This document presents a mathematical model for assessing the reliability of 250-5000 watt pulse width modulation (PWM) power inverters in Nigeria. The part stress method is used to predict reliability by considering factors like environmental conditions, power supply quality, and human factors. Reliability data on PWM inverters in Sokoto, Nigeria is analyzed and compared to the expected reliability in China where they were designed. The results show lower reliability for the inverters in Nigeria due to differences in the operating environment compared to China. Key equations for mean time between failures and failure rate are presented to calculate reliability metrics.
Power Quality Improvement using DVR (Dynamic Voltage Restorer) Under Various ...IRJET Journal
1) The document discusses a Dynamic Voltage Restorer (DVR) which is used to improve power quality by mitigating voltage sags and swells.
2) A DVR injects voltage into the distribution system through a series transformer to keep the load voltage constant during faults.
3) It describes the components of a DVR including an energy storage device, voltage source inverter, series injection transformer, and control unit with PI controller for PWM switching of the inverter.
4) The paper presents simulation results of a DVR's performance under different fault conditions to demonstrate its effectiveness in improving voltage quality.
This document summarizes a research paper that models and simulates a Dynamic Voltage Restorer (DVR) using MATLAB to improve power quality in a distribution system. It describes the components and operating principles of a DVR, including different compensation techniques. The document then outlines the simulation setup in MATLAB/Simulink that tests a DVR under various fault conditions. The results show that the DVR is able to rapidly inject compensating voltages to maintain a balanced and constant load voltage during faults. The paper concludes the DVR is effective for mitigating voltage sags while having a simple control scheme and fast response.
STATE OF THE ART: DYNAMIC VOLTAGE RESTORER FOR POWER QUALITY IMPROVEMENTecij
Improved and controlled power quality is one of the essential and fundamental need in any power driven industry for optimum utilization of resources. However critical problems in power quality have been recognized such as sags, swells, harmonic distortions and other interruptions. Out of these sags and swells
are predominantly found and have severe impact on the electrical devices or electrical machines and therefore needs to be compensated at an earliest to ensure any mal-operation or failure. To crack these problems custom power devices are used like unified power-quality conditioner (UPQC), distributionSTATCOM (DSTATCOM) and dynamic voltage restorer (DVR). The DVR is a one of the custom power device used for the compensation of voltage sag and swell with an advantage of active/reactive power control. A major volume of literature reported in past several years on different configurations of DVR and different control technique used in it. In context of this a detailed review on DVR has been presented with different possible power circuit topologies and control techniques available to reconcile these power quality issues. This review article will contribute in better selection of control strategy and power circuit for optimum performance of DVR for a particular requirement. Also it presents a very helpful investigation for the researcher in this field.
This document provides a review of Dynamic Voltage Restorer (DVR) systems used for compensating voltage sags in power distribution systems. It discusses that voltage sags are a serious power quality problem and DVR is an efficient custom power device to mitigate this issue. The document reviews the components, configurations, operating modes and control strategies of DVR systems. It describes that DVR injects voltage into the distribution system using a voltage source converter to regulate the load voltage during sags or disturbances.
This document provides an overview and introduction to connecting generators to power systems in Western Australia. It discusses key power system components such as generators, transformers, transmission and distribution lines, and substations. It also covers topics such as different generator and energy source types, power quality issues, faults, earthing, protection, operation, generation/load balance, and governance. The intended purpose is to help generator proponents understand the technical requirements for connecting to the grid, while noting that engineering expertise is required to fully understand all aspects of the complex power system.
Analysis of Total Harmonic Distortion (THD) Level of Distribution Network Usi...IJERA Editor
The modern sensitive, Non-linear and sophisticated load affects the power quality. Dynamic Voltage Restorer (DVR) provides the fast, flexible and efficient solution to improve the power quality for such distribution network [8]. The active power, reactive power, variation of voltage, flicker, harmonics, and electrical behavior of switching operations are the major source of affecting power quality. The intent of this paper is to demonstrate the improvements obtained with DVR in power system network using MATLAB/SIMULINK. In this paper, an overview of the DVR, its functions, configurations, components, control strategies are reviewed. The Simulation results are presented to illustrate the performance of DVR in Total Harmonic Distortion (THD). The results showed clearly the performance of using DVR in improving THD level.
Mitigation of Power Quality Problems Using Custom Power Devices: A Reviewijeei-iaes
Electrical power quality (EPQ) in distribution systems is a critical issue for commercial, industrial and residential applications. The new concept of advanced power electronic based Custom Power Devices (CPDs) mainly distributed static synchronous compensator (D-STATCOM), dynamic voltage restorer (DVR) and unified power quality conditioner (UPQC) have been developed due to lacking the performance of traditional compensating devices to minimize power quality disturbances. This paper presents a comprehensive review on D-STATCOM, DVR and UPQC to solve the electrical power quality problems of the distribution networks. This is intended to present a broad overview of the various possible DSTATCOM, DVR and UPQC configurations for single-phase (two wire) and three-phase (three-wire and four-wire) networks and control strategies for the compensation of various power quality disturbances. Apart from this, comprehensive explanation, comparison, and discussion on D-STATCOM, DVR, and UPQC are presented. This paper is aimed to explore a broad prospective on the status of D-STATCOMs, DVRs, and UPQCs to researchers, engineers and the community dealing with the power quality enhancement. A classified list of some latest research publications on the topic is also appended for a quick reference.
IRJET-Review on Power Quality Enhancement in weak Power Grids by Integration ...IRJET Journal
Prathmesh Mayekar, Mahesh Wagh, Nilkanth Shinde "Review on Power Quality Enhancement in weak Power Grids by Integration of Renewable Energy Technologies", International Research Journal of Engineering and Technology (IRJET), Volume2,issue-01 April 2015.e-ISSN:2395-0056, p-ISSN:2395-0072. www.irjet.net
Abstract
During Last decade power quality problems has become more complex at all level of power system. With the increased use of sophisticated electronics, high efficiency variable speed drive, power electronic controllers and also more & more non-linear loads, Power Quality has become an increasing concern to utilities and customers. The modern sensitive, Non-linear and sophisticated load affects the power quality. This paper deals with the issues of low power quality in weak power grids. Initially the various power quality issues are discussed with their definition or occurrence and then finally the solution to mitigate this power quality issues are discussed. The innovative solutions like integration of renewable energy systems along with energy storage to enhance power quality by interfacing with custom power devices are explained in detail. Nearly all sorts of solution for mitigating power quality issue require some sort of DC source for providing active power, which can be supplied by renewable energy source. Also the various energy storage systems are studied.
Power Quality Improvement using DVR (Dynamic Voltage Restorer) Under Various ...IRJET Journal
1) The document discusses a Dynamic Voltage Restorer (DVR) which is used to improve power quality by mitigating voltage sags and swells.
2) A DVR injects voltage into the distribution system through a series transformer to keep the load voltage constant during faults.
3) It describes the components of a DVR including an energy storage device, voltage source inverter, series injection transformer, and control unit with PI controller for PWM switching of the inverter.
4) The paper presents simulation results of a DVR's performance under different fault conditions to demonstrate its effectiveness in improving voltage quality.
This document summarizes a research paper that models and simulates a Dynamic Voltage Restorer (DVR) using MATLAB to improve power quality in a distribution system. It describes the components and operating principles of a DVR, including different compensation techniques. The document then outlines the simulation setup in MATLAB/Simulink that tests a DVR under various fault conditions. The results show that the DVR is able to rapidly inject compensating voltages to maintain a balanced and constant load voltage during faults. The paper concludes the DVR is effective for mitigating voltage sags while having a simple control scheme and fast response.
STATE OF THE ART: DYNAMIC VOLTAGE RESTORER FOR POWER QUALITY IMPROVEMENTecij
Improved and controlled power quality is one of the essential and fundamental need in any power driven industry for optimum utilization of resources. However critical problems in power quality have been recognized such as sags, swells, harmonic distortions and other interruptions. Out of these sags and swells
are predominantly found and have severe impact on the electrical devices or electrical machines and therefore needs to be compensated at an earliest to ensure any mal-operation or failure. To crack these problems custom power devices are used like unified power-quality conditioner (UPQC), distributionSTATCOM (DSTATCOM) and dynamic voltage restorer (DVR). The DVR is a one of the custom power device used for the compensation of voltage sag and swell with an advantage of active/reactive power control. A major volume of literature reported in past several years on different configurations of DVR and different control technique used in it. In context of this a detailed review on DVR has been presented with different possible power circuit topologies and control techniques available to reconcile these power quality issues. This review article will contribute in better selection of control strategy and power circuit for optimum performance of DVR for a particular requirement. Also it presents a very helpful investigation for the researcher in this field.
This document provides a review of Dynamic Voltage Restorer (DVR) systems used for compensating voltage sags in power distribution systems. It discusses that voltage sags are a serious power quality problem and DVR is an efficient custom power device to mitigate this issue. The document reviews the components, configurations, operating modes and control strategies of DVR systems. It describes that DVR injects voltage into the distribution system using a voltage source converter to regulate the load voltage during sags or disturbances.
