scholarly journals Multi-Target Control Strategy of DFIG Using Virtual Synchronous Generator Based on Extended Power Resonance Control under Unbalanced Power Grid

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2232
Author(s):  
Dan Sun ◽  
Yangming Wang ◽  
Tianlong Jiang ◽  
Xiaohe Wang ◽  
Jun Sun ◽  
...  
Keyword(s):  
Synchronous Generator ◽  
Induction Generator ◽  
Doubly Fed Induction Generator ◽  
Electromagnetic Torque ◽  
Stator Current ◽  
Unbalanced Voltage ◽  
Doubly Fed ◽  
Unbalanced Grid ◽  
Extended Power ◽  
Virtual Synchronous Generator

Virtual synchronous generator control is considered as an effective solution to optimize the frequency response characteristics of doubly fed induction generator. However, due to the insufficient control bandwidth of the original virtual synchronous generator, it has little control effect over the oscillating components of the power caused by the unbalanced grid voltage. Therefore, long-term unbalanced voltage will cause a series of problems, such as distortion of stator and rotor currents, as well as oscillations of power and electromagnetic torque, which seriously affect the power quality and the operating performance of the doubly fed induction generator. To solve these problems, the concept of extended power is introduced, and the second-order generalized integrator-based resonant controller is used to control the extended power and traditional power. Control targets of the extended power method are discussed and extended, so that the doubly fed induction generator system using extended power resonant control-based virtual synchronous generator control can realize three different control targets under the unbalanced grid condition. The three control targets are: balanced and sinusoidal stator current, sinusoidal stator current and constant active power, and sinusoidal stator current and constant reactive power and electromagnetic torque. The three control targets can also be flexibly switched according to the real-time requirements of the grid with unbalanced voltage. The simulation results verify the effectiveness of the control method.

scholarly journals Short-Circuit Current Calculation and Harmonic Characteristic Analysis for a Doubly-Fed Induction Generator Wind Turbine under Converter Control

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2471 ◽  
Author(s):  
Jing Li ◽  
Tao Zheng ◽  
Zengping Wang
Keyword(s):  
Wind Turbine ◽  
Analytical Model ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Induction Generator ◽  
Doubly Fed Induction Generator ◽  
Stator Current ◽  
Dc Bus ◽  
Bus Voltage ◽  
Doubly Fed

An accurate calculation of short-circuit current (SCC) is very important for relay protection setting and optimization design of electrical equipment. The short-circuit current for a doubly-fed induction generator wind turbine (DFIG-WT) under excitation regulation of a converter contains the stator current and grid-side converter (GSC) current. The transient characteristics of GSC current are controlled by double closed-loops of the converter and influenced by fluctuations of direct current (DC) bus voltage, which is characterized as high order, multiple variables, and strong coupling, resulting in great difficulty with analysis. Existing studies are mainly focused on the stator current, neglecting or only considering the steady-state short-circuit current of GSC, resulting in errors in the short-circuit calculation of DFIG-WT. This paper constructs a DFIG-WT total current analytical model involving GSC current. Based on Fourier decomposition of switch functions and the frequency domain analytical method, the fluctuation of DC bus voltage is considered and described in detail. With the proposed DFIG-WT short-circuit current analytical model, the generation mechanism and evolution law of harmonic components are revealed quantitatively, especially the second harmonic component, which has a great influence on transformer protection. The accuracies of the theoretical analysis and mathematical model are verified by comparing calculation results with simulation results and low-voltage ride-through (LVRT) field test data of a real DFIG.

scholarly journals Oscillation Damping for Wind Energy Conversion System with Doubly Fed Induction Generator Association with Synchronous Generator

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5067
Author(s):  
Farag K. Abo-Elyousr ◽  
Hossam S. Abbas ◽  
Ali M. Yousef ◽  
Nguyen Vu Quynh ◽  
Ziad M. Ali ◽  
...  
Keyword(s):  
Power System ◽  
Energy Conversion ◽  
Synchronous Generator ◽  
Induction Generator ◽  
Doubly Fed Induction Generator ◽  
Rotor Speed ◽  
Linear Quadratic ◽  
Interconnected Power System ◽  
Wind Energy Conversion ◽  
Doubly Fed

The main purpose of this paper is to enhance the operation of renewable wind energy conversion (WEC) systems connected to power systems. To achieve this, we consider a linear quadratic Gaussian (LQG) control approach for regulating the effects of a WEC system with doubly fed induction generator (DFIG) on the synchronous generator (SG) rotor speed of the interconnected power system. First, we present the mathematical formulation of the interconnected power system comprises a single synchronous generator and a wind turbine with DFIG connected to an infinite bus bar system through a transmission line. We consider that the system is operated under various loading conditions and parameters variation. Second, a frequency damping oscillation observer is designed via Kalman filtering together with an optimal linear quadratic regulator to mitigate the impacts of the WEC system on the SG rotor speed. The performance of the developed interconnected power system is simulated using a MATLAB/SIMULINK environment to verify the effectiveness of the developed controller. In comparison with previously reported results, the proposed approach can stabilize the interconnected power system within 1.28 s compared to 1.3 s without the DFIG.

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