The document discusses power flow analysis and various power flow solution methods. It begins by explaining the necessity of power flow studies for planning and operating power systems. It then derives the static power flow equations and describes different types of buses in a power system network. Several iterative power flow solution methods are covered, including Gauss-Seidel, Newton-Raphson in both polar and rectangular coordinates, and decoupled methods which improve computational efficiency for large systems. The document provides detailed explanations of implementing each of these power flow analysis techniques.
The document discusses power flow analysis, which determines the voltage, current, real power, and reactive power at points in an electrical network under normal operating conditions. It provides three key points:
1. Power flow analysis is important for planning, operations, and future expansion of power systems by studying the effects of new loads, generators, or transmission lines.
2. The analysis involves classifying buses as slack, generator, or load buses and formulating the network equations based on the bus admittance matrix.
3. Solving the load flow problem involves determining the complex voltages across all buses given the network configuration and bus demands. This provides critical information for monitoring overloads and voltage deviations.
IRJET- Comparative Analysis of Load Flow Methods on Standard Bus SystemIRJET Journal
The document compares different load flow analysis methods (Gauss-Seidel, Newton-Raphson, Fast Decoupled) on standard test systems (IEEE 5, 9, 26, 30 bus systems) using MATLAB. Load flow analysis is important for power system planning and operation to ensure stable and economic energy transfer. The methods are compared based on number of iterations, maximum power mismatch, and computational time to determine the best method for a given network system. Gauss-Seidel is an iterative method that uses updated voltages at each iteration but requires more iterations to converge compared to other methods.
IRJET- Load Flow Analysis of IEEE 14 Bus Systems in Matlab by using Fast Deco...IRJET Journal
The document presents a simulation of load flow analysis for the IEEE 14 bus system using the Fast Decoupled method in MATLAB. The Fast Decoupled method calculates voltage magnitude and phase angle as well as active and reactive power for each bus through an iterative process. The results show that the Fast Decoupled method requires fewer iterations and less computation time than traditional methods for solving load flow problems, making it preferable for analysis of distribution systems.
Voltage Stability Assessment Using the Concept of GVSMiosrjce
To assessment of voltage stability of multi bus power system, the main requirement is equivalent twobus
network models, which is fulfilled by lumping all the series impedances and shunt admittances of
transmission lines within a series equivalent impedance. This paper shows the development of an equivalent pi
network model using a new technology or methodology called generalized global voltage stability margin
(GVSM). This is used to assess the overall voltage stability status of the system accurately. Simulation results
for IEEE 14 Test bus system, IEEE 30 Test bus system , IEEE 118 Test bus system are establish that the piequivalent
model obtained by the proposed method is highly accurate for assessing voltage stability of any
power system at any operating point in a better way as compared to series equivalent model
This document presents a new methodology called generalized global voltage stability margin (GVSM) to assess voltage stability in power systems. The methodology develops an equivalent pi-network model of the power system by lumping all series impedances and shunt admittances of transmission lines. Simulation results on IEEE 14, 30, and 118 test systems show the pi-equivalent model accurately represents the system and allows assessment of voltage stability at any operating point. The GVSM value indicates how close the system is to voltage collapse, and decreases as load increases, becoming zero at the point of collapse. The methodology provides a better representation of voltage stability compared to a traditional series equivalent model.
Abstract: In this paper three phase load flow analysis on four bus system using Mi Power software is reformed. As power system never operates under steady state condition therefore single phase load flow analysis doesn’t provide accurate results. Hence three phase load flow analysis which can be performed under different contingencies, provide data when system is unbalanced. The system is analysing on the basis of parameter values in MW & MVAR for transmission line and generator buses. Harmonic values of resistance, reactance, and susceptance can predict the condition of small and large kind of system network. This type of analysis is useful for solving the power flow problem in different power systems which will useful to calculate the unknown parameter.
The document discusses power flow analysis, which determines bus voltages and power flows in a power system under normal steady-state operating conditions. It provides the mathematical formulation of the power flow problem as a set of nonlinear algebraic equations that must be solved iteratively. Buses are classified as slack, generator, or load buses depending on which two of four associated quantities - real power, reactive power, voltage magnitude, and voltage angle - are specified versus solved for. Solution methods like the Gauss-Seidel method are commonly used to iteratively solve the power flow equations until bus voltages converge.
The document discusses power flow analysis, which determines the voltage, current, real power, and reactive power at points in an electrical network under normal operating conditions. It provides three key points:
1. Power flow analysis is important for planning, operations, and future expansion of power systems by studying the effects of new loads, generators, or transmission lines.
2. The analysis involves classifying buses as slack, generator, or load buses and formulating the network equations based on the bus admittance matrix.
3. Solving the load flow problem involves determining the complex voltages across all buses given the network configuration and bus demands. This provides critical information for monitoring overloads and voltage deviations.
IRJET- Comparative Analysis of Load Flow Methods on Standard Bus SystemIRJET Journal
The document compares different load flow analysis methods (Gauss-Seidel, Newton-Raphson, Fast Decoupled) on standard test systems (IEEE 5, 9, 26, 30 bus systems) using MATLAB. Load flow analysis is important for power system planning and operation to ensure stable and economic energy transfer. The methods are compared based on number of iterations, maximum power mismatch, and computational time to determine the best method for a given network system. Gauss-Seidel is an iterative method that uses updated voltages at each iteration but requires more iterations to converge compared to other methods.
IRJET- Load Flow Analysis of IEEE 14 Bus Systems in Matlab by using Fast Deco...IRJET Journal
The document presents a simulation of load flow analysis for the IEEE 14 bus system using the Fast Decoupled method in MATLAB. The Fast Decoupled method calculates voltage magnitude and phase angle as well as active and reactive power for each bus through an iterative process. The results show that the Fast Decoupled method requires fewer iterations and less computation time than traditional methods for solving load flow problems, making it preferable for analysis of distribution systems.