This document provides an overview and introduction to connecting generators to power systems in Western Australia. It discusses key power system components such as generators, transformers, transmission and distribution lines, and substations. It also covers topics such as different generator and energy source types, power quality issues, faults, earthing, protection, operation, generation/load balance, and governance. The intended purpose is to help generator proponents understand the technical requirements for connecting to the grid, while noting that engineering expertise is required to fully understand all aspects of the complex power system.
Analysis of Total Harmonic Distortion (THD) Level of Distribution Network Usi...IJERA Editor
The modern sensitive, Non-linear and sophisticated load affects the power quality. Dynamic Voltage Restorer (DVR) provides the fast, flexible and efficient solution to improve the power quality for such distribution network [8]. The active power, reactive power, variation of voltage, flicker, harmonics, and electrical behavior of switching operations are the major source of affecting power quality. The intent of this paper is to demonstrate the improvements obtained with DVR in power system network using MATLAB/SIMULINK. In this paper, an overview of the DVR, its functions, configurations, components, control strategies are reviewed. The Simulation results are presented to illustrate the performance of DVR in Total Harmonic Distortion (THD). The results showed clearly the performance of using DVR in improving THD level.
Mitigation of Power Quality Problems Using Custom Power Devices: A Reviewijeei-iaes
Electrical power quality (EPQ) in distribution systems is a critical issue for commercial, industrial and residential applications. The new concept of advanced power electronic based Custom Power Devices (CPDs) mainly distributed static synchronous compensator (D-STATCOM), dynamic voltage restorer (DVR) and unified power quality conditioner (UPQC) have been developed due to lacking the performance of traditional compensating devices to minimize power quality disturbances. This paper presents a comprehensive review on D-STATCOM, DVR and UPQC to solve the electrical power quality problems of the distribution networks. This is intended to present a broad overview of the various possible DSTATCOM, DVR and UPQC configurations for single-phase (two wire) and three-phase (three-wire and four-wire) networks and control strategies for the compensation of various power quality disturbances. Apart from this, comprehensive explanation, comparison, and discussion on D-STATCOM, DVR, and UPQC are presented. This paper is aimed to explore a broad prospective on the status of D-STATCOMs, DVRs, and UPQCs to researchers, engineers and the community dealing with the power quality enhancement. A classified list of some latest research publications on the topic is also appended for a quick reference.
IRJET-Review on Power Quality Enhancement in weak Power Grids by Integration ...IRJET Journal
Prathmesh Mayekar, Mahesh Wagh, Nilkanth Shinde "Review on Power Quality Enhancement in weak Power Grids by Integration of Renewable Energy Technologies", International Research Journal of Engineering and Technology (IRJET), Volume2,issue-01 April 2015.e-ISSN:2395-0056, p-ISSN:2395-0072. www.irjet.net
Abstract
During Last decade power quality problems has become more complex at all level of power system. With the increased use of sophisticated electronics, high efficiency variable speed drive, power electronic controllers and also more & more non-linear loads, Power Quality has become an increasing concern to utilities and customers. The modern sensitive, Non-linear and sophisticated load affects the power quality. This paper deals with the issues of low power quality in weak power grids. Initially the various power quality issues are discussed with their definition or occurrence and then finally the solution to mitigate this power quality issues are discussed. The innovative solutions like integration of renewable energy systems along with energy storage to enhance power quality by interfacing with custom power devices are explained in detail. Nearly all sorts of solution for mitigating power quality issue require some sort of DC source for providing active power, which can be supplied by renewable energy source. Also the various energy storage systems are studied.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
IRJET- A Review Paper on Power Quality Issues and Monitoring TechniquesIRJET Journal
This document summarizes a research paper on power quality issues and monitoring techniques. It discusses various power quality issues like voltage sag, interruptions, harmonics, and monitoring methods including portable monitors, permanent monitors, and real-time monitoring systems. Power quality monitoring is important to identify issues, maintain reliability, and prevent equipment damage. Different analysis techniques are used to classify disturbances and identify their causes in order to select appropriate mitigation methods.
Sag mitigation in distribution system by using Dynamic voltage Restorer (DVR)IJERA Editor
Power quality is most important concern in the current age. It’s now a day’s necessary with the refined devices, where performance is very perceptive to the quality of power supply. Power quality crisis is an incidence manifest as a typical voltage, current or frequency that results in a failure of end use equipments. One of the major crises dealt here is the power sag. Perceptive industrial loads and distribution networks suffer from different types of service interruptions and outages which results in a major financial loss. To improve the power quality, custom power-devices are used. The device considered in this work is Dynamic Voltage Restorer. This paper shows modelling, analysis and simulation of a DVR test systems using MATLAB.
I have considered single line to ground fault for linear load. The role of DVR is to “compensate load voltage” is examined during the different fault conditions like voltage sag, single phase to ground faults.
This document discusses distributed generation (DG), defined as small power generation units connected to distribution networks. It covers DG definitions, drivers for DG integration including environmental, economic, technological and regulatory factors. Key benefits of DG integration are improved reliability, power quality, reduced losses and costs. Various DG technologies are classified and compared. Optimal DG planning techniques aim to minimize losses and costs while satisfying constraints like voltage limits.
A Novel Multi Level Converter Unified Power – Quality (MC-UPQC) Conditioning ...IRJET Journal
This document discusses a novel multi-level converter unified power quality conditioning system (MC-UPQC) capable of simultaneously compensating for voltage and current in multi-bus/multi-feeder systems. The proposed MC-UPQC topology includes one shunt voltage-source converter and two or more series VSCs, allowing power to be transferred between feeders to compensate for sags, swells, and interruptions. Simulation results show the MC-UPQC can significantly reduce power losses, mitigate under voltages, and enhance voltage stability in distribution networks compared to other designs. The MC-UPQC provides a more efficient solution for under voltage mitigation in multi-feeder systems.
IRJET- Mollification Parameter Control by Dynamic Voltage Restorer (DVR)IRJET Journal
The document discusses using a Dynamic Voltage Restorer (DVR) to mitigate voltage sags. A DVR is a series-connected device that uses power electronics to quickly restore load voltage to pre-fault levels during voltage sags. It works by injecting the missing voltage back into the system. A DVR consists of an inverter, filter, booster transformer, DC storage such as capacitors, and control system. It monitors the voltage and injects only the amount needed to compensate for the sag using pulse width modulation of the inverter. This allows it to restore the voltage quickly and improve power quality for sensitive loads affected by voltage sags.
IRJET-Simulation and Modeling of Dynamic Voltage Restorer for Compensation Of...IRJET Journal
The document describes the simulation and modeling of a dynamic voltage restorer (DVR) for mitigating voltage sags and swells in a power distribution system. A DVR is a custom power device that injects voltage in series with the distribution line to regulate the voltage at a load. The simulation model includes a DVR connected between a power source and sensitive load. Simulation results show that during a 50% voltage sag or 25% voltage swell, the DVR is able to quickly inject the appropriate compensating voltage to keep the load voltage at its nominal level. The DVR utilizes a control scheme based on dq0 transformation to identify voltage disturbances and determine the offset voltage required for compensation.
These slides focus on preliminary discussions about wide area monitoring, protection and control in future smart grid. Later in the class i will show its application through simulation and case study results.
A Review on Optimization Techniques for Power Quality Improvement using DSTAT...ijtsrd
This document summarizes a research paper that proposes using a neural network approach to optimize techniques for improving power quality using a DSTATCOM (Distribution Static Compensator). It begins by introducing common power quality issues like voltage sags, swells, and harmonics. It then discusses different custom power devices used to address these issues, focusing on the DSTATCOM. The paper proposes a control algorithm using a backpropagation neural network to extract reference currents and control the DSTATCOM for reactive power compensation, load balancing, and voltage regulation. Simulation results showed the DSTATCOM was able to satisfactorily compensate for different types of loads using this neural network approach.
This presentation on Power Quality Improvement Techniques: A Review presented by Sahid Raja Khan student of B. Tech. Electrical Engineering of Compucom Institute of Technology and Management Jaipur. It describes the improvement technique of Power Quality at GSS and other Substations including Generating Stations.
This slide presents about the basic and importance about load shedding in smart microgrid distribution systems. Later of the class i will discuss about in detail on the process of executing the load shedding.
Variable Frequency on Wireless Power Transfer for Pacemaker using Embedded Te...IRJET Journal
This document describes a proposed wireless power transfer system for powering implantable medical devices like pacemakers. It discusses the challenges with using batteries in implants and proposes using inductive coupling between an external coil and implanted coil for contactless power transfer. The system would use a microcontroller to control power transmission frequency and rectifiers to convert the received AC power to DC for use in the implant. Design considerations like coil sizes, capacitors for impedance matching, and efficiency are analyzed. The document outlines the various circuit components that would be needed for the transmitter, receiver, and power regulation components for a wireless power transfer system for medical implants.
Performance of DVR under various Fault conditions in Electrical Distribution ...IOSR Journals
1) The document describes the performance of a Dynamic Voltage Restorer (DVR) under various fault conditions in an electrical distribution system.
