A method of power system simulation model reduction for transmission grid frequency response analysis (original) (raw)
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International Journal of Electrical and Computer Engineering (IJECE), 2025
Since power systems are designed to work at the fundamental frequency, the presence of other frequencies from various sources may induce series and parallel resonances, leading to damage. The behavior of the power system in the presence of harmonics becomes evident with knowledge of harmonic impedance. Measurement offers the most accurate means of estimating harmonic impedance. However, when precise data of the power system parameters are available, highly satisfactory results can be achieved through calculation methods, particularly regarding loads, which are unknown and always change. This paper presents a study on estimating harmonic impedance using the Electromagnetic Transients Program Alternative Transient Program Draw (EMTP-ATPDraw) program, applied to an authentic network of Petrovice line 67, 22/0.4 kV, located in the Czech Republic. Hypothetically, the network was subjected to harmonic injection from a source (3rd, 5th, 7th, 9th, and 11th harmonics), and the harmonic impedance was calculated for three different variants: individual harmonics, all harmonics, and all except the 9th harmonic. The results show that the presence of the 9th harmonic can lead to a parallel resonance. This study is the first to employ EMTP-ATPDraw for programming this network. It gives the possibility to create a network database for different operating conditions, offering an asset for future project planning.
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Journal of Control, Automation and Electrical Systems, 2014
Currently, there is a lack of standard methodology to characterize frequency responses of electric power grids for power line communication purpose. As a result, fair comparisons among measurement campaigns carried out in different parts of the world are missing. Aiming at to deal with this issue, this contribution discusses a complete soundingbased methodology to estimate frequency responses of electric power grids combining sampling frequency offset error estimation and correction, timing synchronization, channel estimation, and channel estimation enhancement techniques. The effectiveness of this methodology is validated by using well-known power line channel models, as well as measured ones, covering the frequency band from 1.7 up to 50 MHz. The attained results show that the methodology provides estimates in shorten period of time in comparison with the network analyzer based methodology and because of that it is capable of characterizing the periodically and time-varying behavior of electric power grids. Additionally, it is shown that the methodology can be successfully applied to characterize frequency responses of electric equipment and, as a conse
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2016
Large power systems are complex and real-time modeling of the grid for electromagnetic simulation (EMT) studies is impractical. In general, there are methods that reduce large power system into an equivalent network that requires less computational resource, while preserving electromechanical (low frequency) and high frequency behavior of the original system. This can be achieved by modeling the area not of interest (external area) as a combination of Transient Stability Analysis (TSA) type phasor model equivalent and Frequency Dependent Network Equivalent (FDNE). TSA retains electromechanical behavior, whereas FDNE retains high frequency behavior of the original power system. To this effect, this paper introduces a method of developing FDNE based on an online recursive least squares (RLS) identification algorithm in z-domain, and modeling of reduced power systems as FDNE and as a combination of TSA and FDNE using real-time digital simulators.
Procedia - Social and Behavioral Sciences, 2015
The subject of the paper is part of the general issue, particularly complex, establishing the means and methods of intervention for maintaining an appropriate quality of power supplied to consumers connected to existing distribution networks, which are subject to more pronounced harmonic pollution. In this context, the analysis in the frequency domain of the normal operating regimes of electrical distribution networks is a mandatory operation, the main instrument being the harmonic impedance seen in the network buses nodes. A typical application of this tool of analysis refers to reactive power compensation in distribution network harmonic polluted, operation that may lead to increased non-sinusoidal regime and consequently to increased negative effects on the operating of installations belonging to the supplier or consumers. Avoidance of harmonic resonances is possible only by knowing the frequency response of the network, more exactly the change of harmonic impedance seen in the network buses. This paper presents, in two parts, the numerical examples carried out on the same area of a real distribution network, two analytical methods: harmonic nodal admittance matrix method, respectively state matrix method. The results are analyzed and compared with the values obtained by the two methods.
