LCL滤波的光伏并网逆变器阻尼影响因素分析

Factors Contributing to Damping of Grid-connected Photovoltaic Inverter with LCL Filter

并网光伏逆变装置越来越多地采用电感—电容—电感(LCL)滤波器,针对其固有谐振特性而采取的阻尼控制策略成为了研究热点。以LCL滤波器、逆变器、电网为整体进行建模研究,用无源阻尼和有源阻尼中最常用的虚拟电阻法,深入分析了逆变器控制行为和电网因素对阻尼效果的影响。研究结果表明,电网的非理想电压源特性、系统控制延迟等因素会影响阻尼性能。在此基础上提出了一种采用有源与无源阻尼相结合的控制方法,有效地减少了系统控制延迟的影响,保证了阻尼具有较好的电网参数适应能力。实验结果证明了所述方法的有效性。

LCL filters are increasingly used in grid-connected photovoltaic inverters as the preferred option.Its inherent resonance character makes the damping strategy a hot topic for research.LCL filter,inverter and the grid are modeled and studied as a whole.The commonly used virtual resistor method of passive and active damping,the impacts of inverter＇s behavior and the grid stiffness on the damping effect are studied in detail.The results show that the non-ideal characteristics of the grid,the proportional gain and the control delay affect the damping properties the most.A hybrid damping method combining active and passive damping is proposed.The method can reduce the impact of control delay and is adaptable for grid change.Experimental results show its effectiveness.