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A new fuzzy logic approach for consistent interpretation of dissolved gas-in-oil analysis

  • Authors: Abu-Siada, Ahmed , Hmood, Sdood , Islam, Syed
  • Date: 2013
  • Type: Text , Journal article
  • Relation: IEEE Transactions on Dielectrics and Electrical Insulation Vol. 20, no. 6 (2013), p. 2343-2349
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  • Description: Dissolved gas analysis (DGA) of transformer oil is one of the most effective power transformer condition monitoring tools. There are many interpretation techniques for DGA results however all these techniques rely on personnel experience more than analytical formulation. As a result, various interpretation techniques do not necessarily lead to the same conclusion for the same oil sample. Furthermore, significant number of DGA results fall outside the proposed codes of the current based-ratio interpretation techniques and cannot be diagnosed by these methods. Moreover, ratio methods fail to diagnose multiple fault conditions due to the mixing up of produced gases. To overcome these limitations, this paper introduces a new fuzzy logic approach to reduce dependency on expert personnel and to aid in standardizing DGA interpretation techniques. The approach relies on incorporating all existing DGA interpretation techniques into one expert model. DGA results of 2000 oil samples that were collected from different transformers of different rating and different life span are used to establish the model. Traditional DGA interpretation techniques are used to analyze the collected DGA results to evaluate the consistency and accuracy of each interpretation technique. Results of this analysis were then used to develop the proposed fuzzy logic model.

A review on chemical diagnosis techniques for transformer paper insulation degradation

A three dimensional imaging-based framework for planning maxillomandibular advancement surgery for the treatment of obstructive sleep apnoea

  • Authors: Islam, Syed , Goonewardene, Mithran , Bennamoun, Mohammed , Lucey, Anthony , Farella, Mauro , Abduo, Jaafar , Cisonni, Julien
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 2013 4th World Congress on Software Engineering, WCSE 2013; Hong Kong, China; 3rd-4th December 2013 p. 301-306
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  • Description: Obstructive Sleep Apnoea (OSA), a sleeping disorder, is a serious health issue with significant public health implications. Due to the interrupted sleep, OSA patients suffer with excessive day-time sleepiness, fatigue and other health complexities that lead to on-road and work-related accidents and incur billions of dollars per year. Traditionally, treatment of OSA begins with nasal continuous positive airway pressure (CPAP). Alternatively, Mandibular Repositioning Appliances or surgical interventions can be used. Although Maxillomandibular Advancement (MMA) surgery is often advised as the last line of treatment due to the expense and significant changes in the facial appearance, it is the only permanent solution to OSA with a definitive outcome especially for the patients with significant facial deformation or anomalies. In this article, three dimensional (3D) image-guided predictive algorithms are proposed to improve the treatment planning and overall outcome of the MMA surgery. 3D analysis of the facial surface data and Computational Biomechanics-based 3D modelling of airway segmented from Cone Beam Computed Tomography (CBCT) data are proposed to predict the required physiological changes to ensure optimal air-flow through the airway. Moreover, 3D Computer Graphics-based techniques are proposed to visualise and demonstrate the expected facial outcomes to inform patients and surgeons prior to this non-reversible surgery.

Analysis of IEC 61850 for a Reliable Communication System between Substations

  • Authors: Yang, Xin , Das, Narottam , Islam, Syed
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 2013 Australasian Universities Power Engineering Conference, AUPEC 2013; Hobart, Australia; 29th September-3rd October 2013 p. 1-6
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  • Description: IEC 61850 Standard was introduced to address the challenge presented by existence of the multiple protocols in substation communications, which include many proprietary protocols; and to address the challenge introduced by legacy complicated substation from both cost and complicity. In this paper, the simulation results of different types of IEC 61850 network system configurations using OPNET Modeler simulation software were presented and the influence on data rate and delay characteristics of these system configurations were evaluated. The simulated results confirm that the ring configured system suitable for higher loading characteristics and higher system reliability.

