Modelling and Validation of a Grid-Connected DFIG by Exploiting the Frequency-Domain Harmonic Analysis

Wind Energy Conversion Systems (WECS) based on a Doubly-Fed Induction Generator (DFIG) represent the most common configuration employed in wind turbines. These systems involve injecting harmonic currents toward an electrical grid from a back-to-back power converter, potentially creating voltage distortions. To assess this phenomenon, a case study of a 3 kW DFIG-based wind turbine connected to the electrical grid is presented for analysis in the harmonic domain. Initially, a DFIG-based load flow analysis for determining the operating conditions is tackled at the fundamental frequency. Then, the modelling of a DFIG under steady-state operating conditions at harmonic frequencies is analyzed discussing its characteristics in the harmonic domain. The high-frequency harmonics in the output voltage of a pulse width modulation-driven inverter feeding the rotor windings of a DFIG and its connection to a three-winding transformer are also analyzed. This investigation produced a complete model of the DFIG connected to the electrical grid. The results demonstrated that although a considerable harmonic contribution up to the 25th order exists, it remains harmless since it is below 5%, according to the Std. IEEE 519.

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Electrical grid reliability assessment by fault tree analysis

Indonesian Journal of Electrical Engineering and Computer Science ◽

10.11591/ijeecs.v17.i3.pp1127-1134 ◽

2020 ◽

Vol 17 (3) ◽

pp. 1127

Author(s):

Ahmed Agwa ◽

Zaky Matter ◽

Ezzat Eisawy ◽

Hamdy Hassan

Keyword(s):

Fault Tree ◽

Flow Analysis ◽

Reliability Assessment ◽

Fault Tree Analysis ◽

Electrical Energy ◽

Load Flow ◽

System Planning ◽

Electrical Grid ◽

Load Flow Analysis ◽

Planning And Operation

<p>The main rule of an electrical grid is to supply electrical energy to consumers as economically as possible, and with an adequate degree of reliability. Reliability is an essential measure and important component of all power system planning and operation procedures. In this paper, the electrical grid reliability is evaluated by Fault Tree (FT) analysis. In this method Alternating Current (AC) load flow analysis is combined with the FT technique. The electrical grid reliability is calculated based on the unreliability of the power supplied to the loads. The verification of the method is performed on a part of the Egyptian electrical grid (Alexandria zone 17-bus). The electrical grid components are sorted according to their influence on the electrical grid reliability.</p>

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Comparison study between seven-level SVPWM and two-level SVPWM strategy in direct vector control of a DFIG-based wind energy conversion systems

International Journal of Applied Power Engineering (IJAPE) ◽

10.11591/ijape.v9.i1.pp12-21 ◽

2020 ◽

Vol 9 (1) ◽

pp. 12

Author(s):

Habib Benbouhenni

Keyword(s):

Wind Energy ◽

Energy Conversion ◽

Vector Control ◽

Pulse Width Modulation ◽

Harmonic Distortion ◽

Doubly Fed Induction Generator ◽

Wind Energy Conversion ◽

Wind Energy Conversion Systems ◽

Energy Conversion Systems ◽

Doubly Fed

<span>In this paper, we present a comparative study between two-level space vector pulse width modulation (SVPWM) and seven-level SVPWM strategy in direct vector control (DVC) of a doubly fed induction generator (DFIG) based wind energy conversion systems (WECSs). The feasibility and effectiveness of the two strategies are demonstrated by simulation results. The obtained results showed that, the proposed DVC strategy with Seven-level SVPWM technique have stator and rotor current with low harmonic distortion and low active and reactive powers ripples than two-level SVPWM strategy.</span>

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Modeling and Load Flow Analysis of a Microgrid Laboratory.

International Journal of Smart Grid and Sustainable Energy Technologies ◽

10.36040/ijsgset.v3i2.1178 ◽

2019 ◽

Vol 3 (2) ◽

pp. 103-111

Author(s):

Taufik ◽

Matthew A. Guevara ◽

Ali Shaban ◽

Ahmad Nafisi

Keyword(s):

Renewable Energy ◽

Hardware Implementation ◽

Flow Analysis ◽

Load Flow ◽

Electric Power System ◽

State University ◽

Electrical Grid ◽

Load Flow Analysis ◽

Simulation Results ◽

Hardware Test

Microgrids-miniature versions of the electrical grid are becoming increasingly more popular as advancements in technologies, renewable energy mandates, and decreased costs drive communities to adopt them. The modern microgrid has capabilities of generating, distributing, and regulating the flow of electricity, capable of operating in both grid-connected and islanded (disconnected) conditions. This paper utilizes ETAP software in the analysis, simulation, and development of a lab-scale microgrid located at Cal Poly State University. Microprocessor-based relays are heavily utilized in both the ETAP model and hardware implementation of the system. Three case studies were studied and simulated to investigate electric power system load flow analysis of the Cal Poly microgrid. Results were compared against hardware test measurements and showed overall agreement. Slight discrepancies were observed in the simulation results due mainly to the non-ideality of actual hardware components and lab equipment.

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Constant Voltage Model of DFIG-Based Variable Speed Wind Turbine for Load Flow Analysis

Energies ◽

10.3390/en14248549 ◽

2021 ◽

Vol 14 (24) ◽

pp. 8549

Author(s):

Rudy Gianto

Keyword(s):

Steady State ◽

Power Systems ◽

Power Factor ◽

Power Plants ◽

Flow Analysis ◽

Load Flow ◽

Constant Voltage ◽

Load Flow Analysis ◽

Proposed Model ◽

Doubly Fed

At present, the penetration of wind-driven electric generators or wind power plants (WPPs) in electric power systems is getting more and more extensive. To evaluate the steady state performances of such power systems, developing a valid WPP model is therefore necessary. This paper proposes a new method in modeling the most popular type of WPP, i.e., DFIG (doubly fed induction generator)-based WPP, to be used in power system steady state load flow analysis. The proposed model is simple and derived based on the formulas that calculate turbine mechanical power and DFIG power. The main contribution of the paper is that, in contrast to the previous models where the DFIG power factor has been assumed to be constant at unity, the constant voltage model proposed in this paper allows the power factor to vary in order to keep the voltage at the desired value. Another important contribution is that the proposed model can be implemented in both sub-synchronous and super-synchronous conditions (it is to be noted that most of the previous models use two different mathematical models to represent the conditions). The case study is also presented in the present work, and the results of the study confirm the validity of the proposed DFIG model.

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