电压暂降引发逆变器并网谐振机理与阻尼抑制方法

Resonance Mechanism and Damping Suppression Method of Grid-connected Inverter Triggered by Voltage Sag

电网单相接地导致新能源发电系统低压穿越风险并伴随电压暂降。电压暂降不仅产生直流分量,还包含高频谐波,可能导致逆变器并网发生谐振进而威胁新能源发电系统的稳定性。采用瞬时电压dq分解法和幅频特性图分析电压暂降对系统谐振的影响。作为实用性较高的谐振抑制策略,混合阻尼被实际工程广泛应用,因此采用混合阻尼方法抑制电压暂降所引发的系统谐振。设计了电网电压暂降的仿真实验模型,结果表明电网电压暂降包含的高次谐波将引起逆变器并网系统谐振,而混合阻尼策略对电压暂降引起的系统谐振有较好的抑制效果。

The single-phase grounding of the grid leads to the low-voltage crossing risk of the new energy power generation system with voltage sag.Voltage sag not only generates DC component,but also contains high-frequency harmonics,which may lead to grid-connected inverter resonance and threaten the stability of new energy power generation system.The transient voltage dq decomposition method and amplitude-frequency characteristic diagram are used to analyze the influence of voltage sag on the system resonance.As a resonant suppression strategy with high practicability,hybrid damping is widely used in practical engineering,so the hybrid damping method is used to suppress the system resonance caused by voltage sag.The simulation experiment model of grid voltage sag is designed.The results show that the high harmonics contained in grid voltage sag will cause the resonance of the grid-connected inverter system,and the mixed damping strategy has a better suppression effect on the system resonance caused by voltage sag.