ABSTRACT:
This
paper proposes a variable speed control scheme for grid-connected wind energy
conversion system (WECS) using permanent magnet synchronous generator (PMSG).
The control algorithm tracks the maximum power for wind speeds below rated
speed of wind turbines and ensures the power will not go over the rated power
for wind speeds over the rated value. The control algorithm employs fuzzy logic
controller (FLC) to effectively do this target. The wind turbine is connected
to the grid via back-to-back PWM-VSC. Two effective computer simulation
packages (PSIM and Simulink) are used to carry out the simulation effectively.
The control system has two controllers for generator side and grid side
converters. The main function of the generator side controller is to track the
maximum power through controlling the rotational speed of the wind turbine
using FLC. In the grid side converter, active and reactive power control has
been achieved by controlling q-axis and d-axis current components,
respectively. The d-axis current is set at zero for unity power factor and the q-axis
current is controlled to deliver the power flowing from the dc-link to the
electric utility grid.
KEYWORDS:
1. Wind
energy systems
2. Permanent
magnet synchronous generator
3. Fuzzy
logic controller
4. Simulation
software packages (PSIM and Simulink)
5.
Maximum power point tracking
SOFTWARE:
MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig. 1. Schematic diagram of
the overall system.
Fig. 2. Different simulation waveforms: (a) wind
speed variation (7–13) m/s, (b)
actual
and reference rotational speed (rad/s), (c) CP, (d) dc-link voltage (v),
(e) active
power
(W), and (f) reactive power (Var).
CONCLUSION:
A
co-simulation (PSIM/Simulink) program has been proposed for WECS in this paper
where PSIM contains the power circuits of the WECS and Matlab/Simulink contains
the control circuit of the WECS. The idea behind integrating these two software
packages is that, the Matlab/Simulink is a powerful tool for modeling the
control system, FLC and mathematical
manipulation whereas PSIM is a powerful tool for modeling power electronics
circuits and switches. Co-simulation (PSIM/Simulink) makes the simulation
process so much easy, efficient, faster in response and powerful. The
integration between PSIM and Simulink is the first time to be used in modeling
WECS which help researchers in modifying the modeling of WECS in the future.
The WT is connected to the grid via back to- back PWM converters which have
been modeled in PSIM. The generator side and the grid side controllers have
been modeled in Simulink. The generator side controller has been used to track
the maximum power generated from WT through controlling the rotational speed of
the turbine using FLC. The PMSG has been controlled in indirect-vector field
oriented control technique and its speed reference has been obtained from FLC.
In the grid side converter, active and reactive power control has been achieved
by controlling q-axis and d-axis grid current components respectively. The d-axis
grid current is controlled to be zero for unity power factor and the qaxis grid
current is controlled to deliver the power flowing from the dc-link to the
grid. The simulation results prove the superiority of FLC and the whole control
system.
REFERENCES:
[1]
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[2]
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[3]
M.R. Dubois, Optimized permanent magnet generator topologies for direct drive wind
turbines, Ph.D. dissertation, Delft Univ. Technol., Delft, The Netherlands,
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[4]
A. Grauers, Design of direct-driven permanent-magnet generators for wind turbines,
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T. Thiringer, J. Linders, Control by variable rotor speed of a fixed pitch wind
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