Voltage Stability Assessment Using the Concept of GVSMiosrjce
To assessment of voltage stability of multi bus power system, the main requirement is equivalent twobus
network models, which is fulfilled by lumping all the series impedances and shunt admittances of
transmission lines within a series equivalent impedance. This paper shows the development of an equivalent pi
network model using a new technology or methodology called generalized global voltage stability margin
(GVSM). This is used to assess the overall voltage stability status of the system accurately. Simulation results
for IEEE 14 Test bus system, IEEE 30 Test bus system , IEEE 118 Test bus system are establish that the piequivalent
model obtained by the proposed method is highly accurate for assessing voltage stability of any
power system at any operating point in a better way as compared to series equivalent model
This document presents a new methodology called generalized global voltage stability margin (GVSM) to assess voltage stability in power systems. The methodology develops an equivalent pi-network model of the power system by lumping all series impedances and shunt admittances of transmission lines. Simulation results on IEEE 14, 30, and 118 test systems show the pi-equivalent model accurately represents the system and allows assessment of voltage stability at any operating point. The GVSM value indicates how close the system is to voltage collapse, and decreases as load increases, becoming zero at the point of collapse. The methodology provides a better representation of voltage stability compared to a traditional series equivalent model.
Abstract: In this paper three phase load flow analysis on four bus system using Mi Power software is reformed. As power system never operates under steady state condition therefore single phase load flow analysis doesn’t provide accurate results. Hence three phase load flow analysis which can be performed under different contingencies, provide data when system is unbalanced. The system is analysing on the basis of parameter values in MW & MVAR for transmission line and generator buses. Harmonic values of resistance, reactance, and susceptance can predict the condition of small and large kind of system network. This type of analysis is useful for solving the power flow problem in different power systems which will useful to calculate the unknown parameter.
The document discusses power flow analysis, which determines bus voltages and power flows in a power system under normal steady-state operating conditions. It provides the mathematical formulation of the power flow problem as a set of nonlinear algebraic equations that must be solved iteratively. Buses are classified as slack, generator, or load buses depending on which two of four associated quantities - real power, reactive power, voltage magnitude, and voltage angle - are specified versus solved for. Solution methods like the Gauss-Seidel method are commonly used to iteratively solve the power flow equations until bus voltages converge.
An Innovative Measurement Approach for Load Flow Analysis in MV Smart Grids.SaiSampath16
This document summarizes a technical seminar presented by a group of students on an innovative load flow analysis approach for medium voltage smart grids. The proposed approach uses power quality analyzer measurements at secondary substations and voltage measurements at the primary substation to perform load flow analysis through an iterative backward/forward algorithm. The approach was validated through simulations comparing results to traditional methods and through experimental measurements on an actual medium voltage grid on the island of Ustica, Italy. The results demonstrated the feasibility and accuracy of the proposed lower-cost measurement approach.
Application of SVC on IEEE 6 Bus System for Optimization of Voltage Stabilityijeei-iaes
The problem of voltage or current unbalance is gaining more attention recently with the increasing awareness on power quality. Excessive unbalance among the phase voltages or currents of a three phase power system has always been a concern to expert power engineers. The study of shunt connected FACTS devices is an associated field with the problem of reactive power compensation related problems in today’s world. In this study an IEEE-6 bus system has been studied & utilized in order to study the shunt operation of FACTS controller to optimize the voltage stability
These slides present an introduction to load flow analysis for distribution system. Later the detail algorithm, matlab coding and application to IEEE radial distribution system will be subsequently provided.
This document outlines the course objectives, units, and outcomes of a Power System Analysis course. The objectives are to teach students how to form Y bus and Z bus matrices, conduct power flow studies using various methods like Gauss-Seidel and Newton-Raphson, perform short circuit analysis, and analyze power system stability. The five units cover topics like network representations, short circuit analysis, power flow methods, and power system stability analysis using the swing equation and equal area criterion. At the end of the course, students should be able to model and analyze power systems, conduct load flow and fault studies, and evaluate power system stability.
Load Flow Analysis of Jamshoro Thermal Power Station (JTPS) Pakistan Using MA...sunny katyara
This article summarizes a study analyzing the load flow of Jamshoro Thermal Power Station (JTPS) in Pakistan using MATLAB programming. The study models the power plant and transmission network in MATLAB to calculate active and reactive power flows, line losses, voltage profiles and angles at different buses. This provides information for efficient scheduling and future planning of the power system. MATLAB code was developed using the Gauss-Siedel iterative method to solve the load flow equations. The results provide voltage magnitudes and angles at each bus and active/reactive power flows on each transmission line. This analysis can help optimize the economic operation and future expansion of the JTPS power system.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
A Study of Load Flow Analysis Using Particle Swarm OptimizationIJERA Editor
Load flow study is done to determine the power system static states (voltage magnitudes and voltage angles) at each bus to find the steady state working condition of a power system. It is important and most frequently car-ried out study performed by power utilities for power system planning, optimization, operation and control. In this project a Particle Swarm Optimization (PSO) is proposed to solve load flow problem under different load-ing/ contingency conditions for computing bus voltage magnitudes and angles of the power system. With the increasing size of power system, this is very necessary to finding the solution to maximize the utilization of ex-isting system and to provide adequate voltage support. For this the good voltage profile is must. STATCOM, if placed optimally can be effective in providing good voltage profile and in turn resulting into stable power sys-tem. The study presents a hybrid particle swarm based methodology for solving load flow in electrical power systems. Load flow is an electrical engineering well-known problem which provides the system status in the steady-state and is required by several functions performed in power system control centers.
Differential Evolution Based Optimization Approach for Power Factor CorrectionIDES Editor
In radial distribution systems, the voltages at buses
reduces when moved away from the substation, also the losses
are high. The reason for decrease in voltage and high losses is
the insufficient amount of reactive power, which can be
provided by the shunt capacitors. For this purpose, in this
paper, two stage methodologies are used. In first stage, the
load flow of pre-compensated distribution system is carried
out using ‘Dimension reducing distribution load flow
algorithm’. In the second stage, Differential Evolution (DE)
technique is used to determine the optimal location and size
of the capacitors. The above method is tested on IEEE 69 bus
system. In this paper a new method is proposed to improve the
power factor of those buses having low power factor (less than
0.8lag) to unity power factor simultaneously by placing the
capacitors.
This document summarizes a research paper that proposes using an improved particle swarm optimization (IPSO) algorithm to optimize reactive power reserve management in power systems. The IPSO algorithm is applied to minimize total reactive power generation from sources like generators and SVCs by adjusting control variables like generator voltages, transformer taps, and SVC settings. Testing on the IEEE 30-bus system shows the IPSO approach reduces reactive power generation and losses compared to the basic PSO algorithm. The IPSO approach also maintains bus voltages within acceptable ranges while optimizing reactive power reserves.
