System stability study is the important parameter of economic, reliable and secure power system planning and operation. Power system studies are important during the planning and conceptual design stages of the project as well as during the operating life of the plant periodically. This paper presents the power system stability analysis for IEEE- 9 bus test system. The fault is created on different busses and transient stability is analyzedfor different load and generation conditions. The critical clearing time (CCT) is calculated by
using time domain classical extended equal area criterion method. The system frequency and voltage variation is observed for different fault locations and CCT. The IEEE-9 bus test system is simulated and stability is analyzed on ETAP software
This presentation begins with a discussion of the generator as a source feeding a very large remote system (the "single-machine infinite-bus" representation).
INTRODUCTION TO POWER SYSTEM STABILITY BY Kundur Power Systems SolutionsPower System Operation
Power System Stability denotes 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 all system variables bounded so that the system integrity is preserved
Integrity of the system is preserved when practically the entire power system remains intact with no tripping of generators or loads, except for those disconnected by isolation of the faulted elements or intentionally tripped to preserve the continuity of operation of the rest of the system
Stability is a condition of equilibrium between opposing forces:
instability results when a disturbance leads to a sustained imbalance between the opposing forces
instability is a run-away or run-down situation
Infinite bus bar is one which keeps constant voltage and frequency although the load varies. Thus it may behave like a voltage source with zero internal impedance and infinite rotational inertia.
This presentation begins with a discussion of the generator as a source feeding a very large remote system (the "single-machine infinite-bus" representation).
INTRODUCTION TO POWER SYSTEM STABILITY BY Kundur Power Systems SolutionsPower System Operation
Power System Stability denotes 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 all system variables bounded so that the system integrity is preserved
Integrity of the system is preserved when practically the entire power system remains intact with no tripping of generators or loads, except for those disconnected by isolation of the faulted elements or intentionally tripped to preserve the continuity of operation of the rest of the system
Stability is a condition of equilibrium between opposing forces:
instability results when a disturbance leads to a sustained imbalance between the opposing forces
instability is a run-away or run-down situation
Infinite bus bar is one which keeps constant voltage and frequency although the load varies. Thus it may behave like a voltage source with zero internal impedance and infinite rotational inertia.
Introduction, Types of Stable System, Routh-Hurwitz Stability Criterion, Disadvantages of Hurwitz Criterion, Techniques of Routh-Hurwitz criterion, Examples, Special Cases of Routh Array, Advantages and Disadvantages of Routh-Hurwitz Stability Criterion, and examples.
Here is a quick review of the topic- Stability in Control System that might help you.
**A system is said to be stable, if its output is under control. Otherwise, it is said to be unstable**
In this presentation we have,
- Intro of Stability
-Types of System
- Concept of Stability
- Routh Hurwitz Criteria
- Limitations of Hurwitz Criterion
- Concluded
Hope this will be beneficial.
Thanking in anticipation.
Objectives: This course will provide a comprehensive overview of power system stability and control problems. This includes the basic concepts, physical aspects of the phenomena, methods of analysis, the integration of MATLAB and SINULINK in the analysis of power system .
Course Content: 1. Power System Stability: Introduction
2. Stability Analysis: Swing Equation
3. Models for Stability Studies
4. Steady State Stability
5. Transient Stability
6. Multimachine Transient Stability
7. Power System Control: Introduction
8. Load Frequency Control
9. Automatic generation Control
10. Reactive Power Control
state space modeling of electrical systemMirza Baig
Introduction
As systems become more complex, representing them with differential equations or transfer functions becomes cumbersome. This is even more true if the system has multiple inputs and outputs. This document introduces the state space method which largely alleviates this problem. The state space representation of a system replaces an nth order differential equation with a single first order matrix differential equation. The state space representation of a system is given by two equations :
The first equation is called the state equation, the second equation is called the output equation. For an nth order system (i.e., it can be represented by an nth order differential equation) with r inputs and m outputs the size of each of the matrices is as follows:
Several features:The state equation has a single first order derivative of the state vector on the left, and the state vector, q(t), and the input u(t) on the right. There are no derivatives on the right hand side.The output equation has the output on the left, and the state vector, q(t), and the input u(t) on the right. There are no derivatives on the right hand side.
q is nx1 (n rows by 1 column)q is called the state vector, it is a function of timeA is nxn; A is the state matrix, a constantB is nxr; B is the input matrix, a constant u is rx1; u is the input, a function of time C is mxn; C is the output matrix, a constant D is mxr; D is the direct transition matrix, a constant y is mx1; y is the output, a function of time
Derivation of of State Space Model (Electrical)
To develop a state space system for an electrical system, they choosing the voltage across capacitors, and current through inductors as state variables. Recall that
so if we can write equations for the voltage across an inductor, it becomes a state equation when we divide by the inductance (i.e., if we have an equation for einductor and divide by L, it becomes an equation for diinductor/dt which is one of our state variable). Likewise if we can write an equation for the current through the capacitor and divide by the capacitance it becomes a state equation for ecapacitor
There are three energy storage elements, so we expect three state equations. Try choosing i1, i2 and e1 as state variables. Now we want equations for their derivatives. The voltage across the inductor L2 is e1 (which is one of our state variables)so our first state variable equation is
This equation has our input (ia) and two state variable (iL2 and iL1) and the current through the capacitor. So from this we can get our second state equation
Our third, and final, state equation we get by writing an equation for the voltage across L1 (which is e2) in terms of our other state variables
references:
http://lpsa.swarthmore.edu/Representations/SysRepSS.html
https://en.wikipedia.org/wiki/State-space_representation
state space representation,State Space Model Controllability and Observabilit...Waqas Afzal
State Variables of a Dynamical System
State Variable Equation
Why State space approach
Block Diagram Representation Of State Space Model
Controllability and Observability
Derive Transfer Function from State Space Equation
Time Response and State Transition Matrix
Eigen Value
A brief and basic presentation of interconnections of pwer system,it covers all the basic aspects of power system interconnection that how systems can be built with interconnections
this is presentation about time response analysis in control engineering. this is presentation on its types and many more like time responses with best example
Introduction, Types of Stable System, Routh-Hurwitz Stability Criterion, Disadvantages of Hurwitz Criterion, Techniques of Routh-Hurwitz criterion, Examples, Special Cases of Routh Array, Advantages and Disadvantages of Routh-Hurwitz Stability Criterion, and examples.
