This document discusses fault current calculation methods. It covers symmetrical and asymmetrical faults, and describes analyzing power systems under both normal and abnormal operating conditions. The infinite bus method and per unit methods for calculating fault current are introduced. Synchronous machine response to asymmetrical faults is examined, including the subtransient, transient, and steady state stages. Fault current envelopes are presented.
Power System Analysis was a core subject for Electrical & Electronics Engineering, Based On Anna University Syllabus. The Whole Subject was there in this document.
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This presentation provides an overview of power quality, including definitions of power quality, common power quality disturbances like sags, swells, harmonics and interruptions. It discusses the increased sensitivity of modern electronic equipment to power quality issues. Real-time power quality monitoring systems are described that can identify issues, locate their sources, and help utilities and customers mitigate problems to reduce costs and equipment damage. The benefits of power quality monitoring include improved reliability, preventative maintenance, and identification of sensitive equipment needing protection.
SYNCHRONOUS MOTOR STARTING METHODS, START करने के METHODS|DAMPER WINDING, AUX...Prasant Kumar
This document discusses different starting methods for synchronous motors. It describes using an auxiliary induction motor or DC motor to bring the synchronous motor rotor up to synchronous speed before excitation. It also covers on-load starting methods like using damper windings to start the motor as an induction motor initially or using a variable frequency drive to gradually increase frequency and avoid high starting torque.
- The document discusses different types of armature windings for DC and AC machines, including lap, wave, simplex, duplex, mush, and double layer windings.
- It describes the characteristics of each winding type such as the connections between coils and how they are arranged in the slots. Key terms related to pitch, spacing, and phase relationships are also defined.
- The final section covers conditions for designing double layer windings for AC machines, distinguishing between integral and fractional slot types.
In analyzing the problems in South Sulawesi transmission system, simulations of PSCAD / EMTDC [5-6] and PWS (Power World Simulator) [7] software were used to simulate changes in electrical current and voltage during a disturbance.
-Single phase to Ground,
-Line to Fault Line,
-Double Line to Ground
-Three phase Short Circuit
This document discusses transformer vector groups and the phase shift between primary and secondary currents. It begins by introducing transformer basics like magnetically coupled circuits and phase relationships between voltages. Diagrams show how polarity markings and connections determine the vector group. Specific examples analyze the Yd1 and Yd11 vector groups in detail, showing how primary and secondary phase currents are related for both positive and negative sequence components. Tables summarize the results, and shortcuts are provided for identifying the vector group from winding configurations.
Design, Planning and Layout of high voltage laboratory vishalgohel12195
Design, Planning and Layout of high voltage laboratory
Test equipment provided in high voltage lab
Activity and study in high voltage lab
Classification of high voltage lab
Clearance of high voltage Lab
Layout of high voltage lab
Safety
Shielding of the high voltage lab
The document discusses one-line diagrams, which are simplified diagrams used in power systems to represent the essential components in a simplified graphical format. A one-line diagram shows the main components of a power system like generators, transmission lines, transformers, and loads using standardized symbols. It represents the paths of power flow through the system from generation to transmission to distribution. The diagram is structured to match the physical layout. Impedance and reactance diagrams are similar but represent electrical elements like generators and lines as impedance/reactance values instead of physical components. An example calculation of voltage drop in a transmission line is provided.
Power System Analysis was a core subject for Electrical & Electronics Engineering, Based On Anna University Syllabus. The Whole Subject was there in this document.
Share with it ur friends & Follow me for more updates.!
This presentation provides an overview of power quality, including definitions of power quality, common power quality disturbances like sags, swells, harmonics and interruptions. It discusses the increased sensitivity of modern electronic equipment to power quality issues. Real-time power quality monitoring systems are described that can identify issues, locate their sources, and help utilities and customers mitigate problems to reduce costs and equipment damage. The benefits of power quality monitoring include improved reliability, preventative maintenance, and identification of sensitive equipment needing protection.
SYNCHRONOUS MOTOR STARTING METHODS, START करने के METHODS|DAMPER WINDING, AUX...Prasant Kumar
This document discusses different starting methods for synchronous motors. It describes using an auxiliary induction motor or DC motor to bring the synchronous motor rotor up to synchronous speed before excitation. It also covers on-load starting methods like using damper windings to start the motor as an induction motor initially or using a variable frequency drive to gradually increase frequency and avoid high starting torque.
- The document discusses different types of armature windings for DC and AC machines, including lap, wave, simplex, duplex, mush, and double layer windings.
- It describes the characteristics of each winding type such as the connections between coils and how they are arranged in the slots. Key terms related to pitch, spacing, and phase relationships are also defined.
- The final section covers conditions for designing double layer windings for AC machines, distinguishing between integral and fractional slot types.
In analyzing the problems in South Sulawesi transmission system, simulations of PSCAD / EMTDC [5-6] and PWS (Power World Simulator) [7] software were used to simulate changes in electrical current and voltage during a disturbance.
-Single phase to Ground,
-Line to Fault Line,
-Double Line to Ground
-Three phase Short Circuit
This document discusses transformer vector groups and the phase shift between primary and secondary currents. It begins by introducing transformer basics like magnetically coupled circuits and phase relationships between voltages. Diagrams show how polarity markings and connections determine the vector group. Specific examples analyze the Yd1 and Yd11 vector groups in detail, showing how primary and secondary phase currents are related for both positive and negative sequence components. Tables summarize the results, and shortcuts are provided for identifying the vector group from winding configurations.
Design, Planning and Layout of high voltage laboratory vishalgohel12195
Design, Planning and Layout of high voltage laboratory
Test equipment provided in high voltage lab
Activity and study in high voltage lab
Classification of high voltage lab
Clearance of high voltage Lab
Layout of high voltage lab
Safety
Shielding of the high voltage lab
The document discusses one-line diagrams, which are simplified diagrams used in power systems to represent the essential components in a simplified graphical format. A one-line diagram shows the main components of a power system like generators, transmission lines, transformers, and loads using standardized symbols. It represents the paths of power flow through the system from generation to transmission to distribution. The diagram is structured to match the physical layout. Impedance and reactance diagrams are similar but represent electrical elements like generators and lines as impedance/reactance values instead of physical components. An example calculation of voltage drop in a transmission line is provided.
This document provides guidance on estimating electric load and demand for commercial and industrial customers. It discusses:
1) How customers provide connected load based on code while utilities determine diversified demand load. Demand is typically 25-75% of connected load.
2) Methods for estimating demand loads for different equipment types like motors, air conditioning, and lighting using demand and diversity factors.
3) Typical demand factors for common equipment to check estimated demand against.
4) Using watts per square foot as a last resort when accurate load data is unavailable, such as for speculative commercial spaces.
1. A document discusses fault analysis in power systems, including symmetrical and unsymmetrical faults. Common fault causes include insulation failure, mechanical issues, over/under voltage, and accidents.
2. Key concepts are introduced, such as different types of reactance (subtransient, transient, steady-state) and how fault current transients have both AC and DC components.
3. Two examples are provided to demonstrate how to calculate fault current and MVA for given systems using per unit calculations and reactance values.