Analysis of incident light angles on nan-grating structure for minimizing reflection losses in GaAs solar cells

  • Authors: Das, Narottam , Charoenpitaks, Korawat , Islam, Syed
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 2013 Australasian Universities Power Engineering Conference, AUPEC 2013; Hobart, Australia; 29th September-3rd October 2013 p. 1-6
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  • Description: Subwavelength grating (SWG) structures make an excellent alternative antireflective (AR) coating due to its capacity to reduce the reflection losses in GaAs solar cells. The SWG structures allow the gradual change in refractive index that confirms an excellent AR coating and the light trapping properties when compare with planar thin film structures. Finite-difference time domain (FDTD) method is used to simulate the reflection losses of the SWG structure in GaAs solar cells. The FDTD simulation results show that the slightly change of incident angle affect the reflection losses of all nano-grating structure. The simulation results also confirmed that the reflection loss of nano-grating structure maintained optimum within ~±5° of incident angle tolerance for the grating height over 300-nm for minimizing the reflection losses in GaAs solar cells.

Assessment of distributed generation capacity mixture for hybrid benefits

  • Authors: Jayaweera, Dilan , Islam, Syed , Neduvelil, Sandeep
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 22nd International Conference and Exhibition on Electricity Distribution, CIRED 2013; Stockholm, Sweden; 10th-13th June 2013 Vol. 2013, p. 1-4
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  • Description: The distributed generation (DG) mixture in an active distribution network can provide different levels of network benefits and benefits external to the network. This paper investigates this problem in detail and proposes an approach to assess the DG mixture for hybrid benefits through the sequential simulation of optimized samples. A case study is performed incorporating Wind and PV generation as intermittent DG, diesels, their life-cycle costs (LCCs), and contribution to greenhouse-gas (GHG) abatement. Results suggest that specific operating conditions in a network can dominate the DG mixture and deliver the combined benefits. Wind and diesel hybrid operation can be the most beneficial DG mixture in an active distribution network compared to any other DG combination with current costing structure.

Digital implementation of a fault emulator for transient study of power transformers used in grid connection of wind farms

  • Authors: Mesbah, Mohsen , Moses, Paul , Islam, Syed , Masoum, Mohammad
  • Date: 2013
  • Type: Text , Journal article
  • Relation: IEEE Transactions on Sustainable Energy Vol. 5, no. 2 (2013), p. 646-654
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  • Description: A real-time digital hardware simulation tool is developed to study the transient performance of three-phase power transformers used in grid connected wind farms. Using vector-based analysis for generating different voltage components, the fault simulator is capable of emulating a multitude of grid connection disturbances such as voltage sag, voltage swell, voltage unbalance, harmonics, dc-bias, and phase jump. This enables realistic real-time evaluation of power system faults and their impacts on critical components such as the interconnection transformers used in wind farms. In this paper, the proposed fault simulator has been employed to conduct an experimental study of the effects of balanced and unbalanced fault conditions on a three-phase three-leg power transformer. The transient current response of three-phase transformers subject to symmetrical/unsymmetrical faults is a complex issue due to the influences of multiple flux paths interacting within the core as well as ferromagnetic nonlinearities and core-structure asymmetry. So far, existing studies of this behavior have been restricted to computer modeling simulations with limited experimental work performed. The main contributions of this paper are to 1) present a new versatile fault simulator using a space vector modulation control approach to generate typical grid disturbances, and 2) apply the fault emulator to study the transient behavior of three-phase power transformers under various fault conditions common to wind farm interconnection transformers. The paper also discusses design, component selection, digital signal processing (DSP), and implementation aspects.

Effect of conducting materials on UV-Vis spectral response characteristics

  • Authors: Abu Bakar, Norazhar , Abu-Siada, Ahmed , Das, Narottam , Islam, Syed
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Universal Journal of Electrical and Electronic Engineering Vol. 1, no. 3 (2013), p. 81-86
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  • Description: Spectroscopic analysis is recently being employed to measure furan concentration in transformer oil. Light absorbance and spectral bandwidth are used as indicators to estimate furan concentration level in transformer oil. However, the possibility of dust and other conducting materials that might exist in transformer oil sample need to be considered as it may influence the spectroscopic performance. In this paper, series of tests are carried out to investigate the impact of dust on the transformer oil spectral response characteristics. Oil sample with various furan concentrations along with certain amount of copper powder are examined. Experimental results show that the spectral response characteristics only affected by dust at the beginning of mix process. However, the characteristic returns to the original one within a few minutes.

