractive investment for small businesses and home owners. PV systems are inherently exposed to lightning phenomena and hence protection of the electrical system is required. In this paper, a simulation approach using MATLAB and Simulink is adopted to analyse the impacts of lightning induced effects on small-scale, rooftop, grid-connected PV systems. It is found that based on different coupling points, lightning surges could cause damage to the PV array, inverter as well as the connected load. The installation of surge protective devices could mitigate the potential damaging effects. In analysing the surge effects on the PV system, an understanding of the associated risk of damage to the PV system can be developed and hence the requirements for lightning protection of small-scale rooftop grid-connected PV systems can be comprehended.
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- Authors: Holland, I. , Doorsamy, W. , Nixon, K.
- Date: 2018
- Subjects: Lightning protection , Modelling , Photovoltaic systems
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/274102 , uj:29227 , Citation: Holland, I., Doorsamy, W. & Nixon, K. 2018. Analysis of lightning surge effects on small-scale rooftop photovoltaic systems.
- Description: Abstract: Small-scale rooftop PV systems have become an attractive investment for small businesses and home owners. PV systems are inherently exposed to lightning phenomena and hence protection of the electrical system is required. In this paper, a simulation approach using MATLAB and Simulink is adopted to analyse the impacts of lightning induced effects on small-scale, rooftop, grid-connected PV systems. It is found that based on different coupling points, lightning surges could cause damage to the PV array, inverter as well as the connected load. The installation of surge protective devices could mitigate the potential damaging effects. In analysing the surge effects on the PV system, an understanding of the associated risk of damage to the PV system can be developed and hence the requirements for lightning protection of small-scale rooftop grid-connected PV systems can be comprehended.
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Analytical condition monitoring system for liquid-immersed transformers
- Van Der Walt, F., Doorsamy, W.
- Authors: Van Der Walt, F. , Doorsamy, W.
- Date: 2018
- Subjects: Liquid immersed transformer , Condition monitoring system , IoT
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/276300 , uj:29563 , Citation: Van Der Walt, F. & Doorsamy, W. 2018. Analytical condition monitoring system for liquid-immersed transformers.
- Description: Abstract: Transformers form an integral part of the electrical power grid are widely employed in a variety of power-system applications inter alia power generation and distribution systems, and arc- and induction-furnace applications. Transformers are among the most expensive components in power systems but the protection and health requirements thereof are still catered for by traditional auxiliary protective devices and cooling control systems. This paper reports the development of an IoT-based condition monitoring system that offers advanced protection and control features. The condition monitoring system is intended to directly contribute to enhancing the lifespan of the transformer by detecting fault conditions at an early stage before catastrophic failure can occur and by ensuring that the quality of the transformer’s insulation is preserved for a greater period through improved cooling techniques.
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- Authors: Van Der Walt, F. , Doorsamy, W.
- Date: 2018
- Subjects: Liquid immersed transformer , Condition monitoring system , IoT
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/276300 , uj:29563 , Citation: Van Der Walt, F. & Doorsamy, W. 2018. Analytical condition monitoring system for liquid-immersed transformers.
- Description: Abstract: Transformers form an integral part of the electrical power grid are widely employed in a variety of power-system applications inter alia power generation and distribution systems, and arc- and induction-furnace applications. Transformers are among the most expensive components in power systems but the protection and health requirements thereof are still catered for by traditional auxiliary protective devices and cooling control systems. This paper reports the development of an IoT-based condition monitoring system that offers advanced protection and control features. The condition monitoring system is intended to directly contribute to enhancing the lifespan of the transformer by detecting fault conditions at an early stage before catastrophic failure can occur and by ensuring that the quality of the transformer’s insulation is preserved for a greater period through improved cooling techniques.
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Condition monitoring of metal-oxide surge arresters using leakage current signature analysis
- Authors: Doorsamy, W. , Bokoro, P.
- Date: 2018
- Subjects: Metal-oxide surge arrestors , Online condition monitoring , Leakage current signature
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/278893 , uj:29937 , Citation: Doorsamy, W. & Bokoro, P. 2018. Condition monitoring of metal-oxide surge arresters using leakage current signature analysis.