The document discusses electricity deregulation and the requirements for a deregulated electricity market. It outlines the benefits of deregulation such as more efficient use of generation capacity, improved consumer choice, and potentially lower prices. In a deregulated market there are different entities like generators, transmitters, distributors, retailers, and customers. Regulation is still needed to prevent monopoly behavior and ensure reliability. The document compares regulated versus deregulated industry structures and different market models for electricity trading. It also discusses issues in deregulated markets like network congestion, supply shortages, defaults, and lack of experience with risk hedging tools. The objective of India's Electricity Act of 2003 was to introduce competition while protecting consumers and ensuring universal access to electricity
An energy meter measures the amount of electrical energy consumed over time using kilowatt-hours. There are two main types: electro-mechanical and electronic. Electro-mechanical meters use a rotating disc to measure usage, but have errors, while electronic meters use digital circuits for more accurate and tamper-resistant readings. Future meters will have remote reading capabilities and allow time-of-day pricing to encourage off-peak usage. Meters are tested using specialized equipment and procedures to check for accuracy and compliance. Tampering methods can be detected by modern meters' sensors and digital components.
This document provides an outline and overview of a hands-on relay school covering transmission protection theory including symmetrical components and fault calculations. It discusses power system problems like faults and disturbances, different fault types, and introduces symmetrical components and how they are used to analyze balanced and unbalanced systems. It also covers per unit systems, calculating sequence networks for faults, and evaluating transmission line, generator, and transformer impedances.
This document provides an overview of power system engineering concepts related to unbalanced system analysis. It begins with an introduction to symmetrical and unsymmetrical faults on three-phase systems. It then discusses percentage reactance and base KVA, the steps for symmetrical fault calculations, and an introduction to symmetrical components and sequence impedances. The document proceeds to explain single line-to-ground faults, line-to-line faults, and double line-to-ground faults. It provides examples of calculating fault currents and sequence components. In summary, the document covers fundamental concepts for analyzing faults in three-phase power systems, including symmetrical and unsymmetrical faults, sequence components, and example calculations.
It gives the basic Idea about Inverter than moving towards the advantages of Multilevel Inverter .In this PPT main focus on Flying Capacitor Multilevel Inverter.
The document discusses electric power supply systems and transmission. It describes how electric power is generated at power stations, transmitted over long distances via transmission lines, and then distributed to consumers. There are three main components of an electric supply system: the power station, transmission lines, and the distribution network. Transmission is typically done using high voltages for efficiency and reduced line losses. While DC transmission has advantages, AC transmission is now universally used due to the ability to easily transform voltages using cost-effective transformers.
The document discusses power quality issues caused by harmonics from non-linear loads. It provides background on the increasing use of non-linear loads and effects of harmonics. Specific sources of harmonics are outlined along with their impact on power quality including overheating, failures, and interference. Mitigation techniques are reviewed such as passive and active filtering. Active power filters are highlighted as an effective solution, with shunt active power filters discussed in detail for compensating harmonic currents and reactive power. The document concludes that active power filtering is still developing and more research is needed on techniques like controls and artificial intelligence to further improve power quality.
SIMULATION AND STUDY OF MULTILEVEL INVERTER (ppt)Arpit Kurel
This document discusses the simulation and study of a multilevel inverter. It aims to simulate a three-phase five-level inverter using MATLAB/Simulink. Multilevel inverters are attractive for medium-voltage high-power applications as they can produce outputs with low distortion at medium voltages. The document reviews literature on multilevel inverters and various topologies. It then discusses objectives of simulating a five-level inverter to reduce harmonics. Simulation results show that a five-level inverter has lower total harmonic distortion and higher efficiency compared to a three-level inverter.
PhD thesis presentation - Advanced Control Strategies for UPQC to Improve Pow...Trinh Quoc Nam
The document presents a thesis on advanced control strategies for unified power quality conditioners (UPQC) to improve power quality in distribution power systems. The thesis proposes control strategies to compensate for current and voltage harmonics, voltage sags, and voltage unbalances. Specifically, it introduces a control method for a shunt active power filter (APF) that eliminates the need for load current measurement and harmonic detection. This is achieved by directly controlling the DC link voltage and supply current. A proportional-integral-virtual phase lead (PI-VPI) current controller is designed to compensate for dominant 6nth harmonic currents without requiring additional filters or controllers. The proposed control strategy aims to simplify UPQC control systems and improve compensation performance.
Power Factor Correction Methods
Fixed Capcitors
Synchronous Condensors
Phase Advancers
Switch Capacitors
Static Var Compensator(SVC)
Static Synchronous Compensator(STATCOM)
Modulated power filter capacitor compensator
Economics of power factor improvement
Economical comparison of increasing the power supply
This document provides an overview of electric power calculations presented by K. James Phillips Jr. at the Rocky Mountain Electrical League. It covers topics such as per phase analysis, short circuit calculations, per unit calculations, and harmonics. Short circuit calculations are used to predict outcomes and ensure equipment can withstand faults without damage. Harmonics from non-linear loads can cause issues like capacitor failure, overheating, and interference. Power factor correction capacitors are added to counter system inductance but their interaction can cause resonance.
Electrical fault is the deviation of voltages and currents from nominal values or states. Under normal operating conditions, power system equipment or lines carry normal voltages and currents which results in a safer operation of the system.
This document discusses the importance of proper grounding and bonding for electrical systems. It defines key terms like grounding, bonding, and ground loops. The primary objectives of grounding are safety, fault protection, and creating a signal reference ground. Improper grounding can cause problems like earth loops, electromagnetic interference, loose connections, and reduced protection. The document outlines requirements for grounding in the National Electrical Code and describes components of effective grounding systems, including ground electrodes, conductors, and techniques like single-point and multipoint grounding. Signal reference grounds are important for sensitive equipment. Overall, the document emphasizes that proper grounding is fundamental to ensuring electrical system stability and preventing shock hazards.
Principles of Electromechanical Energy ConversionYimam Alemu
This document is the first chapter of a textbook on electromechanical energy conversion. It introduces key concepts such as electrical energy conversion to mechanical energy using magnetic fields. It discusses different types of electromechanical devices and the principle of energy conservation. It also covers energy balance analysis in conversion systems and determining forces and torques from the energy and coenergy of magnetic systems, including those with permanent magnets. The chapter objectives are to understand electromechanical conversion analysis and components, and how to determine forces and torques from energy considerations.
HVDC Bridge and Station Configurations
1. General HVDC – HVAC Comparisons
2. Components of a Converter Bridge
3. HVDC scheme configurations
Operation of the HVDC converter
1. General assumptions
2. Rectifier operation with uncontrolled valves and X = 0
3. Rectifier operation with controlled valves and X = 0
4. Rectifier operation with controlled valves and X 0
5. Inverter operation with controlled valves and X 0
6. Commutation and Commutation Failure
7. Reactive Power Requirements
8. Short-circuit capacity requirements for an HVDC terminal.
9. Harmonics and filtering on the AC and DC sides
The document appears to be a technical paper on electrical engineering topics related to symmetrical components, transformer energization, and fault analysis. It includes diagrams of symmetrical component representations of faults, discussions of transformer magnetic flux and core saturation during energization, and waveform diagrams of currents and voltages under different fault conditions.
