基于虚拟阻尼控制的三相VSI启动冲击电流抑制

Restraint of Start-up Inrush Current of Three-phase VSI Based on Virtual Damping Control

三相电压源型并网逆变器(voltage-source inverters,VSI)在并网启动过程中存在冲击电流问题,为有效抑制冲击电流影响,提出了一种基于虚拟阻尼控制思想的冲击电流抑制新方法。首先在dq坐标系下建立数学模型,分析出冲击电流产生的根本原因为并网期间系统阻尼比的下降;然后给出了虚拟阻尼控制策略的详细设计过程;最后通过仿真和实验验证了所提方法的正确性与有效性。结果表明,加入虚拟阻尼前,冲击电流可达额定电流的2倍以上;加入虚拟阻尼后可实现无冲击电流并网,且能够提高系统的鲁棒稳定性、动态电流品质和设备运行安全性。

There exists a start-up inrush current problem during the grid-connection period within the three-phase voltage-source inverters(VSI). Consequently, we propose a new method to suppress the inrush current effectively based on the virtual damping control. Firstly, a mathematical model is established based on the dq coordinate frame, and it is recognized that the primary cause of inrush current is the decrement in the damping ratio during the grid-connection period. Then, the detailed design process of the virtual damping control method is given, and the correctness and effectiveness of the proposed method are verified by simulation and experiments. The results show that the inrush current can be more than twice the rated current before adding virtual damping, the grid connection without inrush current can be realized after adding virtual damping, and it can also improve the robust stability of the system, the dynamic current quality, and equipment safety in operation.