Power Quality Improvement in Microgrids using STATCOM under Unbalanced Voltag...mohammad hossein mousavi
The document describes a method for improving power quality in microgrids using a static synchronous compensator (STATCOM) under unbalanced voltage conditions. A double synchronous reference frame (DDSRF) control scheme is proposed for the STATCOM to independently control the positive and negative sequence components of voltage. This helps compensate for unbalanced voltage at the point of common coupling and reduces oscillating interactions between the positive and negative sequences. Simulation results show the proposed DDSRF control strategy effectively balances voltage and improves power quality under unbalanced conditions compared to conventional control methods.
Selective localization of capacitor banks considering stability aspects in po...IAEME Publication
The issue of voltage stability has become predominant in larger power systems, since the
system is operated close to its capabilities in recent years. Addressing this concern considering the
economic constraints is a challenge .This draws attention towards the localization of the reactive
components that can improve the overall voltage profile in the system. This paper discusses a
methodology for suitable selection of position (bus) for the placement of capacitor bank wherein the
injection of fixed amount of reactive power is made to depict a picture of the overall improved
voltage in the system considering the stability aspect for respective injection at that bus. The reduced
jacobian is used to determine the impact of reactive power injection in the form of system voltage
improvement.
Load flow studies analyze the steady state operation of a power system by determining voltage magnitudes and angles, as well as active and reactive power flows. The key purposes of load flow analysis include designing, planning, and optimizing the operation of a power system. The analysis models each bus in the system where generators, transmission lines, and loads connect. Buses are classified based on which two of four parameters - voltage magnitude, voltage angle, active power, and reactive power - are specified as inputs. Load flow equations are then solved to calculate the unknown parameters.
IRJET-Power Flow & Voltage Stability Analysis using MATLAB IRJET Journal
This document presents a MATLAB program for power flow analysis and voltage stability analysis of power systems. It begins with an introduction to power flow analysis and its importance. It then discusses voltage stability concepts like voltage collapse and improvement methods. The methodology section describes the Newton-Raphson power flow method and P-V and Q-V curves used for voltage stability analysis. It also provides the algorithm and case study details for the IEEE 14 bus system implemented in MATLAB. The program allows for power flow solutions, calculation of P-V and Q-V curves, and voltage stability assessment of power systems.
Power Flow & Voltage Stability Analysis using MATLAB IRJET Journal
This document presents a MATLAB program for power flow analysis and voltage stability analysis of power systems. It begins with an introduction to power flow analysis and its importance. It then discusses voltage stability concepts like voltage collapse and improvement methods. The methodology section describes the Newton-Raphson power flow method and P-V and Q-V curves used for voltage stability analysis. It also provides the algorithm and case study details for the IEEE 14 bus system implemented in MATLAB. The program allows for power flow solutions, calculation of P-V and Q-V curves, and voltage stability assessment of power systems.
Iaetsd static network equivalents for large power systemsIaetsd Iaetsd
This document describes different techniques for creating static network equivalents to reduce the size of large power systems for power flow studies. It discusses REI (radial equivalent independent) equivalents and Ward equivalents. The Ward equivalent is widely used but does not allow for reactive power support in the equivalized area. The document proposes using a Ward equivalent with a buffer zone to improve accuracy by providing some reactive power support. It presents the algorithm for creating an REI equivalent and compares the performance of different equivalence methods.
Moizuddin Mohammed is seeking a position in electrical power systems engineering. He has an MS in Electrical Engineering from Michigan Technological University with a 3.62 GPA expected in December 2015. His areas of expertise include power system protection, load flow studies, and power electronics. His projects include series and shunt compensation techniques, designing a distance protection scheme, and developing programs for unit commitment and economic dispatch. He has skills in software like ASPEN, PowerWorld, GAMS, and MATLAB. He completed an internship at Bharat Heavy Electricals where he studied circuit breaker testing and dielectric mediums.
This document summarizes a study that proposes a new method to improve voltage profiles in power systems by determining optimal locations for reactive power compensation devices like capacitor banks. The method utilizes modal analysis and calculates a reactive participation index (RPI) to identify buses that would most effectively improve voltage levels when compensated. The method is tested on the South Sulawesi power system in Indonesia, identifying key under-voltage buses. Capacitors are added iteratively at the buses with the highest RPI until all voltages are within limits. The results demonstrate improved voltage profiles and increased stability compared to alternative configurations.
How to Make a Field Mandatory in Odoo 17Celine George
In Odoo, making a field required can be done through both Python code and XML views. When you set the required attribute to True in Python code, it makes the field required across all views where it's used. Conversely, when you set the required attribute in XML views, it makes the field required only in the context of that particular view.
An Innovative Measurement Approach for Load Flow Analysis in MV Smart Grids.SaiSampath16
This document summarizes a technical seminar presented by a group of students on an innovative load flow analysis approach for medium voltage smart grids. The proposed approach uses power quality analyzer measurements at secondary substations and voltage measurements at the primary substation to perform load flow analysis through an iterative backward/forward algorithm. The approach was validated through simulations comparing results to traditional methods and through experimental measurements on an actual medium voltage grid on the island of Ustica, Italy. The results demonstrated the feasibility and accuracy of the proposed lower-cost measurement approach.
Application of SVC on IEEE 6 Bus System for Optimization of Voltage Stabilityijeei-iaes
The problem of voltage or current unbalance is gaining more attention recently with the increasing awareness on power quality. Excessive unbalance among the phase voltages or currents of a three phase power system has always been a concern to expert power engineers. The study of shunt connected FACTS devices is an associated field with the problem of reactive power compensation related problems in today’s world. In this study an IEEE-6 bus system has been studied & utilized in order to study the shunt operation of FACTS controller to optimize the voltage stability
These slides present an introduction to load flow analysis for distribution system. Later the detail algorithm, matlab coding and application to IEEE radial distribution system will be subsequently provided.
This document outlines the course objectives, units, and outcomes of a Power System Analysis course. The objectives are to teach students how to form Y bus and Z bus matrices, conduct power flow studies using various methods like Gauss-Seidel and Newton-Raphson, perform short circuit analysis, and analyze power system stability. The five units cover topics like network representations, short circuit analysis, power flow methods, and power system stability analysis using the swing equation and equal area criterion. At the end of the course, students should be able to model and analyze power systems, conduct load flow and fault studies, and evaluate power system stability.
