电网电压不平衡双馈风力发电机改进控制方法

Improved Control of DFIG Wind Turbines with Unbalanced Grid Voltage

为了有效地改善电网电压不平衡时双馈发电机(DFIG)的控制效果,提高发电机发出的电能质量,文中提出一种新的控制方法,在发电机转子侧转换器和网侧变换器使用正dq旋转坐标系正反馈的基础上增加了负dq旋转坐标系反馈控制,转子侧负反馈控制目的是降低电压不平衡引起的发电机电磁转矩的振荡,电网侧负反馈的控制目标是抑制发电机输出的不平衡电流。通过PSCAD/EMTDC环境下的仿真研究表明,该控制方法能够有效地改善电网电压不平衡时双馈发电机的性能。

In order to effective improve operating performance and power quality of a doubly fed induction generators wind turbine under unbalanced grid voltage conditions, a novel control scheme was proposed. The rotor-side converter and grid-side converter of the DFIG are controlled in a positive dq reference frame as well as in a negative dq reference frame. The supplementary control of the rotor-side converter in dq reference frame restrains the electromagnetic torque pulsations of the DFIG caused by the unbalanced grid voltage, and the supplementary control of grid-side converter in dq reference frame minimizes the unbalance output currents of the turbine. The proposed control scheme was implemented in PSCAD/EMTDC on a DFIG wind turbine connected to a power grid with unbalanced voltage. Results show that it improves the operating performance of the DFIG wind turbine system.