Environmental Engineering Reference
In-Depth Information
3.6.2 Step Changes in the Source Voltage
The amplitude of source voltage reduces by 20 % at 0.75 s and restores to initial value
at 0.85 s. The load current is 15 A. The DC-link voltage responses to step changes of
the voltage in the power grid in Fig.
3.12
. It can be seen that the DC-link voltage
almost has no fluctuations when the system is controlled by high-order TSM control.
The q-andd-axis current responses to step changes in source voltage are depicted in
Figs.
3.13
and
3.14
. The control signals of the inverter are displayed in Fig.
3.15
.
3.7 Conclusions
This chapter has described the control issues in grid integration of WECS. A
structure of dual PWM inverter is presented in the wind energy integration into
power network. Both of two PWM inverters are controlled separately using one
control system. A control strategy for the grid-side PWM inverter has been
designed to guarantee that the WECS has a unit power ratio. Sliding-mode control
theory and technique have been used to optimize the control of WECS. A control
strategy for the grid-side PWM converter of DFIG-based wind power system has
been developed. The high-order TSM control technique provides the fast con-
vergence, strong robustness, and high tracking accuracy. A smooth control signal
of the controller can be generated by utilizing the second-order sliding-mode
technique. The effect of the equivalent low pass filter in the high-order sliding-
mode mechanism can be regulated optionally. The simulation results have shown
the correctness of the proposed method.
Although a lot of theoretical research work on the control of WECS has been
done, the future work will involve providing more efficient and robust control
algorithms, and trying to do experiments in practical application environments.
Acknowledgments This work was supported in part by the National Natural Science Foundation
of China (61074015), and also in part by ARC Linkage Project (LP100200538) of the Australian
Research Council.
References
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