This document describes modeling the components of a wind farm in order to accurately simulate its transient response under lightning conditions. It details models for the wind turbines, transformers, transmission lines, surge arresters, and other components. The models include frequency dependence to capture transient behavior. The wind farm model is implemented and validated in ATP/EMTP software. Comparison is made between models with and without frequency dependence. This accurate modeling of wind farm components allows simulation of the transient response and analysis of lightning hazards.
This document summarizes a research paper that proposes and analyzes a multilevel line-commutated inverter topology for solar PV-based grid-connected inverters. The proposed topology uses a multi-winding transformer to provide multiple voltage levels and reduce harmonic distortion in the line current compared to a conventional square-wave inverter. A three-level implementation is modeled in Simulink and experimentally tested. Simulation and experimental results show the proposed topology reduces total harmonic distortion and improves power transfer characteristics compared to a conventional line-commutated inverter.
1. The document examines the power capacity of transmission lines using coaxial cables as a case study.
2. The power capacity of transmission lines depends on cable size and type and is limited by voltage breakdown, which typically occurs at 3x106 V/m for air at sea level pressure. Reflections can further reduce capacity.
3. Larger coaxial cables and rectangular waveguides have greater power capacities than smaller ones. At 10 GHz, coaxial cables can transmit up to 520 kW peak power while rectangular waveguides can transmit up to 2,300 kW.
A transformer transfers electrical energy between two or more circuits through electromagnetic induction. It works on the principle of mutual induction between two or more windings due to a changing magnetic field. Transformers are used to increase or decrease alternating voltages in power applications. The primary winding is supplied with alternating current which produces a changing magnetic flux in the transformer core. This changing flux induces a changing voltage in the secondary winding due to electromagnetic induction based on Faraday's law of induction. Real transformers have losses such as core losses from hysteresis and eddy currents, as well as winding resistance losses. Transformers can be modeled using an equivalent circuit to represent these losses and other factors.
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
The document summarizes key aspects of transmission line design and components. It discusses the methodology for designing transmission lines, including gathering design data, selecting reliability levels, and calculating loads. It also covers the selection and design of various transmission line components such as conductors, insulators, towers, and grounding systems. Design considerations include voltage levels, safety clearances, mechanical requirements, and optimization of costs.
Transformer wikipedia, the free encyclopediaBibek Chouhan
The document summarizes key aspects of transformers:
1. Transformers transfer energy through inductive coupling between winding circuits, with a varying current in the primary winding creating a varying magnetic flux that induces a voltage in the secondary winding.
2. Transformers range in size from small units in microphones to large units connecting power grids. They are essential for transmission, distribution and use of electrical energy.
3. An ideal transformer induces a secondary voltage proportionate to the primary voltage and winding turn ratios, with no losses. Real transformers have additional factors like core losses, winding impedances and leakage flux.
TRANSFORMER WINDING DEFORMATION ANALYSIS USING SFRA TECHNIQUEJournal For Research
The sweep rate response analysis is wide used technique for establish veiled fault and circumstance observance of power electrical device. The action is administrated by provide a coffee voltage signal of changeable frequencies to the electrical device windings and measures each the input and output signals. These 2 signals provide the specified response of the magnitude relation is named the transfer operate of the electrical device from that each the magnitude and section may be obtained. Frequency response is modification as deliberate by SFRA techniques might indicate a state change within the electrical device, so causes of fault recognized and examination is needed for root cause analysis.
Concept of energy transmission & distribution ZunAib Ali
Downlaod is NOW Allowed (08/06/2016)
for more help: email me at zunaib_91@yahoo.com
Purpose of Electrical Transmission System
Main Parts of Power System
One-Line Diagram of Generating Station
Main Parts of Generating Station
Components of a Transmission Line
This document summarizes a research paper that proposes and analyzes a multilevel line-commutated inverter topology for solar PV-based grid-connected inverters. The proposed topology uses a multi-winding transformer to provide multiple voltage levels and reduce harmonic distortion in the line current compared to a conventional square-wave inverter. A three-level implementation is modeled in Simulink and experimentally tested. Simulation and experimental results show the proposed topology reduces total harmonic distortion and improves power transfer characteristics compared to a conventional line-commutated inverter.
1. The document examines the power capacity of transmission lines using coaxial cables as a case study.
2. The power capacity of transmission lines depends on cable size and type and is limited by voltage breakdown, which typically occurs at 3x106 V/m for air at sea level pressure. Reflections can further reduce capacity.
3. Larger coaxial cables and rectangular waveguides have greater power capacities than smaller ones. At 10 GHz, coaxial cables can transmit up to 520 kW peak power while rectangular waveguides can transmit up to 2,300 kW.
A transformer transfers electrical energy between two or more circuits through electromagnetic induction. It works on the principle of mutual induction between two or more windings due to a changing magnetic field. Transformers are used to increase or decrease alternating voltages in power applications. The primary winding is supplied with alternating current which produces a changing magnetic flux in the transformer core. This changing flux induces a changing voltage in the secondary winding due to electromagnetic induction based on Faraday's law of induction. Real transformers have losses such as core losses from hysteresis and eddy currents, as well as winding resistance losses. Transformers can be modeled using an equivalent circuit to represent these losses and other factors.
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
The document summarizes key aspects of transmission line design and components. It discusses the methodology for designing transmission lines, including gathering design data, selecting reliability levels, and calculating loads. It also covers the selection and design of various transmission line components such as conductors, insulators, towers, and grounding systems. Design considerations include voltage levels, safety clearances, mechanical requirements, and optimization of costs.
Transformer wikipedia, the free encyclopediaBibek Chouhan
The document summarizes key aspects of transformers:
1. Transformers transfer energy through inductive coupling between winding circuits, with a varying current in the primary winding creating a varying magnetic flux that induces a voltage in the secondary winding.
2. Transformers range in size from small units in microphones to large units connecting power grids. They are essential for transmission, distribution and use of electrical energy.
3. An ideal transformer induces a secondary voltage proportionate to the primary voltage and winding turn ratios, with no losses. Real transformers have additional factors like core losses, winding impedances and leakage flux.
TRANSFORMER WINDING DEFORMATION ANALYSIS USING SFRA TECHNIQUEJournal For Research
The sweep rate response analysis is wide used technique for establish veiled fault and circumstance observance of power electrical device. The action is administrated by provide a coffee voltage signal of changeable frequencies to the electrical device windings and measures each the input and output signals. These 2 signals provide the specified response of the magnitude relation is named the transfer operate of the electrical device from that each the magnitude and section may be obtained. Frequency response is modification as deliberate by SFRA techniques might indicate a state change within the electrical device, so causes of fault recognized and examination is needed for root cause analysis.
Concept of energy transmission & distribution ZunAib Ali
Downlaod is NOW Allowed (08/06/2016)
for more help: email me at zunaib_91@yahoo.com
Purpose of Electrical Transmission System
Main Parts of Power System
One-Line Diagram of Generating Station
Main Parts of Generating Station
Components of a Transmission Line
This document provides an overview of distribution transformers including their design, selection, operation, and efficiency. It discusses the need for large power stations and transformers to achieve economies of scale. It also covers transformer design components, equivalent circuits, vector groups, parallel operation, effects of nonlinear loads, and improvements in efficiency over time through better magnetic steel.
MATLAB Simulink for single phase PWM inverter in an uninterrupted power supplyIJMER
Now a day’s Uninterrupted power supply is very necessary for industry, and domestic purpose.
This paper presents the design and implementation of UPS for using personal computer. Here solar
energy is used for charging the battery in sunny days and in absence of solar energy it will automatically
connect to main AC supply. Also MATLAB simulation work is done for PWM single phase inverter and
full bridge rectifier.. Here microcontroller is used for switching between solar plate and main AC supply
to Battery. By using this method we can save our electricity bill which is consumed in charging of battery
This document provides an overview of transformers and their operation. It discusses:
- The history and development of transformers from the 1880s to present day
- The basic components and construction of transformers
- How an ideal transformer works based on Faraday's law of induction
- How voltages and currents are related in an ideal transformer based on turn ratios
- How real transformers approximate ideal transformer behavior
- Examples of analyzing circuits containing transformers by referring their sides
- The theory of operation for real single-phase transformers based on mutual and leakage fluxes
Power Circuits and Transforers-Unit 3 Labvolt Student Manualphase3-120A
This document discusses determining equivalent capacitance for series and parallel capacitors. It explains that capacitance opposes changes in voltage across capacitor terminals and depends on factors like dielectric material and plate size/spacing. The exercise objectives are to calculate equivalent capacitance using circuit measurements and explain how capacitance values combine in series and parallel configurations.
Pocket book on energy efficiency in elec systemsSuresh Kumar
This document discusses energy efficiency in electrical systems, focusing on transformers and motors. It provides information on transformer types, ratings, losses and efficiency optimization. Key points covered include:
1. Transformers are inherently very efficient but efficiency depends on load percentage, with maximum efficiency occurring between 40-60% for distribution transformers and 60-80% for power transformers.
2. Motor and transformer loads can be optimized through proper sizing and power factor correction techniques like capacitors to reduce losses and improve efficiency.
3. Harmonics from non-linear loads increase equipment losses and temperatures, potentially causing premature failure, so proper filtering is required. Standards help regulate harmonics levels.
Power Circuits and Transformers-Unit 2 Labvolt Student Manualphase3-120A
This document discusses alternating current (AC) and sine waves. It explains that AC voltage continually changes polarity and amplitude, and can be considered a DC voltage that is changing. The frequency of an AC voltage is the number of times per second its polarity changes. Sine waves are well-suited for electrical systems as they allow for efficient power transfer. Key parameters of sine waves include amplitude, frequency, phase, and phase shift. Circuit laws like Ohm's Law apply to AC circuits as well.
This document discusses the parameters of transmission lines. It covers:
1. The structure of power systems including generating stations, transmission lines, and distribution systems. Transmission lines transfer power from generating stations to distribution systems.
2. The parameters that characterize transmission lines including resistance, inductance, and capacitance. Resistance causes power losses while inductance and capacitance determine the line's electrical behavior.
3. The modeling of single and three-phase transmission lines, covering topics like loop inductance, symmetrical and asymmetrical conductor spacing, and their effects on voltage regulation.