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Energies, 2020
Harmonic simulations play a key role in studying and predicting the impact of nonlinear devices on the power quality level of distribution grids. A frequency-domain approach allows higher computational efficiency, which has key importance as long as complex networks have to be studied. However, this requires proper frequency-domain behavioral models able to represent the nonlinear voltage–current relationship characterizing these devices. The Frequency Transfer Matrix (FTM) method is one of the most widespread frequency domain modeling approaches for power system applications. However, others suitable techniques have been developed in the last years, in particular the X-parameters approach, which comes from radiofrequency and microwave applications, and the simplified Volterra models under quasi-sinusoidal conditions, that have been specifically tailored for power system devices. In this paper FTM, X-parameters and simplified Volterra approaches are compared in representing the nonl...
Harmonic Analysis in Frequency and Time Domain IEEE Task Force on Harmonics Modeling and Simulation
—This paper presents a review with a concise description and analysis of the fundamentals, characteristics, analytical details, merits, and drawbacks associated with existing methods in frequency and time domain for harmonic analysis in practical power networks. The description and analysis are centered on methods developed in the harmonic domain, hybrid frequency-time domain, and time domain, respectively. Validation of the reviewed methods for harmonic analysis, against one of the widely accepted digital simulators, such as EMTP, EMTDC, or MATLAB/SIMULINK, is reported in the cited individual contributions.
Implementation of the frequency dependent line model in a real-time power system simulator
In this paper is described the implementation of the frequency-dependent line model (FD-Line) in a real-time digital power system simulator. The main goal with such development is to describe a general procedure to incorporate new realistic models of power system components in modern real-time simulators based on the Electromagnetic Transients Program (EMTP). In this procedure are described, firstly, the steps to obtain the time domain solution of the differential equations that models the electromagnetic behavior in multi-phase transmission lines with frequency dependent parameters. After, the algorithmic solution of the FD-Line model is implemented in Simulink environment, through an S-function programmed in C language, for running off-line simulations of electromagnetic transients. This implementation allows the free assembling of the FD-Line model with any element of the Power System Blockset library and also, it can be used to build any network topology. The main advantage of having a power network built in Simulink is that can be executed in real-time by means of the commercial eMEGAsim simulator. Finally, several simulation cases are presented to validate the accuracy and the real-time performance of the FD-Line model.
International Journal of Numerical Modelling: Electronic Networks, Devices and Fields
This study presents the application of Proper Generalized Decomposition on transmission line models involving frequency dependent parameters. Frequency dependence of parameters can be due to a number of reasons including phenomena such as "Ground Return Effects", "Proximity Effects" and "Skin Effects". In the current study, simplified methods of skin effects based on Bessel functions are used in order to showcase the method. Although we implement our study using a specific model for skin effects to demonstrate the effectiveness of the proposed method to accomodate frequency dependent effects in PGD, the present work is not meant to discuss the merits of any particular skin effects model. The method can easily accommodate other effects which induces frequency dependence in the transmission line parameters. In time domain modeling, the parameters are assumed constant and these models prove inefficient when incorporating these parameters as function of frequency. Therefore, a frequency domain simulation is implemented using harmonic analysis. PGD presents a separated representation and provides a quick and accurate solution for such problems.
2018
To study the stability and to observe how the power system behaves, during normal and abnormal conditions, availability of a simulation model of the considering Power System is very important. It is very important to ascertain that the simulation model’s performance is identical or approximately equal to the corresponding real time power system’s behavior. Since one of the aims of this research is to address frequency degradation due to Generation—Load imbalance situations in Sri Lanka, it has been decided to simulate the power system of Sri Lanka. Convenience of collecting required data from the Ceylon Electricity Board (the only utility available in Sri Lanka) on request, was an added advantage. Therefore a simulation model of the Power System of Sri Lanka (Transmission network—132 and 220 kV) was designed using the software PSCAD/EMTDC. All basic components of the transmission network such as synchronous generators, transformers, transmission lines, under-ground cables, governors...