- Description: Abstract: Online condition assessment of surge arresters is necessary for early detection of problems and subsequent replacement of the device to avoid unplanned downtime and/or damage to the equipment being protected. The most common technique of monitoring and assessing the condition of the arrester is extraction of the resistive component of the leakage current. There are many drawbacks to this method arising from inaccuracies in the model-based approach and deficiencies in the understanding of the leakage current signal. This paper presents leakage current signature analysis (LCSA) as a method of assessing the condition of the surge arrester where the harmonics components of the current signal, extracted using Bayesian spectrum estimation, are used as indicators of degradation. An experimental methodology comprising measurement of the leakage current of arresters undergoing constant-stress accelerated degradation testing is employed. Results indicate that a consistent increase in the DC component of the leakage current signature in the case of degrading samples is the most likely indicator of condition.
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- Authors: Doorsamy, W. , Bokoro, P.
- Date: 2018
- Subjects: Metal-oxide surge arrestors , Online condition monitoring , Leakage current signature
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/278893 , uj:29937 , Citation: Doorsamy, W. & Bokoro, P. 2018. Condition monitoring of metal-oxide surge arresters using leakage current signature analysis.
- Description: Abstract: Online condition assessment of surge arresters is necessary for early detection of problems and subsequent replacement of the device to avoid unplanned downtime and/or damage to the equipment being protected. The most common technique of monitoring and assessing the condition of the arrester is extraction of the resistive component of the leakage current. There are many drawbacks to this method arising from inaccuracies in the model-based approach and deficiencies in the understanding of the leakage current signal. This paper presents leakage current signature analysis (LCSA) as a method of assessing the condition of the surge arrester where the harmonics components of the current signal, extracted using Bayesian spectrum estimation, are used as indicators of degradation. An experimental methodology comprising measurement of the leakage current of arresters undergoing constant-stress accelerated degradation testing is employed. Results indicate that a consistent increase in the DC component of the leakage current signature in the case of degrading samples is the most likely indicator of condition.
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Investigation of lightning surge effects on a grid-connected PV plant
- Authors: Bokoro, P. , Doorsamy, W.
- Date: 2018
- Subjects: Photovoltaic plant , Induced surges , Lightning protection
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/278891 , uj:29936 , Citation: Bokoro, P. & Doorsamy, W. 2018. Investigation of lightning surge effects on a grid-connected PV plant.
- Description: Abstract: This paper investigates the indirect effects of lightning on a medium-scale photovoltaic plant. The purpose of the investigation is to analyse the surge effects on the photovoltaic plant and interconnected systems in order to develop an understanding of the associated risk of damage to the plant and ascertain the requirements for lightning protection. The investigated plant consists of four photovoltaic arrays, each comprising 2500 modules connected in series-parallel configurations, with inverters and connection to the high voltage transmission grid via a system of parallel buses, insulated power cables and power transformers. The presented study makes use of the electro-magnetic transient program-restructured version (EMTP-RV) software platform to investigate induced effects of lightning on grid-connected PV systems and provide system designers with a means of analysing and mitigating lightning risk. Results obtained show significant risk associated to voltage rise of 7.4% on the DC side and 1.2 p.u on the AC side.
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- Authors: Bokoro, P. , Doorsamy, W.
- Date: 2018
- Subjects: Photovoltaic plant , Induced surges , Lightning protection
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/278891 , uj:29936 , Citation: Bokoro, P. & Doorsamy, W. 2018. Investigation of lightning surge effects on a grid-connected PV plant.
- Description: Abstract: This paper investigates the indirect effects of lightning on a medium-scale photovoltaic plant. The purpose of the investigation is to analyse the surge effects on the photovoltaic plant and interconnected systems in order to develop an understanding of the associated risk of damage to the plant and ascertain the requirements for lightning protection. The investigated plant consists of four photovoltaic arrays, each comprising 2500 modules connected in series-parallel configurations, with inverters and connection to the high voltage transmission grid via a system of parallel buses, insulated power cables and power transformers. The presented study makes use of the electro-magnetic transient program-restructured version (EMTP-RV) software platform to investigate induced effects of lightning on grid-connected PV systems and provide system designers with a means of analysing and mitigating lightning risk. Results obtained show significant risk associated to voltage rise of 7.4% on the DC side and 1.2 p.u on the AC side.
