An Experimental System for LVRT of Direct-Drive PMSG Wind Generation System

In this paper, a LVRT experimental platform for direct-drive permanent magnet synchronous generator (D-PMSG) wind generation system is constructed. The paper uses DC motors, gearboxes and flywheels to simulate the torque characteristic, low speed characteristic and big inertia characteristic of actual wind turbine. Considering the voltage sag of actual power grid, different types of voltage sag are analyzed, and a control strategy for voltage sag generator, which can generate voltage sag of different types, sag depth and sag duration, is proposed. A coordinated control strategy of active power and reactive power for full power converters is proposed. When the grid voltage sag, the reactive power was conveyed to the power grid preferentially. Then the active power is transported furthest. Simulation and experiment show that the voltage sag generator can generate all types of power grid voltage sag waveform, and the LVRT platform can verify the effectiveness of the proposed control strategy effectively.