2) A DVR is connected in series with the distribution network to inject voltage and compensate for voltage sags and swells, maintaining the load voltage at its nominal value.
3) Simulation results using MATLAB/Simulink show that the DVR is able to effectively compensate for voltage disturbances caused by single line-to-ground faults, double line-to-ground faults, line-to-line faults, and three-phase faults, keeping the load voltage stable at its desired level.
Modeling Analysis& Solution of Power Quality Problems Using DVR & DSTATCOMijsrd.com
A Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure or a disoperation of end use equipment. Utility distribution networks, sensitive industrial loads, and critical commercial operations all suffer from various types of outages and service interruptions which can cost significant financial loss per incident based on process down-time, lost production, idle work forces, and other factors. With the restructuring of Power Systems and with shifting trend towards Distributed and Dispersed Generation, the issue of Power Quality is going to take newer dimensions. The aim therefore, in this work, is to identify the prominent concerns in the area and thereby to recommend measures that can enhance the quality of the power, keeping in mind their economic viability and technical repercussions. In this paper electromagnetic transient studies are presented for the following two custom power controllers: the distribution static compensator (DSTATCOM), and the dynamic voltage restorer (DVR). Comprehensive results are presented to assess the performance of each device as a potential custom power solution.
IRJET- Study on Power Quality Problem and its Mitigation Techniques in Electr...IRJET Journal
This document discusses power quality problems in electrical power systems and techniques to mitigate them. It begins by defining power quality and listing some common power quality issues like voltage sags, swells, interruptions, harmonics, and waveform distortions. Potential causes of these issues are also provided. The document then discusses various techniques that can be used to improve power quality, including surge protection devices, UPS systems, filters, custom devices like DVRs, STATCOMs and UPQC. It concludes by stating that power quality must be maintained as power needs increase and sensitive loads become more common, and discusses the need for mitigation techniques to address issues like voltage sags and harmonics.
IRJET- Power Quality Improvement using Dynamic Voltage Restorer (DVR)IRJET Journal
1) The document discusses power quality issues such as voltage sags and proposes using a Dynamic Voltage Restorer (DVR) to improve power quality.
2) A DVR injects voltage into the distribution system through an injection transformer to compensate for voltage sags and restore the load voltage to its normal level.
3) The document presents a MATLAB simulation of a DVR connected to a distribution system with two loads - a sensitive load and a normal load. When a fault is created, the DVR injects voltage and is able to maintain the sensitive load voltage at its normal level, protecting it from the voltage sag.
Improved performance of asd under voltage sag conditionsIAEME Publication
This document summarizes a research paper that proposes a new combination technique using a neutral linked Vienna rectifier and Z-source inverter to improve the performance of adjustable speed drives (ASDs) under voltage sag conditions. The technique aims to control voltage sags at the front end to prevent issues in the inverter at the back end. Simulation results show the proposed combination provides more stable DC link voltage and motor speed during sags compared to a normal rectifier and Z-source inverter alone. The research presents the design methodology, calculations, circuit diagram, and experimental waveforms that validate the improved ride through capability of the motor drive system using the neutral linked Vienna rectifier and Z-source inverter combination.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Este documento presenta las competencias, resultados de aprendizaje, principios de procedimiento y criterios de evaluación de la asignatura Didáctica General del Grado de Pedagogía. Describe seis competencias generales, 16 competencias transversales y 22 competencias específicas agrupadas en siete bloques temáticos. También enumera 12 resultados de aprendizaje y cinco principios de procedimiento para la asignatura. Finalmente, establece cinco criterios de evaluación y calificación.
El documento presenta una introducción a la programación interactiva con eventos y Swing en Java. Explica cómo manejar diferentes tipos de eventos como acciones de usuario, eventos del mouse, teclado y más. Incluye ejemplos de código que muestran cómo implementar listeners para cada tipo de evento y procesar las acciones del usuario.
Mandated Reporter Training Supplementary Participant MaterialsJim McKay
The document discusses parental and family factors that may lead to child maltreatment. It lists 10 factors such as parental immaturity, unrealistic expectations of children, social isolation of parents, mental illness, substance abuse issues, and exposure of children to dangerous home environments. It then provides physical and behavioral indicators of different types of child abuse including physical abuse, neglect, and their associated caregiver characteristics. The document is intended to help recognize signs of possible child maltreatment.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
IRJET- A Review Paper on Power Quality Issues and Monitoring TechniquesIRJET Journal
This document summarizes a research paper on power quality issues and monitoring techniques. It discusses various power quality issues like voltage sag, interruptions, harmonics, and monitoring methods including portable monitors, permanent monitors, and real-time monitoring systems. Power quality monitoring is important to identify issues, maintain reliability, and prevent equipment damage. Different analysis techniques are used to classify disturbances and identify their causes in order to select appropriate mitigation methods.
Sag mitigation in distribution system by using Dynamic voltage Restorer (DVR)IJERA Editor
Power quality is most important concern in the current age. It’s now a day’s necessary with the refined devices, where performance is very perceptive to the quality of power supply. Power quality crisis is an incidence manifest as a typical voltage, current or frequency that results in a failure of end use equipments. One of the major crises dealt here is the power sag. Perceptive industrial loads and distribution networks suffer from different types of service interruptions and outages which results in a major financial loss. To improve the power quality, custom power-devices are used. The device considered in this work is Dynamic Voltage Restorer. This paper shows modelling, analysis and simulation of a DVR test systems using MATLAB.
I have considered single line to ground fault for linear load. The role of DVR is to “compensate load voltage” is examined during the different fault conditions like voltage sag, single phase to ground faults.
This document discusses distributed generation (DG), defined as small power generation units connected to distribution networks. It covers DG definitions, drivers for DG integration including environmental, economic, technological and regulatory factors. Key benefits of DG integration are improved reliability, power quality, reduced losses and costs. Various DG technologies are classified and compared. Optimal DG planning techniques aim to minimize losses and costs while satisfying constraints like voltage limits.
A Novel Multi Level Converter Unified Power – Quality (MC-UPQC) Conditioning ...IRJET Journal
This document discusses a novel multi-level converter unified power quality conditioning system (MC-UPQC) capable of simultaneously compensating for voltage and current in multi-bus/multi-feeder systems. The proposed MC-UPQC topology includes one shunt voltage-source converter and two or more series VSCs, allowing power to be transferred between feeders to compensate for sags, swells, and interruptions. Simulation results show the MC-UPQC can significantly reduce power losses, mitigate under voltages, and enhance voltage stability in distribution networks compared to other designs. The MC-UPQC provides a more efficient solution for under voltage mitigation in multi-feeder systems.
IRJET- Mollification Parameter Control by Dynamic Voltage Restorer (DVR)IRJET Journal
The document discusses using a Dynamic Voltage Restorer (DVR) to mitigate voltage sags. A DVR is a series-connected device that uses power electronics to quickly restore load voltage to pre-fault levels during voltage sags. It works by injecting the missing voltage back into the system. A DVR consists of an inverter, filter, booster transformer, DC storage such as capacitors, and control system. It monitors the voltage and injects only the amount needed to compensate for the sag using pulse width modulation of the inverter. This allows it to restore the voltage quickly and improve power quality for sensitive loads affected by voltage sags.
IRJET-Simulation and Modeling of Dynamic Voltage Restorer for Compensation Of...IRJET Journal
The document describes the simulation and modeling of a dynamic voltage restorer (DVR) for mitigating voltage sags and swells in a power distribution system. A DVR is a custom power device that injects voltage in series with the distribution line to regulate the voltage at a load. The simulation model includes a DVR connected between a power source and sensitive load. Simulation results show that during a 50% voltage sag or 25% voltage swell, the DVR is able to quickly inject the appropriate compensating voltage to keep the load voltage at its nominal level. The DVR utilizes a control scheme based on dq0 transformation to identify voltage disturbances and determine the offset voltage required for compensation.
These slides focus on preliminary discussions about wide area monitoring, protection and control in future smart grid. Later in the class i will show its application through simulation and case study results.
A Review on Optimization Techniques for Power Quality Improvement using DSTAT...ijtsrd
This document summarizes a research paper that proposes using a neural network approach to optimize techniques for improving power quality using a DSTATCOM (Distribution Static Compensator). It begins by introducing common power quality issues like voltage sags, swells, and harmonics. It then discusses different custom power devices used to address these issues, focusing on the DSTATCOM. The paper proposes a control algorithm using a backpropagation neural network to extract reference currents and control the DSTATCOM for reactive power compensation, load balancing, and voltage regulation. Simulation results showed the DSTATCOM was able to satisfactorily compensate for different types of loads using this neural network approach.
This presentation on Power Quality Improvement Techniques: A Review presented by Sahid Raja Khan student of B. Tech. Electrical Engineering of Compucom Institute of Technology and Management Jaipur. It describes the improvement technique of Power Quality at GSS and other Substations including Generating Stations.
This slide presents about the basic and importance about load shedding in smart microgrid distribution systems. Later of the class i will discuss about in detail on the process of executing the load shedding.