Load Flow Analysis of Jamshoro Thermal Power Station (JTPS) Pakistan Using MA...sunny katyara
This article summarizes a study analyzing the load flow of Jamshoro Thermal Power Station (JTPS) in Pakistan using MATLAB programming. The study models the power plant and transmission network in MATLAB to calculate active and reactive power flows, line losses, voltage profiles and angles at different buses. This provides information for efficient scheduling and future planning of the power system. MATLAB code was developed using the Gauss-Siedel iterative method to solve the load flow equations. The results provide voltage magnitudes and angles at each bus and active/reactive power flows on each transmission line. This analysis can help optimize the economic operation and future expansion of the JTPS power system.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
A Study of Load Flow Analysis Using Particle Swarm OptimizationIJERA Editor
Load flow study is done to determine the power system static states (voltage magnitudes and voltage angles) at each bus to find the steady state working condition of a power system. It is important and most frequently car-ried out study performed by power utilities for power system planning, optimization, operation and control. In this project a Particle Swarm Optimization (PSO) is proposed to solve load flow problem under different load-ing/ contingency conditions for computing bus voltage magnitudes and angles of the power system. With the increasing size of power system, this is very necessary to finding the solution to maximize the utilization of ex-isting system and to provide adequate voltage support. For this the good voltage profile is must. STATCOM, if placed optimally can be effective in providing good voltage profile and in turn resulting into stable power sys-tem. The study presents a hybrid particle swarm based methodology for solving load flow in electrical power systems. Load flow is an electrical engineering well-known problem which provides the system status in the steady-state and is required by several functions performed in power system control centers.
Differential Evolution Based Optimization Approach for Power Factor CorrectionIDES Editor
In radial distribution systems, the voltages at buses
reduces when moved away from the substation, also the losses
are high. The reason for decrease in voltage and high losses is
the insufficient amount of reactive power, which can be
provided by the shunt capacitors. For this purpose, in this
paper, two stage methodologies are used. In first stage, the
load flow of pre-compensated distribution system is carried
out using ‘Dimension reducing distribution load flow
algorithm’. In the second stage, Differential Evolution (DE)
technique is used to determine the optimal location and size
of the capacitors. The above method is tested on IEEE 69 bus
system. In this paper a new method is proposed to improve the
power factor of those buses having low power factor (less than
0.8lag) to unity power factor simultaneously by placing the
capacitors.
This document summarizes a research paper that proposes using an improved particle swarm optimization (IPSO) algorithm to optimize reactive power reserve management in power systems. The IPSO algorithm is applied to minimize total reactive power generation from sources like generators and SVCs by adjusting control variables like generator voltages, transformer taps, and SVC settings. Testing on the IEEE 30-bus system shows the IPSO approach reduces reactive power generation and losses compared to the basic PSO algorithm. The IPSO approach also maintains bus voltages within acceptable ranges while optimizing reactive power reserves.
Power Quality Improvement in Microgrids using STATCOM under Unbalanced Voltag...mohammad hossein mousavi
The document describes a method for improving power quality in microgrids using a static synchronous compensator (STATCOM) under unbalanced voltage conditions. A double synchronous reference frame (DDSRF) control scheme is proposed for the STATCOM to independently control the positive and negative sequence components of voltage. This helps compensate for unbalanced voltage at the point of common coupling and reduces oscillating interactions between the positive and negative sequences. Simulation results show the proposed DDSRF control strategy effectively balances voltage and improves power quality under unbalanced conditions compared to conventional control methods.
Selective localization of capacitor banks considering stability aspects in po...IAEME Publication
The issue of voltage stability has become predominant in larger power systems, since the
system is operated close to its capabilities in recent years. Addressing this concern considering the
economic constraints is a challenge .This draws attention towards the localization of the reactive
components that can improve the overall voltage profile in the system. This paper discusses a
methodology for suitable selection of position (bus) for the placement of capacitor bank wherein the
injection of fixed amount of reactive power is made to depict a picture of the overall improved
voltage in the system considering the stability aspect for respective injection at that bus. The reduced
jacobian is used to determine the impact of reactive power injection in the form of system voltage
improvement.
Load flow studies analyze the steady state operation of a power system by determining voltage magnitudes and angles, as well as active and reactive power flows. The key purposes of load flow analysis include designing, planning, and optimizing the operation of a power system. The analysis models each bus in the system where generators, transmission lines, and loads connect. Buses are classified based on which two of four parameters - voltage magnitude, voltage angle, active power, and reactive power - are specified as inputs. Load flow equations are then solved to calculate the unknown parameters.
IRJET-Power Flow & Voltage Stability Analysis using MATLAB IRJET Journal
This document presents a MATLAB program for power flow analysis and voltage stability analysis of power systems. It begins with an introduction to power flow analysis and its importance. It then discusses voltage stability concepts like voltage collapse and improvement methods. The methodology section describes the Newton-Raphson power flow method and P-V and Q-V curves used for voltage stability analysis. It also provides the algorithm and case study details for the IEEE 14 bus system implemented in MATLAB. The program allows for power flow solutions, calculation of P-V and Q-V curves, and voltage stability assessment of power systems.
Power Flow & Voltage Stability Analysis using MATLAB IRJET Journal
This document presents a MATLAB program for power flow analysis and voltage stability analysis of power systems. It begins with an introduction to power flow analysis and its importance. It then discusses voltage stability concepts like voltage collapse and improvement methods. The methodology section describes the Newton-Raphson power flow method and P-V and Q-V curves used for voltage stability analysis. It also provides the algorithm and case study details for the IEEE 14 bus system implemented in MATLAB. The program allows for power flow solutions, calculation of P-V and Q-V curves, and voltage stability assessment of power systems.
Iaetsd static network equivalents for large power systemsIaetsd Iaetsd
This document describes different techniques for creating static network equivalents to reduce the size of large power systems for power flow studies. It discusses REI (radial equivalent independent) equivalents and Ward equivalents. The Ward equivalent is widely used but does not allow for reactive power support in the equivalized area. The document proposes using a Ward equivalent with a buffer zone to improve accuracy by providing some reactive power support. It presents the algorithm for creating an REI equivalent and compares the performance of different equivalence methods.
Moizuddin Mohammed is seeking a position in electrical power systems engineering. He has an MS in Electrical Engineering from Michigan Technological University with a 3.62 GPA expected in December 2015. His areas of expertise include power system protection, load flow studies, and power electronics. His projects include series and shunt compensation techniques, designing a distance protection scheme, and developing programs for unit commitment and economic dispatch. He has skills in software like ASPEN, PowerWorld, GAMS, and MATLAB. He completed an internship at Bharat Heavy Electricals where he studied circuit breaker testing and dielectric mediums.