Power Circuits and Transformers-Unit 4 Labvolt Student Manualphase3-120A
The document discusses equivalent inductance for series and parallel inductors. It states that equivalent inductance is greater for series combinations and smaller for parallel combinations, similar to equivalent resistance. Formulas are provided to calculate equivalent inductance for series and parallel configurations. The exercise objective is to determine equivalent inductance using these formulas and circuit measurements of voltage and current.
Power system is the transfer of electricity from generation to the point of user location. Power system is composed of generation of power, its transmission and distribution. Transmission system is the main part out of these three in which mostly losses occur. The unchanging factors of the transmission line on which these losses depend are inductance, resistance and capacitance. These constants or unchanging factors play a vital role in the performance of transmission line. For example the capacitance effect will be more and its performance will be affected if the height of transmission line is less from the ground. On the other hand its capacitance will be less but tension will be high if the height of the transmission is high. For this reason a transmission line is connected in a curved or catenary shape known as sag. To minimize tension sag is provided in a transmission line. Sag and tension must be adjusted in safe limits. This immediate paper gives a simulation structure to calculate sag and tension of AAAC (All Aluminum Alloy Conductors of overhead transmission lines with same span length for minimum operating temperature. Three different cases are presented with different towers height and are explained in detail for unequal level span. The results show that the tension and sag increased with height. So great the height difference, higher tensions upon higher towers.
Transformers are necessary in power systems to step up voltage for efficient transmission and step down voltage for safe distribution. They operate on the principle of electromagnetic induction and have a core made of laminated steel, with coils of wire wound around the core. The ratio of the number of turns in the primary and secondary windings determines the voltage transformation ratio. Power losses in transformers include copper losses from winding resistance and iron losses from hysteresis and eddy currents in the core. Efficiency is highest when load matches the ratio of iron to copper losses.
Power Circuits and Transforers-Unit 7 Labvolt Student Manualphase3-120A
This document discusses an exercise on measuring and understanding the voltage and current characteristics of a single-phase transformer. Key points include:
- Measurements showed that the ratio of primary to secondary voltage equals the transformer turns ratio, and the ratio of primary to secondary current equals the inverse of the turns ratio.
- Core saturation was observed at higher voltages, where the exciting current increased more rapidly and the voltage ratio was affected.
- The exercise demonstrated how to properly connect transformer windings in series-aiding and series-opposing configurations.
Swartley b santinia_maled_jaccinob-destructive-arcong-of-insulated-joints-in-...Gilberto Mejía
The document summarizes a study conducted by Metro-North Railroad and Long Island Rail Road to analyze destructive arcing occurring at insulated joints where electric trains change tracks. The study found that inductive elements in the railroads' traction power and train propulsion systems contribute to high voltages forming across insulated joints when train wheels break contact. Field testing was performed under various conditions to measure currents and voltages during arcing. The results suggest methods to mitigate arcing by reducing inductive effects in the traction return circuit and train circuits.
Power Circuits and Transforers-Unit 5 Labvolt Student Manualphase3-120A
* Active power (P) = 3 kW = 3,000 W
* Inductive reactive power (Q) = 4 kvar
* Using the power triangle:
* Apparent power (S) = √(P^2 + Q^2)
* = √(3,000^2 + 4,000^2)
* = √(9,000,000 + 16,000,000)
* = √25,000,000
* = 5,000 VA = 5 kVA
The apparent power is 5 kVA. The answer is b.
The document discusses electrical transmission lines and their key components. It describes how transmission lines can be modeled as 2-port networks and discusses the ABCD constants that characterize different types of transmission lines from short to long. It also covers how power flow is affected by load power factor, with received voltage decreasing for lagging loads and increasing for leading loads. The power handling capability and limits of transmission lines are also summarized.
This document summarizes the simulation of a brushless DC motor (BLDC) fed by two types of multilevel inverters - a five-level diode clamped inverter and a five-level cascaded H-bridge inverter. It first describes the operating principles and switching techniques of the two inverter topologies. It then presents the modeling of the BLDC motor. Simulation results are shown for the firing pulses, line voltages, stator currents, back EMF, speed, torque, etc. of the BLDC motor when powered by each inverter configuration. The performance of the motor fed by the two multilevel inverters is compared.
Power Circuits and Transforers-Unit 8 Labvolt Student Manualphase3-120A
This exercise explores connecting transformers in parallel and measuring their efficiency. Two 100-VA transformers are connected in parallel to supply a 200-VA load. Efficiency is calculated as the ratio of output power to input power. Measurements of input and output power will be taken to determine the overall efficiency and verify that the load is shared between the two transformers. Connecting transformers in parallel allows supplying power greater than the rating of a single transformer.
Power Circuits and Transforers-Unit 6 Labvolt Student Manualphase3-120A
This document provides instruction on analyzing balanced three-phase AC circuits connected in wye and delta configurations. It discusses the differences between line and phase voltages and currents. Formulas are presented for calculating active, reactive, and apparent power in balanced three-phase circuits. Exercises are included to measure voltages and currents in wye- and delta-connected resistive loads to verify the theoretical calculations and relationships between line and phase values.
The document discusses steelmaking optimization in mini-mills using high impedance AC electric arc furnace (EAF) arc regulation with AMI Automation's Power Input Optimization system. It describes how using reactors and transformer taps allows operating the EAF at higher impedance for longer arcs with lower current and harmonics. Case studies show the system increased average power 3-5%, reduced energy and electrode consumption, and improved productivity at various steel mills. The system monitors conditions and automatically selects transformer taps and arc length to optimize power input over the heat.
Reactive Power Compensation and Control via Shunt Reactors and Under Ground P...IJERA Editor
In this paper we will cover the techniques used locally to accomplish the reactive power compensation. First, the importance of reactive power compensation is explained through defining the different types of electrical power and showing the effect of power compensation on the electric power network quality. The power under ground cable is the first technique used to compensate for the inductance of overhead transmission lines and power transformers during heavy loading of the network. Then, we explore the application of the two types of shunt reactors in different locations of the network to compensate for the capacitance of the network during light loading. Finally, a conclusion is presented.
This document provides information about magnetic circuits, transformers, and their components. It begins with reviewing laws of magnetism, flux, and their relationship. It then discusses analysis of magnetic circuits and single phase transformers. The document outlines basic concepts and construction features of transformers, including voltage and current transformation, equivalent circuits, and transformer tests.
journal publishing, how to publish research paper, Call For research paper, i...IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Modeling of Wind Energy on Isolated AreaIJPEDS-IAES
In this paper, a model of the wind turbine (WT) with permanent magnet generator (PMSG) and its associated controllers is presented. The increase of wind power penetration in power systems has meant that conventional power plants are gradually being replaced by wind farms. In fact, today wind farms are required to actively participate in power system operation in the same way as conventional power plants. In fact, power system operators have revised the grid connection requirements for wind turbines and wind farms and now demand that these installations be able to carry out more or less the same control tasks as conventional power plants. For dynamic power system simulations, the PMSG wind turbine model includes an aerodynamic rotor model, a lumped mass representation of the drive train system and generator model. In this paper we propose a model with an implementation in MATLAB / Simulink, each of the system components off-grid small wind turbines.
This document provides an overview of distribution transformers including their design, selection, operation, and efficiency. It discusses the need for large power stations and transformers to achieve economies of scale. It also covers transformer design components, equivalent circuits, vector groups, parallel operation, effects of nonlinear loads, and improvements in efficiency over time through better magnetic steel.
MATLAB Simulink for single phase PWM inverter in an uninterrupted power supplyIJMER
Now a day’s Uninterrupted power supply is very necessary for industry, and domestic purpose.
This paper presents the design and implementation of UPS for using personal computer. Here solar
energy is used for charging the battery in sunny days and in absence of solar energy it will automatically
connect to main AC supply. Also MATLAB simulation work is done for PWM single phase inverter and
full bridge rectifier.. Here microcontroller is used for switching between solar plate and main AC supply
to Battery. By using this method we can save our electricity bill which is consumed in charging of battery
This document provides an overview of transformers and their operation. It discusses:
- The history and development of transformers from the 1880s to present day
- The basic components and construction of transformers
- How an ideal transformer works based on Faraday's law of induction
- How voltages and currents are related in an ideal transformer based on turn ratios
- How real transformers approximate ideal transformer behavior
- Examples of analyzing circuits containing transformers by referring their sides
- The theory of operation for real single-phase transformers based on mutual and leakage fluxes
Power Circuits and Transforers-Unit 3 Labvolt Student Manualphase3-120A
This document discusses determining equivalent capacitance for series and parallel capacitors. It explains that capacitance opposes changes in voltage across capacitor terminals and depends on factors like dielectric material and plate size/spacing. The exercise objectives are to calculate equivalent capacitance using circuit measurements and explain how capacitance values combine in series and parallel configurations.
Pocket book on energy efficiency in elec systemsSuresh Kumar
This document discusses energy efficiency in electrical systems, focusing on transformers and motors. It provides information on transformer types, ratings, losses and efficiency optimization. Key points covered include:
1. Transformers are inherently very efficient but efficiency depends on load percentage, with maximum efficiency occurring between 40-60% for distribution transformers and 60-80% for power transformers.
2. Motor and transformer loads can be optimized through proper sizing and power factor correction techniques like capacitors to reduce losses and improve efficiency.
3. Harmonics from non-linear loads increase equipment losses and temperatures, potentially causing premature failure, so proper filtering is required. Standards help regulate harmonics levels.
Power Circuits and Transformers-Unit 2 Labvolt Student Manualphase3-120A
This document discusses alternating current (AC) and sine waves. It explains that AC voltage continually changes polarity and amplitude, and can be considered a DC voltage that is changing. The frequency of an AC voltage is the number of times per second its polarity changes. Sine waves are well-suited for electrical systems as they allow for efficient power transfer. Key parameters of sine waves include amplitude, frequency, phase, and phase shift. Circuit laws like Ohm's Law apply to AC circuits as well.
This document discusses the parameters of transmission lines. It covers:
1. The structure of power systems including generating stations, transmission lines, and distribution systems. Transmission lines transfer power from generating stations to distribution systems.
2. The parameters that characterize transmission lines including resistance, inductance, and capacitance. Resistance causes power losses while inductance and capacitance determine the line's electrical behavior.
3. The modeling of single and three-phase transmission lines, covering topics like loop inductance, symmetrical and asymmetrical conductor spacing, and their effects on voltage regulation.
