Stability identification for grid-connected inverters with LCL filters considering grid-voltage feedforward regulator
Stability identification for grid-connected inverters with LCL filters considering grid-voltage feedforward regulator
复制标题
考虑电网电压前馈调节器的LCL滤波器并网逆变器稳定性辨识
作者：
Minghui Lu;F. Blaabjerg
本文确定了采用电网电压前馈调节器（GVFR）的并网逆变器的稳定谐振频率范围。从不考虑GVFR的电流环稳定性分析入手，在z域中解析地研究了系统极点分布，从而计算出临界频率以及控制增益极限。然后，本文揭示了在弱电力系统中，GVFR会改变系统的稳定性，识别并比较了两个频率边界和三个典型的谐振频率范围。系统极点分布表明，当系统共振频率低于ωs/3时，GVFR具有阻尼作用，超过ω s/3时，GVFR将使系统失稳。基于实验室规模的原型的实验测试的理论分析进行了验证。
This paper identifies stable resonance frequency range for grid-connected inverter with Grid-Voltage Feedforward Regulator (GVFR). Beginning with the current loop stability analysis without GVFR, system poles distribution is analytically studied in z-domain, the critical frequency is therefore calculated as well as the control gain limit. Then, this paper reveals the GVFR would change the system stability in the weak power system, two frequency boundaries and three typical resonance frequency ranges are identified and compared. System poles distribution shows that GVFR can offer damping effects when resonance frequency is below ωs/3, in contrast, over which GVFR will destabilize the system. The theoretical analysis is validated by experimental tests based on a laboratory-scale prototype.