This document summarizes a study that proposes a new method to improve voltage profiles in power systems by determining optimal locations for reactive power compensation devices like capacitor banks. The method utilizes modal analysis and calculates a reactive participation index (RPI) to identify buses that would most effectively improve voltage levels when compensated. The method is tested on the South Sulawesi power system in Indonesia, identifying key under-voltage buses. Capacitors are added iteratively at the buses with the highest RPI until all voltages are within limits. The results demonstrate improved voltage profiles and increased stability compared to alternative configurations.
How to Make a Field Mandatory in Odoo 17Celine George
In Odoo, making a field required can be done through both Python code and XML views. When you set the required attribute to True in Python code, it makes the field required across all views where it's used. Conversely, when you set the required attribute in XML views, it makes the field required only in the context of that particular view.
A Visual Guide to 1 Samuel | A Tale of Two HeartsSteve Thomason
These slides walk through the story of 1 Samuel. Samuel is the last judge of Israel. The people reject God and want a king. Saul is anointed as the first king, but he is not a good king. David, the shepherd boy is anointed and Saul is envious of him. David shows honor while Saul continues to self destruct.
Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
This presentation was provided by Rebecca Benner, Ph.D., of the American Society of Anesthesiologists, for the second session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session Two: 'Expanding Pathways to Publishing Careers,' was held June 13, 2024.
Level 3 NCEA - NZ: A Nation In the Making 1872 - 1900 SML.pptHenry Hollis
The History of NZ 1870-1900.
Making of a Nation.
From the NZ Wars to Liberals,
Richard Seddon, George Grey,
Social Laboratory, New Zealand,
Confiscations, Kotahitanga, Kingitanga, Parliament, Suffrage, Repudiation, Economic Change, Agriculture, Gold Mining, Timber, Flax, Sheep, Dairying,
Temple of Asclepius in Thrace. Excavation resultsKrassimira Luka
The temple and the sanctuary around were dedicated to Asklepios Zmidrenus. This name has been known since 1875 when an inscription dedicated to him was discovered in Rome. The inscription is dated in 227 AD and was left by soldiers originating from the city of Philippopolis (modern Plovdiv).
LAND USE LAND COVER AND NDVI OF MIRZAPUR DISTRICT, UPRAHUL
This Dissertation explores the particular circumstances of Mirzapur, a region located in the
core of India. Mirzapur, with its varied terrains and abundant biodiversity, offers an optimal
environment for investigating the changes in vegetation cover dynamics. Our study utilizes
advanced technologies such as GIS (Geographic Information Systems) and Remote sensing to
analyze the transformations that have taken place over the course of a decade.
The complex relationship between human activities and the environment has been the focus
of extensive research and worry. As the global community grapples with swift urbanization,
population expansion, and economic progress, the effects on natural ecosystems are becoming
more evident. A crucial element of this impact is the alteration of vegetation cover, which plays a
significant role in maintaining the ecological equilibrium of our planet.Land serves as the foundation for all human activities and provides the necessary materials for
these activities. As the most crucial natural resource, its utilization by humans results in different
'Land uses,' which are determined by both human activities and the physical characteristics of the
land.
The utilization of land is impacted by human needs and environmental factors. In countries
like India, rapid population growth and the emphasis on extensive resource exploitation can lead
to significant land degradation, adversely affecting the region's land cover.
Therefore, human intervention has significantly influenced land use patterns over many
centuries, evolving its structure over time and space. In the present era, these changes have
accelerated due to factors such as agriculture and urbanization. Information regarding land use and
cover is essential for various planning and management tasks related to the Earth's surface,
providing crucial environmental data for scientific, resource management, policy purposes, and
diverse human activities.
Accurate understanding of land use and cover is imperative for the development planning
of any area. Consequently, a wide range of professionals, including earth system scientists, land
and water managers, and urban planners, are interested in obtaining data on land use and cover
changes, conversion trends, and other related patterns. The spatial dimensions of land use and
cover support policymakers and scientists in making well-informed decisions, as alterations in
these patterns indicate shifts in economic and social conditions. Monitoring such changes with the
help of Advanced technologies like Remote Sensing and Geographic Information Systems is
crucial for coordinated efforts across different administrative levels. Advanced technologies like
Remote Sensing and Geographic Information Systems
9
Changes in vegetation cover refer to variations in the distribution, composition, and overall
structure of plant communities across different temporal and spatial scales. These changes can
occur natural.
2. Students should able to
Necessity of power flow studies.
Derivation of static power flow equations.
Power flow solution using
Gauss-Seidel Method
Newton Raphson Method
(Rectangular and polar coordinates form)
Decoupled
Fast Decoupled methods
Power Flow Studies
3. Students should able to
Power flow studies are undertaken for various reasons, some of
which are the following:
1.The line flows
2. The bus voltages and system voltage profile
3. The effect of change in configuration and incorporating new
circuits on system loading
4. The effect of temporary loss of transmission capacity and/or
generation on system loading and accompanied effects
5. The effect of in-phase and quadrative boost voltages on system
loading
6. Economic system operation
7. System loss minimization
8. Transformer tap setting for economic operation
9. Possible improvements to an existing system by change of
conductor sizes and system voltages.
NECESSITY OF POWER
FLOW STUDIES
4. Students should able to
Load flow studies are one of the most important
aspects of power system planning and operation.
The load flow gives us the sinusoidal steady state of the
entire system - voltages, real and reactive power
generated and absorbed and line losses.
Since the load is a static quantity and it is the power
that flows through transmission lines, it is prefer to
call this Power Flow studies rather than load flow
studies.
NECESSITY OF POWER
FLOW STUDIES
5. Students should able to
Through the load flow studies it can be obtained the voltage
magnitudes and angles at each bus in the steady state.
it is required to held the bus voltages within a specified
limits.
Once the bus voltage magnitudes and their angles are
computed using the load flow, the real and reactive power
flow through each line can be computed.
Also based on the difference between power flow in the
sending and receiving ends, the losses in a particular line
can also be computed.
Furthermore, from the line flow we can also determine the
over and under load conditions.
NECESSITY OF POWER
FLOW STUDIES
6. Students should able to
The power system network is a such a large interconnected
network, where various buses are connected through a
transmission lines.
At any bus, complex power is injected into the bus by the
generators and complex power is drawn by the loads.
The complex power Si at any bus i is given by,
Where Vi is voltage at bus i with angle δi.
Vi = |Vi| ∟δi = |Vi| (cos δi + j sin δi)
Yik = Gik + j Bik
POWER FLOW
EQUATIONS
9. Students should able to
The general practice in power-flow studies is to
identify types of buses in the network.