Power Circuits and Transformers-Unit 4 Labvolt Student Manualphase3-120A
The document discusses equivalent inductance for series and parallel inductors. It states that equivalent inductance is greater for series combinations and smaller for parallel combinations, similar to equivalent resistance. Formulas are provided to calculate equivalent inductance for series and parallel configurations. The exercise objective is to determine equivalent inductance using these formulas and circuit measurements of voltage and current.
Power system is the transfer of electricity from generation to the point of user location. Power system is composed of generation of power, its transmission and distribution. Transmission system is the main part out of these three in which mostly losses occur. The unchanging factors of the transmission line on which these losses depend are inductance, resistance and capacitance. These constants or unchanging factors play a vital role in the performance of transmission line. For example the capacitance effect will be more and its performance will be affected if the height of transmission line is less from the ground. On the other hand its capacitance will be less but tension will be high if the height of the transmission is high. For this reason a transmission line is connected in a curved or catenary shape known as sag. To minimize tension sag is provided in a transmission line. Sag and tension must be adjusted in safe limits. This immediate paper gives a simulation structure to calculate sag and tension of AAAC (All Aluminum Alloy Conductors of overhead transmission lines with same span length for minimum operating temperature. Three different cases are presented with different towers height and are explained in detail for unequal level span. The results show that the tension and sag increased with height. So great the height difference, higher tensions upon higher towers.
Transformers are necessary in power systems to step up voltage for efficient transmission and step down voltage for safe distribution. They operate on the principle of electromagnetic induction and have a core made of laminated steel, with coils of wire wound around the core. The ratio of the number of turns in the primary and secondary windings determines the voltage transformation ratio. Power losses in transformers include copper losses from winding resistance and iron losses from hysteresis and eddy currents in the core. Efficiency is highest when load matches the ratio of iron to copper losses.
Power Circuits and Transforers-Unit 7 Labvolt Student Manualphase3-120A
This document discusses an exercise on measuring and understanding the voltage and current characteristics of a single-phase transformer. Key points include:
- Measurements showed that the ratio of primary to secondary voltage equals the transformer turns ratio, and the ratio of primary to secondary current equals the inverse of the turns ratio.
- Core saturation was observed at higher voltages, where the exciting current increased more rapidly and the voltage ratio was affected.
- The exercise demonstrated how to properly connect transformer windings in series-aiding and series-opposing configurations.
Swartley b santinia_maled_jaccinob-destructive-arcong-of-insulated-joints-in-...Gilberto Mejía
The document summarizes a study conducted by Metro-North Railroad and Long Island Rail Road to analyze destructive arcing occurring at insulated joints where electric trains change tracks. The study found that inductive elements in the railroads' traction power and train propulsion systems contribute to high voltages forming across insulated joints when train wheels break contact. Field testing was performed under various conditions to measure currents and voltages during arcing. The results suggest methods to mitigate arcing by reducing inductive effects in the traction return circuit and train circuits.
Power Circuits and Transforers-Unit 5 Labvolt Student Manualphase3-120A
* Active power (P) = 3 kW = 3,000 W
* Inductive reactive power (Q) = 4 kvar
* Using the power triangle:
* Apparent power (S) = √(P^2 + Q^2)
* = √(3,000^2 + 4,000^2)
* = √(9,000,000 + 16,000,000)
* = √25,000,000
* = 5,000 VA = 5 kVA
The apparent power is 5 kVA. The answer is b.
The document discusses electrical transmission lines and their key components. It describes how transmission lines can be modeled as 2-port networks and discusses the ABCD constants that characterize different types of transmission lines from short to long. It also covers how power flow is affected by load power factor, with received voltage decreasing for lagging loads and increasing for leading loads. The power handling capability and limits of transmission lines are also summarized.
This document summarizes the simulation of a brushless DC motor (BLDC) fed by two types of multilevel inverters - a five-level diode clamped inverter and a five-level cascaded H-bridge inverter. It first describes the operating principles and switching techniques of the two inverter topologies. It then presents the modeling of the BLDC motor. Simulation results are shown for the firing pulses, line voltages, stator currents, back EMF, speed, torque, etc. of the BLDC motor when powered by each inverter configuration. The performance of the motor fed by the two multilevel inverters is compared.
Power Circuits and Transforers-Unit 8 Labvolt Student Manualphase3-120A
This exercise explores connecting transformers in parallel and measuring their efficiency. Two 100-VA transformers are connected in parallel to supply a 200-VA load. Efficiency is calculated as the ratio of output power to input power. Measurements of input and output power will be taken to determine the overall efficiency and verify that the load is shared between the two transformers. Connecting transformers in parallel allows supplying power greater than the rating of a single transformer.
Power Circuits and Transforers-Unit 6 Labvolt Student Manualphase3-120A
This document provides instruction on analyzing balanced three-phase AC circuits connected in wye and delta configurations. It discusses the differences between line and phase voltages and currents. Formulas are presented for calculating active, reactive, and apparent power in balanced three-phase circuits. Exercises are included to measure voltages and currents in wye- and delta-connected resistive loads to verify the theoretical calculations and relationships between line and phase values.
The document discusses steelmaking optimization in mini-mills using high impedance AC electric arc furnace (EAF) arc regulation with AMI Automation's Power Input Optimization system. It describes how using reactors and transformer taps allows operating the EAF at higher impedance for longer arcs with lower current and harmonics. Case studies show the system increased average power 3-5%, reduced energy and electrode consumption, and improved productivity at various steel mills. The system monitors conditions and automatically selects transformer taps and arc length to optimize power input over the heat.
Reactive Power Compensation and Control via Shunt Reactors and Under Ground P...IJERA Editor
In this paper we will cover the techniques used locally to accomplish the reactive power compensation. First, the importance of reactive power compensation is explained through defining the different types of electrical power and showing the effect of power compensation on the electric power network quality. The power under ground cable is the first technique used to compensate for the inductance of overhead transmission lines and power transformers during heavy loading of the network. Then, we explore the application of the two types of shunt reactors in different locations of the network to compensate for the capacitance of the network during light loading. Finally, a conclusion is presented.
This document provides information about magnetic circuits, transformers, and their components. It begins with reviewing laws of magnetism, flux, and their relationship. It then discusses analysis of magnetic circuits and single phase transformers. The document outlines basic concepts and construction features of transformers, including voltage and current transformation, equivalent circuits, and transformer tests.
journal publishing, how to publish research paper, Call For research paper, i...IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Modeling of Wind Energy on Isolated AreaIJPEDS-IAES
In this paper, a model of the wind turbine (WT) with permanent magnet generator (PMSG) and its associated controllers is presented. The increase of wind power penetration in power systems has meant that conventional power plants are gradually being replaced by wind farms. In fact, today wind farms are required to actively participate in power system operation in the same way as conventional power plants. In fact, power system operators have revised the grid connection requirements for wind turbines and wind farms and now demand that these installations be able to carry out more or less the same control tasks as conventional power plants. For dynamic power system simulations, the PMSG wind turbine model includes an aerodynamic rotor model, a lumped mass representation of the drive train system and generator model. In this paper we propose a model with an implementation in MATLAB / Simulink, each of the system components off-grid small wind turbines.
Wind parks are made up of a large number of
saturable inductances (power transformers, inductive voltage
transformers (IVTs)), as well as capacitors (cables, wind turbine
harmonic filters, capacitor voltage transformers (CVTs), voltage
grading capacitors in circuit-breakers). Therefore, they may
present scenarios in which ferroresonance occurs. This paper
presents the scenarios that can lead to ferroresonant circuits in
doubly fed induction generator (DFIG) based wind parks.
Proposed PV Transformer-Less Inverter Topology Technique for Leakage Current ...IJPEDS-IAES
Importance and demand of using renewable energy is dramatically escalated globally. Hence, the use of renewable energy is going to touch in peak. This demand is varying according to the site choosing. For instance, Wind is preferable where air is following highly as well as solar recommended place is high sun ray reducing places. Especially, the renewable system is highly recommended for electrification issues where it’s possible to produce the electricity for fulfilling rural and remote areas electricity problem. The photovoltaic (PV) panel of connecting with transformer based system is popular where some limitations are occurred especially cost and weight. In contrast, in this paper is focusing these issues where the transformer-less inverter system is used. Here will discuss some transformer-based and transformer-less inverter topologies and the leakage current issue which is occurred when transformer-less inverter system is used. Moreover, here is proposed a topology for reducing the leakage current after doing switching technique in both 50% and 75% duty cycle where output voltage remains quite same.
Analysis and Modeling of Transformerless Photovoltaic Inverter SystemsIJMER
This document summarizes a research paper that analyzes and models transformerless photovoltaic inverter systems. It discusses:
- The need for decentralized renewable energy like solar to balance power demands and issues with transformer-based inverters.
- How transformerless inverters can have problems with leakage currents damaging solar panels and safety issues.
- Models developed for photovoltaic modules using mathematical equations to analyze output voltage and temperature based on light intensity and ambient temperature.
- A review of different transformerless inverter topologies like full bridge, half bridge, and their limitations in minimizing leakage currents.
- Simulation results of a developed dynamic model for a PV module in MATLAB/Sim
Wind-Driven SEIG Systems: A Comparison StudyCSCJournals
This document compares three methods for regulating the voltage and frequency of a wind turbine-driven self-excited induction generator (SEIG).
System 1 connects the SEIG to the load through a voltage source inverter, allowing control of output voltage by adjusting the inverter's modulation index while frequency is fixed. System 2 directly connects the load to the SEIG, using the inverter to provide additional reactive power and control voltage via modulation index as load varies. System 3 involves a doubly fed induction generator configuration.
Simulation results are presented comparing the output voltage and frequency regulation performance of the three systems under varying wind speed and load conditions. The advantages and disadvantages of each approach are highlighted, such as the need for pitch control
TCSC AND SVC OPTIMAL LOCATION TO IMPROVE THE PERFORMANCE OF POWER SYSTEM WITH...eeiej_journal
Wind generation connection to power system affects steady state and transient stability. Furthermore, this
effect increases with the increase of wind penetration in generation capacity. In this paper optimal location
of FACTS devices is carried out to solve the steady state problems of wind penetration. Two case studies
are carried out on modified IEEE39 bus system one with wind reduction to 20% and the second with wind
penetration increase by 50% in the two cases system suffer from outage of one generator with load at bus
39 decreases from 1104 MW to 900 MW.
