scholarly journals Simulation of Low Inertia Power Systems Based on Shifted Frequency Analysis

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1860
Author(s):  
Jan Dinkelbach ◽  
Ghassen Nakti ◽  
Markus Mirz ◽  
Antonello Monti
Keyword(s):  
Power Systems ◽  
Power System ◽  
Frequency Analysis ◽  
Time Domain ◽  
Step Size ◽  
Modeling Approaches ◽  
Dynamic Phasors ◽  
Instantaneous Values ◽  
The Time Domain ◽  
Synchronous Generation

New types of power system transients with lower time constants are emerging due to the replacement of synchronous generation with converter interfaced generation and are challenging the modeling approaches conventionally applied in power system simulation. Quasi-stationary simulations are based on classical phasor models, whereas EMT simulations calculate the instantaneous values of models in the time domain. In addition to these conventional modeling approaches, this paper investigates simulation based on dynamic phasor models, as has been proposed by the Shifted Frequency Analysis. The simulation accuracy of the three modeling approaches was analyzed for characteristic transients from the electromagnetic to the electromechanical phenomena range, including converter control as well as low inertia transients. The analysis was carried out for systems with converter interfaced and synchronous generation whilst considering the simulation step size as a crucial influence parameter. The results show that simulations based on dynamic phasors allow for larger step sizes than simulations that calculate the instantaneous values in the time domain. This can facilitate the simulation of more complex component models and larger grid sizes. In addition, with dynamic phasors, more accurate simulation results were obtained than with classical phasors, in particular—but not exclusively—in a low inertia case. Overall, the presented work demonstrates that dynamic phasors can enable fast and accurate simulations during the transition to low inertia power systems.

scholarly journals Power System Stabilizer Tuning Algorithm in a Multimachine System Based on S-Domain and Time Domain System Performance Measures

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5644
Author(s):  
Predrag Marić ◽  
Ružica Kljajić ◽  
Harold R. Chamorro ◽  
Hrvoje Glavaš
Keyword(s):  
Power Systems ◽  
Power System ◽  
Time Domain ◽  
Synchronous Generator ◽  
Pole Placement ◽  
Power System Stabilizer ◽  
Weight Functions ◽  
Novel Approach ◽  
The Time Domain ◽  
System Stabilizer

One of the main characteristics of power systems is keeping voltages within given limits, done by implementing fast automatic voltage regulators (AVR), which can raise generator voltage (i.e., excitation voltage) in a short time to ceiling voltage limits while simultaneously affecting the damping component of the synchronous generator electromagnetic torque. The efficient way to increase damping in the power system is to implement a power system stabilizer (PSS) in the excitation circuit of the synchronous generator. This paper proposes an enhanced algorithm for PSS tuning in the multimachine system. The algorithm is based on the analysis of system participation factors and the pole placement method while respecting the time domain behavior of the system after being subdued with a small disturbance. The observed time-domain outputs, namely active power, speed, and rotor angle of the synchronous generator, have been classified and validated with proposed weight functions based on the minimal square deviation between the initial values in a steady-state and all sampled values during the transitional process. The system weight function proposed in this algorithm comprises s-domain and time-domain indices and represents a novel approach for PSS tuning. The proposed algorithm performance is validated on IEEE 14-bus system with a detailed presentation of the results in a graphical and table form.

scholarly journals Enhancing Oscillation Damping in an Interconnected Power System with Integrated Wind Farms Using Unified Power Flow Controller

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 322 ◽  
Author(s):  
Ping He ◽  
Seyed Arefifar ◽  
Congshan Li ◽  
Fushuan Wen ◽  
Yuqi Ji ◽  
...  
Keyword(s):  
Power Systems ◽  
Power System ◽  
Time Domain ◽  
Power Flow ◽  
Unified Power Flow Controller ◽  
Time Domain Simulation ◽  
Interconnected Power System ◽  
Dynamic Time ◽  
Oscillation Damping ◽  
Power Flow Controller