This document discusses different types of firing angle control schemes for HVDC converters, including individual phase control (IPC) and equidistant phase control (EPC). IPC allows independent control of each phase's firing angle based on commutation voltages. EPC generates firing angles at equal intervals through a ring counter. Higher-level controllers are also discussed that can control DC power modulation for frequency regulation, emergency control, reactive power control, and damping of sub-synchronous oscillations. Voltage source converter control is mentioned, where the modulation index and phase angle are used to regulate active and reactive power flow.
1) The document describes procedures for measuring parameters of a synchronous machine, including open-circuit voltage and short-circuit current characteristics to determine synchronous reactance and short circuit ratio (SCR).
2) Key machine parameters like unsaturated and saturated reactance are calculated from the open-circuit voltage and short-circuit current characteristics plotted versus field current.
3) The short-circuit ratio is also determined, which relates the field currents required for rated voltage and current and can be used to calculate the synchronous reactance.
A step-by-step approach to prepare fault studies of electrical power systemsH. Kheir
The following are covered: the classification of faults, sources of fault currents, sequence impedance networks, the calculation of the fault currents for different types of shunt faults, the preparation of coordination studies and the inclusion of the different current time characteristics curves, damage curves/points and inrush (energization) currents.
This document provides guidance on estimating electric load and demand for commercial and industrial customers. It discusses:
1) How customers provide connected load based on code while utilities determine diversified demand load. Demand is typically 25-75% of connected load.
2) Methods for estimating demand loads for different equipment types like motors, air conditioning, and lighting using demand and diversity factors.
3) Typical demand factors for common equipment to check estimated demand against.
4) Using watts per square foot as a last resort when accurate load data is unavailable, such as for speculative commercial spaces.
1. A document discusses fault analysis in power systems, including symmetrical and unsymmetrical faults. Common fault causes include insulation failure, mechanical issues, over/under voltage, and accidents.
2. Key concepts are introduced, such as different types of reactance (subtransient, transient, steady-state) and how fault current transients have both AC and DC components.
3. Two examples are provided to demonstrate how to calculate fault current and MVA for given systems using per unit calculations and reactance values.
The document discusses electricity deregulation and the requirements for a deregulated electricity market. It outlines the benefits of deregulation such as more efficient use of generation capacity, improved consumer choice, and potentially lower prices. In a deregulated market there are different entities like generators, transmitters, distributors, retailers, and customers. Regulation is still needed to prevent monopoly behavior and ensure reliability. The document compares regulated versus deregulated industry structures and different market models for electricity trading. It also discusses issues in deregulated markets like network congestion, supply shortages, defaults, and lack of experience with risk hedging tools. The objective of India's Electricity Act of 2003 was to introduce competition while protecting consumers and ensuring universal access to electricity
An energy meter measures the amount of electrical energy consumed over time using kilowatt-hours. There are two main types: electro-mechanical and electronic. Electro-mechanical meters use a rotating disc to measure usage, but have errors, while electronic meters use digital circuits for more accurate and tamper-resistant readings. Future meters will have remote reading capabilities and allow time-of-day pricing to encourage off-peak usage. Meters are tested using specialized equipment and procedures to check for accuracy and compliance. Tampering methods can be detected by modern meters' sensors and digital components.
This document provides an outline and overview of a hands-on relay school covering transmission protection theory including symmetrical components and fault calculations. It discusses power system problems like faults and disturbances, different fault types, and introduces symmetrical components and how they are used to analyze balanced and unbalanced systems. It also covers per unit systems, calculating sequence networks for faults, and evaluating transmission line, generator, and transformer impedances.
This document provides an overview of power system engineering concepts related to unbalanced system analysis. It begins with an introduction to symmetrical and unsymmetrical faults on three-phase systems. It then discusses percentage reactance and base KVA, the steps for symmetrical fault calculations, and an introduction to symmetrical components and sequence impedances. The document proceeds to explain single line-to-ground faults, line-to-line faults, and double line-to-ground faults. It provides examples of calculating fault currents and sequence components. In summary, the document covers fundamental concepts for analyzing faults in three-phase power systems, including symmetrical and unsymmetrical faults, sequence components, and example calculations.
It gives the basic Idea about Inverter than moving towards the advantages of Multilevel Inverter .In this PPT main focus on Flying Capacitor Multilevel Inverter.
The document discusses electric power supply systems and transmission. It describes how electric power is generated at power stations, transmitted over long distances via transmission lines, and then distributed to consumers. There are three main components of an electric supply system: the power station, transmission lines, and the distribution network. Transmission is typically done using high voltages for efficiency and reduced line losses. While DC transmission has advantages, AC transmission is now universally used due to the ability to easily transform voltages using cost-effective transformers.
The document discusses power quality issues caused by harmonics from non-linear loads. It provides background on the increasing use of non-linear loads and effects of harmonics. Specific sources of harmonics are outlined along with their impact on power quality including overheating, failures, and interference. Mitigation techniques are reviewed such as passive and active filtering. Active power filters are highlighted as an effective solution, with shunt active power filters discussed in detail for compensating harmonic currents and reactive power. The document concludes that active power filtering is still developing and more research is needed on techniques like controls and artificial intelligence to further improve power quality.
SIMULATION AND STUDY OF MULTILEVEL INVERTER (ppt)Arpit Kurel
This document discusses the simulation and study of a multilevel inverter. It aims to simulate a three-phase five-level inverter using MATLAB/Simulink. Multilevel inverters are attractive for medium-voltage high-power applications as they can produce outputs with low distortion at medium voltages. The document reviews literature on multilevel inverters and various topologies. It then discusses objectives of simulating a five-level inverter to reduce harmonics. Simulation results show that a five-level inverter has lower total harmonic distortion and higher efficiency compared to a three-level inverter.
PhD thesis presentation - Advanced Control Strategies for UPQC to Improve Pow...Trinh Quoc Nam
The document presents a thesis on advanced control strategies for unified power quality conditioners (UPQC) to improve power quality in distribution power systems. The thesis proposes control strategies to compensate for current and voltage harmonics, voltage sags, and voltage unbalances. Specifically, it introduces a control method for a shunt active power filter (APF) that eliminates the need for load current measurement and harmonic detection. This is achieved by directly controlling the DC link voltage and supply current. A proportional-integral-virtual phase lead (PI-VPI) current controller is designed to compensate for dominant 6nth harmonic currents without requiring additional filters or controllers. The proposed control strategy aims to simplify UPQC control systems and improve compensation performance.
Power Factor Correction Methods
Fixed Capcitors
Synchronous Condensors
Phase Advancers
Switch Capacitors
Static Var Compensator(SVC)
Static Synchronous Compensator(STATCOM)
Modulated power filter capacitor compensator
Economics of power factor improvement
Economical comparison of increasing the power supply
This document provides an overview of electric power calculations presented by K. James Phillips Jr. at the Rocky Mountain Electrical League. It covers topics such as per phase analysis, short circuit calculations, per unit calculations, and harmonics. Short circuit calculations are used to predict outcomes and ensure equipment can withstand faults without damage. Harmonics from non-linear loads can cause issues like capacitor failure, overheating, and interference. Power factor correction capacitors are added to counter system inductance but their interaction can cause resonance.