Here is a quick review of the topic- Stability in Control System that might help you.
**A system is said to be stable, if its output is under control. Otherwise, it is said to be unstable**
In this presentation we have,
- Intro of Stability
-Types of System
- Concept of Stability
- Routh Hurwitz Criteria
- Limitations of Hurwitz Criterion
- Concluded
Hope this will be beneficial.
Thanking in anticipation.
Objectives: This course will provide a comprehensive overview of power system stability and control problems. This includes the basic concepts, physical aspects of the phenomena, methods of analysis, the integration of MATLAB and SINULINK in the analysis of power system .
Course Content: 1. Power System Stability: Introduction
2. Stability Analysis: Swing Equation
3. Models for Stability Studies
4. Steady State Stability
5. Transient Stability
6. Multimachine Transient Stability
7. Power System Control: Introduction
8. Load Frequency Control
9. Automatic generation Control
10. Reactive Power Control
state space modeling of electrical systemMirza Baig
Introduction
As systems become more complex, representing them with differential equations or transfer functions becomes cumbersome. This is even more true if the system has multiple inputs and outputs. This document introduces the state space method which largely alleviates this problem. The state space representation of a system replaces an nth order differential equation with a single first order matrix differential equation. The state space representation of a system is given by two equations :
The first equation is called the state equation, the second equation is called the output equation. For an nth order system (i.e., it can be represented by an nth order differential equation) with r inputs and m outputs the size of each of the matrices is as follows:
Several features:The state equation has a single first order derivative of the state vector on the left, and the state vector, q(t), and the input u(t) on the right. There are no derivatives on the right hand side.The output equation has the output on the left, and the state vector, q(t), and the input u(t) on the right. There are no derivatives on the right hand side.
q is nx1 (n rows by 1 column)q is called the state vector, it is a function of timeA is nxn; A is the state matrix, a constantB is nxr; B is the input matrix, a constant u is rx1; u is the input, a function of time C is mxn; C is the output matrix, a constant D is mxr; D is the direct transition matrix, a constant y is mx1; y is the output, a function of time
Derivation of of State Space Model (Electrical)
To develop a state space system for an electrical system, they choosing the voltage across capacitors, and current through inductors as state variables. Recall that
so if we can write equations for the voltage across an inductor, it becomes a state equation when we divide by the inductance (i.e., if we have an equation for einductor and divide by L, it becomes an equation for diinductor/dt which is one of our state variable). Likewise if we can write an equation for the current through the capacitor and divide by the capacitance it becomes a state equation for ecapacitor
There are three energy storage elements, so we expect three state equations. Try choosing i1, i2 and e1 as state variables. Now we want equations for their derivatives. The voltage across the inductor L2 is e1 (which is one of our state variables)so our first state variable equation is
This equation has our input (ia) and two state variable (iL2 and iL1) and the current through the capacitor. So from this we can get our second state equation
Our third, and final, state equation we get by writing an equation for the voltage across L1 (which is e2) in terms of our other state variables
references:
http://lpsa.swarthmore.edu/Representations/SysRepSS.html
https://en.wikipedia.org/wiki/State-space_representation
state space representation,State Space Model Controllability and Observabilit...Waqas Afzal
State Variables of a Dynamical System
State Variable Equation
Why State space approach
Block Diagram Representation Of State Space Model
Controllability and Observability
Derive Transfer Function from State Space Equation
Time Response and State Transition Matrix
Eigen Value
A brief and basic presentation of interconnections of pwer system,it covers all the basic aspects of power system interconnection that how systems can be built with interconnections
this is presentation about time response analysis in control engineering. this is presentation on its types and many more like time responses with best example
TRANSIENT STABILITY ENHANCEMENT BY USING DSSC AND PSSIAEME Publication
Synchronous operation of generators in power system is required to supply continuous electricity to customers. Proper transient stability must be maintained for stable operation of power system. To enhance the transient stability of power system FACTS or D-FACTS technology can be used. In this paper, Distributed Static Series Compensator (DSSC) which, belongs to D-FACTS technology is used to enhance the transient stability of two-machine system with Power System Stabilizer (PSS) as an auxiliary controller and it is found that DSSC along with PSS is able to maintain required transient stability during severe three-phase to ground fault.
Transient Stability Assessment and Enhancement in Power SystemIJMER
Power system is subjected to sudden changes in load levels. Stability is an important concept
which determines the stable operation of power system. For the improvement of transient stability the
general methods adopted are fast acting exciters, circuit breakers and reduction in system transfer
reactance. The modern trend is to employ FACTS devices in the existing system for effective utilization
of existing transmission resources. The critical clearing time is a measure to assess transient instability.
Using PSAT, the critical clearing time (CCT) corresponding to various faults are calculated. The most
critical faults were identified using this calculation. The CCT for the critical faults were found to change
with change in operating point. The CCT values are predicted using Artificial Neural Network (ANN) to
study the training effects of ANN. TCSC is selected as the FACTS device for transient stability
enhancement. Particle Swarm Optimization method is used to find the optimal position of TCSC using
the objective function real power loss minimization. The result shows that the technique effectively
increases the transient stability of the system
DYNAMIC STABILITY ENHANCEMENT IN MULTIMACHINE POWER SYSTEMS BY DIFFERENT FACT...IAEME Publication
Modern Power system are becoming increasingly stressed due to increasing demand of electricity and restriction on new transmission network .This effect of power network is that transmission power loss increases and decreasing power transmission capability of network. And also stability of synchronous alternator is lost. There are electronic based FACTS (Flexible AC Transmission system) devises is established to enhance the power transmitting capacity. A major important function of FACTS devises is to enhanced power transmission capacity of power system network without increasing power generation capacity of power system. Because system voltage is inversely proportional to transmission loses.