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.
IRJET- FPGA Controlled Three Level Diode Clamped Multilevel Inverter for Sola...IRJET Journal
This document discusses a three-level diode clamped multilevel inverter controlled by an FPGA for a solar PV system. It begins with an abstract that outlines the working principle and simulation of the FPGA-controlled three-level inverter fed by a solar PV DC bus. It then discusses the principles of two-level and multilevel inverters, focusing on the diode clamped topology. The document introduces the proposed three-level diode clamped inverter with FPGA control and discusses its advantages like fast switching speeds and low cost. It then shows simulations of the system in MATLAB Simulink and Xilinx, including waveforms that demonstrate the stepped output waveform and reduced harmonics.
Renewable Energy Harvesting Using SuperCapacitorIRJET Journal
This document summarizes research on renewable energy harvesting using supercapacitors. It discusses using supercapacitors instead of batteries for energy storage in low-power smart sensor systems. Various energy transducers are described that convert ambient energy sources like solar, thermal, vibration and wireless power into electricity. Circuit designs are discussed that maximize energy harvesting efficiency and charge supercapacitors. Key advantages of supercapacitors over batteries are their longer lifecycles, faster charging/discharging, and ability to withstand many charge/discharge cycles. The document concludes supercapacitor-based energy harvesting can enable cost-effective, compact and long-lived smart sensor nodes.
Analysis characteristics of power PV cells and wind turbine from power genera...IOSR Journals
This paper presents the implementation of a generalized photovoltaic model using Matlab Simulink
software package, which can be representative of PV cell, module, and array for easy use on simulation
platform. The proposed model is designed with a user-friendly icon and a dialog box like Simulink block
libraries. This makes the generalized PV model easily simulated and analyzed in conjunction with power
electronics for a maximum power point tracker. Taking the effect of sunlight irradiance and cell temperature
into consideration, the output current and power characteristics of PV model are simulated and optimized using
the proposed model. This enables the dynamics of PV power system to be easily simulated, analyzed, and
optimized.
For Wind Turbine modeling and simulation of wind driven electricity generation system or WECS (an
acronym for Wind Energy Conversion System) has been done. Our aim is to design and test a power 300W
capacity, operating at 3 m/s to 6 m/s , induction permanent magnet generator Matlab simulation. The different
components of a wind energy system namely the wind turbine, generator, rectifier, as per the scope of this
project following which the design steps and modeling of the system in Matlab simulation environment -
Simulink was undertaken
IRJET- Transmission of Ac Power from Offshore to Onshore by using Low Frequen...IRJET Journal
This document discusses the transmission of AC power from offshore wind farms to onshore grids using low frequency AC transmission. Some key points:
1) Offshore wind farms generate power at medium voltage DC which is converted to low frequency AC (e.g. 20Hz) using cycloconverters for transmission through undersea cables.
2) At the receiving end, the low frequency AC is converted back to standard grid frequency AC using phase shift transformers before connecting to the onshore grid.
3) Low frequency AC transmission allows use of the same undersea cable designs as used for standard frequency but increases transmission capacity and distance. It provides an alternative to HVAC and HVDC transmission for medium length offshore connections.
How to conduct the lightning impulse withstand test on 550kv GIS?Fang Sam
Abstract: With the rapid development of power grid in China, an increasing number of GIS are adopted in new substations. The lightning impulse test is recommended after the installation of GIS in order to check its insulation performance and reduce the risk of equipment failure. However, owing to the design and production, common lightning impulse generator with large capacitance load especially GIS cannot generate lightning impulse waveform, which meets the requirement. Therefore, based on lightning impulse withstand test of Three Gorges Right Bank 550kV GIS, models of lightning impulse generator and field equipment are established, and simulation calculation is done. According to the result, a method of installing the inductor in the impulse circuit is put forward to generate oscillating lightning impulse which meets the requirement of the test. This method is successfully applied in the test and results are good. Valuable experience has been accumulated for the lightning impulse test on GIS of 750kV, 1000kV substations in China. (http://www.himalayal.com/Impulse-Generator/HowtoConductLightningImpulseTestOnGIS.html)
Improved Control Strategy for Low Voltage Ride Through Capability of DFIG wit...ecij
This paper deals with a protection and control strategy to enhance the low voltage ride through capability of a wind turbine driven doubly fed induction generator (DFIG). As the wind power penetration continues to increase, wind turbines are required to provide Low Voltage Ride-Through (LVRT) capability. Crowbars are commonly used to protect the power converters during voltage dips and their main drawback is that the DFIG absorbs reactive power from the grid during grid faults. According to emergency grid code requirements, wind farms should have the ability to stay connected and continue generation under external voltage failure conditions, that is, wind turbines have to keep in connection with grid and own continue reactive power supply. This paper proposes a hysteresis current control strategy for the crowbar protection
and a reactive power control to satisfy the grid code requirements. Consequently, the dynamic model of double fed wind turbines is established to study the transient behavior of DFIG. Simulation results are presented to show the effectiveness of the proposed control scheme.
Wind turbine doubly-fed induction generator defects diagnosis under voltage dipsTELKOMNIKA JOURNAL
Voltage dips are brief but frequent disturbances that can be defined as the most important problem affecting all electrical grids, it cannot be completely avoided and represent the main priority for the industry. This study remains part of monitoring the quality of electrical energy’s field. Its aim is to apply two approaches signals for improving the failure recognition in wind turbine conversion chain. One is based on the combination of spectral analysis of stator current by fast Fourier transform and Lissajous curves technique of grid currents. The second approach is based on the stator current analysis by discrete wavelet transform which is considered an ideal tool for this purpose due to its time-frequency localization. These defects diagnosis methods have shown their efficiency in detection, visualization and analysis of voltage dips in order to develop a control strategy for a wind turbine requiring continuity of its service despite the presence of voltage dips.
Power factor and Quality improvement of Wind based system with Fuzzy Logic Co...IRJET Journal
This document summarizes a research paper that proposes using a thyristor inductive filter (TIF) and static synchronous compensator (STATCOM) to improve the power quality and power factor of a wind power system connected to the grid. It presents the main circuit topology of the system, which includes double-fed induction generators, a new grid-connected transformer with filtering windings, and TIF branches and STATCOM connected to the filtering windings. Mathematical models are developed to analyze the harmonic filtering mechanism and reactive power compensation characteristics of the system. Simulation results indicate the approach can enhance the low-voltage ride-through capability of wind turbines and prevent harmonics from flowing into the grid.
IRJET- Improved IUPQC Controller to Provide Grid Voltage as a STATCOMIRJET Journal
This document discusses an improved controller for the integrated Unified Power Quality Conditioner (iUPQC) that expands its capabilities. The iUPQC can now provide reactive power support to regulate both the load bus voltage and grid side bus voltage, allowing it to function as a Static Synchronous Compensator (STATCOM) on the grid side while still providing conventional UPQC compensation on the load side. Experimental results confirm the new functionality of the device. The iUPQC with the enhanced controller provides power quality compensation like a UPQC as well as reactive power and voltage regulation like a STATCOM.
Wind energy conversion systems using fuzzy controlled statcom for power quaIAEME Publication
This document summarizes a research paper that investigates power quality issues when connecting a wind energy conversion system to a distribution system. A fuzzy controlled static compensator (F-STATCOM) is proposed to mitigate harmonics produced at the source and load sides. The F-STATCOM controller is modeled and simulated in MATLAB/Simulink. Simulation results show that the F-STATCOM is effective at reducing total harmonic distortion and improving power quality by minimizing voltage variations and harmonics at both the source and load sides.
PROJECT DESCRIPTION
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The main objective of this project is to develop a device for wireless power transfer. The concept of wireless power transfer was realized by Nikolas tesla. Wireless power transfer can make a remarkable change in the field of the electrical engineering which eliminates the use conventional copper cables and current carrying wires.
Based on this concept, the project is developed to transfer power within a small range. This project can be used for charging batteries those are physically not possible to be connected electrically such as pace makers (An electronic device that works in place of a defective heart valve) implanted in the body that runs on a battery.
The patient is required to be operated every year to replace the battery. This project is designed to charge a rechargeable battery wirelessly for the purpose. Since charging of the battery is not possible to be demonstrated, we are providing a DC fan that runs through wireless power.
This project is built upon using an electronic circuit which converts AC 230V 50Hz to AC 12V, High frequency. The output is fed to a tuned coil forming as primary of an air core transformer. The secondary coil develops a voltage of HF 12volt.
Thus the transfer of power is done by the primary(transmitter) to the secondary that is separated with a considerable distance(say 3cm). Therefore the transfer could be seen as the primary transmits and the secondary receives the power to run load.
Moreover this technique can be used in number of applications, like to charge a mobile phone, iPod, laptop battery, propeller clock wirelessly. And also this kind of charging provides a far lower risk of electrical shock as it would be galvanically isolated.
Power Quality Improvement Using Custom Power Devices in Squirrel Cage Inducti...IJPEDS-IAES
1) The document describes a system using a UPQC (Unified Power Quality Conditioner) to improve power quality when connecting a squirrel cage induction generator wind farm to a weak grid. The UPQC regulates the wind farm terminal voltage and mitigates harmonics at the point of common coupling.
2) It uses a neuro-fuzzy control strategy to manage the active and reactive power exchange between the series and shunt converters of the UPQC via the DC link.
3) Simulation results show the UPQC is able to compensate for voltage fluctuations at the point of common coupling due to variations in wind power generation and regulate the voltage during load connection/disconnection events.
Similar to Towards An Accurate Modeling of Frequency-dependent Wind Farm Components Under Transient Conditions (20)
Effects of the Droop Speed Governor and Automatic Generation Control AGC on G...IJAPEJOURNAL
In power system, as any inequality between production and consumption results in an instantaneous change in frequency from nominal, frequency should be always monitored and controlled. Traditionally, frequency regulation is provided by varying the power output of generators which have restricted ramp rates. The Automatic Generation Control AGC process performs the task of adjusting system generation to meet the load demand and of regulating the large system frequency changes. A result of the mismatches between system load and system generation, system frequency and the desired value of 50 Hz is the accumulation of time error. How equilibrium system frequency is calculated if load parameters are frequency dependent, and how can frequency be controlled. Also, how do parameters of a speed governor affect generated power. The transient processes before system frequency settles down to steady state. Finally, AGC in what way is it different from governor action. This paper presents new approaches for AGC of power system including two areas having one steam turbines and one hydro turbine tied together through power lines.
