Coordinated control of rotor kinetic energy and pitch angle for large‐scale doubly fed induction generators participating in system primary frequency regulation

For an electric power grid that has large penetration levels of variable renewable energy including wind generation and photovoltaics, the system frequency stability is jeopardized, which is manifest in lowering frequency nadir and settling frequency. This paper suggests an enhanced primary frequency response strategy of a doubly-fed induction generator (DFIG) in association with pitch angle control. The DFIG works in de-loaded operation with a certain reserve power via pitch angle control prior to disturbances for frequency regulation. To address this, a function of the pitch angle is employed that decreases the pitch angle with time to slowly feed the active power to the power gird. The simulation results demonstrate the effectiveness and feasibility of the proposed primary frequency response strategy including the settling frequency and frequency nadir.

Download Full-text

An Improved Droop Control Scheme of a Doubly-Fed Induction Generator for Various Disturbances

Energies ◽

10.3390/en14237980 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7980

Author(s):

Yien Xu ◽

Pei Chen ◽

Xinsong Zhang ◽

Dejian Yang

Keyword(s):

Rate Of Change ◽

Frequency Regulation ◽

Droop Control ◽

Doubly Fed Induction Generator ◽

Control Coefficient ◽

Induction Generators ◽

Doubly Fed Induction Generators ◽

Control Scheme ◽

Doubly Fed ◽

System Frequency

Doubly-fed induction generators (DFIGs) participate in the system frequency regulation using a fixed-coefficient droop control scheme. Nevertheless, the frequency-supporting capability of this control scheme with fixed gain is limited for different disturbances. This paper suggests an improved droop control scheme for a DFIG that can both alleviate the frequency nadir and maximum rate of change of frequency (ROCOF) during the frequency regulation. To achieve this, an adaptive droop control coefficient based on the ROCOF is suggested. The proposed droop control coefficient is a linear function of the ROCOF. Therefore, the proposed scheme can adjust the control coefficient according to the varying ROCOF. Simulation results clearly demonstrate that the proposed droop control scheme shows better effectiveness in improving the maximum ROCOF and frequency nadir under various sizes of disturbance, even in a varying wind speed.

Download Full-text

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

Applied Sciences ◽

10.3390/app10082934 ◽

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.

Download Full-text

System frequency regulation in doubly fed induction generators

International Journal of Electrical Power & Energy Systems ◽

10.1016/j.ijepes.2012.05.039 ◽

2012 ◽

Vol 43 (1) ◽

pp. 977-983 ◽

Cited By ~ 32

Author(s):

Xue Yingcheng ◽

Tai Nengling

Keyword(s):

Frequency Regulation ◽

Induction Generators ◽

Doubly Fed Induction Generators ◽

Doubly Fed ◽

System Frequency

Download Full-text

Stochastic model predictive control for wind turbines with doubly fed induction generators

2016 IEEE Power and Energy Society General Meeting (PESGM) ◽

10.1109/pesgm.2016.7741108 ◽

2016 ◽

Author(s):

Peng Kou ◽

Deliang Liang ◽

Lin Gao

Keyword(s):

Model Predictive Control ◽

Stochastic Model ◽

Predictive Control ◽

Wind Turbines ◽

Induction Generators ◽

Doubly Fed Induction Generators ◽

Doubly Fed ◽

Stochastic Model Predictive Control

Download Full-text

Dynamic Low Voltage Ride through Detection and Mitigation in Brushless Doubly Fed Induction Generators

Energies ◽

10.3390/en14154461 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4461

Author(s):

Ahsanullah Memon ◽

Mohd Wazir Mustafa ◽

Muhammad Naveed Aman ◽

Mukhtar Ullah ◽

Tariq Kamal ◽

...

Keyword(s):

Fuzzy Logic ◽

Fuzzy Logic Controller ◽

Low Voltage ◽

Voltage Drop ◽

Low Voltage Ride Through ◽

Induction Generators ◽

Doubly Fed Induction Generators ◽

Reactive Current ◽

Doubly Fed ◽

Rotor Side Converter

Brushless doubly-fed induction generators have higher reliability, making them an attractive choice for not only offshore applications but also for remote locations. These machines are composed of two back-to-back voltage source converters: the grid side converter and the rotor side converter. The rotor side converter is typically used for reactive current control of the power winding using the control winding current. A low voltage ride through (LVRT) fault is detected using a hysterisis comparison of the power winding voltage. This approach leads to two problems, firstly, the use of only voltage to detect faults results in erroneous or slow response, and secondly, sub-optimal control of voltage drop because of static reference values for reactive current compensation. This paper solves these problems by using an analytical model of the voltage drop caused by a short circuit. Moreover, using a fuzzy logic controller, the proposed technique employs the voltage frequency in addition to the power winding voltage magnitude to detect LVRT conditions. The analytical model helps in reducing the power winding voltage drop while the fuzzy logic controller leads to better and faster detection of faults, leading to an overall faster response of the system. Simulations in Matlab/Simulink show that the proposed technique can reduce the voltage drop by up to 0.12 p.u. and result in significantly lower transients in the power winding voltage as compared to existing techniques.

Download Full-text