The load flow problem consists of determining the
magnitudes and phase angles of Voltages at each
bus and active and reactive power flow in each line.
While solving power flow problem, the system is
assumed to be operating under balanced condition.
The quantities associated with each bus are: δi,
|Vi|, Pi and Qi.
TYPES OF BUSES
10. Students should able to
Depending upon which two variables are
specified a priori, the buses are classified into
three categories.
Load bus: A non generator bus is called load
bus. At this bus, the real power demand and
reactive power demands are specified. The
parameters is to be determined are δi and |Vi|. A
load bus is often called as P-Q bus.
TYPES OF BUSES
11. Students should able to
Voltage controlled Bus: Any bus of the system
at which the voltage magnitude is kept constant
is said to be voltage controlled.
At each bus to which there is a generator
connected, the megawatt generation can be
controlled by adjusting the prime mover, and the
voltage magnitude can be controlled by adjusting
the generator excitation .
These buses are the generator buses.
TYPES OF BUSES
12. Students should able to
At these buses, the real power generation and
voltage magnitudes are specified. The other two
parameters δi and reactive powers has to be
determined.
These buses are also called P-V bus.
Some load buses with continuous reactive
power variation capability are also called
voltage controlled bus at which the real power
generation is simply zero.
TYPES OF BUSES
13. Students should able to
Slack Bus: This bus is also called slack bus or swing
bus, which is taken as reference to the entire system.
The voltage angle of the slack bus serves as
reference for the angles of all other bus voltages.
The real and reactive powers are not specified at
this bus.
Generally Bus 1 is considered to be a slack bus.
The voltage magnitude and phase angles are
specified at this bus.
TYPES OF BUSES
14. Students should able to
In any load flow study, the losses in the system
cannot be known a priori, without the solution of
voltages at all the buses.
The slack bus supplies the difference between the
total system load plus losses and the sum of the
complex powers at the remaining buses.
Slack bus is a generator bus as it needs to supply
the losses.
The bus connected to the largest generating station
is normally selected as slack bus.
TYPES OF BUSES
16. Students should able to
The GS method is most popular iterative
algorithm for solving non linear algebraic
equations.
At every subsequent iteration, the solution is
updated till convergence is reached.
It is applied to power flow problem as described
in subsequent sections.
GAUSS-SEIDEL
(GS) METHOD
18. Students should able to
Starting from an initial estimate of all the bus
voltages, the most recent values of the bus voltages
are substituted.
One iteration of the method involves computation
of all bus voltages.
The values of the updated voltages are used in the
computation of subsequent voltages in the same
iteration.
Iterations are carried out till the magnitudes of all
bus voltages do not change more than the
tolerance value.
GS METHOD
19. Students should able to
In GS method, number of iterations increases
with increase of size of the system.
It can be reduced, if the corrections in voltage
at each bus is accelerated.
Therefore, a multiplication factor called
acceleration factor (α) is introduced.
Generally, α is taken between 1.6 to 2.0.
A wrong value of α may lead to divergence.
GS METHOD
27. Students should able to
Case (ii):
In case of any PV Bus in a system:
1. Calculate Q at that bus.
2. Calculate V by using above Q value.
3. Since, it is a PV bus |V| = V specified,
but angle only has to be updated.
GS METHOD
28. Students should able to
Case (iii):
In case Q limits specified at PV Bus in a system:
1. Calculate Q at that bus.
2. Check for Q limits, If the limits are not satisfied,
treat that PV bus as PQ bus with Q as follows:
GS METHOD
29. Students should able to
The most widely used method for solving
simultaneous non linear algebraic equations.
NEWTON – RAPHSON
METHOD
33. Students should able to
In the above equation, bus 1 is assumed to be
slack bus. The Jacobian matrix gives the
linearized relation between small changes in
with small changes in real and
reactive power Elements of jacobian
matrix are the partial derivatives of power flow
equations. It can be written as:
NEWTON – RAPHSON
METHOD (Polar Co-ordinates)
50. Students should able to
When solving large scale power system, an alternative strategy for
improving computational efficiency and reducing computer
storage is introduced called Decoupled power flow method.
This makes use of an approximate version of NR method.
The basic principle underlying the decoupled approach is based
on two observations:
Change in the voltage angle δ at a bus primarily affects the flow of
real power P in the transmission lines and leaves the flow of
reactive power Q relatively unchanged.
Change in the voltage magnitude IVI at a bus primarily affects the
flow of reactive power Q in the transmission lines and leaves the
flow of real power P relatively unchanged.
Decoupled Load
flow
51. Students should able to
The first observation states essentially that is
dP/dδ much larger than dQ/dδ, which we now
consider to be approximately zero.
The second observation states that dQ/d|v| is
much larger than dP/d|V| , which is also
considered to be approximately zero.
Incorporation of these approximations into the
jacobian:
J2=0 and also J3=0;
Decoupled Load
flow
53. Students should able to
These equations are decoupled in the sense that the
voltage-angle corrections ∆δ are calculated using only
real power mismatches ∆P, while the voltage-magnitude
corrections are calculated using only ∆ Q mismatches.
However, these two interdependent.
But this scheme would still require evaluation and
factoring of the two coefficient matrices at each
iteration.
To avoid such computations, we introduce further
simplifications, which are justified by the physics of
transmission line power flow.
Decoupled Load
flow
54. Students should able to
In a well-designed and properly operated power
transmission system:
The angular differences (δi - δj) between typical
buses of the system are usually so small that
Cos(δi - δj) = 1; Sin(δi - δj) = (δi - δj);
The line susceptances Bij are many times larger
than the line conductances, Gij so that,
Gij Sin(δi - δj) << Bij Cos(δi - δj) << Bij
Fast Decoupled
Load flow
64. Students should able to
The Bus impedance matrix (ZBUS) can be
formulated by two methods.
1. Formulating YBUS and taking the inverse.
2. Based on algorithm.
By using system parameters and coded bus
numbers.
Construction of the network is carried out by
adding one element at a time.
Z–BUS FORMULATION
65. Students should able to
Consider the following partial network with
‘m’ no. of buses and ‘0’ as the reference
node.
Algorithm for
Z–BUS FORMULATION
The performance equation in the
bus frame of reference:
EBUS = ZBUS IBUS
EBUS is the vector of bus voltages of size
mx1 measured w.r.to reference node.
IBUS is the vector of bus currents of size
mx1.