Electrical fault is the deviation of voltages and currents from nominal values or states. Under normal operating conditions, power system equipment or lines carry normal voltages and currents which results in a safer operation of the system.
This document discusses the importance of proper grounding and bonding for electrical systems. It defines key terms like grounding, bonding, and ground loops. The primary objectives of grounding are safety, fault protection, and creating a signal reference ground. Improper grounding can cause problems like earth loops, electromagnetic interference, loose connections, and reduced protection. The document outlines requirements for grounding in the National Electrical Code and describes components of effective grounding systems, including ground electrodes, conductors, and techniques like single-point and multipoint grounding. Signal reference grounds are important for sensitive equipment. Overall, the document emphasizes that proper grounding is fundamental to ensuring electrical system stability and preventing shock hazards.
Principles of Electromechanical Energy ConversionYimam Alemu
This document is the first chapter of a textbook on electromechanical energy conversion. It introduces key concepts such as electrical energy conversion to mechanical energy using magnetic fields. It discusses different types of electromechanical devices and the principle of energy conservation. It also covers energy balance analysis in conversion systems and determining forces and torques from the energy and coenergy of magnetic systems, including those with permanent magnets. The chapter objectives are to understand electromechanical conversion analysis and components, and how to determine forces and torques from energy considerations.
HVDC Bridge and Station Configurations
1. General HVDC – HVAC Comparisons
2. Components of a Converter Bridge
3. HVDC scheme configurations
Operation of the HVDC converter
1. General assumptions
2. Rectifier operation with uncontrolled valves and X = 0
3. Rectifier operation with controlled valves and X = 0
4. Rectifier operation with controlled valves and X 0
5. Inverter operation with controlled valves and X 0
6. Commutation and Commutation Failure
7. Reactive Power Requirements
8. Short-circuit capacity requirements for an HVDC terminal.
9. Harmonics and filtering on the AC and DC sides
The document appears to be a technical paper on electrical engineering topics related to symmetrical components, transformer energization, and fault analysis. It includes diagrams of symmetrical component representations of faults, discussions of transformer magnetic flux and core saturation during energization, and waveform diagrams of currents and voltages under different fault conditions.
This document discusses different types of firing angle control schemes for HVDC converters, including individual phase control (IPC) and equidistant phase control (EPC). IPC allows independent control of each phase's firing angle based on commutation voltages. EPC generates firing angles at equal intervals through a ring counter. Higher-level controllers are also discussed that can control DC power modulation for frequency regulation, emergency control, reactive power control, and damping of sub-synchronous oscillations. Voltage source converter control is mentioned, where the modulation index and phase angle are used to regulate active and reactive power flow.
1) The document describes procedures for measuring parameters of a synchronous machine, including open-circuit voltage and short-circuit current characteristics to determine synchronous reactance and short circuit ratio (SCR).
2) Key machine parameters like unsaturated and saturated reactance are calculated from the open-circuit voltage and short-circuit current characteristics plotted versus field current.
3) The short-circuit ratio is also determined, which relates the field currents required for rated voltage and current and can be used to calculate the synchronous reactance.
A step-by-step approach to prepare fault studies of electrical power systemsH. Kheir
The following are covered: the classification of faults, sources of fault currents, sequence impedance networks, the calculation of the fault currents for different types of shunt faults, the preparation of coordination studies and the inclusion of the different current time characteristics curves, damage curves/points and inrush (energization) currents.
DigSILENT PF - 06 (es) short circuit theoryHimmelstern
This document provides an overview of short-circuit calculations, including the basic principles, models used, and time dependence of short-circuit currents. It discusses the symmetrical components method for analyzing faults and different types of short circuits based on involved phases. Models for common electrical components like transformers, lines, and generators are also presented. The document is intended as training material for performing short-circuit analyses.
This document provides an overview of short-circuit calculations, including the following key points:
- Short-circuit calculations are used for system planning and operations to ensure equipment ratings are not exceeded and protective devices are properly coordinated.
- The time dependence of short-circuit current is important, as it affects equipment loading. Key current parameters analyzed at different time domains are defined.
- The symmetrical components method is used to split three-phase systems into positive, negative, and zero sequence networks to simplify analysis.
- Short-circuits are classified based on the phases involved: three-phase, phase-to-phase, phase-to-phase-ground, or single-phase ground.
- Common system elements
This document presents a new algorithm for transformer overcurrent protection based on symmetrical components that can better discriminate faults from non-fault events like transformer energization. The algorithm analyzes the positive, negative, and zero sequence components of current. It defines a criterion function R that is close to 0 for faults, indicating a large negative sequence, and close to 1 for non-faults like energization, where the negative sequence is small. Simulations show that R can reliably detect faults while avoiding tripping during non-fault events. The algorithm provides improved performance over conventional techniques and is not dependent on current magnitude.
This document discusses fault analysis in power systems:
- Faults occur due to insulation breakdown from factors like lightning, wind, animals, or pollution. The most common faults are single line-to-ground and line-to-line faults.
- During a fault, generators contribute the bulk of fault current from their stored energy. Generators can be modeled as a constant voltage behind a time-varying reactance.
- A example fault analysis calculates the fault current in a power system network with a generator and motor by modeling the devices and solving the linear circuit. The fault current was determined to be 9.09 per unit.
The document discusses analyzing a single-phase power system and its theoretical variations through per unit analysis using MATLAB. It provides the theory behind per unit analysis and calculates the per unit values of the system parameters. It then manually solves the system using per unit analysis and compares the results to those obtained through simulation in MATLAB.
A novel four wire inverter system using SVPWM technique for ups applicationsIRJET Journal
This document describes a novel four-wire inverter system using space vector pulse width modulation (SVM) technique for uninterruptible power supply (UPS) applications. It introduces the concept of SVM for four-wire voltage source inverters. A four-wire inverter provides a neutral connection for three-phase four-wire systems to handle neutral current from unbalanced or non-linear loads. The SVM technique approximates the reference voltage vector during each sampling interval using the three nearest inverter switching state vectors. Simulation results using MATLAB/Simulink analyze the performance of the four-wire SVM inverter under different loading conditions in terms of total harmonic distortion.
This presentation, given by Georgia Power for the Caribbean Meter School, covers transformer rated service installations including field meter testing, instrument transformers, system analyzers, and safety protocols. Several grids are included showing single phase service, three phase services, power factor, harmonics, and more.
The document discusses short-circuit analysis based on ANSI standards. It describes the different types of short-circuit faults, how fault current is calculated, and the components that contribute current. The ANSI method models sources using an internal voltage behind an impedance and represents them in multiple networks to calculate fault currents at different time periods. It also explains how fault currents are used to verify protective device ratings and settings.
Power systems can be modeled and analyzed using per-unit representations of components. Key models include:
1) Generator models that specify real and reactive power injection or terminal voltage and current.
2) Transformer models using an equivalent circuit with magnetizing reactance and resistance.
3) Load models like constant impedance, current, or power to represent different load characteristics.
4) Transmission lines modeled as series impedances.
The per-unit system allows analysis of different voltage levels on a common scale and simplifies modeling of components.
