An Improved Droop Control Scheme of a Doubly-Fed Induction Generator for Various Disturbances
Abstract
:1. Introduction
2. Modeling of a Doubly-Fed Induction Generator
3. Proposed Adaptive Droop Control Scheme of a DFIG
4. Model System
4.1. Conventional Synchronous Generators
4.2. DFIG-Based Wind Power Plant
5. Case Studies
5.1. Case 1: Wind Speed of 8.5 m/s, Disturbance of 60 MW with Various Settings of Quotient
5.2. Case 2: Wind Speed of 8.5 m/s and Disturbance of 60 MW
5.3. Case 3: Wind Speed of 8.5 m/s and Disturbance of 120 MW
5.4. Case 4: Random Wind Conditions and Disturbance of 120 MW
6. Conclusions
- (1)
- The proposed control droop coefficient is coupled with the ROCOF which can reflect the size of the disturbance. Furthermore, a power function to regulate the control coefficient. Thus, the proposed droop control scheme can adaptively adjust the frequency response capability under various disturbances.
- (2)
- Based on the fixed control gain for the conventional scheme, a supplementary function of the ROCOF is suggested. Thus, the proposed scheme can generate more power to improve the frequency-supporting capability of the DFIG.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
Nomenclature
β | Pitch angle |
ωs | Rotor speed of the grid |
ir | Current at rotor circuit |
is | Current at stator circuit |
Ir | Current at rotor circuit for dq-axis |
Is | Current at stator circuit for dq-axis |
ug | Voltage at GSC |
ig | Current at GSC |
Ug | Grid voltage for dq-axis |
Ig | Grid current for dq-axis |
Udc | Voltage at DC-link |
Reference voltage at DC-link | |
Qg | Reactive power at GSC |
Power reference at GSC | |
current reference at GSC for d-axis | |
current references at GSC for q-axis | |
Reactive Power reference at RSC | |
cp | Power coefficient |
S | Swept area |
λ | Tip-speed ratio |
Β | Pitch angle |
vw | Wind speed |
R | Blade length |
λopt | Optimal tip-speed ratio |
Tem | Mechanical torque from the turbine |
Te | Generator electrical torque |
Ht | Turbine inertia constant |
Hg | Generator inertia constant |
Tls | Torques of the low-speed shaft |
Ths | Torques of the high-speed shaft |
ωt | Turbine rotor speed |
ωr | Generator rotor speed |
K | Spring constant |
θs | Torsional twist |
D | Damping constant |
ωls | Rotor angular velocity of the low-speed shaft |
PMPPT | Output of MPPT operation |
ΔPdroop | Incremental power for the droop control loop |
KAG | Adaptive gain |
Δf | Frequency deviation |
K0 | Basic control coefficient for the droop control |
k1 | Droop control factor |
DFIGs | Doubly-fed induction generators |
ROCOF | Rate of change of frequency |
TSGs | Traditional synchronous generators |
FN | Frequency nadir |
RSC | Rotor-side controller |
GSC | Grid-side controller |
MPPT | Maximum power point tracking |
RSC | Rotor-side controller |
GSC | Grid-side controller |
EMPT-RV | Energy Management Training Program, Restructured Version |
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Xu, Y.; Chen, P.; Zhang, X.; Yang, D. An Improved Droop Control Scheme of a Doubly-Fed Induction Generator for Various Disturbances. Energies 2021, 14, 7980. https://doi.org/10.3390/en14237980
Xu Y, Chen P, Zhang X, Yang D. An Improved Droop Control Scheme of a Doubly-Fed Induction Generator for Various Disturbances. Energies. 2021; 14(23):7980. https://doi.org/10.3390/en14237980
Chicago/Turabian StyleXu, Yien, Pei Chen, Xinsong Zhang, and Dejian Yang. 2021. "An Improved Droop Control Scheme of a Doubly-Fed Induction Generator for Various Disturbances" Energies 14, no. 23: 7980. https://doi.org/10.3390/en14237980