66. Students should able to
The voltage equations can be written as:
E1= Z11I1+Z12I2+…..+Z1kIk+….+Z1mIm
.
.
Ek= Zk1I1+Zk2I2+…..+ZkkIk+….+ZkmIm
.
.
Em= Zm1I1+Zm2I2+…..+ZmkIk+….+ZmmIm
By injecting the currents at Kth bus, by keeping all
other bus current injections as ‘0’.
Ii = 0 , i≠k
Algorithm for
Z–BUS FORMULATION
67. Students should able to
Ek= Zkk Ik
Ei= Zik Ik
Now Ik= 1.0 pu
Ek= Zkk
Ei= Zik
The ZBus formulation can be carried out in
two aspects.
When an element p-q is added to the partial
network, it may be branch or a link as
shown in figures.
Algorithm for
Z–BUS FORMULATION
68. Students should able to
Algorithm for
Z–BUS FORMULATION
P is an existing bus in
a partial network and
q is a new bus, this
results into p-q
branch.
Both p and q are
existing in the partial
network in this case
p-q is a link.
69. Students should able to
Let us assume, the added branch p-q is mutually
coupled with some elements of the partial network.
The performance equation with the added branch
is:
Addition of a
Branch
70. Students should able to
If the elements of the network are bilateral passive
elements: Zqi = Ziq
Addition of a
Branch
Where, Zqi is the voltage
at qth bus by injecting
1.0 pu current at ith
bus.
The voltage across the
added element is:
Vpq= Ep - Eq
71. Students should able to
The current through the element pq is:
Ipq : Current through the element pq
Irs : Current through the elements of partial network.
Vpq : Voltage across the element pq
Vrs : Voltage across the elements of partial network.
Ypq pq = Self admittance of added element.
Ypq rs = Vector of mutual admittance between pq-rs of
partial networks.
Yrs rs = Primitive admittance of partial network
Yrs pq = [Ypq rs ]T
Addition of a
Branch
72. Students should able to
Since pq is a branch, ipq = 0 but Vpq ≠ 0. Vrs= Er – Es
Addition of a
Branch
73. Students should able to
To obtain Zqq, inject 1 p.u current at qth node and at
remaining ‘0’
Addition of a
Branch
75. Students should able to
The link is an element added in between two
existing buses.
Addition of a
Link
Firstly, an voltage
source ‘el’ is
connected in series
with the added
element.
This creates a
fictitious node 'l'.
The el is selected
such that Ipq = 0.
So that the p-l is
treated as an
addition of branch.
76. Students should able to
The performance equations are given by:
Addition of a
Link
80. Students should able to
Since, the node l is added which is a fictitious, its effect is to
be eliminated. Mathematically, it can be done by short
circuiting the series voltage source.
Addition of a
Link
88. Students should able to
The change of bus impedance matrix includes in following
cases:
Removal of elements:
It can be done by modifying the already existing Zbus.
By adding an element in parallel, whose impedance is equal
to negative of the impedance of the element to be removed, if
the element is not mutually coupled to any of the element in
the partial network.
This is nothing but addition of a link.
Modification of Z-Bus
89. Students should able to
Changes in the impedance of elements:
BY adding an link in parallel with the element such that the
equivalent impedance of the two elements is the desired
value.
Modification of Z-Bus
90. Students should able to
• Transients on a Transmission line-Short circuit
of synchronous machine(on no-load)
• 3–Phase short circuit currents and reactances
of synchronous machine
• Short circuit MVA calculations
• Series reactors and their Selection of reactors.
Symmetrical Fault
Analysis
91. Students should able to
• A number of undesirable but unavaoidable
incidents can temporarily disrupt this
condition. Such incidents can be said as a
fault.
• A fault in a circuit is an event, which causes
a deviation from the normal flow of current.
• This deviates the power system behavior.
Symmetrical Fault
Analysis
92. Students should able to
A fault may occur on a power system due to
number of reasons.
Some of them are listed below:
• Insulation failure of equipment
• Flashover of lines initiated by lightning
stroke.
• Falling of a tree along a line.
• Overloading of underground cables.
• Wind and Ice loading on the transmission
line.
• Accidental faulty operation.
Reasons for fault
93. Students should able to
• When a fault occurs on a system, the system get short
circuited.
• The current flowing into the fault depends on the path
met by the current, on the severity and nearness of
fault to the sources of power.
• The system must be protected against flow of heavy
short circuit currents, other wise it leads to the damage
of electrical equipment.
• This can be done by separating the faulty part of the
system from the healthy part by properly selecting
Faults
94. Students should able to
Basic two main types of faults are:
Series faults: The fault occurs through a high impedance
in series with the line.
Ex: Open circuit, This occurs when a circuit breaker or a
line is opened.
Shunt faults: In this type a low impedance is connected
between the line and ground.
Ex: Short circuit of lines.
Protective relays are employed to trip the circuit breaker
under faulty condition.
Types of Faults
95. Students should able to
The shunt faults are again classified into:
1. Symmetrical faults:
• In this all the three phases are short circuited to
each other and to the earth also.
• These are balanced and symmetrical.
• The voltages and currents remains balanced after
the occurrence of fault also.
• It is sufficient to consider one phase for the fault
analysis. Ex: 3- Phase short circuit faults.
Types of Faults
96. Students should able to
2. UnSymmetrical faults:
In this type only one or two phases only involves in
a fault.
The voltages and currents becomes unbalanced
after the occurrence of the fault.
Each phase has to be analyzed separately, for the
fault current calculations.
Ex: Line to Ground (LG) , Line to Line (LL/2L),
Double line to ground (LLG/2L-G).
Types of Faults
97. Students should able to
• The computation of fault currents for
unsymmetrical faults involves method of
symmetrical components.
• Frequency of faults in decreasing severity
Types of Faults
Type of fault Frequency of
occurrence
Three Phase faults 5 %
LLG 10 %
LL 15 %
LG 70 %
114. Students should able to
The current limiting reactor is an inductive coil having a
large inductive reactances in comparison to their
resistance and is used for
limiting short circuit currents during fault conditions.
Reduce the voltage disturbances on the rest of the
system.
It is installed in feeders and ties, in generators leads, and
between bus sections, for reducing the magnitude of
short circuit currents and the effect of the respective
voltage disturbance.
Current Limiting
Reactor
115. Students should able to
Location of Reactors
Reactors are located at different location in a power
system for reducing the short circuit current. These
reactors may be connected in series with the
generators, feeders or in bus-bars as explained below.