This document is used for power engineers in the third stage of their Journey in power engineering .
It's related to the synchronous machines and their operation
weather operating alone or paralleled with other generators of the same size or when paralleled to an infinite bus .
It also contains a summary of what occurs when governor set points changes from state to another.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Effects of Different Parameters on Power System Transient Stability StudiesPower System Operation
The transient stability studies plays a vital role in
providing secured operating configurations in power systems.
This paper shows an analysis of the effects of various parameters
on the transient stability studies of power system. The various
parameters for which the analysis is presented include the Fault
Clearing Time (FCT), Fault location, load increasing, machine
damping coefficient D, and Generator Armature Resistance
GAR. Under the condition that the power system is subjected to a
three-phase short-circuit fault, the Critical Clearing Time (CCT)
is calculated using numerical integration method. The analysis
has been carried out on the IEEE 30-bus test system. From this
analysis, we can conclude the importance of these different
parameters on power system transient stability studies.
Multi-Machine Stability Using Dynamic Inversion Technique IJECEIAES
Stability studies of multi machine system are a major concern to power system engineers due to the increasing complexity involved. This paper deals with the application of a nonlinear technique called Dynamic Inversion, to TCSC for the improvement of stability of multi-machine system. The transient stability studies for various cases: without any controller, with 75% line compensation and with Dynamic Inversion technique, are compared. The critical clearing time as well as the maximum loading ability is also discussed. The result for the nonlinear controller is found to be better than all the other cases.
STUDY OF TRANSIENT STABILITY BY TRANSIENT ENERGY FUNCTIONcscpconf
Stability analysis programs are a primary tool used by power system planning and operating engineers to predict the response of the system to various disturbances. Important onclusionsand decisions are made based on the results of stability studies. The conventional method of analyzing stability is to calculate the transient behaviour of generators due to a given disturbance. Direct methods of stability analysis identify whether or not the system will remain stable once the disturbance is removed by comparing it with a calculated threshold value.Direct methods not only avoid the time consuming solutions required in the conventional
method, but also provide a quantitative measure of the degree of system stability. Thisadditional information makes direct methods very attractive when the relative stability of
different plans must be compared or when stability limits must be calculated quickly. Directmethods of transient stability analysis of a multi machine power system, using a
function describing the system's transient energy, are discussed. By examining thetrajectory of the disturbed system, the following fundamental questions are dealt with:the concept of a controlling unstable equilibrium point (U.E.P), the manner in whichsome generators tend to lose synchronism, and identifying the energy directlyresponsible for system separation. Resolving this issue will substantially improve transient stability analysis by direct method.
DYNAMIC STABILITY ANALYSIS (Small Signal Stability) – 1
Small-Signal Stability of Multi-machine Systems
Special techniques for analysis of very large systems
Characteristics of Small-Signal Stability Problems
Local problems
Global problems
DYNAMIC STABILITY ANALYSIS – 2
Introduction
Overview of the Proposed Method
Generating Unit
Synchronous Machine
Calculation of Equilibrium State Conditions
Excitation and Governor Control Systems
Excitation System
Turbine-Governor System
Combined Model of Generating Unit
Steady state stability analysis and enhancement of three machine nine bus pow...eSAT Journals
Abstract
Power System stability study is the important parameter of economic, reliable and secure system planning and operation. Studies
are important during the planning and conceptual design stages of the project as well as during the operating life of the plant
periodically. This paper presents the power system steady state stability analysis for IEEE- 9 bus test system and examines
influence of TCPS FACTS device based controller on test system. It is assumed that system under study has been perturbed from a
steady state equilibrium that prevailed prior to the application of the disturbance. If system is stable, we would expect that for
temporary or permanent disturbance, system will acquire initial or new operating state after a transient period. The stability
study is accessed using Lyapunov’s first method. The effectiveness of damping controller in enhancing the steady state stability is
investigated by incorporating available constraints. For analysis MATLAB software is employed. The conclusions have been
drawn here, based on theoretical and mathematical analysis so as to provide an insight and better understanding of steady state
stability of considered multi machine power system.
Key Words: Lyapunov’s first method, Steady-state stability, Phase portrait, FACTS device, supplementary modulation
controller, eigen value, synchronizing power coefficient, IEEE-9 Bus Test System, Load Flow Study, Differential
algebraic equation.
VOLTAGE STABILITY IN NIGERIA 330KV INTEGRATED 52 BUS POWER NETWORK USING PATT...Onyebuchi nosiri
ABSTRACT Detecting the voltage instability in advance enables remedial actions and preventive measures to cushion the effect of the oncoming voltage collapse phenomenon in power systems. This was achieved by implementing Pattern Recognition Techniques (PRTs) in conjunction with Power System Simulator for Engineering (PSSE) program. It was then deployed in Nigeria 330KV Integrated 52 bus power system to actualize Regularized Least Squares Classification (RLSC) and Classification and Regression Trees (CART) heuristic methods. The methods were deployed for separating voltage stability and unstable cases that resulted under system contingencies and fault conditions. Dynamic simulation, system voltage stability and unstable/instability cases results, and the channel outputs of these voltage cases against time were realized.