The well-developed unified power flow controller (UPFC) has demonstrated its capability in providing voltage support and improving power system stability. The objective of this paper is to demonstrate the capability of the UPFC in mitigating oscillations in a wind farm integrated power system by employing eigenvalue analysis and dynamic time-domain simulation approaches. For this purpose, a power oscillation damping controller (PODC) of the UPFC is designed for damping oscillations caused by disturbances in a given interconnected power system, including the change in tie-line power, the changes of wind power outputs, and others. Simulations are carried out for two sample power systems, i.e., a four-machine system and an eight-machine system, for demonstration. Numerous eigenvalue analysis and dynamic time-domain simulation results confirm that the UPFC equipped with the designed PODC can effectively suppress oscillations of power systems under various disturbance scenarios.

Techniques for the Identification of Critical Nodes Leading to Voltage Collapse in a Power System

2018 ◽  
Vol 19 (2) ◽  
Author(s):  
Isaiah Adebayo ◽  
Adisa Jimoh ◽  
Adedayo Yusuff
Keyword(s):  
Power Systems ◽  
Power System ◽  
Power Flow ◽  
Eigenvalue Decomposition ◽  
Step Size ◽  
Suggested Approach ◽  
Voltage Instability ◽  
Critical Nodes ◽  
Voltage Stability Enhancement ◽  
Stability Enhancement

AbstractThis paper proposes two techniques for the identification of critical buses in a power system. The technique of Network Structural Theory Participation Factor (NSTPF) depends on the network structural interconnection of buses as captured by the admittance matrix of the system and is formulated based on the fundamental circuit theory law using eigenvalue decomposition method. Another power flow based technique which depends on the system maximum loadability, the system step size among other factors is also proposed. Traditional power flow based techniques are used as benchmarks to determine the significance of the proposed methods. To ensure voltage stability enhancement, STATCOM FACTS device is installed at the selected weak load buses of the practical Nigerian 24 bus and IEEE 30 bus test systems. The results of the simulation obtained show that, the suggested approach of NSTPF is more suitable in the identification of weak buses that are liable to voltage instability in power systems as it requires less computational burden and also saves time compared to techniques based on power flow solutions.

AN INNOVATIVE TECHNIQUE FOR QUALITY CONTROL OF GEAR PUMPS

2002 ◽  
Vol 09 (04) ◽  
pp. 383-392
Author(s):  
GIULIO FANTI ◽  
ROBERTO BASSO ◽  
MICHELE BERNARDI ◽  
UMBERTO VERZA
Keyword(s):  
Quality Control ◽  
Fourier Transform ◽  
Frequency Analysis ◽  
Time Domain ◽  
Mathematical Tool ◽  
Pressure Data ◽  
Innovative Technique ◽  
Gear Pumps ◽  
The Time Domain ◽  
Discharge Pressure

This paper describes an innovative technique for the quality control of gear pumps based on the frequency analysis of the oscillations of the discharge pressure using a new mathematical tool called "the spectrum of the power cepstrum." It consists in applying Fourier transform of the pressure data sampled in the time domain three times consecutively. The innovative technique makes it possible to obtain an acceptance mask for a set of gear pumps in the same series, in which the class and entity of a defect can be detected.

Time‐domain estimation of MT Impedance tensor

Geophysics ◽  
1994 ◽  
Vol 59 (5) ◽  
pp. 712-721 ◽  
Author(s):  
Umberto Spagnolini
Keyword(s):  
Time Domain ◽  
Bayes Estimation ◽  
Impedance Tensor ◽  
Data Sets ◽  
Least Mean Square ◽  
Step Size ◽  
Juan De Fuca ◽  
The Time Domain ◽  
Reference Processing ◽  
Frequency Domain Techniques

The spectral analysis of magnetotelluric (MT) data for impedance tensor estimation requires the stationarity of measured magnetic (H) and electric (E) fields. However, it is well known that noise biases timedomain tensor estimates obtained via an iterative search by a descent algorithm to determine the least‐mean‐square residual between measured and estimated E data obtained from H data. To limit the noise that slows down, or even prevents convergence, the steepest descent step size is based upon the statistics of the residual (Bayes’ estimation). With respect to uncorrelated noise, the time‐domain technique is more robust than frequency‐domain techniques. Furthermore, the technique requires only short‐time stationarity. The time‐domain technique is applied to data sets (Lincoln Line sites) from the EMSLAB Juan de Fuca project (Electromagnetic Sounding of the Lithosphere and Asthenosphere Beneath the Juan de Fuca Plate), as well as to data from a southern Italian site. The results of EMSLAB data analysis are comparable to those obtained by robust remote reference processing where larger data sets were used.