• Generators Reactors
• Feeders Reactors
• Bus-Bar Reactor
Current Limiting
Reactor
116. Students should able to
Generators Reactors
Generator reactors are inserted
between the generator and the
generator bus. Such reactors
protect the machines individually.
In power station generator, reactors
are installed along with the
generators. The magnitude of
reactors is approximately about
0.05 per unit. The main
disadvantages of such type of
reactors are that if the fault occurs
on one feeder, then the whole of the
system will be adversely affected by
117. Students should able to
Feeder Reactors
Reactors, which is connected in
series with the feeder is called
feeders reactor. When the fault
occurs on any one feeder, then
the voltage drops occur only in its
reactors and the bus bar is not
affected much. Hence the
machines continue to supply the
load. The other advantage is that
the fault occurs on a feeder will
not affect the others feeders, and
thus the effects of fault are
localized
The disadvantage of such type
of reactors is that it does not
provide any protection to the
generators against short circuit
faults occurs across the bus
bars. Also, there is a constant
voltage drop and constant
power loss in reactors during
normal operating conditions.
118. Students should able to
Bus-Bar Reactors (Ring System)
Bus-bar reactors are used to tie together the
separate bus sections. In this system sections
are made of generators and feeders and these
sections are connected to each other to a
common bus bar.
In such type of system normally one feeder is fed
from one generator. In normal operating
conditions a small amount of power flows
through the reactors. Therefore voltage drop and
the power loss in the reactor is low. The bus bar
reactor, therefore, made with high ohmic
resistance so that there is not much voltage drop
across it.
Bus-Bar Reactors
119. Students should able to
Bus-Bar Reactors
When the fault occurs on any
one feeders, only one
generator feeds the fault while
the current of the other
generator is limited because
of the presence of the bus-bar
reactors.
The heavy current and voltage
disturbances caused by a
short circuit on a bus section
are reduced and restricted to
that faulty section only. The
only drawback of such type of
reactor is that it does not
protect the generators
connected to the faulty
sections.
120. Students should able to
Bus-bar Reactors (Tie-
Bus System)
This is the modification of the above
system. In tie-bus system, the
generator is connected to the
common bus-bar through the
reactors, and the feeder is fed from
generator side.
The operation of the system is
similar to the ring system, but it has
got additional advantages.
In this system, if the number of
sections is increased, the fault
current will not exceed a certain
value, which is fixed by the size of
the individual reactors
122. Stability
• Definition (IEEE / CIGRE ):
Power system stability is the ability of an electric
power system, for a given initial operating condition,
to regain a state of operating equilibrium after being
subjected to a physical disturbance, with most system
variables bounded so that practically the entire
system remains intact.
• The disturbances mentioned in the definition could be
faults, load changes, generator outages, line outages,
voltage collapse or some combination of these.
124. • The study of steady state stability is basically concerned with
the determination of the upper limit of machine loadings
before losing synchronism, provided the loading is increased
gradually.
• The system is said to be dynamically stable if the oscillations
do not acquire more than certain amplitude and die out
quickly.
– Dynamic stability can be significantly improved through the use of
power system stabilizers.
• For a large disturbances in angular differences may be so
large as to cause the machines to falling out of step. This
type of instability is known as transient instability and is a
fast phenomenon.
126. Dynamics of a synchronous Machines
• Inertia constant: It is defined as the ratio of
energy stored in mega joules to the rating of the
machines in MVA.
• Energy stored = H x G
• Kinetic energy stored by the rotating body is
given by:
128. Swing Equation
• The Swing Equation of a
generator describes the
relative motion between
the rotor axis and the
synchronously rotating stator
filed axis with respect to time.
• it describes the rotor dynamics for a synchronous machine.
• It is a second-order differential equation.
• This equation is very helpful in analyzing the stability of
connected machines.
143. Transient Stability
• It involves to find whether the system retained its synchronism
after machine has been subjected to severe disturbances.
• The disturbances may be sudden application of load, loss of
generation, loss of large load or occurrence of fault on a
system.
• In these instants the swing equation becomes highly non
linear and difficult to solve.
• A method known as Equal Area Criterion is used for a quickly
prediction of stability.
• This method is applicable to one machine connected to infinite
bus or two machine system.
145. Applications of Equal Area Criterion
The Equal Area Criterion can be imply in the following
cases and the transient stability analysis can be
performed.
• Sudden change in mechanical input.
• Sudden loss of one of the parallel lines.
• Sudden short circuit on one of the parallel lines.
Short circuit at one end
Short circuit away from the line ends
146. Sudden change in mechanical input
• Consider the following system SMIB.
• The electrical power transmitted is given by
147.
148.
149. Critical clearing time and Critical clearing angle
• Consider a system operating with mechanical input Pm
at steady angle of δ0.
• If a 3 phase fault occurs at point p of the outgoing
radial line, the electrical output of the generator
instantly reduces to zero. i.e. Pe = 0.
150.
151.
152.
153.
154.
155.
156.
157.
158.
159.
160.
161. Methods to improve Steady State Stability
1. Reduction of transfer reactance
• A power system which has a lower value of transfer reactance can
have better steady-state stability limit. This can be achieved by:
i) use of parallel lines
ii) use of series capacitors
• If the power has to be transferred through long distance
transmission lines, use of parallel lines reduce transfer reactance as
well as improve voltage regulations.
• Similarly series capacitors are sometimes employed in lines to get
the same features.
2. Increase in the magnitudes of E and V.
Higher and fast field excitation system enhances steady-state
power limits
162. Methods to improve Transient stability
• Transient stability of the system can be improved by increasing the system voltage.
• Increase in the X/R ratio in the power system increases the power limit of the line. Thus
helps to improve the stability.
• High speed circuit breakers helps to clear the fault as quick as possible. The quicker the
breaker operates, the faster the fault cleared and better the system restores to normal
operating conditions.
• By Turbine fast valving: One of the main reason for the instability in the power system is
due to the excess energy supplied by the turbine during the fault period. Fast Valving helps
in reducing the mechanical input power when the generator is under acceleration during
the fault and hence improves the stability of the system.
• Use of Auto Re-closing: Majority of the faults in the power system will be momentary and
can be self cleared. Hence circuit breakers employed for fault clearance opens in sensing
the fault with time delay of 2 cycles and re-closes after particular time to determine whether
the fault is cleared.
• Some of the other ways to improve the transient stability are by
employing lightning arresters, high neutral grounding impedance, single pole switching,
quick Automatic Voltage Regulators.