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Oscillatory Stability Prediction Using PSO Based Synchronizing and Damping To...journalBEEI
This paper presents the assessment of stability domains for the angle stability condition of the power system using Particle Swarm Optimization (PSO) technique. An efficient optimization method using PSO for synchronizing torque coefficients Ksand damping torque coefficients Kd to identify the angle stability condition on multi-machine system. In order to accelerate the determination of angle stability, PSO is proposed to be implemented in this study. The application of the proposed algorithm has been justified as the most accurate with lower computation time as compared to other optimization techniques such as Evolutionary Programming (EP) and Artificial Immune System (AIS). Validation with respect to eigenvalues determination, Least Square (LS) method and minimum damping ratio ξmin confirmed that the proposed technique is feasible to solve the angle stability problems.
VOLTAGE STABILITY IN NIGERIA 330KV INTEGRATED 52 BUS POWER NETWORK USING PATT...Onyebuchi nosiri
ABSTRACT Detecting the voltage instability in advance enables remedial actions and preventive measures to cushion the effect of the oncoming voltage collapse phenomenon in power systems. This was achieved by implementing Pattern Recognition Techniques (PRTs) in conjunction with Power System Simulator for Engineering (PSSE) program. It was then deployed in Nigeria 330KV Integrated 52 bus power system to actualize Regularized Least Squares Classification (RLSC) and Classification and Regression Trees (CART) heuristic methods. The methods were deployed for separating voltage stability and unstable cases that resulted under system contingencies and fault conditions. Dynamic simulation, system voltage stability and unstable/instability cases results, and the channel outputs of these voltage cases against time were realized.
Transient Stability Analysis of IEEE 9 Bus System in Power World SimulatorIJERA Editor
It is widely accepted that transient stability is an important aspect in designing and upgrading electric power
system.
The objective of this paper was to investigate and understand the stability of power system
In this paper, modelling and transient stability analysis of IEEE 9 bus system was performed using POWER
WORLD SIMULATOR. The load flow studies were performed to determine pre-fault conditions in the system
using Newton-Raphson method. With the help of three-phase balanced fault, the variations in power angle and
frequency of the system were studied. Frequency is a reliable indicator if deficiency condition in the power
systems exists or not. For three-phase balanced fault, fast fault clearing time was analysed to bring back the
system to the stability. Further, comparison between Runga method and Euler method for better results was
performed. Hence, impact of load switching on system was also computed so as to bring system to steady state.
Transient Stability Analysis of IEEE 9 Bus System in Power World SimulatorIJERA Editor
It is widely accepted that transient stability is an important aspect in designing and upgrading electric power
system.
The objective of this paper was to investigate and understand the stability of power system
In this paper, modelling and transient stability analysis of IEEE 9 bus system was performed using POWER
WORLD SIMULATOR. The load flow studies were performed to determine pre-fault conditions in the system
using Newton-Raphson method. With the help of three-phase balanced fault, the variations in power angle and
frequency of the system were studied. Frequency is a reliable indicator if deficiency condition in the power
systems exists or not. For three-phase balanced fault, fast fault clearing time was analysed to bring back the
system to the stability. Further, comparison between Runga method and Euler method for better results was
performed. Hence, impact of load switching on system was also computed so as to bring system to steady state.
Fuzzy-Logic-Controller-Based Fault Isolation in PWM VSI for Vector Controlled...iosrjce
IOSR Journal of Electrical and Electronics Engineering(IOSR-JEEE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of electrical and electronics engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electrical and electronics engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Electrical & Computer Engineering: An International Journal (ECIJ)ecij
Electrical & Computer Engineering: An International Journal (ECIJ) is a peer-reviewed, open access journal that addresses the impacts and challenges of Electrical and Computer Engineering. The journal documents practical and theoretical results which make a fundamental contribution for the development Electrical and Computer Engineering.
Electrical & Computer Engineering: An International Journal (ECIJ)ecij
Electrical & Computer Engineering: An International Journal (ECIJ) is a peer-reviewed,
open access journal that address the impacts and challenges of Electrical and Computer
Engineering. The journal documents practical and theoretical results which make a fundamental
contribution for the development Electrical and Computer Engineering.
Electrical & Computer Engineering: An International Journal (ECIJ)ecij
Electrical & Computer Engineering: An International Journal (ECIJ) is a peer-reviewed,
open access journal that address the impacts and challenges of Electrical and Computer
Engineering. The journal documents practical and theoretical results which make a fundamental
contribution for the development Electrical and Computer Engineering.
Electrical & Computer Engineering: An International Journal (ECIJ)ecij
Electrical & Computer Engineering: An International Journal (ECIJ) is a peer-reviewed,
open access journal that address the impacts and challenges of Electrical and Computer
Engineering. The journal documents practical and theoretical results which make a fundamental
contribution for the development Electrical and Computer Engineering
This work investigates and evaluates the electric energy interruptions to the residential sector resulting from severe power outages. The study results show that this sector will suffer tangible and intangible losses should these outages occur during specific times, seasons, and for prolonged durations. To reduce these power outages and hence mitigate their adverse consequences, the study proposes practical measures that
can be adopted without compromising the consumers’ needs, satisfaction, and convenience.
GRID SIDE CONVERTER CONTROL IN DFIG BASED WIND SYSTEM USING ENHANCED HYSTERES...ecij
The standard grid codes suggested, that the wind generators should stay in connected and reliable active and reactive power should be provided during uncertainties. This paper presents an independent control of Grid Side Converter (GSC) for a doubly fed induction generator (DFIG). A novel GSC controller has
been designed by incorporating a new Enhanced hysteresis comparator (EHC) that utilizes the hysteresis band to produce the suitable switching signal to the GSC to get enhanced controllability during grid unbalance. The EHC produces higher duty-ratio linearity and larger fundamental GSC currents with
lesser harmonics. Thus achieve fast transient response for GSC. All these features are confirmed through
time domain simulation on a 15 KW DFIG Wind Energy Conversion System (WECS).
Electrical & Computer Engineering: An International Journal (ECIJ)ecij
Electrical & Computer Engineering: An International Journal (ECIJ) is a peer-reviewed,
open access journal that address the impacts and challenges of Electrical and Computer
Engineering. The journal documents practical and theoretical results which make a fundamental
contribution for the development Electrical and Computer Engineering.