Estimation of induction motor parameters using hybrid algorithms for power system dynamic studies

Image processing-based on-line technique to detect power transformer winding faults

  • Authors: Abu-Siada, Ahmed , Islam, Syed
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 39th Annual Conference of the IEEE Industrial Electronics Society, IECON 2013; Vienna, Austria; 10th-14th November 2013 p. 1-6
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  • Description: Frequency Response Analysis (FRA) has been growing in popularity in recent times as a tool to detect mechanical deformation within power transformers. To conduct the test, the transformer has to be taken out of service which may cause interruption to the electricity grid. Moreover, because FRA relies on graphical analysis, it calls for an expert person to analyse the results as so far, there is no standard code for FRA interpretation worldwide. In this paper an online technique is introduced to detect the internal faults within a power transformer by constructing the voltage-current (V-I) locus diagram to provide a current state of the transformer health condition. The technique does not call for any special equipment as it uses the existing metering devices attached to any power transformer to monitor the input voltage, output voltage and the input current at the power frequency and hence online monitoring can be realised. Various types of faults have been simulated to assess its impact on the proposed locus. A Matlab code based on digital image processing is developed to calculate any deviation of the V-I locus with respect to the reference one and to identify the type of fault.

Impact of axial displacement on power transformer FRA signature

  • Authors: Hashemnia, Naser , Abu-Siada, Ahmed , Islam, Syed
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 2013 IEEE Power and Energy Society General Meeting, PES 2013; Vancouver, Canada; 21st-25th July 2013 p. 1-4
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  • Description: Frequency response analysis (FRA) is gaining global popularity in detecting power transformer winding movement due to the development of FRA test equipment. However, because FRA relies on graphical analysis, interpretation of its signatures is still a very specialized area that calls for skillful personnel to detect the sort and likely place of the fault as so far, there is no reliable standard code for FRA signature classification and quantification. This paper investigates the impact of transformer winding axial displacement on its FRA signature as a step toward the establishment of reliable codes for FRA interpretation. In this context a detailed model for a singlephase transformer is simulated using 3D finite element analysis to emulate a close to real transformer. The impact of axial displacement on the electrical distributed parameters model that are calculated based on the transformer physical dimension is examined to investigate how model’s parameters including inductance and capacitance matrices change when axial displacement takes place within a power transformer.

Impact of buckling deformation on the FRA signature of power transformer

  • Authors: Amini, Arman , Das, Narottam , Islam, Syed
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 2013 Australasian Universities Power Engineering Conference, AUPEC 2013; Hobart, Australia; 29th September-3rd October 2013 p. 1-4
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  • Description: Power transformer is an important asset within the electrical power system network. Frequency Response Analysis (FRA) has been developing in popularity in recent years as a tool to detect mechanical deformation of power transformers winding. Since the FRA has been relying on graphical analysis, it calls for an expert person to analyze the results to detect the type of the fault and its location. There are no reliable guidelines for FRA signature in the event that a failure occurs in service and the impact can be far reaching. The concept of FRA has been successfully used as a diagnostic technique to detect the winding deformation, core and clamping structure for the power transformers. This paper investigated the impact of the forced and free winding buckling based on the variation of the electrical parameters to show how these faults vary the FRA signature.