Variable Frequency on Wireless Power Transfer for Pacemaker using Embedded Te...IRJET Journal
This document describes a proposed wireless power transfer system for powering implantable medical devices like pacemakers. It discusses the challenges with using batteries in implants and proposes using inductive coupling between an external coil and implanted coil for contactless power transfer. The system would use a microcontroller to control power transmission frequency and rectifiers to convert the received AC power to DC for use in the implant. Design considerations like coil sizes, capacitors for impedance matching, and efficiency are analyzed. The document outlines the various circuit components that would be needed for the transmitter, receiver, and power regulation components for a wireless power transfer system for medical implants.
Performance of DVR under various Fault conditions in Electrical Distribution ...IOSR Journals
1) The document describes the performance of a Dynamic Voltage Restorer (DVR) under various fault conditions in an electrical distribution system.
2) A DVR is connected in series with the distribution network to inject voltage and compensate for voltage sags and swells, maintaining the load voltage at its nominal value.
3) Simulation results using MATLAB/Simulink show that the DVR is able to effectively compensate for voltage disturbances caused by single line-to-ground faults, double line-to-ground faults, line-to-line faults, and three-phase faults, keeping the load voltage stable at its desired level.
Modeling Analysis& Solution of Power Quality Problems Using DVR & DSTATCOMijsrd.com
A Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure or a disoperation of end use equipment. Utility distribution networks, sensitive industrial loads, and critical commercial operations all suffer from various types of outages and service interruptions which can cost significant financial loss per incident based on process down-time, lost production, idle work forces, and other factors. With the restructuring of Power Systems and with shifting trend towards Distributed and Dispersed Generation, the issue of Power Quality is going to take newer dimensions. The aim therefore, in this work, is to identify the prominent concerns in the area and thereby to recommend measures that can enhance the quality of the power, keeping in mind their economic viability and technical repercussions. In this paper electromagnetic transient studies are presented for the following two custom power controllers: the distribution static compensator (DSTATCOM), and the dynamic voltage restorer (DVR). Comprehensive results are presented to assess the performance of each device as a potential custom power solution.
IRJET- Study on Power Quality Problem and its Mitigation Techniques in Electr...IRJET Journal
This document discusses power quality problems in electrical power systems and techniques to mitigate them. It begins by defining power quality and listing some common power quality issues like voltage sags, swells, interruptions, harmonics, and waveform distortions. Potential causes of these issues are also provided. The document then discusses various techniques that can be used to improve power quality, including surge protection devices, UPS systems, filters, custom devices like DVRs, STATCOMs and UPQC. It concludes by stating that power quality must be maintained as power needs increase and sensitive loads become more common, and discusses the need for mitigation techniques to address issues like voltage sags and harmonics.
IRJET- Power Quality Improvement using Dynamic Voltage Restorer (DVR)IRJET Journal
1) The document discusses power quality issues such as voltage sags and proposes using a Dynamic Voltage Restorer (DVR) to improve power quality.
2) A DVR injects voltage into the distribution system through an injection transformer to compensate for voltage sags and restore the load voltage to its normal level.
3) The document presents a MATLAB simulation of a DVR connected to a distribution system with two loads - a sensitive load and a normal load. When a fault is created, the DVR injects voltage and is able to maintain the sensitive load voltage at its normal level, protecting it from the voltage sag.
Improved performance of asd under voltage sag conditionsIAEME Publication
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IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Este documento presenta las competencias, resultados de aprendizaje, principios de procedimiento y criterios de evaluación de la asignatura Didáctica General del Grado de Pedagogía. Describe seis competencias generales, 16 competencias transversales y 22 competencias específicas agrupadas en siete bloques temáticos. También enumera 12 resultados de aprendizaje y cinco principios de procedimiento para la asignatura. Finalmente, establece cinco criterios de evaluación y calificación.
El documento presenta una introducción a la programación interactiva con eventos y Swing en Java. Explica cómo manejar diferentes tipos de eventos como acciones de usuario, eventos del mouse, teclado y más. Incluye ejemplos de código que muestran cómo implementar listeners para cada tipo de evento y procesar las acciones del usuario.
Mandated Reporter Training Supplementary Participant MaterialsJim McKay
The document discusses parental and family factors that may lead to child maltreatment. It lists 10 factors such as parental immaturity, unrealistic expectations of children, social isolation of parents, mental illness, substance abuse issues, and exposure of children to dangerous home environments. It then provides physical and behavioral indicators of different types of child abuse including physical abuse, neglect, and their associated caregiver characteristics. The document is intended to help recognize signs of possible child maltreatment.
Clear Channel Communications reported financial results for the third quarter of 2004. Revenue increased 4% compared to the same period last year to $2.6 billion. Net income was $261.2 million, an increase of 10% excluding on-time gains and losses from the prior year. The company continued repurchasing shares during the quarter and believes this is the best use of free cash flow. Operating income is expected to increase in the mid-single digits for the full year 2004, while earnings per share are forecasted to increase in the mid to high teens.
Este documento presenta una guía de promoción de salud para agentes de salud comunitarios en el Área 1 de Atención Primaria de Madrid. La guía fue desarrollada por más de 80 profesionales de la salud y está organizada en cinco centros de interés: salud-enfermedad, autocuidados, educación para la salud, salud medioambiental y modelos de atención a la salud. Cada centro de interés incluye información sobre el tema y sugerencias para diseñar programas de educación para la comunidad,
This summary provides an overview of key points from the document:
1) The document discusses efforts in Congress to pass legislation encouraging voluntary reporting of medical errors by establishing legal protections for such reported data and information.
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3) The proposed Patient Safety and Quality Improvement Act aimed to implement the recommendation for a voluntary reporting system by protecting error reports from legal discovery and requiring analysis to identify system vulnerabilities and improvements.
Tara wakes David up early to go on an adventure. They banter back and forth, with David questioning if Tara has "gone upper class". Tara reveals she wants to go to her orphanage to find her file and learn about her birth parents. They sneak in by posing as doctors. Tara is able to hack into the computer system and finds her file. She learns her birth parents died in a car crash when she was three months old. David supports her as she comes to terms with the reality that she is truly alone.
GLOBE Advisors - British Columbia's Green Economy - Securing the Workforce of...GLOBE Series
Powering the Business of the Environment
GLOBE Advisors is a boutique sustainability consulting firm headquartered in Vancouver, Canada, that specializes in providing project management, partnership development, market research, and strategic consulting services. We invite you to explore our website to find out how GLOBE Advisors can assist your organization with its strategic goals and objectives
www.globeadvisors.ca
Advancing Opportunities for Business and the Environment
GLOBE Advisors, a subsidiary of the Vancouver-based not-for-profit GLOBE Foundation, was established in response to an increasing demand for project-based sustainability consulting services in the environmental business sector.
The "GLOBE" name was established in 1990 and has become a recognized brand, both in Canada and internationally, with respect to the "business of the environment" - due in large part to the GLOBE Series of Conferences and Trade Fair Exhibitions held in Vancouver every two years and organized by the not-for-profit GLOBE Foundation.
In 2012, the company's President and CEO, Dr. John Wiebe, was recognized as one of Canada's "Clean 16" for his outstanding contributions to clean capitalism.
Our philosophy? Environmental challenges bring enormous opportunity for the business sector. Moreover, companies can do well by doing good for the environment, without sacrificing their bottom lines.
Our three guiding principles:
-Environmental problems are business opportunities.
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Race, crime, the law and civil unrest - Race Conflict and Change Week 8Alana Lentin
The perceived threat to Britain and corresponding moral panic about immigrants and the racial ‘other’ has often been constructed in terms of law and order, and particularly ‘black criminality’. In this Week we will focus on the relationship between ‘race, the law, crime and civil unrest. We will examine the relationship between race, crime and social, political and economic inequality or exclusion, how racial ‘other’ has been constructed and represented as a threat to law and order, how ‘black criminality’ has been constructed and represented, how the state and the police have dealt with black populations in terms of law, order and crime, and how this has affected race relations in Britain. We will also examine the various race riots which occurred in the 1960s-1980s and explore how these relate to the question of racial, social, political and economic inequality, exclusion, oppression and conflict, particularly with the State and police, and how these were constructed not as cases of political protest or unrest but as an extension of the same phenomenon of ‘black criminality’. This backdrop will help us understand the present-day racialization of crime, violence and, most notably terrorism. We will look at how two areas – so-called ‘black-on-black’ gun crime and ‘Islamic terrorism’ are currently affecting the way in which threat is constructed. Specifically, we shall examine how these perceptions are institutionalized and turned into law resulting in a host of measures that impact on the civil liberties of everyone living in Britain.
Clear Channel Communications reported a 7% increase in revenue to $1.8 billion for the third quarter of 2006 compared to the third quarter of 2005. Income before discontinued operations increased 8% to $185.9 million. Diluted earnings per share increased 19% to $0.38. OIBDAN, or operating income before depreciation and amortization, increased 10% to $595.4 million. Radio revenues increased 5% and outdoor advertising revenues increased 8%.
