Abstract The control and power production of a Doubly Fed Induction Generator (DFIG) wind turbine are highly dependent on grid parameters. To reach the maximum power point (MPPT) and hence to maximize the power output from the wind energy system, the MPPT algorithms used are generally dependent on the grid voltage measurements. Therefore, any deviation of the grid voltage from its rated value can reduce both the power production efficiency and the reactive power performance of the wind turbine. The main sources of these deviations are voltage unbalance and grid disturbances. Deep investigations of a year of data from the Nouadhibou wind farm located in Mauritania, have shown that DFIG wind turbines are very sensitive to the operating conditions defined by the grid code. This grid code specifies two operation modes: unlimited temporal operation and limited operation. In many situations, the wind farm exceeds the allowed time for limited operation, leading to grid disconnection. This paper proposes a new reactive power control strategy to reduce DFIG’s sensitivity to grid voltage variations. The proposed control compares the measured Phase-Locked Loop (PLL) signal with the reference voltage. Based on this comparison, the controller chooses the suitable combination of capacitors to generate or absorb the required reactive power for voltage regulation. This method allows the wind turbine to remain in unlimited operation mode, preventing unwanted disconnections. Furthermore, it reduces reactive power exchange between the DFIG and the grid while keeping the Point of Common Coupling (PCC) voltage within optimal limits.
Mehdi et al. (Thu,) studied this question.