scholarly journals Comparison of the Time Domain Windows Specified in the ISO 18431 Standards Used to Estimate Modal Parameters in Steel Plates

2016 ◽  
Vol 2016 ◽  
pp. 1-7
Author(s):  
Jhonatan Camacho-Navarro ◽  
R. Guzmán-López ◽  
Sergio Gómez ◽  
Marco Flórez
Keyword(s):  
Fourier Transform ◽  
Frequency Analysis ◽  
Time Domain ◽  
Steel Plate ◽  
Theoretical Method ◽  
Steel Plates ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Time Frequency ◽  
The Time Domain

The procedures used to estimate structural modal parameters as natural frequency, damping ratios, and mode shapes are generally based on frequency methods. However, methods of time-frequency analysis are highly sensible to the parameters used to calculate the discrete Fourier transform: windowing, resolution, and preprocessing. Thus, the uncertainty of the modal parameters is increased if a proper parameter selection is not considered. In this work, the influence of three different time domain windows functions (Hanning, flat-top, and rectangular) used to estimate modal parameters are discussed in the framework of ISO 18431 standard. Experimental results are conducted over an AISI 1020 steel plate, which is excited by means of a hammer element. Vibration response is acquired by using acceleration records according to the ISO 7626-5 reference guides. The results are compared with a theoretical method and it is obtained that the flat-top window is the best function for experimental modal analysis.

MOM formulation for nonlinear low-frequency analysis in the time domain

1998 ◽  
Vol 34 (5) ◽  
pp. 2609-2612 ◽  
Author(s):  
A. Musolino ◽  
M. Raugi ◽  
A. Tellini
Keyword(s):  
Frequency Analysis ◽  
Time Domain ◽  
Low Frequency ◽  
The Time Domain

scholarly journals OpenIPSL: Open-Instance Power System Library — Update 1.5 to “iTesla Power Systems Library (iPSL): A Modelica library for phasor time-domain simulations”

SoftwareX ◽  
2018 ◽  
Vol 7 ◽  
pp. 34-36 ◽  
Author(s):  
Maxime Baudette ◽  
Marcelo Castro ◽  
Tin Rabuzin ◽  
Jan Lavenius ◽  
Tetiana Bogodorova ◽  
...  
Keyword(s):  
Power Systems ◽  
Power System ◽  
Time Domain

Time-Frequency Analysis for Power System Oscillations

2013 ◽  
Vol 336-338 ◽  
pp. 928-931
Author(s):  
Chia Liang Lu ◽  
Pei Hwa Huang
Keyword(s):  
Power Systems ◽  
Power System ◽  
Frequency Analysis ◽  
Low Frequency ◽  
Normal Operation ◽  
Intrinsic Mode Functions ◽  
Time Frequency Analysis ◽  
Hilbert Huang Transform ◽  
Time Frequency ◽  
Low Frequency Oscillations

Low frequency oscillations due to the lack of damping may occur in power systems under normal operation and will cause system instability. These oscillations are essentially nonlinear power responses which are difficult to extract the inherent characteristics by the time domain method. This paper aims to analyze nonlinear power responses by using the Hilbert-Huang transform (HHT) which is a time-frequency signal processing method which comprises steps of the empirical mode decomposition and the Hilbert transform. Dynamic power system responses, including generator output power and line power are to be processed by the HHT and a set of intrinsic mode functions and the associated Hilbert spectrum are obtained. The generator with most effects on the system will be accordingly found out through the time-frequency analysis and the power system stabilizer will be placed at the generator. Numerical results from a sample power system are demonstrated to show the validity of the time-frequency approach in the study of power system low frequency oscillations.

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