The document provides an overview of power systems concepts including:
- Single-phase and three-phase power calculations including real, reactive, and apparent power.
- Modeling of common power system components like generators, transformers, loads, and transmission lines.
- The per-unit system used for power system analysis and its advantages.
This document discusses three-phase induction motors. It begins by listing advantages such as being widely used, cheap, easy to maintain, and having fewer mechanical parts than other machines. Problems discussed include grounding faults causing insulation breakdown, isolation failures between coils, and broken rotor bars affecting torque. Methods of motor maintenance like corrective, preventive, and predictive are introduced. Parameter estimation techniques involving time-domain, frequency-domain, using motor construction data, or based on steady-state models are summarized. Finally, recursive least squares estimation is described as a method to determine electrical and mechanical parameters in real-time using motor voltage, current and speed measurements.
1. The document discusses symmetrical components, which allow representation of unbalanced three-phase quantities as the sum of three balanced components.
2. It introduces the positive, negative, and zero sequence components and the transformation matrix used to relate the symmetrical components to the original unbalanced quantities.
3. Symmetrical components are useful for simplifying analysis of unbalanced conditions like single line-to-ground faults in power systems. Sequence impedances can be used to model devices and transmission lines.
ECNG 3015 Industrial and Commercial Electrical SystemsChandrabhan Sharma
This document discusses symmetrical components and symmetrical component networks which are used to analyze unbalanced faults in power systems. It explains that a 3-phase unbalanced system can be represented as three balanced systems known as positive, negative, and zero sequence networks. It provides details on constructing these networks for different system components like generators, transmission lines, and transformers. The networks are then used to calculate fault currents and voltages under different fault conditions.
The document provides an overview of power system analysis and modeling. It discusses modeling of various power system components like generators, transformers, transmission lines, and induction motors using equivalent circuits. It also covers per unit calculations and formation of impedance and reactance diagrams from a single line diagram. The document further discusses power flow analysis using bus admittance matrix and different iterative methods. It covers balanced and unbalanced fault analysis using symmetrical components. It concludes with discussing power system stability including steady state, transient, and voltage stability.
This document discusses various types of motors and motor control. It begins by describing stepper motors and how their position can be directly controlled without sensing. It then discusses DC motors and how their speed can be controlled by varying the voltage input. The rest of the document discusses various position sensors, motor control strategies like PID control, sampling considerations, and motor drive components. It provides an overview of concepts important for controlling motors in robotic applications.
1) The document describes a power system simulation experiment using MATLAB. It involves simulating various faults on a 3-bus system and analyzing the results. Graphs of voltages and currents are presented for different fault types.
2) The experiment also involves performing load flow analysis on a 3-6 bus system using Gauss-Seidel, Newton-Raphson, and Fast Decoupled methods. Relevant equations and sample data for a IEEE 30-bus test system are provided.
3) Key components in the MATLAB Simulink model used for fault analysis are described, including transformers, transmission lines, circuit breakers, fault blocks. The conclusions observed from the fault simulations are also summarized.
The document discusses power system fault analysis. It provides an overview of the purposes of fault analysis, which include calculating currents and voltages during faults, checking breaking capacity, determining quantities for relay detection, selecting relay characteristics, and ensuring plant ratings are not exceeded. It also discusses various fault types, balanced and unbalanced faults, generator modeling, transformer modeling, and per-unit systems. Specific topics covered include symmetrical components, fault calculations methods using vectors and calculators, generator contribution to faults, and motor contribution to faults.
How to Add Chatter in the odoo 17 ERP ModuleCeline George
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3. Fault Analysis
Analysis Type
Power Flow: normal operating conditions
Faults: abnormal operating conditions
Fault Types
Balanced or Symmetrical Fault
Three Phase Short Circuit
Unbalanced or Unsymmetrical Faults
Single line-to-ground
Double line-to-ground
Line-to-line
What are the results used for?
o Determining the circuit breaker rating
o Protective Relaying settings
4. Various Types of Faults
Fault
l
Symmetrica
)
a
Fault
cal
Unsymmetri
)
b
Fault
line
-
to
-
line Fault
ground
-
to
-
line
double Fault
ground
-
to
-
line
fault
1
F
Z
Z
V
)
(3
I
l-fault
Symmetrica
fault
0
2
1
F
fault
3Z
)
3
Z
(
Z
Z
3V
ground)
-
to
-
(Line
I
n
Z
fault
2
1
F
fault
Z
Z
Z
V
3
line)
-
to
-
(line
I
j
a
b
c
a
b
c
a
b
c
a
b
c
a
b
c
6. R-L Circuit Transients
R
+
-
0
@
t
Closed
SW
L
)
sin(
2
)
(
wt
V
t
e
0
)
sin(
2
)
(
)
(
:
t
t
V
t
Ri
dt
t
di
L
Equation
]
)
sin(
)
[sin(
2
)
(
)
(
)
(
: T
t
e
t
Z
V
t
i
t
i
t
i
Solution dc
ac
amp
t
Z
V
t
iac )
sin(
2
)
(
T
t
e
Z
V
t
idc
)
sin(
2
)
(
2
2
2
2
)
( l
R
X
R
Z
R
wl
tg
R
X
tg 1
1
fR
X
R
X
R
L
T
2
:
)
(
/ forced
Current
Fault
State
Steady
Fault
l
Symmetrica :
)
(transient
Current
Offset
dc
Solution
forced Solution
natural
7. Asymmetrical fault
]
)
sin(
)
[sin(
2
)
(
)
(
)
( T
t
e
t
Z
V
t
i
t
i
t
i dc
ac
•Dc offset Magnitude depends on angle α:
ac
I
offset
dc 2
0
)
2
(
Z
V
current
fault
ac
rms
I
where ac
)
(
:
]
)
2
[sin(
2
)
(
)
(
)
(
)
2
(
:
T
t
e
t
I
t
i
t
i
t
i
Set
ac
dc
ac
•In order to get the largest fault current:
8. Asymmetrical fault
Note: i(t) is not completely periodic. So, how do we
get the rms value of i(t) ?
Assume :
Now calculate the RMS Asymmetrical Fault Current:
)
constant
(
C
e T
t
Amp
e
I
e
I
I
I
I
t
i T
t
ac
T
t
dc
ac
dc
ac
rms
2
2
2
2
2
2
1
]
2
[
]
[
)
(
)
(
)
(
cycles
in
time
is
where
f
t
fR
X
R
X
R
X
R
L
T
Note
;
&
2
:
Amp
e
I
e
I
e
I
t
i R
X
ac
fR
X
f
ac
T
t
ac
rms
)
/
(
4
2
2
2
2
1
2
1
2
1
)
(
Unit
Per
2
1
factor
al
asymmetric
)
(
:
)
(
)
( )
/
(
4
R
X
ac
rms e
k
where
I
k
I
9. Asymmetrical Fault Calculation
Example: In the following Circuit, V=2.4kV, L=8mH,
R=0.4Ω, and ω=2π60 rad/sec. Determine (a) the rms
symmetrical fault current; (b) the rms asymmetrical fault
current; (c) the rms asymmetrical fault current for .1 cycle
& 3 cycle after the switch closes, assuming the maximum
dc offset.
