scholarly journals Torque Limit-Based Inertial Control of a DFIG for Rapid Frequency Stabilization

2021 ◽  
Vol 9 ◽  
Author(s):  
Yien Xu ◽  
Hongmei Wang
Keyword(s):  
Kinetic Energy ◽  
Power Grid ◽  
Frequency Stabilization ◽  
Rotor Speed ◽  
Point Tracking ◽  
Frequency Drop ◽  
Inertial Control ◽  
Power Point ◽  
Doubly Fed ◽  
High Level

With the increasing penetration of renewable energy generation, the frequency stability of a power grid can be significantly threatened. A doubly-fed induction generator (DFIG) participates in the frequency support of a power grid by releasing kinetic energy (KE) to boost the frequency nadir (FN). However, during rotor speed restoration, it is difficult to counterbalance the size of a second frequency drop (SFD) and the rotor speed recovery duration. This paper proposes an improved torque limit-based inertial control (TLBIC) to raise the FN by releasing less kinetic energy while guaranteeing rapid frequency stabilization with reduced SFD. To this end, when detecting a disturbance, the DFIG enhances the active reference power to the torque limit, and then the active power reduces smoothly based on an exponential function until the maximum power point tracking (MPPT) curve is met, and the rotor speed reverts to the initialization operating condition along the MPPT curve. A simulation system model with various wind power penetrations is established in EMTP-RV. Results show that the proposed scheme boosts the FN at a high level with less KE and guarantees rapid frequency stabilization.

scholarly journals Fast Frequency Response of a Doubly-Fed Induction Generator for System Inertia Support

2020 ◽  
Vol 10 (8) ◽  
pp. 2934
Author(s):  
Dejian Yang ◽  
Hong-Chao Gao ◽  
Lei Zhang ◽  
Jingjiao Li ◽  
Xinsong Zhang ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Recovery Process ◽  
Test Results ◽  
Rotor Speed ◽  
Short Term ◽  
Induction Generators ◽  
Doubly Fed Induction Generators ◽  
Frequency Drop ◽  
Doubly Fed ◽  
System Inertia

Converter-interfaced doubly-fed induction generators (DFIGs) can provide short-term frequency support (STFS) capability by releasing rotating kinetic energy. After arresting the frequency decrease, the rotor speed should return to its initial operating condition. During the rotor speed recovery process, special attention should paid to the performance of the rotor speed restoration duration and size of the second frequency drop (SFD). This paper suggests an enhanced STFS method of DFIGs to preserve better performance of the frequency nadir with less released rotating kinetic energy and accelerate the rotor speed restoration. To this end, a rotor speed-varying incremental power is proposed and is added to the maximum power tracking (MPT) operation reference during STFS, thereby releasing less rotating kinetic energy from DFIGs; afterward, the power reference smoothly decreases to the reference for MPT operation during the preset period. Test results clearly demonstrate that since even less rotating kinetic energy is utilized, the proposed method can preserve better performance of heightening the frequency nadir; furthermore, the proposed method accelerates the rotor speed restoration when the proposed strategy produces the same SFD as the conventional method, thereby improving the power grid resilience.

scholarly journals Inertia and Droop Frequency Control Strategy of Doubly-Fed Induction Generator Based on Rotor Kinetic Energy and Supercapacitor

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3697
Author(s):  
Xiangwu Yan ◽  
Xuewei Sun
Keyword(s):  
Kinetic Energy ◽  
Control Strategy ◽  
Power Loss ◽  
Frequency Control ◽  
Frequency Regulation ◽  
Doubly Fed Induction Generator ◽  
Rotor Speed ◽  
Frequency Drop ◽  
Doubly Fed

The large-scale application of wind power eases the shortage of conventional energy, but it also brings great hidden danger to the stability and security of the power grid because wind power has no ability for frequency regulation. When doubly-fed induction generator (DFIG) based wind turbines use rotor kinetic energy to participate in frequency regulation, it can effectively respond to frequency fluctuation, but has the problems of secondary frequency drop and output power loss. Furthermore, it cannot provide long-term power support. To solve these problems, a coordinated frequency control strategy based on rotor kinetic energy and supercapacitor was proposed in this paper. In order to ensure the DFIG provides fast and long-term power support, a supercapacitor was used to realize the droop characteristic, and rotor kinetic energy was used to realize the inertia characteristic like synchronous generator (SG). Additionally, the supercapacitor is also controlled to compensate for the power dip of the DFIG when rotor kinetic energy exits inertia support to avoid secondary frequency drop. Additionally, a new tracking curve of DFIG rotor speed and output power was adopted to reduce the power loss during rotor speed recovery.