PREPARATION OF POROUS AND RECYCLABLE PVA-TIO2HYBRID HYDROGELecij
Nano TiO2, one of the most effective photocatalysts, has extensive usein fields such as air purification,
sweage treatment, water spitting, reduction of CO2, and solar cells. Nowadays, the most promising method to
recycle nano TiO2during the photocatalysis is to immobilize TiO2onto matrix, such as polyvinyl alcohol
(PVA). However, due to the slow water permeability of PVA after cross-linking, the pollutants could not
contact with nano TiO2photocatalyst in time. To overcome this problem, we dispersed calcium carbonate
particles into a PVA-TiO2 mixture and then filmed the glass. PVA-TiO2-CaCO3 films were obtained by
drying. Through thermal treatment, we obtained the cross-linked PVA-TiO2-CaCO3 films. Finally, the
calcium carbonate in the film was dissolved by hydrochloric acid, and the porous PVA-TiO2 composite
photocatalyst was obtained. The results show the addition of CaCO3 has no obvious effect on PVA
cross-linking and that a large number of cavities have been generated on the surface and inside of porous
PVA-TiO2 hybrid hydrogel film. The size of the holes is about 5-15μm, which is consistent with that of
CaCO3.The photocatalytic rate constant of porous PVA-TiO2 hybrid hydrogel film is 2.49 times higher than
that of nonporous PVA-TiO2 hybrid hydrogel film.
4th International Conference on Electrical Engineering (ELEC 2020)ecij
4th International Conference on Electrical Engineering (ELEC 2020)aims to bring together researchers and practitioners from academia and industry to focus on recent systems and techniques in the broad field of Electrical Engineering. Original research papers, state-of-the-art reviews are invited for publication in all areas of Electrical Engineering.
Electrical & Computer Engineering: An International Journal (ECIJ)ecij
Electrical & Computer Engineering: An International Journal (ECIJ) is a peer-reviewed, open access journal that addresses the impacts and challenges of Electrical and Computer Engineering. The journal documents practical and theoretical results which make a fundamental contribution for the development Electrical and Computer Engineering.
4th International Conference on Bioscience & Engineering (BIEN 2020) ecij
4th International Conference on Bioscience & Engineering (BIEN 2020) will provide an excellent International forum for sharing knowledge and results in theory, methodology and applications impacts and challenges of Bioscience and Engineering. The goal of this Conference is to bring together researchers and practitioners from academia and industry to focus on Bioscience and Engineering advancements and establishing new collaborations in these areas. Original research papers, state-of-the-art reviews are invited for publication in all areas of Bioscience and Engineering.
Electrical & Computer Engineering: An International Journal (ECIJ)ecij
Scope & Topics
Electrical & Computer Engineering: An International Journal (ECIJ) is a peer-reviewed, open access journal that addresses the impacts and challenges of Electrical and Computer Engineering. The journal documents practical and theoretical results which make a fundamental contribution for the development Electrical and Computer Engineering.
Electrical & Computer Engineering: An International Journal (ECIJ)
ISSN: 2201-5957
https://wireilla.com/engg/ecij/index.html
Paper Submission
Authors are invited to submit papers for this journal through E-mail: ecijjournal@wireilla.com .
Important Dates
•Submission Deadline: March 28, 2020
Contact US
Here's where you can reach us: ecijjournal@wireilla.com
GRID SIDE CONVERTER CONTROL IN DFIG BASED WIND SYSTEM USING ENHANCED HYSTERES...ecij
The standard grid codes suggested, that the wind generators should stay in connected and reliable active and reactive power should be provided during uncertainties. This paper presents an independent control of Grid Side Converter (GSC) for a doubly fed induction generator (DFIG). A novel GSC controller has been designed by incorporating a new Enhanced hysteresis comparator (EHC) that utilizes the hysteresis band to produce the suitable switching signal to the GSC to get enhanced controllability during grid unbalance. The EHC produces higher duty-ratio linearity and larger fundamental GSC currents with lesser harmonics. Thus achieve fast transient response for GSC. All these features are confirmed through time domain simulation on a 15 KW DFIG Wind Energy Conversion System (WECS).
UNION OF GRAVITATIONAL AND ELECTROMAGNETIC FIELDS ON THE BASIS OF NONTRADITIO...ecij
The traditional principle of solving the problem of combining the gravitational and electromagnetic fields is associated with the movement of the transformation of parameters from the electromagnetic to the gravitational field on the basis of Maxwell and Lorentz equations. The proposed non-traditional principle
is associated with the movement of the transformation of parameters from the gravitational to the electromagnetic field, which simplifies the process. Nave principle solving this task by using special physical quantities found by M. Planck in 1900: - Planck’s length, time and mass), the uniqueness of which is that they are obtained on the basis of 3 fundamental physical constants: the velocity c of light in vacuum, the Planck’s constant h and the gravitational constant G, which reduces them to the fundamentals of the Universe. Strict physical regularities were obtained for the based on intercommunication of 3-th
fundamental physical constants c, h and G, that allow to single out wave characteristic νG from G which is identified with the frequency of gravitational field. On this base other wave and substance parameters were strictly defined and their numerical values obtained. It was proved that gravitational field with the given wave parameters can be unified only with electromagnetic field having the same wave parameters that’s why it is possible only on Plank’s level of world creation. The solution of given problems is substantiated by well-known physical laws and conformities and not contradiction to modern knowledge about of material world and the Universe on the whole. It is actual for development of physics and other branches of science and technique.