+
- 0
@
t
Closed
SW
mH
L 20
)
sin(
2400
2
)
(
wt
t
e
4
R
10. Asymmetrical Fault Calculation
Solution:
4
.
82
042
.
3
4
.
82
042
.
3
016
.
3
4
.
0
)
10
8
)(
60
2
(
4
.
0
)
(
) 3
Z
Z
j
x
j
L
j
R
jX
R
Z
a
A
95
.
788
042
.
3
2400
volts
Z
V
Iac
A
46
.
1366
2
1
95
.
788
)
0
(
)
0
(
;
0
@
)
k
I
I
t
b ac
rms
00
.
1
10
739
.
6
1
2
1
)
3
(
641
.
1
693
.
1
1
2
1
)
1
.
0
(
54
.
7
4
.
0
016
.
3
)
(
)
3
54
.
7
)
3
(
4
54
.
7
)
1
.
0
(
4
x
e
cycle
k
e
cycle
k
Ratio
R
X
c
A
95
.
788
)
3
(
)
3
(
A
69
.
294
,
1
641
.
1
)
1
.
0
(
)
1
.
0
(
cycle
k
I
cycle
I
x
cycle
k
I
cycle
I
ac
rms
ac
rms
+
- 0
@
t
Closed
SW
mH
L 20
)
sin(
400
,
2
2
)
(
wt
t
e
4
R
11. Asymmetrical Fault-Unloaded
Synchronous Machine
Three Stages: Subtransient, Transient, and Steady State
constant
time
armature
T
/
I
/
I
/
I
:
offset
dc
Maximum
2
2
)
(
)
2
sin(
]
1
)
1
1
(
)
1
1
[(
2
)
(
Current
ous
Instantane
)
(
)
(
)
(
A
Reactance
State
Steady
Reactance/
s
Synchronou
axix
direct
'
'
Reactance
Transient
axix
direct
'
Reactance
nt
Subtransie
axix
direct
"
/
"
/
"
'
'
"
"
"
'
"
d
g
d
d
g
d
d
g
d
T
t
T
t
d
g
dc
d
T
t
d
d
T
t
d
d
g
ac
X
E
X
X
E
X
X
E
X
Where
e
I
e
X
E
t
i
t
X
e
X
X
e
X
X
E
t
i
t
i
t
i
t
i
A
A
d
d
dc
ac
A
d
d
d
d
d X
X
X
T
,
T
,
T
Constants
Time
&
Reactances
Machine
:
provide
eres
Manufactur
:
Note
'
"
,
'
,
"
Stator
Uniform air-gap
Stator winding
Rotor
Rotor winding
N
S
d-axis
q-axis
axis
quadrature
axis
q
axis
direct
axis
d
12. Synchronous Machine
Asymmetrical Fault Envelopes
Asymmetry Sources: (1) Open Phase and (2) SLG Fault
d
g
X
E
I "
"
d
g
X
E
I '
'
d
g
X
E
I
Current
fault
nt
Subtransie
Current
fault
Transient
Current
fault
S.S
)
(t
iac
t
envelopes
current
AC
A
A T
t
T
t
d
g
e
I
e
X
E
"
"
MAX
-
dc 2
2
(t)
i
"
2I
I
2
'
2I
15. Fault Current Analysis
Power System Review
Four methods to calculate the fault current:
1.Ohmic Method (not preferred)
2.Infinite Bus Method (Convenient & Easy)
3.Per Unit Method (Most Common)
4.MVA Method (Quick & Easy)
Note: This course will focus on PU & MVA Methods
17. Ohmic Method
Power System Review
This Method Requires:
Transferring all impedances to high/low
voltage side of transformer using square
of XFMR turn ratio
Using your AC circuit theory knowledge
Voltage & Current dividers
Thevenin & Norton equivalents
Kramer’s Rule, etc
2
1
2
2
2
1
N
N
OR
N
N
20. 7.5%
Z
kV
kV/4.16
13.8
KVA
5000
VS
Infinite Bus Calculation
Unknown Utility SC Data
A
4
.
9252
95
.
693
333
.
13
actual
I
:
Step4
A
95
.
693
16
.
4
3
5000
kV
x
3
3
KVA
I
Calculate
:
Step3
333
.
13
075
.
0
.
1
0
.
1
I
Calculate
:
Step2
075
.
0
100
5
.
7
100
Z%
Z
Calculate
:
Step1
SC
LL
Base
pu
x
I
x
I
kV
x
Z
pu
SC
Bsae
pu
pu
SC
Example1: Calculate the maximum 3ᶲ fault current on 5000 KVA
Transformer’s secondary bus.
Data
Source
No
21. 7.5%
Z
kV
kV/4.16
13.8
KVA
5000
VS
Infinite Bus Calculation
with Known Utility SC Data
A
6426
95
.
693
26
.
9
actual
I
:
Step4
A
95
.
693
16
.
4
3
5000
kV
x
3
3
KVA
I
Calculate
:
Step3
26
.
9
108
.
0
0
.
1
0
.
1
I
Calculate
:
Step2
108
.
0
075
.
033
.
0
Z
Calculate
:
Step1
SC
LL
Base
)
(
total
x
I
x
I
kV
x
Z
pu
Z
Z
SC
Bsae
pu
total
pu
SC
r
transforme
utility
Example2: Calculate the maximum 3ᶲ fault current on 5000 KVA
Transformer’s secondary bus.
150MVA
SC
pu
Z
Z
pu
x
S
S
kV
kV
Z
Z
pu
r
transforme
Old
base
New
base
new
old
pu
Utility
SC
base
utility
Old
New
075
.
0
100
5
.
7
100
%
033
.
150
5
16
.
4
16
.
4
1
1
150
150
MVA
MBA
Z
Z
Z
Z
Calculate
2
2
r
transforme
utility
toal
pu
108
.
0
33
0
.
0
0.075
Ztotal
utility
Z
:
Steps
n
Calculatio
23. Power System Review
Fault Current Analysis:
Per-Unit Method
PU analysis is used for both symmetrical &
unsymmetrical fault calculations.
•All components are defined in PU system.
•Analysis is performed using equivalent per phase
circuit modeling.
•Requires knowledge of symmetrical components
•Requires selecting two system bases for
calculating all base & PU quantities:
kVBase & MVAbase
24. Power System Review
Fault Current Analysis:
Per-Unit Method
This Method requires:
•Knowledge of symmetrical components
Positive sequence (+ SEQ)
Negative sequence(-SEQ)
Zero sequence (0 SEQ)
•Interconnecting positive, negative, and
zero networks for calculating the various
unsymmetrical faults(LG, LL/LLG, and 3ᶲ)
25. Symmetrical Components
Power System Review
Steps involved:
1. Draw a single-line diagram of the desired
power system(equivalent per phase)
2. Define zones using transformation point as
a point of demarcation
3. Select a common MVAbase for all zones
4. Select a kVBase for one zone & Calculate
a. kVBase for other zones
b. Zbase, and Ibase for all zones
26. Symmetrical Components..cont
Power System Review
6. Replace each component with its
equivalent reactance in per-unit
7. Draw sequence networks(+, -, 0)
8. Use (+)SEQ network for Symmetrical
Fault analysis
9. Combine appropriate networks for
calculating various Unsymmetrical
Fault analysis
28. 3Φ Symmetrical Fault Analysis
(PU Method)
Symmetrical Fault refers to a balanced 3Φ
fault, in a balanced 3Φ system operating in
steady state, which is either :
Bolted fault: LLLG fault with Zfault=0
Non-Bolted fault: LLLG fault with Zfault≠0
Only the (+)SEQ network exists.
