Transient Phenomena In Power Systems Research Articles

Estimation of dominant mode parameters in power systems using correlation analysis

This paper proposes a hybrid Prony-cross-correlation real-time tracking dominant mode and parameter estimation using simulated and phasor measurement unit (PMU) data. It proposes a new method for detecting the dominant mode during the transient phenomena in electrical power systems. The performance of the proposed method has been compared to some of the existing methods for estimating the frequency and damping factor of a signal under noisy conditions, such as the Prony and EKF methods. In contrast to the traditional Prony and EKF methods for estimating the modes parameters, which require the order of the model and the initial parameters of the mode, the hybrid Prony-cross-correlation does not require any previous information. Three Brazilian systems (reduced, north and NIS) have been studied for both stationary and transient phenomena in power systems to determine the robustness and the accurate estimates even in the presence of noise in the measured signal by the proposed method.

Spectral Shape Estimation in Data Compression for Smart Grid Monitoring

This paper proposes a transform-based compression algorithm for waveforms associated with power quality and transient phenomena in power systems. This method uses the wavelet transform, a dynamic bit allocation in the transform domain through estimation of the spectral shape, as well as entropy coding in order to minimize residual redundancy. Five distinct approaches for estimating the spectral shape are proposed. Four of them are based on analytical models that seek to describe the decreasing behavior of the transformed coefficients: 1) decreasing linear bit allocation shape; 2) decreasing quadratic bit allocation shape; 3) decreasing exponential bit allocation shape; 4) rotated sigmoid bit allocation shape; and 5) the fifth approach—the neural shape estimator (NSE)—is an adaptive model that uses an artificial neural network to map the changes in the spectrum shape. Results with databases of real signals and a performance evaluation using objective measures are reported. The results indicate that the NSE approach outperforms the other proposed solutions that use spectral shape estimation for coding, as well as other compression contributions reported in the literature.

Development of Power System Transient Analysis Program based on Traveling Wave Theory using MATLAB

Abstract: In power system, there are various events such as fault. When this event are occurred, transient phenomena on power system are observed. To analyze the transient phenomena on power system, various theory or simulation/analysis tools are used. Traveling wave theory is also one of the analysis method for power system transient phenomena. Already, traveling wave theory is utilized various area, such as fault location on transmission system or electrical railroad system. It is known that analysis method based on traveling wave theory has advantage on the aspect of accuracy. In this paper, the traveling wave theory is implement on MATLAB program. Also, using MATLAB program based on traveling wave theory, power system transient phenomena is analyzed. To verify the accuracy of MATLAB program result, comparison with result of ElectroMagnetic Transient Program (EMTP) is performed.

Tools for Characterization and Assessment of Ferroresonance Using 3-D Bifurcation Diagrams

Ferroresonance is one of the most destructive transient phenomena in power systems. This complex phenomenon involves the association of nonlinear magnetizing inductances and capacitances, and may be initiated in many different ways, which makes its characterization very difficult. This work links EMTP and MATLAB and presents some computer tools that have been developed for assessing ferroresonance behavior. These tools allow users to visualize 2-D and 3-D bifurcation diagrams which can be used for performing sensitivity analysis, predicting the phenomenon at different stages, and finding safety zones for power system parameter design.

Phasor measurement based on IEC 61850-9-2 and Kalman–Filtering

This paper proposes a new technique for estimating phasors during the transient phenomena in the electrical power systems. Unlike traditional Phasor Measurement Units (PMUs) that estimates phasors at process level, the proposed technique estimates phasors at bay level. The estimation technique relies on a robust recursive Kalman–Filtering, which is employed for computing the phasors based on the time-critical IEC 61850-9-2 Sampled Measured Values casted by the substation Merging Units (MUs). Many evolution tests of the proposed technique have been carried out for both stationary and transient phenomena in power systems to determine the accuracy of the measurements obtained at various conditions. The proposed estimator can produce phasors at bay level with reporting rate of 100 frames per second, which is encouraged in IEEE Std C37.118 and can satisfy higher accuracies than provided by the traditional Phasor Measurement Units, which are 0.01 degree and 0.01% for phase and magnitude, respectively.

A Crank–Nicolson Galerkin approach to the analysis of electromechanical oscillations in stressed power systems

The primary goal of this research is directed toward the study and characterization of nonlinear power system transient phenomena following large perturbations. A novel analytical framework based on a nonlinear Galerkin method and a finite difference scheme is introduced. The proposed method is designed primarily to capture strong nonlinear behavior and may be applied to model reduction, nonlinear characterization and control design.A nonlinear system model is first developed by Galerkin projections onto basis of eigenfunctions obtained from the proper orthogonal decomposition (POD) method that includes the representation of higher-order nonlinear effects. The scheme is coupled with a modified Crank–Nicolson finite difference method to characterize the nonlinear system dynamics following severe perturbations. Several extensions and generalizations of the method are suggested and tested and criteria are then developed for systematically analyzing complicated system oscillations.The theory is illustrated on two test power systems. Results obtained using the Galerkin procedures are compared with transient stability simulations. Factors that influence the quality of the nonlinear Galerkin approximations are discussed and issues concerning the implementation of the method and numerical calculations are also highlighted.

Simulation Model of Brushless Excitation System

Excitation system is key element in the dynamic performance of electric power systems, accurate excitation models are of great importance in simulating and investigating the power system transient phenomena. Parameter identification of the Brushless excitation system was presented. First a block diagram for the EXS parameter was proposed based on the documents and maps in the power station. To identify the parameters of this model, a test procedure to obtain step response, was presented. Using the Genetic Algorithm with the Matlab-software it was possible to identify all the necessary parameters of the model. Using the same measured input signals the response from the standard model showed nearly the same behavior as the excitation system.

