Noninvasive Online Parametric Identification of Three-Phase AC Power Impedances to Assess the Stability of Grid-Tied Power Electronic Inverters in LV Networks
Noninvasive Online Parametric Identification of Three-Phase AC Power Impedances to Assess the Stability of Grid-Tied Power Electronic Inverters in LV Networks
复制标题
三相交流电源阻抗的无创在线参数识别，用于评估低压网络中并网电力电子逆变器的稳定性
DOI：
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发表时间：
2018
影响因子：
5.5
通讯作者：
A. Monti
中科院分区：
文献类型：
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作者：
A. Riccobono;M. Mirz;A. Monti
针对并网逆变器系统的小干扰稳定性问题，提出了一种基于阻抗比稳定判据的在线无创三相交流功率阻抗参数辨识方法。该识别技术被集成到现有并网逆变器的控制中，以在其原始功率转换功能的基础上估计宽带交流电网阻抗。这在实践中是通过在逆变器控制环路上注入短时间小信号伪随机二进制序列(PRBS)来实现的，PRBS是白噪声的数字近似，本质上是宽带，从而可以同时激励阻抗测量点上的所有感兴趣的频率。然后，在综合控制平台上进行数字处理，从PRBS注入长度上的电压和电流测量中提取参数交流电网阻抗。此外，还给出了如何识别逆变器输出阻抗的步骤，以便利用参数源和负载阻抗通过广义奈奎斯特稳定性判据来验证系统的稳定性。通过半实物实时仿真验证了该方法的有效性。本文重点研究了dq坐标系下平衡三相交流阻抗的辨识和典型低压配电网的dq对角占优稳定分析。
This paper presents a noninvasive online parametric identification of three-phase ac power impedances to assess small-signal stability of grid-tied inverter systems by using well-known impedance-ratio-based stability criteria. The identification technique is integrated into the control of an existing grid-tied inverter for the estimation of wide bandwidth ac grid impedances, on top of its original power conversion function. This is accomplished in practice by injecting a short-time small-signal pseudorandom binary sequence (PRBS), a digital approximation of white noise which is wide bandwidth in nature, on the inverter control loop so that all frequencies of interest at the impedance measurement point can be excited at once. Then, digital processing is performed in the integrated control platform where the parametric ac grid impedance is extracted from the measurement of voltage and current over the length of PRBS injection. Moreover, a procedure on how to identify the output impedance of the inverter is deployed so that the parametric source and load impedances can be used to verify the system stability by means of the generalized Nyquist stability criterion. The technique is validated via hardware-in-the-loop real-time simulation. This paper focuses on the identification of balanced three-phase ac impedances in dq reference frame and a dq diagonal-dominant stability analysis which is typical of low-voltage distribution grids.