(0)SEQ & (-)SEQ currents are equal to “Zero”.
Power System Review
29. Symmetrical Fault Modeling
for a Bolted Fault (PU Method)
Z0 eq
Note: VF=Pre Fault Voltage
+
_
Vo=0
Z2 eq
VF
Z1 eq
+
_
+
_
V1=0
I0=0
I1 Ia
Ib
Ic
Vc
Vb
Va
+
+
+
_ _ _
Ib = -Ia = Ic = ISC
Vbg = Vag = Vcg =0
Phase
g
+
_
V2=0
I2=0
)
(
1
)
(
)
(
1
PU
eq
PU
f
Z
V
I PU
fault
0
2
I
0
0
I
SEQ
SEQ
)
(
SEQ
)
(
SEQ
)
0
(
30. Practice Example (PU Method):
In the following power system Calculate(a)3ᶲ Symmetrical
fault current @ Bus3 and select an appropriate Breaker
Size @ Bus 3
G1
G2
PU
.15
0
X
kV
13.8
MVA
500
"
.15PU
0
T1
Υ
115kV
/
Δ
13.8kV
MVA
500
"
X
PU
.20
0
X
kV
13.2
MVA
750
"
.18PU
0
T2
kV
8
.
13
/
115kV
MVA
750
"
X
6
XT1
2
X 13
T
17.63
Zbase
115kV
Kvbase
MVA
750
Sbase
1
Bus 2
Bus
3
Bus
4
X 23
T
.254
Zbase
13.8kV
Kvbase
MVA
750
Sbase
.254
Zbase
13.8kV
Kvbase
MVA
750
Sbase
MVA
750
SBase
31. Breaker Selection
Modern Circuit Breaker standards are designed based on
ISymmetrical. The following steps are required to determine an
appropriate breaker size:
1. Use “E/X” method to calculate the minimum ISymmetrical.
2. Calculate X/R ratio:
1. If X/R <15 →Use ISymmetrical
2. If X/R>15 →It means the dc offset has not decayed
to an acceptable level. Thus, calculate IAsymmetrical.
3. Calculate IAsymmetrical at calculated fault location.
4. Breaker Interrupting Capability should be 20% greater
than the calculated fault current.
32. Breaker Selection Criterion
Generator/ Synchronous Motor/Large Induction motors
Breakers:
Use subtransient Reactance X”d to calculate ISymmetrical.
Use 2 cycle Breaker
Transmission Breakers:
Use 3 cycle Breakers if X/R>15
Use 5 cycle Breaker if X/R<15
Distribution Breakers:
Use 3 cycle or 5 cycle Breakers
If X/R ratio is unknown Use:
8
.
0
I
I
l
Symmetrica
Capability
ng
Interrupti
Breaker
Unknown
R
X
33. A
2
.
614
,
16
8
.
0
13,291.2
I Capability
ng
Interrupti
Breaker
G1 G2
PU
.15
0
X
kV
13.8
MVA
500
"
.15PU
0
T1
Υ
115kV
/
Δ
13.8kV
MVA
500
"
X
PU
.20
0
X
kV
13.2
MVA
750
"
.18PU
0
T2
kV
8
.
13
/
115kV
MVA
750
"
X
6
XT1
2
X 13
T
17.63
Zbase
115kV
Kvbase
MVA
750
Sbase
1
Bus 2
Bus
3
Bus
4
X 23
T
.254
Zbase
13.8kV
Kvbase
MVA
750
Sbase
.254
Zbase
13.8kV
Kvbase
MVA
750
Sbase
MVA
750
SBase
kV
115
:
Class
Voltage
Breaker
:
Selection
Breaker
cycle
3
:
Cycle
Breaker
Practice Example (PU Method):
A
2
.
291
,
13
I l
Symmetrica
35. Fault Current Calculation-MVA Method
This method follows a four steps process:
1. Calculate the Admittance of every component in its own
infinite bus.
2. Multiply the calculated admittances in step(1) by the
MVA rating of each component to get MVASC.
3. Combine short-circuit MVAs & follow the Admittance
series & parallel rules:
4. Convert MVAs to Symmetrical fault current
Power System Review
%
100
)
Admittance
(
Z
Y
)
Admittance
(
Y
x
MVA
MVAsc
n
total MVA
MVA
MVA
MVA ........
:
MVAs
Parallel
a)
2
1
n
total MVA
MVA
MVA
MVA
1
........
1
1
1
:
MVAs
Series
b)
2
1
ll
kV
x
Total
MVAsc
al
Isymmetric
3
)
(
37. Why Use the MVA Method?
This method is internationally used and accepted by most
protection engineers.
The network set up is easier than Ohmic or PU method.
You can calculate Ifault in a shorter time period.
This method makes it easier to see the fault contributions
@ every point in the system.
Calculation accuracy is within 3% to 5% compared to PU &
Ohmic method.
Power System Review
38. MVA Method Assumptions
Power System Review
10
.
1
R
X
Two Conditions must be satisfied:
Operation
State
Steady
.
2
39. Symmetrical Fault Current
Analysis...MVA-Method
Power System Review
)
(
3
: KA
I
x
kV
x
MVAsc
MVA
Utility sc
ll
fault
)
(
:
2
Z
kV
MVA
Cable
ll
fault
%
100
:
/ "
Gen
d
fault
X
x
MVA
MVA
Motor
us
Sycnhroono
Generator
%
100
:
xfmr
fault
Z
x
MVA
MVA
r
Transforme
Formulas:
Note: Impedances (Z) are steady state values
40. Where: X”d=direct-axis Subtransient Reactance
X”d= I Full-load amp/I Locked Rotor amp
Power System Review
Symmetrical Fault Current
Analysis...MVA-Method
%
100
: "
Gen
d
motor
fault
X
x
MVA
MVA
Motor
amp
load
full
rotor
locked
motor
fault
I
I
x
MVA
MVA
Motor
Induction
:
:
Motor
41. Summary:
Power System Review
Symmetrical Fault Current
Analysis...MVA-Method
LL
kV
x
MVA
I
total
KA
fault
3
)
(
)]
/
1
(
)
/
1
(
)
/
1
[(
1
2
1 n
MVA
MVA
MVA
total
series
MVA
n
MVA
MVA
MVA
total
parallel
MVA
2
1
42. Example1:Fault Calculation(MVA method)
Generator
M
Utility Source
13.8kV, 15KA fault current
Motor
2MVA Y
4.16kV
X”d=0.25pu
3-500McM cables, 2000 ft
Z=0.2Ω
Transformer
7MVA
13.8kV/4.16kV
Z=9%
1.5MVA Y
4.16kV
X”d=0.15pu
Bus 1 13.8kV
Bus 2 4.16kV
In the following Power System, Calculate the fault current @ Bus2 & fault current
contributions from both Gen & Motor?
