Research on Low Voltage Ride-through Control of Permanent Magnet Direct Drive Wind Turbine Generators during Grid Faults

Low voltage ride-through (LVRT) mandates that wind turbines stay connected to the grid during voltage drops. To satisfy the LVRT criteria for permanent magnet direct-drive wind turbines, this paper proposes a control strategy involving an energy-dissipating circuit on the machine-side and reactive power compensation on the grid. The machine-side energy-dissipating circuit, known as the Braking Chopper (BC) circuit, is utilized, while grid-side reactive power compensation employs the Port-Controlled Hamiltonian Algorithm (PCH). When the grid voltage drops, the BC circuit absorbs excess power generated during the fault to maintain stability in the DC bus voltage, while the PCH provides reactive power compensation. Once the grid voltage returns to normal, the BC circuit is disconnected, and the PCH resumes normal grid-connected operation. Using Matlab/Simulink, a simulation model was constructed, and simulations were conducted. The results demonstrate that the control strategy proposed in this paper enables successful LVRT during symmetrical grid faults.