Simulation Model of Brushless Excitation System

Excitation system is key element in the dynamic performance of electric power systems, accurate excitation models are of great importance in simulating and investigating the power system transient phenomena. Parameter identification of the Brushless excitation system was presented. First a block diagram for the EXS parameter was proposed based on the documents and maps in the power station. To identify the parameters of this model, a test procedure to obtain step response, was presented. Using the Genetic Algorithm with the Matlab-software it was possible to identify all the necessary parameters of the model. Using the same measured input signals the response from the standard model showed nearly the same behavior as the excitation system.

Transient Voltage Stability and Voltage Sag Discrimination by Matching Pursuit-Based Transient Modeling and Neural Networks

This article presents a method to discriminate between transient voltage stability and voltage sag. Transient modeling based on matching pursuit with an overcomplete dictionary of wavelet functions is a powerful tool in the analysis of the transient phenomena in power systems because of its ability to accurately represent them in both time and frequency domains with a minimum amount of information. This is a desirable feature when looking for accuracy and computational cost, as discrimination is performed by combining the information provided by the signal analysis tool with a neural network. In our approach, the information provided by the matching pursuit-based transient modeling stage is applied to train a neural network in a fast and accurate fashion. The simulated results presented clearly show that the proposed technique can discriminate accurately between transient voltage stability and voltage sag in power system protection with low computation cost.

Detecting transient voltage stability and voltage sag

This paper presents method to discriminate between transient voltage stability and voltage sag. The discrete wavelet transform (WT) is a powerful tool in the analysis of the transient phenomena in power systems because of its ability to extract information in both the time and frequency domain. This paper introduces a technique for accurate discrimination by combining WTs with neural networks (NNs). The WT is first applied to decompose the signals into a series of detailed wavelet components. The wavelet components are calculated and then employed to train a NN. The simulated results presented clearly show that the proposed technique can accurately discriminate between transient voltage stability and voltage sag in power system protection.

A new framework for estimation of generator dynamic parameters

The accuracy of generator dynamic parameters is one of the crucial factors in correctly simulating the power system transient phenomena. This paper proposes a general procedure for estimating the generator dynamic parameters from measurements. The proposed procedure employs a gradient based simulation optimization technique to estimate the parameters. Effectiveness of the simulation optimization method is shown in some examples for estimating the exciter and governor model parameters. Impacts of noise and parameter uncertainties are briefly discussed in the paper.

Running EMTP on PCs (power systems)

The Electromagnetic Transients Program (EMTP) is a computer program for the simulation of electric power system transient phenomena. The program provides a large set of device models permitting accurate modeling of power system components over a wide frequency range. Traditionally, this program has existed only in mainframe and minicomputer environments, limiting its use to engineers and companies with access to these facilities. Recently, the EMTP has been made available for use on IBM and compatible personal computers using the IBM OS/2 and Microsoft Windows operating systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Interactive Electromagnetic Transients Program for Electrical Engineering Education

An electromagnetic transient analysis program using Dommel's method [5] has been implemented on a 16-bit microcomputer running under MS-DOS operating system. The program has been mainly tailored for classroom teaching purposes; however, by proper modeling the program can be used to study transient phenomena in practical systems. The program provides tabular display, printer plots, and high resolution graphic plots as output. The interactive feature allows the user to change the network parameters and observe the consequent system response. The program can be used for a range of problems, such as transient response of electrical networks with discrete elements, switching surge calculations, effects of breaker closing resistance and shunt reactor, TRV calculations, and faulted system transients. Any general configuration of resistances, inductances, capacitors, and transmission lines with both current and voltage sources can be studied. A three-phase system is modeled using the corresponding positive sequence equivalent network. This paper describes the salient features of the program and its usage, through a range of examples. The program will assist an engineer or student to understand transient phenomena in power systems conceptually and focus attention on power system modeling using the most appropriate network model for transient analysis.

Interactive Electromagnetic Transients Program for Electrical Engineering Education

An electromagnetic transient analysis program using Dommel's method has been implemented on a 16-bit microcomputer running under MS-DOS operating system. The program has been mainly tailored for classroom teaching purposes,however,by proper modelling the program can be used to study transient phenomena in practical systems. The program is command driven and is resilient to data errors. The program provides tabular display, printer plots and high resolution graphic plots as output. The interactive feature allows the user to change the network parameters and observe the consequent system response. The program can be used for a range of problems, such as, transient response of electrical networks with discrete elements, switching surge calculations, effects of breaker closing resistance and shunt reactor, TRV calculations and faulted system transients. Any general configuration of resistances, inductances, capacitors and transmission (distributed parameter) lines with both current and voltage sources can be studied. A three-phase system is modelled using the corresponding positive sequence equivalent network. This paper describes the salient features of the program and its usage, through a range of examples. The program will assist an engineer or student to understand transient phenomena in power systems conceptually and focus attention on power system modelling using the most appropriate network model for transient analysis.

A magnetic tape oscillograph for power system analysis

A unique magnetic pickup device makes the magnetic tape recorder adaptable to the recording of power system transient phenomena. Besides eliminating the inconvenience and expense of conventional photographic methods, this technique produces a permanent record starting well in advance of the transient being recorded.

A Magnetic Tape Oscillograph for Power System Analysis

A unique magnetic pickup device makes the magnetic tape recorder adaptable to the recording of power system transient phenomena. Besides eliminating the inconvenience and expense of conventional photographic methods, this technique produces a permanent record starting well in advance of the transient being recorded.