43. Step1:Network Modeling(MVA Method)
Generator
M
Utility Source
13.8kV, 15KA fault current
Motor
2MVA Y
4.16kV
X”d=0.25
3-500McM cables, 2000 ft
Z=0.2Ω
Transformer
7MVA
13.8kV/4.16kV
Z=9%
1.5MVA Y
4.16kV
X”d=0.15
MVA
x
x
MVAsource 5
.
358
)
kA
15
(
)
kv
8
.
13
(
3
MVA
x
Z
x
MVA
MVA
xfmr
r
transforme 77
.
77
9
100
7
%
100
MVA
x
X
x
MVA
MVA
d
Generator 10
15
.
0
1
5
.
1
1
"
MVA
x
X
x
MVA
MVA
d
Motor 8
25
.
0
1
2
1
"
52
.
358
77
.
77
10
8
MVA
Z
kV
MVA
line
Line 53
.
86
2
.
0
)
16
.
4
( 2
2
53
.
86
Bus1 13.8kV
Bus2 4.16kV
46. Generator
M
Utility Source
13.8kV, 15KA fault current
Motor
2MVA Y
4.16kV
X”d=0.25
3-500McM cables, 2000 ft
Z=0.2Ω
Transformer
7MVA
13.8kV/4.16kV
Z=9%
1.5MVA
Y
4.16kV
X”d=0.15
Bus1 13.8kV
Bus2 4.16kV
pu
Vf 0
.
1
2
)
( Bus
for
Network
SEQ
utility
Z
Xfmr
Z
Line
Z
Gen
Z motor
Z
In the following Power System, Calculate the fault current @ Bus2 & fault current
contributions from both Gen & Motor using PU Method?
Example1:Fault Analysis(PU Method)
47. Example 1: Symmetrical Fault Current
Calculation Comparison between
PU & MVA Methods
Amp
I Bus
fault 3
.
600
,
7
2
@
A
7
.
605
,
7
A
879
,
13
548
.
0
)
(
2
@
x
xI
pu
I
I base
fault
Bus
fault
:
n
calculatio
method
MVA
:
n
calculatio
Method
Unit
Per
49. Ex1:Symmetrical Fault Current Analysis
PU & MVA Methods Comparison
Amp
I motor
f 3
.
110
,
1
A
110
,
1
f-motor
I
:
n
calculatio
method
MVA
:
n
calculatio
Method
Unit
Per
50. Symmetrical Fault Current Calculation
MVA Method
Example2: Calculate the Symmetrical fault current @ Bus2 using the MVA Method
Generator
M
M
Generator
Utility Source
22.86kV, 15KA fault current
Transformer
20MVA Delta-Yn
22.86/4.16kV
Z=9% 5MVA
4.16kV
Z=12%
Transformer
3.5MVA Delta-Yn
4.16kV/480V
Z=7%
Motor
2MVA Y
4.16kV
Z=15%
Motor
1.5MVA Y
480V
Z=16%
Y
Y
3-500McM cables, 2000 ft
Z=.18 Ω
Bolted Fault
Generator
2MVA
480 V
Z=14%
BUS 1
BUS 2
903
.
593
15
86
.
22
3
kA
x
kV
x
MVA LL
fault
22
.
903
,
2
18
.
0
)
86
.
22
( 2
2
kV
Z
kV
MVA
line
fault
50
07
.
0
5
.
3
100
%
222
.
222
09
.
0
20
100
%
Z
MVA
MVA
Z
MVA
MVA
Xfmr
fault
Xfmr
fault
MVA
Z
MVA
G
MVA
MVA
Z
MVA
G
MVA
fault
fault
286
.
14
14
.
0
2
100
%
)
2
(
667
.
41
12
.
0
5
100
%
)
1
(
MVA
Z
MVA
G
MVA
MVA
Z
MVA
M
MVA
fault
fault
375
.
9
16
.
0
5
.
1
100
%
)
2
(
333
.
13
15
.
0
2
100
%
)
1
(
58. Example2: Symmetrical Fault
Current Analysis…MVA-Method
Bus2 (total) = 40.323+14.286+9.375=63.984 MVA
Now, Calculate the Short Circuit MVA @Bus1?
Power System Review
Available Fault Current @Bus 2:
Ifault=63.984 MVA/[ x 0.48kV]=76,963 A
3
59. Ex2:Calculate Short Circuit MVA@ Bus1
(MVA method)
153.864
MVA
41.667
MVA
50 MVA
9.375
MVA
14.286
MVA
13.333
MVA
195.531
MVA
13.333
MVA
50
MVA
9.375+14.286=23.661
MVA
208.864+16.051=224.915 MVA
208.864= 195.531+13.333
MVA
1/[(1/50)+(1/23.661)]=1/.0623=16.051
MVA
Power System Review
BUS 1 BUS 1
BUS 1
BUS 1
BUS 2
MVA
531
.
195
667
.
41
846
.
153
parallel
MVA
MVA
915
.
224
1
@
Bus
fault
MVA
60. S.C or Fault MVA @ Bus1:
S.C or Fault MVA= 224.915
I fault @Bus1= 224.915 MVA/( x4.16kV)
Power System Review
Ex2: Calculate Short Circuit MVA
@ Bus 1 (MVA method)
3
Available Fault Current at Bus 1:
I fault @Bus1=31,216 A
61. Example 3: Symmetrical Fault Analysis
Power System Review
Source M
1500 MVA
Fault
69 kV
X=2.8Ω
10 MVA
X=8.5%
69kV Δ/Υ-n 13.8kV
13.2 kV
X=0.2
Calculate the symmetrical fault current at the secondary terminals of a 10 MVA XFMR
using both the PU-Method & the MVA Method. Use 15 MVA & 69 kV base values for
the transmission line.
5 MVA Υ-n
Zone 1 Zone 2
kV
V 69
1
Base
-
lL
A
kV
x
S
IBase 57
.
627
3 1
Base
Base
2
4
.
317
15
69
S
2
Base
Base
2
Base
1
1
1
kV
Z
MVA
S 15
Base
MVA
S 15
Base
7
.
12
15
8
.
13 2
Base2
Z
kV
V 8
.
13
2
Base
-
lL
63. Symmetrical Fault Calculation
Comparison Between PU & MVA
Methods
I fault= 5,410.3 Amp
I fault = 5,432.3 Amp
:
method
PU
:
method
MVA
Example 3:
Power System Review
64. References
1. J.D. Golver, M.S. Sarma, Power System Analysis and design,
4th ed., (Thomson Crop, 2008).
2. M.S. Sarma, Electric Machines, 2nd ed., (West Publishing Company,
1985).
3. A.E. Fitzgerald, C. Kingsley, and S. Umans, Electric
Machinery, 4th ed. (New York: McGraw-Hill, 1983).
4. P.M. Anderson, Analysis of Faulted Power systems(Ames, IA: Iowa
Satate university Press, 1973).
5.W.D. Stevenson, Jr., Elements of Power System Analysis, 4th
ed. (New York: McGraw-Hill, 1982).