Underwater Target Tracking Using Unscented Kalman FilterIJAPEJOURNAL
Unlike conventional active sonar, that transmits the sound signals and revealing their presence and position to enemy forces. The probable advantage of passive sonar is that it detects the signals emitted by the target, leads to improve localization, target tracking, and categorization. The challenging aspect is to estimate the true bearing and frequency measurements from the noisy measurements of the target. Here in this paper, it is recommended for the Unscented Kalman Filter (UKF) to track the target by using these noisy measurements. The Target Motion Analysis (TMA), which is the way to find the target’s trajectory by using frequency and bearing measurements, is explored. This method provides a tactical advantage over the classical bearing only tracking target motion analysis. It makes the observer maneuver unnecessary.
Investigation of Dependent Rikitake System to Initiation PointIJAPEJOURNAL
In this paper we investigate depending of the Rikitake system to initiation point, and monitor changing behavior of this system. We will have 4 initiation points in Cartesian system. We at 4 positions, will monitor behavior of this system, while holding constant other values, and after per position, will draw operation of system on axes of x, y, z and 3-D plot. We want to know, what is the effect of initiation point on Rikitake system? Numerical simulations to illustrate the effect of initiation point are presented, and at the end conclusions and comparing the states together are obtained.
Optimization of Economic Load Dispatch with Unit Commitment on Multi MachineIJAPEJOURNAL
Economic load dispatch (ELD) and Unit Commitment (UC) are significant research applications in power systems that optimize the total production cost of the predicted load demand. The UC problem determines a turn-on and turn-off schedule for a given combination of generating units, thus satisfying a set of dynamic operational constraints. ELD optimizes the operation cost for all scheduled generating units with respect to the load demands of customers. The first phase in this project is to economically schedule the distribution of generating units using Gauss seidal and the second phase is to determine optimal load distribution for the scheduled units using dynamic programming method is applied to select and choose the combination of generating units that commit and de-commit during each hour. These precommitted schedules are optimized by dynamic programming method thus producing a global optimum solution with feasible and effective solution quality, minimal cost and time and higher precision. The effectiveness of the proposed techniques is investigated on two test systems consisting of five generating units and the experiments are carried out using MATLAB R2010b software. Experimental results prove that the proposed method is capable of yielding higher quality solution including mathematical simplicity, fast convergence, diversity maintenance, robustness and scalability for the complex ELD-UC problem.
Impact of Buried Conductor Length on Computation of Earth Grid ResistanceIJAPEJOURNAL
Effective design of substation earth grid implies achieving low earth grid resistance and fulfillment of the safety criteria at the lowest possible cost. This paper presents an evaluation of IEEE Standard 80-2000 Equations 50 to 52 to determine the impact of buried conductor length on computation of earth grid resistance. Calculated results indicated that a saturation point is reached beyond which further addition of more conductor length does not significantly reduce the earth grid resistance but incurs more economic implications. These were validated by earth grids designed using CDEGS where good agreement between the calculated and simulated results was found.
Enhancing Photoelectric Conversion Efficiency of Solar Panel by Water CoolingIJAPEJOURNAL
Photovoltaic solar cell generates electricity by receiving solar irradiance. The electrical efficiency of photovoltaic (PV) cell is adversely affected by the significant increase of cell operating temperature during absorption of solar radiation. This undesirable effect can be partially avoided by cooling the back side of the photovoltaic panel using water absorption sponge which was fixed on of PV panel and maintain wet condition by circulation of drop by drop water. The objective of the present work is to reduce the temperature of the solar cell in order to increase its electrical efficiency. Experiments were performed with and without water cooling. A linear trend between the efficiency and temperature was found. Without cooling, the temperature of the panel was high and solar cells were achieved an efficiency of 8–9%. However, when the panel was operated under water cooling condition, the temperature dropped maximally by 40C leading to an increase in efficiency of solar cells by 12%.
PMU-Based Transmission Line Parameter Identification at China Southern Power ...IJAPEJOURNAL
China Southern Power Grid Company (CSG) recently developed and implemented an online PMU-based transmission line (TL) parameter identification system (TPIS). Traditionally, TL parameters are calculated based on transmission tower geometries, conductor dimension, estimates of line length, conductor sags, etc. These parameters only approximate the effect of conductor sag and ignore the dependence of impedance parameters on temperature variation. Recent development in PMU technology has made it possible to calculate TL parameters accurately. The challenges are that such application requires highly accurate PMU data while the accuracy of PMU measurements under different working/system conditions can be uncertain. With a large number of PMUs widely installed in its system, CSG plans to improve and update the EMS database using the newly developed TPIS. TPIS provides an innovative yet practical problem formulation and solution for TL parameter identification. In addition, it proposes a new metric that can be used to determine the credibility of the calculated parameters, which is missing in the literature. This paper discusses the methodologies, challenges, as well as implementation issues noticed during the development of TPIS.
Investigation of Electric Field Distribution Inside 500/220 kV Transformation...IJAPEJOURNAL
This study depicts the electric field distributions inside a typical 500/220 kV open distribution substation under actual loading conditions and during different working conditions, Hot-Stick position and Bar-Hand position. The electric field is investigated for different workers heights of 1m, 1.5m and 1.8m above ground during normal working condition (Hot-Stick position) inside this substation. This in addition to assessment of the electric field at a height levels of 8m, 11m, 14m and 17m above ground as positions for live line maintenance under 220 kV Busbars, 500 kV Busbars, 220 kV Incoming and Outgoing feeders and 500 kV Incoming and Outgoing feeders respectively. In this study the simulation results of the electric field obtained using three dimensional (3D) computer model for existing typical high voltage transformation substation are compared with field values measured inside this typical substation and presented and discussed not only in the form of contour maps but also in the form 3D surface and wireframe maps. The simulation results are good matched and agreed with measured values. This in addition to the electric field will be tabulated and compared to international guidelines for personnel exposure to electric field. This study will serve for planning service works or for inspection of equipment inside high voltage (HV) power transformation substations.
Economic Load Dispatch for Multi-Generator Systems with Units Having Nonlinea...IJAPEJOURNAL
This document presents an economic load dispatch problem that uses the Gravity Search Algorithm to minimize total generation costs for multi-generator power systems. It discusses how practical constraints like valve point loading, multi-fuel operation, and forbidden zones result in non-ideal, non-continuous generator cost curves. The Gravity Search Algorithm is applied to find the optimal dispatch schedule that accounts for these realistic cost functions and minimizes the total cost of generation while satisfying demand. The algorithm is tested on sample power systems and able to find solutions within acceptable timeframes that outperform traditional optimization methods for large, complex problems.
Improving Light-Load Efficiency by Eliminating Interaction Effect in the Grid...IJAPEJOURNAL
A wind turbine equipped with doubly-fed induction generator (DFIG) is used in wind power plant industry. This paper studies the maximum power extraction of DFIG via evaluation of state-space equations in closed loop control condition for improving light-load efficiency. The DFIG state-space equations have been considered in the form of a multi-input- multi output (MIMO) system. Also, the tracing table has been used to determine the speed which the generated power will be proportional to the maximum load. The tracing table input is the generator speed, and its output is the optimum active power that has been considered as the reference power of the active power control system of the convertor. A controller is presented for the tracing table and the extracted power is able to follow the reference power with minimum ripple. Then, the results are compared with the single-input and single-output (SISO) case, for the values up to 0.2 times of the rated load. Therefore, in MIMO modeling, in the case that the DFIG connected to the grid, by eliminating the interaction effect, the efficiency in light-load can be increased
An Application of Ulam-Hyers Stability in DC MotorsIJAPEJOURNAL
In this paper, a generalization to nonlinear systems is proposed and applied to the motor dynamic, rotor model and stator model in DC motor equation. We argue that Ulam-Hyers stability concept is quite significant in design problems and in design analysis for the class of DC motor’s parameters. We prove the stability of nonlinear partial differential equation by using Banach’s contraction principle. As an application, the Ulam-Hyers stability of DC motor dynamics equations is investigated. To the best of our knowledge this is the first time Ulam-Hyers stability is considered from the applications point of view.
Implementation of Hybrid Generation Power System in PakistanIJAPEJOURNAL
A solar-wind hybrid power generation system has been presented here. The application based system illustrated in this paper is designed on the basis of the solar and wind data for Pakistan. The power generated by the system is intended for domestic use. The most common source of unconventional power in homes is battery based UPS (Uninterrupted power supply) inverter. The UPS inverter charges the battery with conventional grid power. This system will charge the battery of UPS inverter by using only wind and solar power, which will make the system cost effective and more reliable. The reason for using both solar and wind is that recent studies have proven that combined system can be more productive and consistent and other thing is that neither of them can be used for continuous power generation. In the system illustrated in this paper the solar-wind system provides power periodically which is controlled by electronic methods and a microcontroller is used to monitor the power from both the inputs. The switching action is provided from the microcontroller to the battery charging based on the power received from solar photovoltaic panel and wind generators. In this paper, an efficient system has been presented comprising of solar panel, wind generator, charge controller and charge storage unit (battery). Solar panel is selected as the main input and the wind resource will be used only in the absence of the solar photovoltaic (PV) output.
Modeling and Simulation of SVPWM Based ApplicationIJAPEJOURNAL
Recent developments in power electronics and semiconductor technology have lead to widespread use of power electronic converters in the power electronic systems. A number of Pulse width modulation (PWM) schemes are used to obtain variable voltage and frequency supply from a three-phase voltage source inverter. Among the different PWM techniques proposed for voltage fed inverters, the sinusoidal PWM technique has been popularly accepted. But there is an increasing trend of using space vector PWM (SVPWM) because of their easier digital realization, reduced harmonics, reduced switching losses and better dc bus utilization. This project focuses on step by step development of SVPWM technique. Simulation results are obtained using MATLAB/Simulink software for effectiveness of the study.
