Coordinated power control method for improving low voltage ride through capability of wind turbines with permanent magnet synchronous generators

Based on an analysis of the low voltage ride through (LVRT) mechanism of wind turbines with permanent magnet synchronous generators (PMSGs), a novel power coordinated control method is proposed for PMSG. In the proposed method, the modified pitch angle control and converter control are used. Under transient state low voltage, part of the energy generated by the wind turbine is undertaken by the rotor and DC bus capacitance. This will weaken the impact of the unbalanced energy on the mechanical shafting. The pitch system is used to decrease the wind energy captured by the wind turbine to relieve the LVRT burden of the unit. To reduce the amplitude of the drop of the grid-side voltage, the grid-side converter is controlled to provide dynamic reactive power to the grid. The coordinated current limiting control is also adopted to guarantee the implementation of the wind turbine's control objectives. The proposed method needs no additional hardware but is able to make full use of the control methods available of the PMSG itself to enhance the LVRT capability of PMSG in the whole wind speed range. Finally, the practicability and effectiveness of the proposed method is verified by the simulation example set in DIgSILENT/Power Factory. © 2015 State Grid Electric Power Research Institute Press.