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Investigation of very fast-front transient overvoltages for selection and placement of surge arresters
- Oliveira, R., Bokoro, P., Doorsamy, W.
- Authors: Oliveira, R. , Bokoro, P. , Doorsamy, W.
- Date: 2018
- Subjects: Very fast-front transient , Voltage magnification , Surge arrester
- Language: English
- Type: Conference proceedings
- Identifier: http://ujcontent.uj.ac.za8080/10210/384178 , http://hdl.handle.net/10210/274101 , uj:29226 , Citation: Oliveira, R., Bokoro, P. & Doorsamy, W. 2018. Investigation of very fast-front transient overvoltages for selection and placement of surge arresters.
- Description: Abstract: An analysis of very fast front transient overvoltages, generated as a result of induced effects of lightning, across a photovoltaic plant is investigated. The EMTP-RV version 3.3 computer software platform is used to simulate surge voltage magnification. Selection and placement of surge arresters for effective protection of power transformers are conducted. Results show that selected arresters placed on bus 4 and coordinated with those placed on bus 5 and 3 ensure surge amplitude reduction of 33% on bus 4.
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- Authors: Oliveira, R. , Bokoro, P. , Doorsamy, W.
- Date: 2018
- Subjects: Very fast-front transient , Voltage magnification , Surge arrester
- Language: English
- Type: Conference proceedings
- Identifier: http://ujcontent.uj.ac.za8080/10210/384178 , http://hdl.handle.net/10210/274101 , uj:29226 , Citation: Oliveira, R., Bokoro, P. & Doorsamy, W. 2018. Investigation of very fast-front transient overvoltages for selection and placement of surge arresters.
- Description: Abstract: An analysis of very fast front transient overvoltages, generated as a result of induced effects of lightning, across a photovoltaic plant is investigated. The EMTP-RV version 3.3 computer software platform is used to simulate surge voltage magnification. Selection and placement of surge arresters for effective protection of power transformers are conducted. Results show that selected arresters placed on bus 4 and coordinated with those placed on bus 5 and 3 ensure surge amplitude reduction of 33% on bus 4.
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Lightning risk assessment of rooftop photovoltaic Systems : a case study approach
- Holland, I., Doorsamy, W., Nixon, K.
- Authors: Holland, I. , Doorsamy, W. , Nixon, K.
- Date: 2018
- Subjects: Lightning protection , Photovoltaic systems , Risk assessment framework
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/276307 , uj:29564 , Citation: Holland, I., Doorsamy, W. & Nixon, K. 2018. Lightning risk assessment of rooftop photovoltaic Systems : a case study approach.
- Description: Abstract: The growth of photovoltaic (PV) technology in a global context is evident due to a drop in costs. In Africa, there is potential for expansive growth of solar PV due to favourable climatological conditions. PV systems, due to their inherent exposure to the elements, are prone to damage caused by lightning. For small- to medium-scale rooftop PV systems in particular, there is currently no well-defined methodology for assessing risk of lightning damage and determining protection requirements. In this paper, a framework for risk assessment of rooftop PV systems is proposed. The framework is applied to two practical case studies. It is found that the larger a rooftop PV system is, the higher the contribution of the PV system to the overall risk of lightning damage to the structure. These findings will lead to the further development of PV standards where in both the African and global context, continuous knowledge production in this regard is necessary.
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- Authors: Holland, I. , Doorsamy, W. , Nixon, K.
- Date: 2018
- Subjects: Lightning protection , Photovoltaic systems , Risk assessment framework
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/276307 , uj:29564 , Citation: Holland, I., Doorsamy, W. & Nixon, K. 2018. Lightning risk assessment of rooftop photovoltaic Systems : a case study approach.
