风力发电用大功率并网逆变器研究

在大功率风力发电系统中，并网逆变器是实现电能馈送电网的重要环节，但是由于并网逆变器采用的PWM信号开关频率较低，导致输出电流含有较大的电流谐波。该文为降低开关频率造成的电流谐波，在并网逆变器中引入T型滤波器取代典型的电感滤波器，并针对采用T型滤波器对并网逆变器系统带来的不稳定性，提出了基于桥臂输出电流闭环与电压电流双前馈相结合的间接控制策略。仿真与实验结果证明采用该控制策略可以有效实现并网逆变器稳定运行，同时具有较好的动静态性能。

Study on Grid-Connected Inverter Used in High-power Wind Generation System

In high-power wind power generation system, voltage source grid-connected inverter is important for energy conversion and transmission. But the output current with harmonic distortion is increased due to the invertar's low switching frequencies. This filter, typically a series inductance, acts to reduce the switching harmonics entering the distribution network. An alternative filter is a T-filter, which can achieve reduced levels of harmonic distortion at lower switching frequencies. But it make instability is bring to system by using a T-filter. This paper proposes a robust strategy for regulating the grid current entering grid from a three-phase VSI system connected via a T-filter. The strategy integrates a loop of bridge current regulator with grid current and voltage feed forward to stabilize the system. Theoretical results of the analysis and simulation are experimentally verified.