This is my deck for the mini-workshop on Mobile Analytics for Internet Summit 2012 in Raleigh, NC.
Use mobile analytics to forecast what features to cut, expand or attract more attention to with 8 actionable metrics to start learning about your users.
The document provides technology skills benchmarks and tutorials for understanding basic computer hardware and software components. It includes tutorials for taking pictures of a CPU, monitor, keyboard, printer, external hard drive, wireless router, and modem. Definitions are provided for each component, with the keyboard defined as an input device modeled after a typewriter, the printer as a device that transfers text and graphics to paper, the monitor as a device that displays signals on a computer screen, the router as a device that forwards data packets between networks, and the modem as a device that converts digital data to analog for transmission over phone or cable lines.
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Singula holomorphic foliations on cp3 shfc zakFrancisco Inuma
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This document provides information about a 3-credit online course titled EdTech 502: The Internet for Educators. The course will be delivered through the Blackboard course management system. It includes the instructor's contact information, required textbooks, software, assignments and projects, grading scale, and alignment to technology education standards. Students will learn how to design websites and digital curriculum using HTML, CSS, and other technologies. Assignments include discussions, creating webpages and other online activities. The course aims to help students locate, evaluate and integrate internet resources into instruction.
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The document summarizes the East Brunswick Girls Soccer Senior Night event held on October 6, 2011. It lists the names of the varsity seniors on the East Brunswick Bears soccer team, along with some of their accomplishments and thoughts on their soccer career and time with the East Brunswick team. It also recognizes the junior, sophomore, and freshman members of the East Brunswick Bears soccer team.
1. O documento apresenta a terceira estimativa da safra de café de 2012 no Brasil.
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This document summarizes a research paper that studies fault tolerance and power quality in a DFIG (Doubly Fed Induction Generator) wind turbine system using a UPFC (Unified Power Flow Controller). It first provides background on issues with integrating large-scale wind power into electric grids. It then describes using a UPFC and relay protection system to mitigate power quality issues in a grid-connected DFIG wind energy system, which is simulated in MATLAB. The document outlines the theory of power flow in a DFIG and issues related to power quality during grid disturbances like voltage dips from faults.
OVER-CURRENT RELAYS IN VOLTAGE DISTRIBUTIONIRJET Journal
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This document presents a summary of a project on islanding detection in microgrids. It begins with an introduction to microgrids and distributed generation. It then discusses islanding, its effects, and various methods for detecting islanding. The objective of this project is to detect islanding using the negative sequence component method and wavelet transform analysis of voltage signals. It describes modeling solid oxide fuel cells, microturbines, wind turbines, and the overall microgrid in simulation software. The simulation results show the negative sequence components and wavelet analysis detecting an islanding condition during a fault. The conclusion is that the proposed technique can successfully detect islanding using negative sequence analysis and wavelet transforms.
IRJET- Tap Changing using Solid State Devices for Single Phase TransformerIRJET Journal
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IRJET- Microcontroller based Automatic Power Change Over MechanismIRJET Journal
This document summarizes a research paper on an automatic power changeover mechanism using a microcontroller. The system is designed to automatically switch power sources between solar, mains electricity, and a diesel generator based on availability to ensure a continuous and reliable power supply. It uses components like a transformer, rectifier, regulator, comparator, and relays controlled by a microcontroller. The switching time is fast compared to manual changeover systems due to the use of electronic components. The system is intended to reduce costs by prioritizing solar power and switching to mains electricity when available before using the diesel generator.
Implementation of a Microcontroller Base Single Phase Automatic Changeover IJSRED
This document describes the design and implementation of a microcontroller-based single-phase automatic changeover system. The system automatically switches power sources between the main power supply and a generator in order to provide continuous power to loads. It uses a microcontroller to control relays that switch the load between available power sources. The system is designed to detect failures in the main power supply and automatically start the generator to power the load until main power is restored, at which point it switches back. The system aims to provide uninterrupted power for applications requiring continuous power such as hospitals, banks, and other critical systems.
LOW VOLTAGE RIDE - THROUGH CAPABILITY OF WIND FARMSEditor IJMTER
Nowadays wind turbines are generally required to offer ancillary services similar to those
provided by conventional generators. One of the most important services wind turbines must offer is
to stay connected to the grid in fault situations delivering the reactive current specified in the recent
grid codes. In this paper, FACTS solutions for fixed speed wind farms such as DVR (Dynamic
Voltage Restorer) are presented as well as classic control and crowbar solutions for variable speed
wind turbines.
The document describes the design and simulation of a DSTATCOM (Distribution Static Compensator) for improving power quality. A DSTATCOM is modeled in Simulink to mitigate voltage sags and swells caused by faults in a distribution system. Simulation results show that the DSTATCOM is able to regulate the voltage at the load point during single phase, double phase, and three phase faults by injecting compensating current. The DSTATCOM control is based on sinusoidal pulse width modulation and requires only measurement of the RMS voltage at the load point.
Design of embedded based three phase preventor and selector system for indust...IAEME Publication
This document summarizes a research paper that presents the design of an embedded-based three-phase preventor and selector system for industrial appliances. The system uses a microcontroller to control MOSFET-based inverters and provide safety operations for industry applications. It protects appliances from damage if one phase fails by using the power from another available phase. The system includes components like a DIP switch, microcontroller, signal amplifier, inverter circuitry, opto-isolator, gate drive power supply and MOSFET-based inverter to selectively provide power from one of three phases to industrial equipment.
Improved performance of asd under voltage sag conditionsIAEME Publication
This document summarizes a research paper that proposes a new combination technique using a neutral linked Vienna rectifier and Z-source inverter to improve the performance of adjustable speed drives (ASDs) under voltage sag conditions. The technique aims to reduce the effects of voltage sags by providing more stable DC link voltage. Simulation results show that the proposed combination is able to maintain the DC link voltage between 150V to 450V during a sag, preventing large reductions in motor speed, and performs better than a system using only a diode rectifier and Z-source inverter. The researchers conclude that the neutral linked Vienna rectifier with Z-source inverter provides improved ride-through capability for motors even during voltage sag events.
Frequency control in a microgrid including controllable loadIAEME Publication
This document summarizes a research paper that proposes a method for frequency control in microgrids that includes renewable energy sources, energy storage devices, and controllable loads. The microgrid model analyzed includes solar power, wind power, batteries, supercapacitors, and electric water heaters. The document describes the components of the microgrid, simulation parameters and assumptions. Frequency control is achieved by coordinating the energy storage devices and generators using optimized proportional-integral controllers. Electric water heaters can also help control frequency by adjusting their operating temperature setpoints in response to frequency deviations.
PHOTOVOLTAIC MANAGEMENT SYSTEM USING POWER LINE COMMUNICATION METHODOLOGYEditor IJMTER
Energy consumption in residential areas is rising; residential areas have deployed a
photovoltaic (PV) system to save energy cost and provide continuous power in the area. The PV
system needs to be continuously monitored to maintain its performance. In addition, it is desirable to
monitor each PV module because one abnormal PV module affects the whole PV system. Here
Power line communication (PLCC) technology is used to monitor each PV module in order to check
the performance of PV system. Power line communication (PLCC) carries data on a conductor that is
also used simultaneously for AC electric power transmission. The parameters in PV module are
monitored by PLC. The system architecture is composed of the following components: PLC modem,
CUK Converter, and inverter connected with AC load. The PLC modems are deployed on each PV
module for continuous monitoring. The CUK converter will provide constant voltage to the battery.
The device retrieves the stored data in microcontroller unit and informs users about the status of the
photovoltaic module.Voltage, Current and Temperature are the parameters which are going to be
noted in PV module. The output of the inverter circuit is given to the AC load by using resistive load.
Users can browse and figure out the PV system performance in detail by using power line
communication technology. The system is installed in the field.It is composed of sixteen PV modules
with 960V; since each PV module provides 60V and a 1kW inverter. This scheme will maintain the
performance of a PV system and can be used for industrial applications.
Renewable Energy Based on Current Fed Switched Inverter for Smart Grid Applic...MangaiK4
Abstract - Renewable energy is used in the current fed switched inverter for high power production. High voltage support, wide yield ranges of operation, shoot-through resistance are a portion of the desired properties of an inverter for a reliable, versatile and less ripple AC inversion. This paper proposes a single stage, high boost inverter with buck-boost capacity which has a few particular advantages over traditional voltage source inverters (VSI) like better EMI noise, wide input and output voltage range of operation, and so on. The proposed inverter is named as Current-Fed Switched Inverter (CFSI). A renewable energy based converter structure of CFSI has been created which supplies both AC and DC loads, at the same time, from a single DC supply which makes it reasonable for DC smart grid application. This paper proposes the operation and control of a CFSI based converter which directs the AC and DC conversion voltages at their reference. The advancement of the proposed converter from essential current fed DC/DC topology is explained. The closed loop controller is verified by using the MATLAB/ Simulink environment.
