A performance comparison of a nonlinear and a linear control for grid connected PMSG wind energy conversion system

• Nonlinear control approach of WECS based on PMSG and interconnected to the grid.
• The nonlinear SMC approach is used to improve the overall efficiency of the WECS.
• The performance has been demonstrated under varying wind and grid fault conditions.
• The performance of the SMC is validated via comparison with that of PI regulators.
• MATLAB simulations show the effectiveness of the proposed control strategies.

With the increased penetration of wind energy on modern power systems all over the world, the Wind Farm Systems (WFS) are today required to participate actively in electric network operation by an appropriate generation control strategy. This paper presents a comparative study of two control strategies for wind farm based on Permanent Magnet Synchronous Generator (PMSG) and interconnected to the distribution network. The 4 MW wind farm consists of 2 PMSGs based on 2 MW generators connected to a common DC-bus system. Each PMSG of the WFS is connected to the DC-bus through a rectifier, but the DC-bus is connected to the grid through only one inverter system. The proposed control laws are based on a sliding mode algorithm and classical Proportional Integral (PI) controllers to regulate both generator and grid-side converters. The control strategy combines a pitch control scheme and Maximum Power Point Tracking (MPPT) to maximize the total generated power of WFS. Furthermore, the aim of the control strategy is to maximize the extracted power with the lowest possible impact in the power network voltage and frequency for fault conditions as well as for normal working conditions. Finally, simulation results with Matlab/Simulink environment confirm that the proposed strategy has excellent performance.

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