Research on Control Strategy of Direct Drive Permanent Magnet Wind Turbine
At present, although the doubly-fed wind power generation system still dominates the entire wind power generation system, the direct drive generator set has begun to receive more and more attention due to its inherent advantages [1]. The direct-drive wind power generation system uses a wind wheel to directly drive a multi-pole low-speed permanent magnet synchronous generator (pmsg) to generate electricity, and then converts the electric energy into a power grid through a power conversion circuit, thereby eliminating the failure in the conventional doubly-fed wind power generation system. This part of the gearbox with higher rate has greatly improved the system efficiency, effectively suppressed the noise and improved the operational reliability of the system, and thus has been favored by the market.
2 direct drive wind turbine converter topology
For the active rectification topology, the three-phase voltage type inverter replaces the uncontrolled rectification and boost chopper unit to control the generator load torque, thereby realizing the adjustment of the motor speed. This topology uses a dual pwm (pulsewidth modulation) full-power converter to achieve high-performance control of the generator, and also avoids the increased complexity of the uncontrolled rectifier and boost chopper two-stage structure, reducing power generation. The copper consumption and iron consumption of the machine, and the power factor of the generator can be adjusted to 1, which has a good development prospect. In view of the different emphasis of the motor-side converter and the grid-side converter control strategy, this paper proposes a control method for the separate control of the motor-side converter and the grid-side converter (the system control block diagram is shown in Figure 2). , it can achieve effective control of it, resulting in high-performance dynamic characteristics.