IRJET- Designing of Single Ended Primary Inductance Converter for Solar P...IRJET Journal
This document describes the design and modeling of a Single Ended Primary Inductance Converter (SEPIC) DC-DC converter for photovoltaic applications. A SEPIC converter is proposed to boost or buck the variable voltage from a solar panel to meet load requirements. An incremental conductance maximum power point tracking (MPPT) algorithm is used for better efficiency. The converter output is fed to a sinusoidal pulse width modulation inverter to convert DC to AC for AC loads. The SEPIC converter design and component selection process is explained. The system is modeled and tested using MATLAB/Simulink software and shown to reduce ripple current and provide a non-inverted output voltage compared to other converter types.
Fuzzy based control of Transformer less Coupled inductor based DC-DC converterIJERA Editor
Most of the industrial applications use any one of the basic DC-DC converter configurations namely buck,
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applications. Flyback converters popularly have known as buck-boost converters uses transformers for
achieving wide range of step down and step up voltages. Coupled inductor based converters or tapped inductor
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step-down and step-up modes is achieved by a proper control scheme. This paper proposes fuzzy logic based
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their membership values, mamdani based rules for development of fuzzy rules and simulation results of a
coupled inductor based DC-DC converter using MATLAB / SIMULINK are concluded.
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Optimization Technique for Power Quality Improvement using DSTATCOM Neural Ne...ijtsrd
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Protecting the wind energy system from a short circuit (requirements - challe...IRJET Journal
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The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
IRJET- Real Time Transformer Health Monitoring System using GSM and IoTIRJET Journal
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Event Report - SAP Sapphire 2024 Orlando - lots of innovation and old challengesHolger Mueller
Holger Mueller of Constellation Research shares his key takeaways from SAP's Sapphire confernece, held in Orlando, June 3rd till 5th 2024, in the Orange Convention Center.
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The 10 Most Influential Leaders Guiding Corporate Evolution, 2024.pdfthesiliconleaders
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This session provided an update as to the latest valuation data in the UK and then delved into a discussion on the upcoming election and the impacts on valuation. We finished, as always with a Q&A
At Techbox Square, in Singapore, we're not just creative web designers and developers, we're the driving force behind your brand identity. Contact us today.
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We will dig deeper into:
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Recruiting in the Digital Age: A Social Media Masterclass
G225159
1. International Journal of Engineering Science Invention
ISSN (Online): 2319 – 6734, ISSN (Print): 2319 – 6726
www.ijesi.org Volume 2 Issue 2 ǁ February. 2013 ǁ PP.51-59
www.ijesi.org 51 | P a g e
Mathematical Modeling for Reliability Assessment of 250-5000
Watts Pulse Width Modulation Power Inverter in Nigeria
M.B. Adamu1
, I.G, Saidu2
, M.B. Abubakar3
, N.S. Jega4
, M.I. Ilyasu5
, A.Tukur
(MIEEE, MIET, MITP)6
, M.A. Yusuf7
1,6
(Physics department, faculty of science, Usman Danfodiyo University, Sokoto – Nigeria)
2,3,5
(physics unit, Sokoto state polytechnic, sokoto- Nigeria)
4
(School of nursing and midwifery, Birnin Kebbi, kebbi state-Nigeria)
7
(Electrical engineering department, Sokoto state polytechnic, Sokoto-Nigeria)
ABSTRACT: A power inverter, or inverter, is an electrical power converter that changes direct current (DC)
to alternating current (AC) the converted AC can be at any required voltage and frequency with the use of
appropriate transformers, switching, and control circuits. The paper presents mathematical modeling for
assessing reliability of PWM power inverter in Nigeria. The part stress method was used to predict the
reliability of the system. Data on the failure of PWM Inverter in Sokoto were used as a case study, with special
consideration given to factors like environmental impact, quality of power supply, service personnel, human
factors (over and under usage). A comparative assessment was made on the reliability and reliability indices of
the power inverter when operated within Sokoto environment and when operated within the environment for
which it was designed (china). The result shows that lower reliability level is associated with the use of PWM
power inverter in Sokoto state of Nigeria, as compared with the country for which it was designed.
Keywords: Failure rate. Inverter, Modeling, PWM, Reliability
I. INTRODUCTION
250-5000 watts PWM DC/AC 220V power inverter is as electrical device which is designed to coverts
direct current DC to alternating current AC with the use of a transformer, switching and control circuits
[13][14]. The reliability of this system, which has an original environment for which it was designed for,
becomes necessary to determine the degree to which it could be relied upon in the applied environment –Sokoto
state Nigeria [1][2][6][7].
1.1 Reliability
Reliability in engineering can generally be defined as the characteristic of an item expressed as the
probability that it will perform a required function understated conditions for a stated period of time [4].
Reliability predictions are an important tool for making design trade-off decisions and estimating future system
reliability [8][11]. This requires the understanding of probability and statistical concepts and has, therefore, been
found to be a very important tool in forecasting the patter of failure for systems and hence the reliability
assessment of the system at hand [10].
1.2 Part stress method
This is one of two methods used in assessing the reliability of electronic equipment. In the part stress
method, the effects of the various stresses on the actual hardware are put into consideration, with the
environmental factor and the quality of the utility. The parts count method (the other method) of assessing the
reliability of system is based on the number of different parts, quality level and application environment. The
aim in both cases is to determine the failure for a given system operating in a specific environment [9].
However, the part stress method is better method for mathematical assessing the reliability of the existing
system, based on the possibility of considering various stress peculiar to the equipment in a specific area of
application [4] and as such cold be relied upon to asses the reliability of the PWM power inverter.
1.3 The PWM power inverter system
Pulse-width modulation (PWM) is a commonly used technique for controlling power to inertial
electrical devices made practical by modern power switches. Power inverter is an electrical device that converts
direct current DC to attempting current AC with the use of a transformer, switching and control circuits. These
are two general types of power inverter: true sine wave or modified-sine wave (square wave). True sine wave
2. Mathematical Modeling For Reliability Assessment Of 250-5000 Watts Pulse
www.ijesi.org 52 | P a g e
inverter produce power that is either identical or sometimes slightly better to power from the public utility
power grid system [13].
Modified sine wave and square wave inverters are the most common types of power inverters on the
market. Modified sine wave produces a power wave that is sufficient for most devices. The power wave is not
exactly the same as electricity from the power grid. It has a wave form that appears as a choppy square off wave
when viewed through an oscilloscope [14].
The schematic circuit design is for a 250 watt output to increase the power of the circuit you have to
add more of the Q7 and Q8 transistor in parallel, each pair you add will increase your power by 250 watts.
If you increase the power transistors you have to enlarge the T2 transformer to match the new needs. The circuit
transformer is rated 25 amps to handle 220V.
220v/12v
0.5 amp
1 16
2 15
3 14
4 13
5 12
6 11
7 10
8 9
IN 7808 OUT
GND
Driver stage
2
1
3
4
T1 –
10uF
+
3.9k (1/2 watt)
BC327
1N4007
100K
10uF
+
+
104
104
104
10K
4.7K
4.7K
100K
R2
100K
C1
2.2K
R1 1K
+
+
+
100K
47uF
1uF
+Vcc
4700uF
20uF
3
D
1K
+
SG3524
Q2
BC337
100
1K
1K 100
Q1
BC337
Power stage
2N6277
2N3055
TIP122Q3
Q4
Q5
Q7
2N6277
2N3055
TIP122
Q6
Q8
+Vcc
D1
D1
T2 220v output
0.1/600V
2.2uF/400V
1 2
Filter
Dc voltage and transformer “t2” winding recommendation:
Power Supply Winding
750W 12VDC p: 24V “12 – 0 – 12” / S: 220V
1500W 24VDC p: 48V “24 – 0 – 24” / S: 220V
2250W 36VDC p: 72V “36 – 0 – 36” / S: 220V
3000W 48VDC p: 96V “48 – 0 – 48” / S: 220V
3750W 60VDC p: 120V “60 – 0 – 60” / S: 220V
4500W 72VDC p: 144V “72 – 0 – 72” / S: 220V
5250W 84VDC p: 168V “84 – 0 – 84” / S: 220V
The transformer should be “centre tapped” at the primary side.
- R1 is to set the PWM to 220V
- R2 is to set the frequency to 50 or 60Hz
- Wiring should be thick enough to handle the huge amps drain from the batteries.
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- A cooling fan will be needed to reduce heat off the heat sinks and transformer, when you power up the
circuit the fan will start this will give you a simple way to know that 220V is present and everything is ok.
- Two circuit breakers are recommended instead of fusses, one on the DC side and one on the AC side,
depending on your design example; for a 24VDC (1500 watts design) put a 6 Amps breaker on the DC side and
a 6 Amp on the AC side. For every 1 Amp of 220AC you will be raining like 8 to 10 Amps from the 12V
battery, make your calculations.
- The two heat sinks should be big enough to cool the transistors, they are separate and should not touch
each other.
- Be caution when building this circuit it involves high voltage which is lethal.