Impact of conducting materials on furan-spectral correlation of transformer oil

  • Authors: Das, Narottam , Abu-Siada, Ahmed , Islam, Syed
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 2013 Australasian Universities Power Engineering Conference, AUPEC 2013; Hobart, Australia; 29th September-3rd October 2013 p. 1-4
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  • Description: This paper investigates the impact of conducting materials on the correlation of furan concentration in transformer oil and its spectral response characteristics. The presence of furan derivatives in aged-transformer oil has been one of the key indicators for solid dielectric deterioration. Identification and quantification of furan derivatives are currently performed using high performance liquid chromatography or gas chromatography-mass spectrometry based on ASTM D5837 standard. Although these techniques are well established, they need an expert personal to conduct the test and to analyse its results. Moreover, the test is relatively expensive and the analysis of oil sample may take days as most utilities sending transformer oil samples to external laboratories to be tested. Recently, it has been proven that furan concentration in transformer oil has a strong correlation to the oil spectral response. This paper is to validate this finding and to investigate the impact of conducting materials within transformer oil on this correlation. In this context, extensive experimental tests are conducted to assess the impact of various concentration of conducting materials (e.g., copper dust) dissolved in transformer oil samples of different furan contents on its absorption and transmission spectra. The measured experimental results show that, the impact of such small amount ofdissolved conducting materials on the oil spectral response is minimal.

Impact of PEV charging and rooftop PV penetration on distribution transformer life

  • Authors: Geiles, Tristan , Islam, Syed
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 2013 IEEE Power and Energy Society General Meeting, PES 2013; Vancouver, Canada; 21st-25th July 2013 p. 1-5
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  • Description: As Plug-in Electric Vehicles (PEVs) take a greater share in the automobile market; their penetration levels may bring potential challenges to the electric utility especially at the distribution level. However with increasing penetration of rooftop photovoltaics (PVs) in residential networks, one major benefit is for rooftop PV units to counterbalance PEV loads, and hence normalize the useful life of distribution transformers. This effect has yet to be quantified in existing literature. This paper presents a study that evaluates the impact of PEV charging imposed on distribution transformer life, in the presence of rooftop PV units. The proposed methodology in this paper is applied to a real distribution system with various scenarios, including diversified PV and PEV penetration levels. Through deterministic and stochastic simulation, results reveal that distribution transformer increased loss-of-life (LOL), as a function of PEV charging, can be negated through the integration of distributed rooftop PV installation. © 2013 IEEE.

Photovoltaic cell modeling for maximum power point tracking using MATLAB/Simulink to improve the conversion efficiency

  • Authors: Das, Narottam , Wongsodihardjo, Hendy , Islam, Syed
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 2013 IEEE Power and Energy Society General Meeting, PES 2013; Vancouver, Canada; 21st-25th July 2013 p. 1-5
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  • Description: This paper focuses on the behavior of maximum power point tracking (MPPT) on photovoltaic (PV) cell systems using MATLAB/Simulink software. The PV cells can offer better simulation results when a double-exponential type, i.e., double-diode model is used. The reason, it is more accurate with the real testing condition even though the efficiency is a bit less. This confirms that theoretical single-diode model still require more improvements. In addition, multijunction solar cell also investigated to obtain its maximum performance compared with the conventional silicon PV cell. The obtained results show that the tandem (or multijunction) cell can provide almost 3-times maximum power compared to the conventional PV cell. Therefore, the multijunction/ tandem PV cells can produce higher power throughout the sunny day due to the higher MPPT capacity. Furthermore, perturb and observe method seems to be very useful because of its simplicity despite the unresolved algorithm for different methods, such as constant voltage tracking technique.

Power transformer winding fault analysis using transfer function

  • Authors: Kalpana, Patel , Das, Narottam , Abu Siada, Ahmed , Islam, Syed
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 2013 Australasian Universities Power Engineering Conference, AUPEC 2013; Hobart, Australia; 29th September-3rd October 2013 p. 1-3
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  • Description: Condition monitoring of power transformers is essential to maintain the reliability of electricity grid. Frequency response analysis (FRA) is a useful tool for the detection of incipient mechanical faults within power transformers. There are various methods of evaluating the frequency spectrum for fault classification and quantification. This paper presents a useful method to detect and to identify various winding faults of a power transformer based on its FRA signature. Simulation results show that location of resonance frequencies which are the key parameters in identifying various winding deformations are uniquely altered due to different faults.