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Nowadays, real-time systems and intelligent systems offer more and more control interface based on voice recognition or human language recognition. Robots and drones will soon be mainly controlled by voice. Other robots will integrate bots to interact with their users, this can be useful both in industry and entertainment. At first, researchers were digging on the side of "ontology reasoning". Given all the technical constraints brought by the treatment of ontologies, an interesting solution has emerged in last years: the construction of a model based on machine learning to connect a human language to a knowledge
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Transient stability analysis and enhancement of ieee 9 bus system
1. Electrical & Computer Engineering: An International Journal (ECIJ) Volume 3, Number 2, June 2014
DOI : 10.14810/ecij.2014.3204 41
TRANSIENT STABILITY ANALYSIS AND
ENHANCEMENT OF IEEE- 9 BUS SYSTEM
Renuka Kamdar1
, Manoj Kumar2
and Ganga Agnihotri3
1,3
Department of Electrical Engineering, MANIT, Bhopal, India
ABSTRACT
System stability study is the important parameter of economic, reliable and secure power system planning
and operation. Power system studies are important during the planning and conceptual design stages of the
project as well as during the operating life of the plant periodically. This paper presents the power system
stability analysis for IEEE- 9 bus test system. The fault is created on different busses and transient stability
is analyzedfor different load and generation conditions. The critical clearing time (CCT) is calculated by
using time domain classical extended equal area criterion method. The system frequency and voltage
variation is observed for different fault locations and CCT. The IEEE-9 bus test system is simulated and
stability is analyzed on ETAP software.
KEYWORDS
Critical Clearing Time (CCT), ETAP, Extended Equal Area Criterion (EEAC), Frequency Stability, IEEE-9
Bus Test System, Load Flow Study, Load Shedding, Transient Stability.
1. INTRODUCTION
Electric power system stability analysis has been recognized as an important and challenging
problem for secure system operation. When large disturbances occur in interconnected power
system, the security of these power systems has to be examined. Power system security depends
on detailed stability studies of system to check and ensure security.
In order to determine the stability status of the power system for each contingency of any
disturbance occurs in power system, many stability studies are defined [1]. Power system stability
analysis may involve the calculation of Critical Clearing time (CCT) for a given fault which is
defined as the maximum allowable value of the clearing time for which the system remains to be
stable. The power system shall remain stable if the fault is cleared within this time. However, if
the fault is cleared after the CCT, the power system is most likely to become unstable. Thus, CCT
estimation is an important task in the transient stability analysis for a given contingency. In this
paper for the Transient Stability Analysis, an IEEE 9 Bus system is considered.
Critical clearing time (CCT) in a way measures the power systems Transient stability. It denotes
the secure and safe time margin for clearing the contingency, usually three-phase ground-fault.
The larger the value of CCT, the power system has ample time to clear the contingency. CCT
depends on generator inertias, line impedances, grid topology, and power systems operating
conditions, fault type and location. For a single machine infinite bus power system, CCT
calculation is straightforward. While for the case of multi-machine power systems, CCT is always
2. Electrical & Computer Engineering: An International Journal (ECIJ) Volume 3, Number 2, June 2014
42
obtained by repeating time-domain simulations, and hence the evaluation of CCT can only be
done off-line The Load Flow study and Transient Stability study is discussed and performed for
the IEEE-9 Bus test system simulated on ETAP 7.5.1.
2. POWER SYSTEM STABILITY
Power system stability is defined as the capability of a system to maintain an operating
equilibrium point after being subjected to a disturbance for given initial operating conditions [4].
Power system stability is categorized based on the following considerations:
i. The nature of the resulting instability mode indicated by the observed instability on certain
system variables.
ii. The size of the disturbance which consequently influences the tool used to assess the system
stability.
iii. The time margin needed to assess system stability.
The classification of power system stability as shown in Fig.1
Fig. 1 Classification of Power System Stability
3. SWING EQUATION
The swing equation governs the motion of the machine rotor relating the inertia torque to the
resultant of the mechanical and electrical torques on the rotor i.e.[5]
ܯ
݀ଶ
ߜ
݀ݐଶ
= ܲ
− ܲ
, ݅ = 1,2,3, … … … … . . , ݊(1)
Where,
ܲ = |ܧ|ଶ
ܩ + ∑ ൣ|ܧ|หܧหหܩห cos(ߜ − ߜ) + |ܧ|หܧหหܤห sin(ߜ − ߜ)൧
ୀଵ (2)
3. Electrical & Computer Engineering: An International Journal (ECIJ) Volume 3, Number 2, June 2014
43
With:
ߜ= rotor angle of the i-th machine;
ܯ= inertia coefficient of the i-th machine;
ܲ
, ܲ
= mechanical and electrical power of the i-th machine;
ܧ = voltage behind the direct axis transient reactance;
ܩ, ܤ= real and imaginary part of the ij-th element of the nodal admittance matrix reduced at
the nodes which are connected to generators
The following steps are taken for stability studies of multimachine system[6]:
1. From the pre-fault load flow data determined ܧvoltage behind transient reactance for all
generators. This establishes generator emf magnitudes |ܧ|which remain constant during
the study and initial rotor angle ߜ
= angle (ܧ). Also record prime mover inputs to
generators, ܲ = ܲீ
.
2. Augmented the load flow network by the generator transient reactance. Shift network
buses behind the transient reactance.
3. Findܻௌfor various network conditions-during, post fault (faulted line cleared), after line
reclosure.
4. For faulted mode, found generator outputs from power angle equation ܲ = |ܧ|ଶ
ܩ +
|ܧ|หܧหหܻห cos(ߜ − ߜ − ߠ) and solve swing equations.
5. The above step is repeated for post fault mode and after line reclosure mode.
6. Examined ߜ()ݐ plots of all generators and established the answer to the stability question.
The following preliminary calculation steps are needed for transient stability analysis of
multi-machine system[4]:
1. Prepare the system data generally at 100 MVA base.
2. Loads are represented by equivalent shunt admittances.
3. Calculate the generator inter voltages and their initial angles.
4. Calculate the admittance bus matrix ܻௌ for each network condition.
5. Except for the internal generator nodes, eliminate all the nodes and obtain the ܻௌ
matrix for the reduced network. The reduced ܻௌ matrix is obtained as shown below :
Let ܫ = ܻܸ
ܫ = ቂ
ܫ
0
ቃ
ቂ
ܫ
0
ቃ =
ܻ ܻ
ܻ ܻ
൨
ܸ
ܸ
൨
Where n denotes generator nodes and r denotes remaining nodes.