Comparison of FACTS Devices for Two Area Power System Stability Enhancement u...IJAPEJOURNAL
This document compares the performance of SVC and STATCOM FACTS devices for enhancing transient stability in a two-area power system modelled in MATLAB. It first provides background on power system stability challenges and the role of FACTS devices in addressing these issues. It then reviews previous research comparing different FACTS devices. The paper models an SVC and STATCOM controller in MATLAB and simulates their performance under a three-phase fault. Simulation results indicate that the STATCOM controller provides better damping of rotor angle oscillations, suggesting it enhances transient stability more than the SVC in the two-area power system model.
Influence of Static VAR Compensator for Undervoltage Load Shedding to Avoid V...IJAPEJOURNAL
In the recent years, operation of power systems at lower stability margins has increased the importance of system protection methods that protect the system stability against various disturbances. Among these methods, the load shedding serves as an effective and last-resort tool to prevent system frequency/voltage instability. The analysis of recent blackouts suggests that voltage collapse and voltage-related problems are also important concerns in maintaining system stability. For this reason, voltage also needs to be taken into account in load shedding schemes. This paper considers both parameters in designing a load shedding scheme to determine the amount of load to be shed and its appropriate location .The amount of load to be shed from each bus is decided using the fixed step size method and it’s location has been identified by using voltage collapse proximity index method. SVC is shunt connected FACTS device used to improve the voltage profile of the system. In this paper impact of SVC on load shedding for IEEE 14 bus system has been presented and analyzed.
Assessment of Electric Field Distribution Inside 500/220 kV Open Distribution...IJAPEJOURNAL
The high level electric field intensity produced by high voltage (HV) equipments inside 500/220 kV substations is harmful for the human (staff) health. Therefore the minimum health and safety requirements regarding the exposure of workers to the risk arising from electric fields produced inside these substations is still considered as a competitive topic for utility designers, world health organization (WHO) and biomedical field researchers. It is very important to have knowledge about levels distribution of electric field intensity within these high voltage substations as early stage in the process of substation design. This paper presents results of investigation 50Hz electric field intensity distribution inside 500/220 kV power transmission substations in Cairo, Egypt. This paper presents a method for assessment the distribution of 50HZ electric field intensity distribution inside this substation, this method of analysis is based on the charge simulation technique (CSM). This study will serve for planning service works or for inspection of equipment on HV power transmission substations.
Hybrid Generation Power System for Domestic ApplicationsIJAPEJOURNAL
This work presents the plan and model of the control strategy for the interconnection of the hybrid energy system able to regulating this load’s voltage and controlling the energy generation with the energy options. The control strategy contains controlling the energy generated through each energy source, in a hierarchical mode using sliding/dropping mode control, while consuming consideration elements that have an impact on each electrical power source and transform the energy generated in order to suitable circumstances for lower power and domestic programs. The cross alternative energy system consists of photovoltaic cellular material, fuel cellular material and battery packs. A numerical equation in order to estimate the perfect voltage involving photovoltaic systems for virtually every solar irradiance and temperature circumstances is suggested. Simulations of a single or a lot more systems interconnected towards the load with the entire proposed control scheme, under different ecological and weight conditions, usually are introduced to indicate this efficiency with the procedure.
Ash Cooler Heat Recovery Under Energy Conservation SchemeIJAPEJOURNAL
A healthy fluidization state in circulating fluidized-bed combustion (CFBC) combustor is attributed to proper quantity of hot bed material (ash), which acts as a thermal fly-wheel. It receives & stores thermal energy from the burning of fuel (lignite) & distributes uniformly throughout the combustor & helps in maintaining a sustained combustion. The quantity of bed ash inside the combustor or size of the bed, depends upon boiler load & subsequently upon combustor temperature, lignite feed rate and ash % in lignite. As these parameters varies during process continuously, sometimes it becomes necessary to drain out the ash from the combustor. As & when differential pressure across the bed is increased from a justified level, draining of hot bed ash starts into Ash Coolers. Bed ash is drained at very high temperature of 850 oC & it also contains burning particles of lignite. This paper describes the heat recovery from bed ash, unloaded from the combustor into ash cooler, by pre-heating the condensate water of turbine cycle in a 125 MW CFB boiler of Surat Lignite Power Plant in India. The thermal performance of ash cooler was derived by doing a heat balance calculation based on the measured temperature of ash and cooling water with different load. From the heat balance calculation influence of ash temperature and ash amount on heat transfer coefficient is determined. Simulation is carried out around main turbine cycle indicates improved thermal economy of the unit, higher plant thermal efficiency, lower plant heat rate and reduce fuel consumption rate. Also simulation result shows that the heat transfer coefficient increase with ash amount and decreases with increase in ash temperature.
Harmonic Voltage Distortions in Power Systems Due to Non Linear LoadsIJAPEJOURNAL
This document summarizes research on harmonic voltage distortions in power systems due to non-linear loads. It describes how non-linear loads can generate harmonics and discusses their effects. It also examines harmonic reduction methods like passive filters. The research uses MiPower software to model a sample IEEE 5-bus power system and analyze harmonic distortions with and without filters. Installation of single and dual passive filters at different buses is shown to significantly reduce total harmonic distortion throughout the system. The document concludes that accurate harmonic analysis of power systems can be achieved using such simulation tools.
A Survey on Quality Changes in Positive, Negative and Combined Switching Stra...IJAPEJOURNAL
In this paper uses positive, negative and combined switching strategies for three phase ac/ac matrix converter .the author compares these strategies. The performance comparison of these three strategies is made under balanced operation. The simulation of three phase matrix converter feeding a three phase load was accomplished by means of the matlab/simulink software. After the simulation the comparison of the waveforms THD in three switching sequence is done. It must be mentioned that the duty cycle of the whole switches in the converter is according to Venturini switching algorithm
artificial intelligence and data science contents.pptxGauravCar
What is artificial intelligence? Artificial intelligence is the ability of a computer or computer-controlled robot to perform tasks that are commonly associated with the intellectual processes characteristic of humans, such as the ability to reason.
› ...
Artificial intelligence (AI) | Definitio
Discover the latest insights on Data Driven Maintenance with our comprehensive webinar presentation. Learn about traditional maintenance challenges, the right approach to utilizing data, and the benefits of adopting a Data Driven Maintenance strategy. Explore real-world examples, industry best practices, and innovative solutions like FMECA and the D3M model. This presentation, led by expert Jules Oudmans, is essential for asset owners looking to optimize their maintenance processes and leverage digital technologies for improved efficiency and performance. Download now to stay ahead in the evolving maintenance landscape.
Null Bangalore | Pentesters Approach to AWS IAMDivyanshu
#Abstract:
- Learn more about the real-world methods for auditing AWS IAM (Identity and Access Management) as a pentester. So let us proceed with a brief discussion of IAM as well as some typical misconfigurations and their potential exploits in order to reinforce the understanding of IAM security best practices.
- Gain actionable insights into AWS IAM policies and roles, using hands on approach.
#Prerequisites:
- Basic understanding of AWS services and architecture
- Familiarity with cloud security concepts
- Experience using the AWS Management Console or AWS CLI.
- For hands on lab create account on [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
# Scenario Covered:
- Basics of IAM in AWS
- Implementing IAM Policies with Least Privilege to Manage S3 Bucket
- Objective: Create an S3 bucket with least privilege IAM policy and validate access.
- Steps:
- Create S3 bucket.
- Attach least privilege policy to IAM user.
- Validate access.
- Exploiting IAM PassRole Misconfiguration
-Allows a user to pass a specific IAM role to an AWS service (ec2), typically used for service access delegation. Then exploit PassRole Misconfiguration granting unauthorized access to sensitive resources.
- Objective: Demonstrate how a PassRole misconfiguration can grant unauthorized access.
- Steps:
- Allow user to pass IAM role to EC2.
- Exploit misconfiguration for unauthorized access.
- Access sensitive resources.
- Exploiting IAM AssumeRole Misconfiguration with Overly Permissive Role
- An overly permissive IAM role configuration can lead to privilege escalation by creating a role with administrative privileges and allow a user to assume this role.
- Objective: Show how overly permissive IAM roles can lead to privilege escalation.
- Steps:
- Create role with administrative privileges.
- Allow user to assume the role.
- Perform administrative actions.
- Differentiation between PassRole vs AssumeRole
Try at [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
Rainfall intensity duration frequency curve statistical analysis and modeling...bijceesjournal
Using data from 41 years in Patna’ India’ the study’s goal is to analyze the trends of how often it rains on a weekly, seasonal, and annual basis (1981−2020). First, utilizing the intensity-duration-frequency (IDF) curve and the relationship by statistically analyzing rainfall’ the historical rainfall data set for Patna’ India’ during a 41 year period (1981−2020), was evaluated for its quality. Changes in the hydrologic cycle as a result of increased greenhouse gas emissions are expected to induce variations in the intensity, length, and frequency of precipitation events. One strategy to lessen vulnerability is to quantify probable changes and adapt to them. Techniques such as log-normal, normal, and Gumbel are used (EV-I). Distributions were created with durations of 1, 2, 3, 6, and 24 h and return times of 2, 5, 10, 25, and 100 years. There were also mathematical correlations discovered between rainfall and recurrence interval.
Findings: Based on findings, the Gumbel approach produced the highest intensity values, whereas the other approaches produced values that were close to each other. The data indicates that 461.9 mm of rain fell during the monsoon season’s 301st week. However, it was found that the 29th week had the greatest average rainfall, 92.6 mm. With 952.6 mm on average, the monsoon season saw the highest rainfall. Calculations revealed that the yearly rainfall averaged 1171.1 mm. Using Weibull’s method, the study was subsequently expanded to examine rainfall distribution at different recurrence intervals of 2, 5, 10, and 25 years. Rainfall and recurrence interval mathematical correlations were also developed. Further regression analysis revealed that short wave irrigation, wind direction, wind speed, pressure, relative humidity, and temperature all had a substantial influence on rainfall.
Originality and value: The results of the rainfall IDF curves can provide useful information to policymakers in making appropriate decisions in managing and minimizing floods in the study area.
Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
This paper describes a speed control device for generating electrical energy on an electricity network based on the doubly fed induction generator (DFIG) used for wind power conversion systems. At first, a double-fed induction generator model was constructed. A control law is formulated to govern the flow of energy between the stator of a DFIG and the energy network using three types of controllers: proportional integral (PI), sliding mode controller (SMC) and second order sliding mode controller (SOSMC). Their different results in terms of power reference tracking, reaction to unexpected speed fluctuations, sensitivity to perturbations, and resilience against machine parameter alterations are compared. MATLAB/Simulink was used to conduct the simulations for the preceding study. Multiple simulations have shown very satisfying results, and the investigations demonstrate the efficacy and power-enhancing capabilities of the suggested control system.