- Description: Abstract: The growth of photovoltaic (PV) technology in a global context is evident due to a drop in costs. In Africa, there is potential for expansive growth of solar PV due to favourable climatological conditions. PV systems, due to their inherent exposure to the elements, are prone to damage caused by lightning. For small- to medium-scale rooftop PV systems in particular, there is currently no well-defined methodology for assessing risk of lightning damage and determining protection requirements. In this paper, a framework for risk assessment of rooftop PV systems is proposed. The framework is applied to two practical case studies. It is found that the larger a rooftop PV system is, the higher the contribution of the PV system to the overall risk of lightning damage to the structure. These findings will lead to the further development of PV standards where in both the African and global context, continuous knowledge production in this regard is necessary.
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Thermal instability analysis of a synchronous generator rotor using direct mapping
- Narain Singh, A., Doorsamy, W., Cronje, W. A.
- Authors: Narain Singh, A. , Doorsamy, W. , Cronje, W. A.
- Date: 2018
- Subjects: Infrared thermography , Synchronous generator , Thermal instability testing
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/260770 , uj:27472 , Citation: Narain Singh, A., Doorsamy, W. & Cronje, W.A. 2018. Thermal instability analysis of a synchronous generator rotor using direct mapping.
- Description: Abstract: Abstract: This paper presents a direct and practical method for mapping the thermal behaviour of a synchronous generator. Since temperature variations can lead to rotor thermal instability which adversely affects the operation of the generating unit, a better understanding of this phenomenon is required. The two main methods of performing thermal instability testing - direct current injection and friction/windage - are found to be practiced internationally without preference. Infrared thermography is used here as a means of determining the thermal performance of the rotor under different testing scenarios. The experimental testing is conducted using a scaled setup of a balancing facility and a 600 MW generator rotor. The results obtained are presented in the form of surface temperature maps. The thermal distribution of the two different methods were found to differ substantially with the friction method exhibiting a uniform surface distribution while the current method exhibited areas of higher temperature concentration around the rotor pole faces.
- Full Text:
- Authors: Narain Singh, A. , Doorsamy, W. , Cronje, W. A.
- Date: 2018
- Subjects: Infrared thermography , Synchronous generator , Thermal instability testing
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/260770 , uj:27472 , Citation: Narain Singh, A., Doorsamy, W. & Cronje, W.A. 2018. Thermal instability analysis of a synchronous generator rotor using direct mapping.
- Description: Abstract: Abstract: This paper presents a direct and practical method for mapping the thermal behaviour of a synchronous generator. Since temperature variations can lead to rotor thermal instability which adversely affects the operation of the generating unit, a better understanding of this phenomenon is required. The two main methods of performing thermal instability testing - direct current injection and friction/windage - are found to be practiced internationally without preference. Infrared thermography is used here as a means of determining the thermal performance of the rotor under different testing scenarios. The experimental testing is conducted using a scaled setup of a balancing facility and a 600 MW generator rotor. The results obtained are presented in the form of surface temperature maps. The thermal distribution of the two different methods were found to differ substantially with the friction method exhibiting a uniform surface distribution while the current method exhibited areas of higher temperature concentration around the rotor pole faces.
- Full Text:
Thermographical analysis of turbo-generator rotor
- Singh, A.N., Doorsamy, W., Cronje, W.
- Authors: Singh, A.N. , Doorsamy, W. , Cronje, W.
- Date: 2018
- Subjects: Turbo-generator rotor , Thermographical analysis , Thermal instability testing
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/276162 , uj:29538 , Citation: Singh, A.N., Doorsamy, W. & Cronje, W. 2018. Thermographical analysis of turbo-generator rotor.
- Description: Abstract: Refurbished or newly constructed utility-scale turbo-generator rotors requires stringent acceptance testing before commissioning and subsequent operation thereof. Conventional methods of testing are inadequate in detecting and locating thermally induced problems. This paper presents a thermographic method for carrying out thermal instability testing of generator rotors. An experimental setup is used to map the thermal distribution of the generator rotor. Implementation and testing of the method is carried out in a laboratory setting using a down-scaled turbo-generator rotor.
- Full Text:
- Authors: Singh, A.N. , Doorsamy, W. , Cronje, W.
- Date: 2018
- Subjects: Turbo-generator rotor , Thermographical analysis , Thermal instability testing
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/276162 , uj:29538 , Citation: Singh, A.N., Doorsamy, W. & Cronje, W. 2018. Thermographical analysis of turbo-generator rotor.