ܫ = ܻܸ + ܻ, 0 = ܻܸ + ܻܸ
From which we eliminateܸ,
ܫ = ൫ܻ − ܻܻ
ିଵ
ܻ൯ܸ
4. Electrical & Computer Engineering: An International Journal (ECIJ) Volume 3, Number 2, June 2014
44
The matrix ൫ܻ − ܻܻ
ିଵ
ܻ൯ is the desired reduced ܻௌ matrix. It is (݊ × ݊) matrix where ݊
is the number of generators.
When large disturbances occur in power system, there is no availability of generalized criteriafor
determining system stability. Hence the experimental approach for the solution of transient
stability problem is all about listing of all important severe disturbances along with their possible
locations to which the system is likely to be subjected.
A plot of power angle ߜand t (time) is called the swing curve which is obtained by numerical
solution of the swing equation in the presence of large severe disturbances. If ߜ starts to decrease
after reaching a maximum value, it is normally assumed that the system is stable and the
oscillation of ߜaround the equilibriumpoint will decay and finally die out. Important
severedisturbances are a short circuit fault or a sudden loss of load [3].
4. CRITICAL CLEARING TIME CALCULATION USING EEAC
Since the time EEAC was proposed in literature, a great interest has been raised on it [7-11],
because it is able to yield fast and accurate transient stability analysis. In order to determine the
stability of the power system as a response to a certain disturbance, the extended equal area
criterion (EEAC) method described in [10] decomposes the multi-machine system into a set of
critical machine(s) and a set of the‘remaining’ generators. In order to form an OMIB system, the
machines in the two groups are aggregated and then transformed into two equivalent machines.
Some basic assumptions for EEAC are : (i) The disturbed system separation depends upon the
angular deviation b/w the following two equivalent clusters: the critical machine group(cmg) and
the remaining machine group(rmg), (ii) The partial centre of angles (PCOA) of the critical
machine group (ߜ) and The partial centre of angles (PCOA) of the remaining machine
group(ߜ):
ߜ =
∑ ܯߜఢ
ܯ
(3)
ܯ = ܯ
ఢ
(4)
ߜ =
∑ ܯߜఢ
ܯ
(5)
ܯ = ܯ(6)
ఢ
On the basis of above assumption, a multi-machine system can be transformed into equivalent
two-machine system. After which, the two machine equivalent is reduced to a single machine
infinite bus system. The equivalent One-machine-Infinite-Bus (OMIB) system model is given by
the following equation:
ܯ
݀ଶ
ߜ
݀ݐଶ
= ܲ − ܲ = ܲ − ሾܲ + ܲ௫ sin(ߜ − ߛ)ሿ (7)
5. Electrical & Computer Engineering: An International Journal (ECIJ) Volume 3, Number 2, June 2014
45
Where,
ܯ =
ܯܯ
ܯ்
ܯ் = ܯ
ୀଵ
δ = δୡ୫ − δ୰୫
ܲ =
ܯ ∑ ܧܧܩ,ఢ − ܯ ∑ ܧܧܩ,ఢ
ܯ்
ܲ =
ܯ ∑ ܲఢ − ܯ ∑ ܲఢ
ܯ்
ܲ௫ = ඥܥଶ + ܦଶ
ߛ = tanିଵ
൬
ܥ
ܦ
൰
ܥ =
ܯ − ܯ
ܯ்
ܧܧܩ
ఢ,ఢ
ܦ =
ܯ − ܯ
ܯ்
ܧܧܤ
ఢ,ఢ
The accelerating and decelerating areas are given by [12]:
ܣ = (ܲ − ܲ)(ߜ − ߜ) + ܲ௫ሾcos(ߜ − ߛ) − cos(ߜ − ߛ)ሿ (8)
ܣௗ = (ܲ − ܲ)(ߨ − ߜ − ߜ + 2ߛ) + ܲ௫ሾcos(ߜ − ߛ) + cos(ߜ − ߛ)ሿ(9)
Where 0 denotes original (pre-fault), D during fault, and P post-fault, ߜ is the critical clearing
time.
The transient stability margin: ߤ = ܣ − ܣௗ, at the critical clearing time ݐ, ߤ = ܣ −
ܣௗ = 0
Solving the equations (13) & (14), the critical clearing angle ߜ can be computed. The value of
critical clearing time (CCT) can be computed [17] by following formula:
ݐ = ට
ଶெ
ఠబ
(ߜ − ߜ) (10)
Where,
ܲ = generator output before fault
ߜ = pre-fault angle
6. Electrical & Computer Engineering: An International Journal (ECIJ) Volume 3, Number 2, June 2014
46
5. SYSTEM SIMULATION AND LOAD FLOW ANALYSIS
In this paper IEEE 9 bus system is used as the test system, which is simulated on ETAP 7.5.1.
Fig. 2 Single Line Diagram of IEEE 9 Bus test system
The single line diagram (SLD) of the simulated test system on ETAP is shown in Fig 2. For this
test system generator and load parameters are given in appendix. The total generation is 313MW
and total load is 312.5MW. The test system contains 6 lines connecting the bus bars in the system
with the generator connected to network through step-up transformer at 230kV transmission
voltage.
It is good practice to have periodic and updated load flow study for every installation. The
purpose of load flow study is
i. To calculate bus voltage levels tocompare to equipment ratings anddistribution system
operatingrequirements
ii. To calculate branch current flows for comparing it to equipment ampacity ratings and
protective device triplevels.