Process-to-bay level peer-to-peer network delay in IEC 61850 substation communication systems

  • Authors: Das, Narottam , Aung, Tin Tun , Islam, Syed
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 2013 Australasian Universities Power Engineering Conference, AUPEC 2013; Hobart, Australia; 29th September-3rd October 2013 p. 1-6
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  • Description: This paper presents the application of IEC 61850 protocol in electrical power engineering industry for data communication systems between substations. This IEC 61850 protocol presents new challenges for real-time communication performance between Intelligent Electronic Devices (IEDs) within substation because of the Generic Object Oriented Substation Event (GOOSE) messages. The analyses of substation Ethernet communication delay, its impact factors, various methods and different network topologies which can improve the real-time performance are discussed. For basic analysis of data flow within a substation, the Optimized Network Engineering Tool (OPNET) software is used. The process to bay level network simulation model is performed by using the OPNET software. The Ethernet delay performance of the process to bay level network simulation results are analyzed which is based on switched, shared Ethernet network or Peer to Peer network.

Security enhancement with nodal criticality based integration of PHEV micro grids

  • Authors: Jayaweera, Dilan , Islam, Syed
  • Date: 2013
  • Type: Text , Conference proceedings , Conference paper
  • Relation: 2013 Australasian Universities Power Engineering Conference, AUPEC 2013; Hobart, Australia; 29th September-3rd October 2013 p. 1-6
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  • Description: Modern distribution networks are increasingly vulnerable to disturbances and improving the security of supply to customers are complex and challenging with the traditional approach. This paper presents a new approach to enhance the security of power supply in an active distribution network by integrating PHEV (Plug-in Hybrid Electric Vehicle) based micro grids on the basis of the nodal criticality. The nodal criticality is assessed by integrating operational uncertainties of events into samples of Monte Carlo simulation and classifying load interruptions on the basis of their magnitudes and frequencies. Criticality of the system stress that results nodal loads shedding is classified into arrays of clusters based on the magnitudes of interrupted loads at samples. The critical clusters that represent largest disturbances to the respective nodal loads are served with PHEV micro grids. Case studies are performed, and the results suggest that the security of distribution networks can be significantly improved with the proposed approach.

Two-stage approach for the assessment of distributed generation capacity mixture in active distribution networks

  • Authors: Jayaweera, Dilan , Islam, Syed , Neduvelil, Sandeep
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Journal of Renewable and Sustainable Energy Vol. 5, no. 5 (2013), p.
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  • Description: Distribution networks are limited with spare capacities to integrate increased volumes of distributed generation (DG). Network constraints and congestion, dynamic thermal limits, intermittent outputs, and the need for reduction in greenhouse gas emission increase the complexity of capturing optimal DG mixture that can safely permit the optimal operation. This paper investigates this problem in detail and proposes a two-stage approach for the quantification of optimal DG capacity mixture in an active distribution network. The approach is aimed at operational planning and takes into account dynamic thermal limits, network internal benefit, and network external benefit and then optimizes samples of DG mixtures through sequential simulation. A case study is performed incorporating wind and photovoltaic generation as intermittent DG and diesel units as standing reserve units. Results suggest that specific operating conditions in an active distribution network can dominate the optimal DG mixture. Wind and diesel hybrid operation can be the most beneficial DG mixture compared to any other DG combination. Dynamic thermal limits of assets can potentially control the type of DG of the optimized mixture.

Understanding power transformer frequency response analysis signatures

  • Authors: Abu-Siada, Ahmed , Hashemnia, Naser , Islam, Syed , Masoum, Mohammad
  • Date: 2013
  • Type: Text , Journal article
  • Relation: IEEE Electrical Insulation Magazine Vol. 29, no. 3 (2013), p. 48-56
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  • Description: This paper presents a comprehensive analysis of the effects of various faults on the FRA signatures of a transformer simulated by a high-frequency model. The faults were simulated through changes in the values of some of the electrical components in the model. It was found that radial displacement of a winding alters the FRA signature over the entire frequency range (10 Hz-1 MHz), whereas changes due to axial displacement occur only at frequencies above 200 kHz. A Table listing various transformer faults and the associated changes in the FRA signature was compiled and could be used in the formulation of standard codes for power transformer FRA signature interpretation.