- Description: Abstract: Refurbished or newly constructed utility-scale turbo-generator rotors requires stringent acceptance testing before commissioning and subsequent operation thereof. Conventional methods of testing are inadequate in detecting and locating thermally induced problems. This paper presents a thermographic method for carrying out thermal instability testing of generator rotors. An experimental setup is used to map the thermal distribution of the generator rotor. Implementation and testing of the method is carried out in a laboratory setting using a down-scaled turbo-generator rotor.
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A study into intelligent Neutral Section fault monitoring system on the Coal line using wireless sensor networks
- Phala, K. M., Doorsamy, W., Paul, B. S.
- Authors: Phala, K. M. , Doorsamy, W. , Paul, B. S.
- Date: 2019
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/400866 , uj:33476 , Citation: Phala, K.M., Doorsamy, W. & Paul, B.S. 2019.
- Description: Abstract: Machine learning a subdivision of artificial intelligence which is popular nowadays particularly where large amounts of data are to be evaluated unsupervised by applying algorithms thereby requiring less human effort to process the measurements. This paper presents an intelligent fault monitoring on the overhead wires using wireless sensor network (WSN). The current method used to monitor failures requires both foot patrols and vehicle measurements using cameras, however these methods are both labour and time intensive in preparing and analysing the data from the inspections. An intelligent method is proposed to reduce the amount of time spent on labour intensive inspections through data aggregation and machine learning. Ma-chine learning offers additional flexibility for identifying the type of the faults, finding otherwise hidden pat-terns and grouping instances of events accordingly based on similarities. WSN will convey the measured data to the cloud via the router for computation thereby providing notifications in real-time and also the data can be viewed anywhere by the operator. K-means clustering algorithm will then be applied later using sensors data via Matlab/Simulink.
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- Authors: Phala, K. M. , Doorsamy, W. , Paul, B. S.
- Date: 2019
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/400866 , uj:33476 , Citation: Phala, K.M., Doorsamy, W. & Paul, B.S. 2019.
- Description: Abstract: Machine learning a subdivision of artificial intelligence which is popular nowadays particularly where large amounts of data are to be evaluated unsupervised by applying algorithms thereby requiring less human effort to process the measurements. This paper presents an intelligent fault monitoring on the overhead wires using wireless sensor network (WSN). The current method used to monitor failures requires both foot patrols and vehicle measurements using cameras, however these methods are both labour and time intensive in preparing and analysing the data from the inspections. An intelligent method is proposed to reduce the amount of time spent on labour intensive inspections through data aggregation and machine learning. Ma-chine learning offers additional flexibility for identifying the type of the faults, finding otherwise hidden pat-terns and grouping instances of events accordingly based on similarities. WSN will convey the measured data to the cloud via the router for computation thereby providing notifications in real-time and also the data can be viewed anywhere by the operator. K-means clustering algorithm will then be applied later using sensors data via Matlab/Simulink.
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An intelligent IoT-based health monitoring system
- Malapane, T., Doorsamy, W., Paul, B. S.
- Authors: Malapane, T. , Doorsamy, W. , Paul, B. S.
- Date: 2020
- Subjects: Internet of Things (IoT) , Wireless Sensor networks (WSN) , Health monitoring
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/453223 , uj:40005 , Citation: Malapane, T., Doorsamy, W. & Paul, B.S. 2020. An intelligent IoT-based health monitoring system.
- Description: Abstract: There is a growing interest globally in the Internet of Things (IoT) paradigm and the use of wireless sensors networks (WSN) in intelligent healthcare facilities. An intelligent healthcare monitoring system - based on IoT and WSN – intended to provide real-time monitoring of patients is presented. The system monitors and tracks different vital signs of patients in healthcare facilities and automatically detects anomalous conditions. In this paper, the design, implementation, preliminary testing and analysis of the system are presented. The system architecture is discussed, including the sensing and communications components. The intelligent algorithm – which employs fuzzy logic – for detection of anomalous conditions is presented together with experimental test results thereof.