Depending upon the type of plant there can be many load flow cases to study. The objective is to
identify the best and worst operating conditions. Several load flow solution algorithms used in
industry such as Gauss-Seidel, Newton-Raphson and current injection. There is requirement of at
least one swing bus in the network for all the Load flow solution algorithms. The utility point of
service is always modeled as swing bus.
The result of load flow analysis when all generators and loads are operating at rated power is
given in Table.1. Calculation of critical clearing time (CCT) by using EEAC for different
generation and loading condition at the different fault locations are shown in Table. 2.
7. Electrical & Computer Engineering: An International Journal (ECIJ) Volume 3, Number 2, June 2014
47
This CCT is then used to operate the circuit breakers near the faulted bus and hence the
corresponding generators are removed from the system. This creates the generation – load
imbalance and hence the system frequency is affected.
When the frequency of the system crosses the permissible limit after the fault has occurred, the
frequency protection scheme is activated. The frequency stability of the system is enhanced using
Load Shedding.
Table.1 Load Flow Report
Bus
No.
Bus
KV
Voltage
Mag.(%)
(%)
Voltage
Angle
Gen.
(MW)
Gen.
(Mvar)
Load
(MW)
Load
(Mvar)
1 16.5 100.0 1.0 73.831 9.738 0 0
2 18.0 100.0 0.3 155.00 92.091 0 0
3 13.8 100.0 -0.2 85.00 41.951 0 0
4 230 98.940 -4.3 0 0 0 0
5 230 98.827 -4.3 0 0 123.947 49.550
6 230 98.834 -4.3 0 0 89.247 29.726
7 230 99.132 -4.3 0 0 0 0
8 230 98.884 -4.3 0 0 99.284 34.790
9 230 99.005 -4.3 0 0 0 0
Table.2CCT for different generation – loading conditions
Cases Fault Bus CCT(sec)
1 Bus 1 0.361109
2 Bus 2 0.31693
3 Bus 3 0.317587
For the above mentioned generation – loading conditions, load shedding was performed till the
system frequency stability is regained. The bus frequency and bus voltage plots for the three cases
are shown in Fig. 3- Fig 8.
Fig.3 Bus voltage when the fault has occurred at bus 1
At t= 1.0 sec 3phase faultoccurred at bus 1, the circuit breaker 1 and 4 are operated before the
CCT calculated for the case i.e. at 1.36 sec. As a result generator 1 is removed from the system
0 5 10 15 20 25 30
50
60
70
80
90
100
110
120
Time(sec)
%BusVoltage
8. Electrical & Computer Engineering: An International Journal (ECIJ) Volume 3, Number 2, June 2014
48
and the power imbalance condition arises. Due to this the load shedding scheme is activated and
an amount of 68 MW load is curtailed to regain the system stability. Similarly when the fault
occurs at bus 2 and 3 leading to generator 2 and 3 outage respectively, the load of 150MW and 84
MW is shed from the system.
Fig.4 Bus voltage when the fault has occurred at bus 2
Fig.5 Bus voltage when the fault has occurred at bus 2
Fig.6 Bus frequencyafter load shedding when fault has occurred at bus1
0 5 10 15 20 25 30
20
30
40
50
60
70
80
90
100
110
120
Time(sec)
%Busvoltage
0 5 10 15 20 25 30
40
50
60
70
80
90
100
110
Time(sec)
%BusVoltage
0 5 10 15 20 25 30
97.5
98
98.5
99
99.5
100
100.5
101
101.5
102
Time(sec)
%Frequency
9. Electrical & Computer Engineering: An International Journal (ECIJ) Volume 3, Number 2, June 2014
49
Fig.7 Bus frequency after load shedding when fault has occurred at bus2
Fig.8 Bus frequency after load shedding when fault has occurred at bus3
6. CONCLUSION
Transient stability analysis has been performed on ETAP software. The Critical Clearing time
(CCT) i.e. the maximum allowable value of the clearing time for which the system remains to be
stable is calculated for a given fault. System frequency and voltage is analyzed for different
loading conditions and faults on busses. The excess amount of load has to be shedded to maintain
system stability.
APPENDEX
Generator data of IEEE 9 bus system
Parameter G1 G2 G3
Operation mode Swing Voltage control Voltage
control
Rated MVA 80 220 110
KV 16.5 18 13.8
Power factor 0.90 0.85 0.85
Type Hydro Thermal Thermal
Speed 1500 1500 1500
'
doT 5.6 5.6 5.6
'
qoT 3.7 3.7 3.7
0 5 10 15 20 25 30
97
98
99
100
101
102
103
Time(sec)%Busfrequency
0 5 10 15 20 25 30
97
98
99
100
101
102
103
Time(sec)
%BusFrequency
10. Electrical & Computer Engineering: An International Journal (ECIJ) Volume 3, Number 2, June 2014
50
Load data of IEEE 9 bus system
Load id Rating
(MVA)
Rated KV
Lump1 71.589 230
Lump2 53.852 230
Lump3 55.902 230
Lump4 31.623 230
Lump5 20.616 230
Lump6 25.495 230
Lump7 31.623 230
Lump8 20.616 230
Lump9 25.495 230
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Authors
Renuka Kamdar was born in Bhopal, India in 1987. She has received her BE degree
(Electrical and Electronics Engineering) from Oriental Institute of Science and
Technology, Bhopal in 2009 and M. Tech degree (Power System) from MANIT Bhopal
in 2013. She is presently working as a JRF in MANIT, Bhopal
Dr. Ganga Agnihotri (M92118974) received BE degree in Electrical engineering from
MACT, Bhopal (1972), the ME degree (1974) and PhD degree (1989) from University of
Roorkee, India. Since 1976 she is with Maulana Azad College of Technology, Bhopal in
various positions. Currently she is Professor. Her research interest includes Power System
Analysis, Power System Optimization and Distribution Operation.