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
Sinan from the Delivery Hero mobile infrastructure engineering team shares a deep dive into performance acceleration with Gradle build cache optimizations. Sinan shares their journey into solving complex build-cache problems that affect Gradle builds. By understanding the challenges and solutions found in our journey, we aim to demonstrate the possibilities for faster builds. The case study reveals how overlapping outputs and cache misconfigurations led to significant increases in build times, especially as the project scaled up with numerous modules using Paparazzi tests. The journey from diagnosing to defeating cache issues offers invaluable lessons on maintaining cache integrity without sacrificing functionality.
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for simulating transient due to lightning is based on the representation of the wind farm components by their
equivalent circuits. Performance of wind farm under lightning requires accurate modeling of its components.
So in this paper wind farm is implemented using high frequency models components as SA, Transformer and
ground electrode to integrally describe this lightning current path. Validation of these models and
computation, characteristics and hazards of back-flow surge in wind farm are analyzed using onshore wind
farm as an example.
2. DESCRIPTION OF THE INVESTIGATED ONSHORE WIND FARM:
Figure1. Shows layout of onshore wind farm composed of two identical wind power generators.
Boost transformers for the generators are installed in vicinity of the wind turbine towers. All boost
transformers are connected to the grid via grid-interactive transformer by overhead distribution line. Surge
arresters are inserted to the primary and secondary sides of the boost and grid-interactive transformers.
Figure 1.Wind farm model [2]
3. MODELING OF THE ELECTRIC COMPONENTS OF THE ONSHORE WIND FARM USING
ATP/EMTP:
In this section, the detailed high frequency modeling of the electric components of the onshore wind
farm using the ATP/EMTP is demonstrated. These components include Transmission line (TL), transformers,
power system grid and surge arresters.
3.1. Lightning Model:
In order to simulate the impact of lightning current on power system or its components with
convenience, the lightning current in the mode of mathematical function is usually represented. After the
long-term speculation and research by many researchers, the approximate mathematical function was
proposed. A current function model called Heidler is now used widely [3, 4, 5]. A 400 Ω lightning path
resistance was parallelly connected to simulate natural lightning. Equation (1) represent the lightning current,
waveform of 51kA-2/631μs is used in this study as shown in Figure 2. The waveform of Heidler lightning
current is simulated by ATP/EMTP software.
2/
2
1
2
1
]1)/[(
)/(
)(
t
o e
t
t
Iti
(1)
Where
I0: the peak of current
τ1, τ2: time constants of current rising and dropping
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Figure 2. The Waveform of 51ka - 2/631μs Lightning Current
3.2. Wind Turbine Generator:
Table 1 gives the required data for modeling the generators of the wind turbines, transmission line
and transformers.
Table 1 a, b, c. Wind Turbines, Transformers Data and connected line data [2]
Wind Turbine Model(Synchronous Generator- Y connected)
Voltage (line rms) 0.660 [kV]
Rated power 1.0 [MVA]
Leakage reactance 0.1 [H]
Frequency 60.0 [Hz]
Transformer Model (Boost, Grid-Interactive)
Connection method Y / Δ , Y / Δ
Voltage (line rms) 0.660/6.6 [kV], 66.0/6.6 [kV]
Rated power 1.0 [MVA], 10.0 [MVA]
Leakage reactance 0.15 [p.u]
Copper losses 0.005 [p.u]
No-load losses neglected
Line Model (values at 60 Hz)
positive / zero phase resistance [Ω/Km] 0.00105/0.021
Positive / zero phase inductance [mH/Km] 0.83556/2.50067
Positive / zero phase capacitance [nF/Km] 12.9445/6.4723
3.3. Wind Turbine Blades and Towers:
The down conductor in the blade and the wind turbine tower have been considered as a lossless
transmission line and they were estimated according to following experimental equation [4, 5, 6, 7], where
the down conductor and the tower often were treated as a cylindrical conductor. Equation (2) represents the
characteristic impedance of tower and the blade.
(f ile modelwind11.pl4; x-v ar t) c:XX0007-X0081A
0.0 0.2 0.4 0.6 0.8 1.0 1.2[ms]
0
10
20
30
40
50
60
[kA]
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)2
22
(ln60 h
r
Z (2)
Where, Z is the surge impedance, r and h are the cylinder radius and height, respectively. The wind
tower is taken as an iron vertical conductor of 60 m height and 3.0 m radius.
3.4. Transmission Lines and cables:
The overhead lines are considered and represented by single-phase positive wave impedance (i.e.
Surge impedance) with the light velocity.
CL/Z0 (3)
sm
LC
v /
1
(4)
Where, C and L are the capacitance and inductance of line, respectively, Z0 is the surge impedance and
v is the propagation velocity [3, 8].
3.5. Transformer:
In order to study the transient involving frequencies up to a few kHz, stray capacitance of
transformer coils must be added to the transformer model. Capacitances are actually distributed, but lumped
parameters at the winding terminals for the total capacitance can be used with reasonable accuracy in this
case [3, 8, 9]. However, the transformer capacitances are often difficult to be determined. Transformer
capacitance is represented by CH, CL and CHL as shown in Figure 3 Where, CH is the capacitance of high
winding to ground, CL is the capacitance of low winding to ground and CHL is the capacitance between high
and low windings. Normally the CL and CHL are greater than CH. This is because the fact that the high voltage
calls for more separation between windings and between windings and core. The present work considers
these capacitances as in a table 2 [3].
Figure 3. High Frequency Transformer Model.
Table 2. Typical Capacitance of Transformers (Capacitance in nF) [3]
Transformer Core Type
MVA CH CHL CL
1 1.2-14 1.2-17 3.1-16
2 1.4-16 1-18 3-16
5 1.2-14 1.1-20 5.5-17
7 2.7-11 3.5-17 8-16
10 4-7 4-11 8-18
25 2.8-4.2 2.5-18 5.2-20
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3.6. Surge Arrester:
Surge arrester devices play an important role for mitigating the overvoltage due to lightning,
switching. Under both normal and abnormal conditions, the arrester handles its operation based on its
nonlinearity, i.e. V-I characteristics [9].
A simplified model was derived from IEEE model [10, 11]. The model circuit is shown in Figure 4.
This model is composed by two sections of nonlinear resistances usually designated by A0 and A1 which are
separated by inductance L1 and L0. A parallel resistance Rp (about 1 MΩ) is added to avoid the numerical
instability of the combination of the current source and nonlinear elements. This model has the same
operating principles as the IEEE model. The main advantage of this model is that the parameters were
determined using only the electrical data and did not take into consideration any physical characteristics of
the surge arrester [12].
Figure 4. Pinceti and Giannettoni model
In case medium and high voltage levels the inductances L1 and L0 in the model are in μH and
calculated using:
Un
Ur
UrTUr
L
20/8
20/82/1
4
1
1
(5)
(6)
In case low voltage levels the inductances L1 and L0 in the model are in μH and calculated using:
L1=0.03 Un (7)
L0=0.01 Un (8)
Where UN is the arrester rated voltage in kV, Ur1/T2 is the residual voltage at 10 kA fast front
current surge (1/T2 μs). Ur8/20 is the residual voltage at 10 kA current surge with 8/20 μs time parameters.
The nonlinear characteristics of the two elements A0 and A1 are based on the pu data published in
[13] and the corresponding nonlinear characteristics of A0 and A1 are shown in Figure 6.
a. A0 non-linear characteristics. b. A1 non-linear characteristic.
Figure 6. Surge Arrester Elements Nonlinear Characteristics.
0.0 5.0 10.0 15.0 20.0
I [kA]0.9
1.0
1.1
1.3
1.4 U [kV]
0.0 5.0 10.0 15.0 20.0
I [kA]0.7
0.8
0.9
1.1
1.2 U [kV]
Un
Ur
UrTUr
L
20/8
20/82/1
12
1
0
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The surge arrester model is simulated and tested using ATP/EMTP circuit shown in Figure 7.
Figure 7. ATP/EMTP Circuit for Surge Arrester.
The arrester model is tested to match the manufacture's data sheet [14] under switching and
lightning characteristics. 440kV SA with L1 and L0 are equal 0.07μH [6] used in low voltage side boast
transformer. A discharge current 8/20 μs, 5 kA and 25 kA for nominal and maximum conditions respectively
are injected to the surge arrester. The error of residual voltage rather than the manufactured data is found
0.22% at the nominal discharge current and -1.7% at the maximum discharge current. This error is computed
as (Ups-Up)/Up, where Ups is simulated residual voltage (the simulated voltage protection level). The
injected current, the residual voltage and the absorbed energy are as shown in Figures 8 and 9 for nominal
and maximum discharge currents, respectively.
a. Injected current (nominal discharge current). b. Residual voltage.
Figure 8. Injected nominal and maximum discharge current and resuidual voltage.
Figure 9. Absorbed Energy under Injected Nominal and Maximum Discharge Current.