1.4 Nigeria
There are three infrastructural indices of development. These are adequate, reliable and always
available energy supply, communication and transportation system. Any society that has got these thee indices is
generally characterized as developed society. Such societies includes USA, UK, Russia, Canada, France, Italy,
Germany and Japan – popularly called G8. Countries which have not attained the three perfect indices above are
generally termed developing countries. Example of such are Nigeria, Malaysia and so on.
Nigeria is mainly considered or at best, assemblers or product designed by developing nations. They inhabit
lands with tropical climates in Africa, Asia and Latin America [5]. The electrical power and hence, have
fluctuating voltages. Some of the region are periodically subjected to every dry dust (harmattan) which is
capable of introducing a high electric field strength of above 4000V/m and sometimes metallic objects moving
in this environment accumulate an average of 1000v/m charge [5].
II. MATERIALS AND METHODS
It is convenient to specify the reliability of electronic equipment by some probability parameters, which
give indication of the failure rate of such system or equipment and does not depend on the operating time [12].
By using such parameters, it is also possible to compare the performance between different systems with
different periods. Two of such parameters that are commonly used are the mean time between failure (MTBF)
and mean time to failure (MTTF) [12].
2.1 Mean Time between Failures (MTBF)
Reliability is quantified as MTBF (Mean Time between Failures) for repairable system. Avoiding
failure in a critical data centre is always a top priority; as such a correct understanding of MTBF is important.
Therefore systems users are usually concerned with the length of time that a system will run without failure.
This is a measure of the reliability of such a system [4][12]. The MTBF can be obtained by running a system for
a predetermined length of time under specified conditions. Hence for the failure rate (the number of failure per
unit time) MTBF is given as [4]:
N
tt
MTTF
n
t
i
1
0
i.e.
N
tttttt
MTTF n 00201
where t0 = starting (reference time)
(t1 – t0) = period to 1st
failure
(t2 – t0) = period to 2nd
failure
(tn– t0) = period to nth
failure
N = total number of failure components.
Consider the case in which a fixed number N0 of identical components are tested.
Let Ns = number surving up to time t.
Nf = number failed up to time t.
N0 = Ns + Nf = total number in operation at t=0
Reliability at any time t becomes
0N
N
tR s
(1)
The failure rate (t) is normally defined by the mathematical relation
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t
N
Nt
t
f
s
1
0
lim
dt
dN
N
f
s
1
(2)
where Ns = number of serving items after a life test
Nf = number of failure item during the time interval, t.
Consider the case in which a fixed number N0 of identical components are tested,
Let Ns = number surving up to time t
Nf = number failed up to time t
N0 = Ns + Nf = total number in operation at t=0
Reliability at anytime t becomes
0N
N
tR s
and failure rate (for constant failure rate)
dt
dN
N
f
f
1
from Equation (2)
dt
dN
NN
f
s
0
1
or
f
s
dN
NN
dt
0
1
introducing the limits
fN
f
s
t
dN
NN
dt
0
0
0
1
0loglog oefoe NNNt
0
0
log
N
NN
t f
e
Thus
0
1
N
N
e ft
(3)
But from Equation (1)
00
0
1
N
N
N
NN
N
N
tR ss
o
s
(4)
Comparing equations (3) and (4), we have
t
etR
(5)
The general expression for MTBF, m is (Epsma 2005, Oroge 1991, Susan, 2010)
0
dttRm (6)
For the case when is constant from equation (5)
t
eR
so equation (6) becomes
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0
0
0
1
1
ee
e
dttRm
t
1
m (7)
If failure are due to chance and if the failure rate is constant, then
MTBF
1
for repairable items
MTTF
1
for non-repairable items
2.2 Equipment Availability
Mathematically, the utilization factor can be express as [4]:
opidm
op
ttt
t
(8)
As seen in equation (8), if the idle time is equal to zero, (i.e. tid = 0) and the maintenance time become as small
as possible, then utilization factor will approach its maximum value and can now be called availability of a unit
or system. Mathematically, this can be expressed as
opm
op
tt
t
(min)
(9)
Where top = the mean time before failure and tm(min) = the mean time to failure
MTTFMTBF
MTBF
A
(10)
2.3 Mean time to failure (MTTF)
The mean time to failure is a term which applies to non-repairable items (such as resistors, capacitors,
electric bulbs and so on, which are disposed off as soon as they fail [12]. MTTF is the average time an item may
be expected to function before failure. This MTTF can be obtained by stressing a large number of components
under known conditions for a period of time and noting the number of failures [4][5]
2.4 Equipment Failure Profile
Over the years, complex equipment and components have been found to follow a familiar pattern of
failure, which has been well documented. Failure rates have been calculated for equal time intervals from
installation to replacement. When the failures rates is plotted against a time scale spanning the equipment life
time, the resulting graph, popularly known as “bathtub is obtained as shown in figure 2.1 [2][4].
It exhibits three district periods or zones, the infant mortality period, the constant failure rates period and the
wear out period.
Infant mortality period
This is the running-in period. During this period, the failure rate has been found to be high, due to other
design or manufacturing errors, misuse. It however, falls off rapidly with operation. Failures in this period can
be avoided during product development through the use of stimulated tests, or by vigorous stressing during
commissioning tests.
Constant Failure Rate Period
This period follows the running-in period. During this period, the failure rate is lowest and is a function
of the basic design. Failure results either through accidents or poor operation or maintenance. In this phase, the
mean time to failure (MTTF) is the reciprocal of the (constant) failure rate.
Wear Out Period
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This period manifests towards the tail end of the equipment component life. During this period, failure
is due to old age, various components are worn-out, metals become embrittled, and insulation dries out and so
on. Failure rates can only be reduced by preventive replacement of these components.
Generally in some systems, one or two of the phase (usually the ecouly failure and wear our failures) could be
more reduced or effectively absent. Therefore, estimates for parameters that affect equipment failure profile of
the constituent components, especially the length of the constant failure rate period and associated failure rates
are essential ingredients for predicting the reliability.
Fig.2. 1. Equipment failure profile – Bathtub-curve
2.5 RELIABILITY ASSESSMENT OF ELECTRONIC EQUIPMENT
The general expression for the parts stress method of mathematically assessing reliability is given as [8][10][15]
i = nB E A Q N (11)
Where
i = the failure rate ith
part
B = The basic failure rate obtained from derated data for each
generic part against normalized stress and temperature factors.
E = Account for the environmental factors other than
temperature
A = Account for secondary stresses (e.g. vibration, shock,
e.t.c.)
Q = Account for the degree of manufacturing control
N = Account for any additional factor that has not been taken care of above.
n = Number of particular component.
For the scope of this work, the above equation (11) for the part stress method was reduced to the expression of:
i = nBTK (12)
Where
i = The failure of the ith
part
n = number of particular component
B = Base failure rate obtained from the derated data for each generic part against normalized stress and
temperature factor.
T = Room temperature of the environment
K = Voltage stress ratio
Voltage stress (K) =
𝑀𝑒𝑎𝑠𝑢𝑟𝑑 𝑣𝑜𝑙𝑡𝑎𝑔𝑒
𝑅𝑎𝑡𝑒 𝑣𝑜𝑙𝑡𝑎𝑔𝑒
The failure rate of the regions under consideration, Sokoto-Nigeria and China are summed up to calculate the
inherent system reliability. These failures are constant and as best described by the exponential distribution law
for useful operation region.
Early failure
rate period
Infant
mortality
Constant failure rate period
Normal useful operation
period
Increasing failure
rate period
Wear out period
FAILURERATE
TIME IN SERVICE
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RELIABILITY ASSESSMENT OF 250-5000 WATTS PWM DC/AC POWR INVERTER
The design criteria presented above will be used to assess 250-5000 watts PWM DC/AC power inverter
in Sokoto-Nigeria and in the country for which it was designed for (China). Hence, we shall have designed
failure rate, as it will be applicable to the system operating in the environment for which it was designed and a
relative failure rate as it will be applicable to the system operating in the Sokoto state Nigerian environment [5].
The conclusion arrived at will be used assess the reliability of the PWM power inverter. The components of the
250 to 5000 watts PWM power inverter with the generic failure rate, which has been taken care of the
environmental factors and the application stress factor and the results of the failure rates are shown in Table 3.
