ABSTRACT:
Wind energy is
a prominent area of application of variable-speed generators operating on the
constant grid frequency. This paper describes the operation and control of one of
these variable-speed wind generators: the direct driven permanent magnet
synchronous generator (PMSG). This generator is connected to the power network
by means of a fully controlled frequency converter, which consists of a pulse width-modulation
(PWM) rectifier, an intermediate dc circuit, and a PWM inverter. The generator
is controlled to obtain maximum power from the incident wind with maximum
efficiency under different load conditions. Vector control of the grid-side
inverter allows power factor regulation of the windmill. This paper shows the
dynamic performance of the complete system. Different experimental tests in a 3-kW
prototype have been carried out to verify the benefits of the proposed system.
KEYWORDS:
1. Permanent-magnet generators
2. Pulse width modulated (PWM) power converters
3. Wind energy
SOFTWARE: MATLAB/SIMULINK
CONCLUSION:
This work shows the performance of a
direct-driven permanent-magnet synchronous generator used in variable speed wind-energy
systems. When exciting the system with a real wind profile, the system is able
to track maximum power using generated power as input. The speed controller
sets the generator torque command, which is achieved through a current control
loop. An efficient generator control has been proposed. To achieve this
objective, the optimum generator d-axis current component is imposed by
the power converter, i.e., the current that leads to the minimum losses. The
proposed system has been implemented in a real-time application, with a
commercial permanent-magnet synchronous generator and a dc drive that emulates
the wind turbine behaviour. The real-time process is running in a dSPACE board
that includes a TMS320C31 floating-point DSP. Experimental results show the
appropriate behavior of the system.
REFERENCES:
[1] A. Grauers, “Efficiency of three
wind energy generator systems” IEEE Trans. Energy Convers, vol. 11, no.
3, pp. 650–657, Sep. 1996.
[2] E. Spooner and A. C. Williamson, “Direct
coupled, permanent magnet generators for wind turbine applications,” Proc.
Inst. Elect. Eng.—Elect. Power Appl., vol. 143, no. 1, pp. 1–8, 1996.
[3] R. Pe˜na, J. C. Clare, and G. M.
Asher, “Doubly fed induction generator using back-to-back PWM converters and
its application to variable-speed wind-energy generation,” Proc. Inst.
Elect. Eng.—Elect. Power Appl., vol. 143, no. 3, pp. 231–241, May 1996.
[4] Z. Chen and E. Spooner, “Simulation
of a direct drive variable speed energy converter,” in Proc. Int. Conf.
Electrical Machines, Istanbul, Turkey, 1998, pp. 2045–2050.
[5] A. Grauers “Design of direct driven
permanent magnet generators for wind turbines,” M.S. thesis, Chalmers Univ.
Technol., G¨oteborg, Sweden, 1996.