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- Authors: Malapane, T. , Doorsamy, W. , Paul, B. S.
- Date: 2020
- Subjects: Internet of Things (IoT) , Wireless Sensor networks (WSN) , Health monitoring
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/453223 , uj:40005 , Citation: Malapane, T., Doorsamy, W. & Paul, B.S. 2020. An intelligent IoT-based health monitoring system.
- Description: Abstract: There is a growing interest globally in the Internet of Things (IoT) paradigm and the use of wireless sensors networks (WSN) in intelligent healthcare facilities. An intelligent healthcare monitoring system - based on IoT and WSN – intended to provide real-time monitoring of patients is presented. The system monitors and tracks different vital signs of patients in healthcare facilities and automatically detects anomalous conditions. In this paper, the design, implementation, preliminary testing and analysis of the system are presented. The system architecture is discussed, including the sensing and communications components. The intelligent algorithm – which employs fuzzy logic – for detection of anomalous conditions is presented together with experimental test results thereof.
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Towards smart teaching and learning : a study in a South African institution of higher learning
- Bokoro, P., Paul, B., Doorsamy, W.
- Authors: Bokoro, P. , Paul, B. , Doorsamy, W.
- Date: 2020
- Subjects: Smart phones , Tablets , University students
- Language: English
- Type: Conference Proceedings
- Identifier: http://hdl.handle.net/10210/465289 , uj:41602 , Citation: Bokoro, P. Paul, B. & Doorsamy, W. 2020. Towards smart teaching and learning : a study in a South African institution of higher learning. , DOI: 10.1109/ISIE.2019.8781425
- Description: Abstract: This study analyses the responses obtained from a survey conducted among three thousand four hundred and ninety seven students of a South African institution of higher learning. The interviews reflected in the survey questionnaire are sought to have an insight into the usage of smart phones, tablets and other electronic devices by students for teaching and learning purposes. Results obtained showed 64.1% of University students consulted in this survey perceived the use of smart devices to be from very important to absolutely essential, which may compel institutions of higher learning to think of fresh interventions pertaining to the use of smart devices for effective teaching and learning.
- Full Text:
- Authors: Bokoro, P. , Paul, B. , Doorsamy, W.
- Date: 2020
- Subjects: Smart phones , Tablets , University students
- Language: English
- Type: Conference Proceedings
- Identifier: http://hdl.handle.net/10210/465289 , uj:41602 , Citation: Bokoro, P. Paul, B. & Doorsamy, W. 2020. Towards smart teaching and learning : a study in a South African institution of higher learning. , DOI: 10.1109/ISIE.2019.8781425
- Description: Abstract: This study analyses the responses obtained from a survey conducted among three thousand four hundred and ninety seven students of a South African institution of higher learning. The interviews reflected in the survey questionnaire are sought to have an insight into the usage of smart phones, tablets and other electronic devices by students for teaching and learning purposes. Results obtained showed 64.1% of University students consulted in this survey perceived the use of smart devices to be from very important to absolutely essential, which may compel institutions of higher learning to think of fresh interventions pertaining to the use of smart devices for effective teaching and learning.
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On the use of Machine Learning for Soil Condition Monitoring
- Rameshar, V., Doorsamy, W., Paul, Babu Sena
- Authors: Rameshar, V. , Doorsamy, W. , Paul, Babu Sena
- Date: 2021
- Subjects: Soil Condition , Agriculture , Data Science
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/495390 , uj:45020 , Citation: Rameshar, V., Doorsamy, W., Paul, B.S., 2021. On the use of Machine Learning for Soil Condition Monitoring. , DOI: 10.1007/978-981-16-6332-1_32
- Description: Abstract: Please refer to full text to view abstract
- Full Text:
- Authors: Rameshar, V. , Doorsamy, W. , Paul, Babu Sena
- Date: 2021
- Subjects: Soil Condition , Agriculture , Data Science
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/495390 , uj:45020 , Citation: Rameshar, V., Doorsamy, W., Paul, B.S., 2021. On the use of Machine Learning for Soil Condition Monitoring. , DOI: 10.1007/978-981-16-6332-1_32
- Description: Abstract: Please refer to full text to view abstract
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