Table 1: failure rates of the pwm dc/ac power inverter
Circuit
Ref
Component
description
Qty
(n)
TD
(0
C)
TN
(0
C)
Voltage stress
ratio K
BD
(x10-6
/hr)
BN
(x10-6
/hr)
eff
D
=
(nKTBD)
eff
(nTKBN)
T1 Transformer 1 25 27 0.1167 0.011 0.019 0.0320925 0.0598671
D1 General purpose
diode (germanium)
1 25 27 0.006 0.0032 0.102 0.00048 0.016524
D2 -do- 1 25 27 0.03875 0.0032 0.102 0.0031 0.1067175
D3 -do- 1 25 27 0.1755 0.0032 0.102 0.01404 0.483327
D4 -do- 1 25 27 0.0125 0.0032 0.102 0.001 0.034425
R1 -do- 1 25 27 0.8 0.0219 0.105 0.438 2.268
R2 -do- 1 25 27 2.0 0.0219 0.105 1.095 5.67
R3 -do- 1 25 27 0.05 0.0219 0.105 0.027375 0.14175
R4 -do- 1 25 27 1.90 0.0219 0.105 1.04025 5.3865
C1 Ceramic capacitor 1 25 27 0.0625 0.033 0.141 0.0515625 0.2379375
C2 -do- 1 25 27 0.045 0.033 0.141 0.037125 0.171315
C3 -do- 1 25 27 0.0512 0.033 0.141 0.04224 0.1949184
IC1 IN 7808 1 25 27 0.125 0.007 0.91 0.021875 3.07125
R5 Film resistor 1 25 27 6.10 0.105 0.0219 16.0125 3.60693
D5 LED 1 25 27 0.0025 0.102 0.0032 0.006375 0.000216
C4 Electrolytic capacitor 1 25 27 0.563 0.033 0.171 0.464475 2.599371
C5 -do- 1 25 27 0.0085 0.033 0.171 0.0070125 0.0392445
Q2 Transistor 1 25 27 0.0975 0.0144 0.860 0.0351 2.26395
R6 Film resistor 1 25 27 0.0340 0.0008 0.011 0.00068 0.010098
D6 Diode 1 25 27 0.0052 0.0066 0.51 0.000858 0.071604
D7 -do- 1 25 27 0.0066 0.0066 0.51 0.001089 0.090882
C6 Electrolytic capacitor 1 25 27 0.5148 0.0047 0.025 0.060489 0.34749
C7 Electrolytic capacitor 1 25 27 0.7613 0.0047 0.025 0.08945275 0.5138775
C8 Film capacitor 1 25 27 0.1145 0.0008 0.011 0.00229 0.0340065
R8 Film resistor 1 25 27 0.0110 0.0008 0.011 0.00022 0.003267
Circuit
Ref
Component
description
Qty
(n)
TD
(0
C)
TN
(0
C)
Voltage stress
ratio K
BD
(x10-6
/hr)
BN
(x10-6
/hr)
eff
D
=
(nKTBD)
eff
(nTKBN)
R9 Film resistor 1 25 27 0.0340 0.0008 0.011 0.00068 0.010098
R10 Film resistor 1 25 27 0.0348 0.0008 0.011 0.000696 0.0103356
IC2 SG3524 1 25 27 0.03875 0.011 0.15 0.1065625 1.569375
R11 Film resistor 1 25 27 0.528 0.0008 0.011 0.01056 0.156816
R12 Variable resistor 1 25 27 0.5097 0.086 1.3 1.095855 17.89047
C9 Electrolytic capacitor 1 25 27 0.5148 0.0047 0.025 0.060489 0.34749
Q2 Power transistor 1 25 27 3.3 0.0085 0.078 0.70125 6.9498
Q3 -do- 1 25 27 3.34 0.0085 0.078 0.70975 7.03404
Q4 -do- 1 25 27 2.77 0.0085 0.078 0.588625 5.83362
Q5 -do- 1 25 27 8.35 0.0085 0.078 1.774375 17.5851
Q6 -do- 1 25 27 11.80 0.0085 0.078 2.5075 24.8508
Q7 -do- 1 25 27 2.74 0.0085 0.078 0.58225 5.77044
Q8 -do- 1 25 27 1.76 0.0085 0.078 0.374 3.70656
Q9 -do- 1 25 27 2.13 0.0085 0.078 0.452625 4.48578
D7 Diode 1 25 27 0.0036 0.0066 0.51 0.000594 0.049572
D8 -do- 1 25 27 0.0018 0.0066 0.51 0.000297 0.024786
T2 High power x4mer 1 25 27 0.1043 0.003 0.047 0.0078225 0.1323567
C10 Polyester film
capacity
1 25 27 0.22 0.0008 0.011 0.0044 0.06534
C11 -do- 1 25 27 0.1167 0.0008 0.011 0.002334 0.0346599
D9 - D12 Bridge rectifier 1 25 27 0.0192 0.0066 0.51 0.003168 0.264384
TOTAL 28.46851425 124.099455
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Where
BN = Base failure rate of the inverter in Sokoto-Nigeria
BD = Base failure rate of the inverter in designed environment (China)
Toc
(D) = Average room temperature of the designed environment (China)
Toc
(N) = Average room temperature of Sokoto-Nigeria
K = Voltage stress ratio
effD = Effective base failure rate for designed environment (China)
effN = Effective base failure rate for the applied environment (Sokoto-Nigeria)
Reliability can be assessed from the failure rates obtained from table 3 for China and the applied environment
(Sokoto-Nigeria).
Table 3: Reliability result
Year 1 Year 2 Year 3 Year 4 Year 5
China 0.779284 0.607283 0.473246 0.368793 0.2873943
Nigeria 0.337190 0.1136968 0.0383374 0.012927 0.0043588
Table 4: Percentage of reliability
Year 1 Year 2 Year 3 Year 4 Year 5
China 77.9284% 60.7283% 47.3246% 36.8793% 28.73943%
Nigeria 33.7190% 11.36968% 3.83374% 1.2927% 0.43588%
Example, for one year, = 365 days x 24 hours = 8760hrs
R = ē(28.4685E – 06 x 8760)
= 0.779284
The reliability result taken over five years for the two environments were plotted against time
0
10
20
30
40
50
60
70
80
90
0 1 2 3 4 5 6
China
Nigeria
Fig.2.2: Graph of reliability Vs year
III. DISCUSSION OF RESULT
From fig.2.2, we can appreciate and compare the reliability of the country for which the system was
designed for and that of Sokoto-Nigeria. And from it we see that the power inverter under consideration has a
relatively higher reliability in the designed country (China) than the applied environment (Sokoto-Nigeria).
The exponentially decaying reliability function graph above shows that the system has a higher failure
rate in Nigeria, due to factors, which are associated with the environment like voltage fluctuation, surge
Year
Reliability
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frequency, high relative humidity, among others. The ratio of the failure rate of Sokoto-Nigeria to China is
approximately 4:1.
Comparatively, the rate of failure of the power inverter in the designed country is much less than the Nigerian
case. From the failure rate of the system obtained for the two environments, we obtain the mean time to failure
(MTTF) of the system as follows
MTTF = 1
effD
MTTFChina = 4.0099 yrs.
MTTFsokoto = 0.92 yrs.
The mean time the system is expected to function before failure (MTTF) in Sokoto-Nigeria is 0.9 years as
against 4.0 years for the designed country. The rate is about four times higher than the Sokoto-Nigerian case.
IV. CONCLUSION AND RECOMMENDAITONS
The comparative results for the system at hand, taken over five years between the country for which the
system was designed for and that of Nigeria, showed that lower reliability is associated with the use of the
system in Nigeria than the designed country (China).
The following steps are recommended for the reliability of the power inverter to be higher in Nigeria:
a. Provision of a parallel configuration in the design so as to reduce the rate of failure of the components in the
system.
b. The design of power inverter that will consider the environmental as well as stress factor in Nigeria.
REFERENCES
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[3]. Arsenault, J.E. (1980) “Reliability and Maintainability of Electronics Systems” Pitman Ltd., United Kingdom. PP 162 – 187.
[4]. Oroge, C.A. (1991) Fundamental of Reliability and Testing Methods; Sooji Press Ltd., Kaduna, Nigeria.
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PhD. Thesis, ABU, Zaria
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April- June, 2006
[7]. Mohammed, A.B, Musa, M., Ismaila, G.S (2012). “Failure events analysis of Uninterruptible Power Supply (UPS) in Nigeria”
International Journal of Engineering Invention. ISSN (Online): 2319-6734, ISSN (Print): 2319-6726, Volume I Issue I
//December. 2012// PP.13-17
[8]. Boston, B.M, (2004) “Reliability Prediction: Part count, part stress and Dormant”. Reliability training course Vol. 41, PP.2-12
[9]. EPSMA, (2005) “Guidelines to understanding Reliability Prediction”. Retrieved August8, 2012 from http://www.epsma.org
[10]. Gupta. R.C; Gupta, R.L and Gupta, R.D (1997), “Modeling failure time by Lehman alternatives”, Communication in statistics-
Theory and Methods, vol.27, PP.887-904
[11]. Quanterion, (2004), “Reliability prediction” Vol.3, No.5 September, 2004. Retrieved October, 2011 from
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[12]. Susan, S. (2010), “MTBF, MTTR and FIT Explanation” Statistical Soc. Series B Vol.20, PP.243-302
[13]. Dr Adel, G (2010), “Advanced power electronics PWM Inverter” Retrieved on 17/02/2013 from http://www.adel.gastli.net
[14]. Berrezzek, F and Omeiri, A. (2009) “ Astudy of new techniques of controlled PWM Inverter” European Journals of Science
Research ISSN 1450-216X Vol.32 No.1 (2009), PP.77-89. http://www.eurojournals.com/ejsr.htm
[15]. MIL-HDBK-217, (1995), “Reliability prediction of Electronic equipment”. Developed by Rome Laboratories, and the United
States, Department of Defense