scholarly journals Fast Stepwise Inertial Control Scheme of a DFIG for Reducing Second Frequency Drop

2021 ◽  
Vol 11 (17) ◽  
pp. 8259
Author(s):  
Yien Xu ◽  
Dejian Yang ◽  
Jiejie Huang ◽  
Xinsong Zhang ◽  
Liang Hua
Keyword(s):  
Wind Speed ◽  
Rotor Speed ◽  
Induction Generators ◽  
Doubly Fed Induction Generators ◽  
Frequency Drop ◽  
Control Scheme ◽  
Grid Codes ◽  
Inertial Control ◽  
Doubly Fed ◽  
System Frequency

With the fast growth in the penetration of wind power, doubly fed induction generators (DFIGs) are recommended for their ability to enforce grid codes that provide inertial control services by releasing rotational energy. However, after supporting the system frequency, a second frequency drop (SFD) is prone to occurring to regain the rotor speed caused by the sudden reduction in output. In this article, we propose a torque limit-based fast stepwise inertial control scheme of a DFIG using a piecewise reference function for reducing the SFD while preserving the frequency nadir (FN) with less rotor energy released. To achieve the first objective, the power reference increases to the torque limit and then decays with the rotor speed toward the preset operating point. To achieve the second objective, the power reference smoothly lessens over time based on the exponential function. The performance of the proposed stepwise inertial control strategy was studied under various scenarios, including constant wind speed and ramp down wind speed conditions. The test results demonstrated that the frequency stability is preserved during the frequency support phase, while the second frequency drop and mechanical stress on the wind turbine reduce during the rotor speed restoration phase when the DFIG implements the proposed stepwise inertial control scheme.

scholarly journals Rotational Speed Control Using ANN-Based MPPT for OWC Based on Surface Elevation Measurements

2020 ◽  
Vol 10 (24) ◽  
pp. 8975
Author(s):  
Fares M’zoughi ◽  
Izaskun Garrido ◽  
Aitor J. Garrido ◽  
Manuel De La Sen
Keyword(s):  
Rotational Speed ◽  
Acoustic Doppler Current Profiler ◽  
Speed Control ◽  
Surface Elevation ◽  
Wells Turbine ◽  
Point Tracking ◽  
Current Profiler ◽  
Power Point ◽  
Doubly Fed ◽  
Rotational Speed Control

This paper presents an ANN-based rotational speed control to avoid the stalling behavior in Oscillating Water Columns composed of a Doubly Fed Induction Generator driven by a Wells turbine. This control strategy uses rotational speed reference provided by an ANN-based Maximum Power Point Tracking. The ANN-based MPPT predicts the optimal rotational speed reference from wave amplitude and period. The neural network has been trained and uses wave surface elevation measurements gathered by an acoustic Doppler current profiler. The implemented ANN-based rotational speed control has been tested with two different wave conditions and results prove the effectiveness of avoiding the stall effect which improved the power generation.

scholarly journals Direct and indirect vector control of a doubly fed induction generator based in a wind energy conversion system

2019 ◽  
Vol 9 (3) ◽  
pp. 1531
Author(s):  
Manale Bouderbala ◽  
Badre Bossoufi ◽  
Ahmed Lagrioui ◽  
Mohammed Taoussi ◽  
Hala Alami Aroussi ◽  
...  
Keyword(s):  
Wind Energy ◽  
Wind Power ◽  
Induction Generator ◽  
Doubly Fed Induction Generator ◽  
Modeling And Control ◽  
Point Tracking ◽  
Power Point Tracking ◽  
Power Point ◽  
Doubly Fed ◽  
And Control

<p>In the recent years, the development and the exploitation of renewable energy knew a great evolution. Among these energy resources, the wind power represents an important potential for that the wind system has been the subject of several researches. The purpose of this study is to improve the power extracted from wind energy, taking into consideration the variation of wind speed which causes a problem in energy production. For this purpose, we have controlled the powers whether it is active or reactive delivered by the generator. This paper, presents essentially the modeling and control of doubly- fed induction generator (DFIG), which is connected to a variable speed wind turbine. Firstly, the model of the wind power system with the maximum power point tracking (MPPT) strategy is shown. Then, the modeling of doubly- fed induction generator (DFIG) and its power control is presented. Finnaly, to ensure the attitude of these controls the simulations is presented in the Matlab/Simulink environment.</p>

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