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
x 10
-4
0
0.5
1
1.5
2
2.5
x 10
4
Time (sec)
Current(A)
Nominal discharge current
Maxmum discharge current
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
x 10
-4
0
500
1000
1500
2000
2500
Time (sec)
Voltage(V)
Residual voltage (nominal current)
Residual voltage (Maxmum current)
ABB
manufacture
data sheet
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
x 10
-4
0
200
400
600
800
1000
1200
1400
Time (sec)
SAconsumptionenergy(J)
SA energy (maxmum current)
SA energy (nominal current)
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The MV surge arrester protecting boost transformer with L1 and L0 are 0.0952 μH and 0.286 μH
respectively [6].from test as shown in Figure 10 find errors within acceptable limits
0
2
4
6
8
10
12
14
16
18
20
22
500A
30/60us
125A
30/60us
20kA
8/20us
10kA
8/20us
5kA
8/20us
2.5kA
8/20us
1kA
8/20us
10kA
1/2us
5kA
1/2us
Residual voltage(data sheet)
Residual voltage (simulation)
Error%
Impulse current
Protectionlevel(kV)
0
10
20
30
40
Error%
Figure 10. MVSA Validation
The HV surge arrester protecting grid transformer with L1 and L0 are 1.62μH and 0.54μH
respectively. From test as shown in Figure 11 find errors within acceptable limits
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
2000A
30/60us
100A
30/60us
500A
30/60us
20kA
8/20us
10kA
8/20us
5kA
8/20us
manufactur data
simulated
Error%
Impulse current
Protectionlevel(kV)
0
5
10
15
20
25
30
35
40 Error%
Figure 11. HVSA Validation
3.7. Vertical ground rod modeling:
Grounding systems behavior is well understood at power frequency. However, during lightning
strokes the grounding systems performance might be different. The waveform of the lightning current has a
major influence on the dynamic performance of ground electrodes. While high lightning current intensity
improves the dynamic grounding performance due to ionization of the soil. In case of high lightning currents
the electric field at the ground electrodes might become larger than the electric strength of the soil. Which
can cause breakdown and sparks discharge in the soil. This phenomenon improves the grounding system
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performance so its ignoring always gives inaccurate results. On the other hand, due to the frequency
dependent phenomena, the grounding performance might be much worse during fast front lightning current
pulses. This can deteriorate the efficiency of the protection. Grounding system of a wind turbine plays a
critical role, since overvoltages caused by lightning strikes and other faults has to be successfully dispersed
into the ground. So, it is important to get an accurate model of the wind turbine grounding system. In this
paper the behavior of the wind turbine under lightning strikes has been studied using two different models for
the grounding resistance [15]. The first model is the linear model of grounding resistance which is based on a
constant value for the grounding resistance i.e. low voltage, low frequency [16]. The constant resistance Ro
of the model is estimated in ohm based on the rod dimensions and the soil parameters [15]:
}1
4
{ln
20
a
l
l
R
(9)
Where, ρ is the soil resistivity (Ω.m), L is the electrode length (m) and a is the electrode radius (m).
The other model is based on the nonlinear performance of the grounding resistance with high
currents i.e. high voltage, high frequency [16]. The nonlinearity nature of the ground resistance can be
represented by a nonlinear resistance, RT, whose value is given as [15];
)(
1
)(
0
0
IgiFor
Ig
i
R
Rt
IgiForRRt
(10)
Where, i is the current through the rod (kA), and Ig is the critical current for soil ionization (kA)
which is given by:
2
0
0
2 R
E
Ig
(11)
Where, E0 is the critical soil ionization gradient.
4. MODEL VALIDATION:
In this study, the wind power generator modeled as a synchronous machine for simplicity. The
grounding model at each wind tower is simulated as three separated ground electrodes, where each electrode
simulated as 10 Ω resistance. There is no connection between the grounding systems for wind turbines. The
distribution line is assumed as overhead line and simulated as transposed distributed line parameters. The
lightning stroke is taken as striking wind turbine (WT#1) as shown in Figure 12.
Figure 12. Lightning hit WT#1 [3]
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4.1. Effect Of Frequency Dependant Surge Arrester and Transformers Model on Back Flow Current
Overvoltages:
In this work, The backflow current-overvoltages is evaluated using different transformer and surge
arrester models in the time domain as well as frequency domain using Fast Fourier Transform (FFT)
considering onshore wind farm. Case#1 Simple model of SA consists of only one non linear element with
characteristics and Power frequency transformer model as shown in figure 13.
Figure 13. Atpdraw Circuit of Two Wind Turbines with Simple Model
Case#2 frequency dependent transformer model and frequency dependent model of SA is a
combination of non linear elements and linear inductances which provides dynamic behavior during
lightning. The SAs are used at low, medium and high voltage levels in the wind farm as shown in figure 14.
Figure 14: Atpdraw Circuit of Two Wind Turbines with Freq. Dependant Model
Figures 15 to 18 show the voltage waveforms, peak value, and frequency spectrum oscillation
comparison at different locations of the wind farm. In different two cases, i.e. Simple and frequency
dependent model, It is observed that the peak magnitude of the generated overvoltage at WT#1 generator
terminal reach to 200kV, at (WT#1) boost transformer secondary side reach to 186kV, at (WT#2) boost
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transformer secondary side reach to 25kV and at grid reach to 28kV in different models. It is clear that small
change in peak value of overvoltages under simple and frequency dependant model. But from frequency
content point of view, it can be seen that the amplitude voltage at different frequencies when using simple
model is higher than that when using frequency dependant model. This can be attributed to the fact that the
reflecting traveling waves at junction of the boost transformer of WT#2 and at the junction of the grid-
interactive transformer are decreased due to the presence of the capacitors in the frequency dependant model.
On the other hand, the frequency dependent model considers very high impedance at high frequencies.
Therefore, for a better surge analysis of wind farm, the capacitance between winding of transformer model
must be taken to get accurate transient results.
A. Waveforms Comparison @Wt#1 In Case Simple
and Frequency Dependant Model
B. Frequency Spectrum Comparison
Figure 15. Overvoltages and Frequency Spectrum @WT#1
c. Waveforms Comparison @WT#2 In Case Simple
And Frequency Dependant Model
d. Frequency Spectrum Comparison
Figure 16. Overvoltage and Frequency Spectrum @WT#2
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c. Waveforms Comparison at Grid In Case Simple
and Frequency Dependant Model
d. Frequency Spectrum Comparison
Figure 17. Overvoltage And Frequency Spectrum At Grid
@WT#1 @WT#2 @Grid
0
20
40
60
80
100
120
140
160
180
200
Frequancy dependant model
Simple model
28.3kV28.5kV25.6kV25.7kV
186.3kV186.3kV
Voltage(kV)
Node
Figure 18. Overvoltage Peak Comparisons At Each Node Under Different Cases
4.2. Effect of Vertical Ground Rod Modeling:
In this work, each wind turbine is grounded using three vertical rods each rod has a length of (3 m)
with diameter of (2.54 cm). Assuming that the spacing between these rods is large and enough to neglect the
interaction between them. The soil parameters are taken as ρ=100 Ω.m, εr=8 and μr =1 [14]. Figures 19 to 27
show comparison of voltage wave forms and GPR with varying grounding model (constant resistance and
non linear resistance). The results show that the ground model is significant effect on the maximum GPR and
overvoltage peak value. The GPR and overvoltage peak value is low when the soil ionization effect is
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considered (nonlinear resistance model). This can be attributed that when the lightning current through the
grounding rods exceeds the critical value, i.e. Ig=5.5KA, the grounding resistance is decreased where the
current in the grounding rods is high. On the other hand, the maximum value of the GPR is high when using
the constant resistance. This is because that the soil ionization is not considered in this model. Therefore, the
soil ionization effect is an important factor and should be considered for transient studies especially in
lightning study.
a. Waveforms Comparison @WT#1 Under
Different Ground Model
b. Frequency Spectrum Comparison @WT#1 Under
Different Ground Model
Figure 19. Overvoltage and Frequency Spectrum @WT#1
a. Waveforms Comparison @Wt#2 Under Different
Ground Model
b. Frequency Spectrum Comparison @Wt#2 Under
Different Ground Model
Figure 20. Overvoltage and frequency spectrum @WT#2
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a. Waveforms Comparison at Grid Under Different
Ground Model
b. Frequency Spectrum Comparison at Grid Under
Different Ground Model
Figure 21. Overvoltage and Frequency Spectrum At Grid
a. GPR Waveform Comparison @WT#1 under
Different Ground Model
b.Frequency Spectrum Comparison @WT#1 under
Different Ground Model
Figure 22. GPR Waveform and Frequency Spectrum @WT#1
a. Gpr Waveform Comparison @Wt#2 Under
Different Ground Model
b.Frequency spectrum comparison @WT#2 under
different ground model
Figure 23. GPR Waveform and Frequency Spectrum @WT#2
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a. GPR Waveform Comparison At Grid Under
Different Ground Model
b.Frequency Spectrum Comparison At Grid Under
Different Ground Model
Figure 24. GPR Waveform and Frequency Spectrum at Grid
@WT#1 @WT#2 @Grid
0
100
200
300
400
500
Soil ionization
fixed resistance
Voltage(kV)
Node
@WT#1 @WT#2 @Grid
0
100
200
300
400
500
Soil ionization
Fixed resistance
Voltage(kV)
Node
Figure 25. Overvoltage Peak Comparison at Each
Node Under Different Cases
Figure 26. GPR Peak Comparison at Each Node
Under Different Cases
5. CONCLUSION
Validation of surge arrester in LV, MV and HV ABB data sheet using ATP/EMTP has been
investigated. The impact of the Pinceti and Giannettoni surge arrester and winding stray capacitance
transformer model has been carried out. The impact of the soil ionization model has been presented.
Performance of wind farm consisting of two wind turbines has been evaluated under lightning strokes.This
investigation has been carried out in time domain as well as frequency domain using FFT. All components of
the system, under study, are simulated by using ATP/EMTP. The main conclusions obtained from the results
are;
In case of the lightning stroke strikes the blade, cause GPR. The increase of the GPR can conduct
backflow current to the distribution system. It generates overvoltage on the thunderstruck and neighbor
turbines. This can cause damage to the wind farm electrical components.
It is clear that small change in peak value of overvoltages under simple and frequency dependant
model. But from frequency content point of view, it can be seen that the amplitude voltage at different
frequencies when using simple model is higher than that when using frequency dependant model, due to the
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presence of the capacitors in the frequency dependant model. On the other hand, the frequency dependent
model considers very high impedance at high frequencies. Therefore, for a better surge analysis of wind
farm, the capacitance between winding of transformer model must be taken to get accurate transient results.
The nonlinearity behavior of the grounding resistance can be attributed to the decrease in the
grounding resistance within the increase in surge current through it. Therefore, the soil ionization effect is
important and should be considered for transient studies especially lightning study.
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[14] Surge Arresters, Datasheet, www.abb.com/arrestersonline.
[15] Amr M. Abd-Elhady, Nehmdoh A. Sabiha and Mohamed A. Izzularab” Evaluation of Different Grounding
Models for Studying Backflow Current-Overvoltages in Wind Farm” International Middle East Power Systems
Conference (MEPCON’12) 23-25 December 2012, Cairo, Egypt.
[16] ANSI/IEEE Std 80-1986‖ AC SUBSTATION GROUNDING‖