提高直驱永磁风机低电压穿越能力的功率协调控制方法

在分析直驱永磁同步风力发电机低电压穿越问题产生机理的基础上,提出了一种适用于直驱风机的新型功率协调控制方法。该方法综合使用改进的双侧变流器和桨距角控制手段,低压暂态时,利用变流器直流母线电容充电储能配合风机转子变速储能承担风机产生的不平衡能量,减弱机组机械轴系所受的冲击作用;使用变桨系统减少风机捕获的风能,减轻机组低电压穿越的负担;通过网侧变流器向电网提供动态无功功率,减小网侧电压的跌落幅度;同时在双侧变流器的控制器中增加协调限流控制环节,用以保证风机有功无功控制目标的有效实现。文中所述方法不附加任何硬件,充分使用直驱风机自身可用的控制手段,能够有效提高直驱风机在全风域范围内的低电压穿越能力。最后,使用DIgSILENT/Power Factory搭建仿真实例,验证了所述方法的实用性和有效性。

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.