ABSTRACT
This paper deals with the operation of doubly fed induction
generator (DFIG) with an integrated active filter capabilities using grid-side
converter (GSC). The main contribution of this work lies in the control of GSC
for supplying harmonics in addition to its slip power transfer. The rotor-side
converter (RSC) is used for attaining maximum power extraction and to supply
required reactive power to DFIG. This wind energy conversion system (WECS)
works as a static compensator (STATCOM) for supplying harmonics even when the
wind turbine is in shutdown condition. Control algorithms of both GSC and RSC
are presented in detail. The proposed DFIG-based WECS is simulated using
MATLAB/Simulink. A prototype of the proposed DFIGbased WECS is developed using
a digital signal processor (DSP). Simulated results are validated with test
results of the developed DFIG for different practical conditions, such as
variable wind speed and unbalanced/single phase loads.
KEYWORDS
1. Doubly fed induction generator (DFIG)
2. Integrated active filter
3. Nonlinear load
4. Power quality
5. Wind energy conversion system (WECS).
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig. 1. Proposed system configuration.
Fig. 2. Control algorithm of the proposed
WECS.
EXPECTED SIMULATION RESULTS
Fig. 3. Simulated performance of the proposed
DFIG-based WECS at fixed wind speed of 10.6 m/s (rotor speed of 1750 rpm).
Fig. 4. Simulated waveform and harmonic
spectra of (a) grid current (iga), (b) load current (ila), (c) stator current (isa), and (d) grid voltage for phase “a”
(vga)
at fixed wind speed of 10.6 m/s (rotor speed of 1750 rpm).
Fig. 5. Simulated performance of the proposed
DFIG-basedWECS working as a STATCOM at zero wind speed.
Fig. 6. Simulated waveforms and harmonic
spectra of (a) load current (ila) and (b) grid current (iga) working as a STATCOM at wind turbine shut
down condition.
Fig. 7. Simulated performance of proposed
DFIG for fall in wind speed.
Fig. 8. Dynamic performance of DFIG-based
WECS for the sudden removal and application of local loads.
CONCLUSION
The
GSC control algorithm of the proposed DFIG has been modified for supplying the
harmonics and reactive power of the local loads. In this proposed DFIG, the
reactive power for the induction machine has been supplied from the RSC and the
load reactive power has been supplied from the GSC. The decoupled control of
both active and reactive powers has been achieved by RSC control. The proposed
DFIG has also been verified at wind turbine stalling condition for compensating
harmonics and reactive power of local loads. This proposed DFIG-based WECS with
an integrated active filter has been simulated using MATLAB/Simulink
environment, and the simulated results are verified with test results of the
developed prototype of this WECS. Steady-state performance of the proposed DFIG
has been demonstrated for a wind speed. Dynamic performance of this proposed
GSC control algorithm has also been verified for the variation in the wind
speeds and for local nonlinear load.
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