中文摘要：

基于下垂控制的孤岛微电网中，由于逆变器电压电流内环的快速响应及并联逆变器单元之间的交互作用，不同长度的传输阻抗会导致各逆变器输出电流产生谐波，引起高频稳定性问题，现有阻抗判据方法作为分析系统高频稳定性行之有效的方法存在判断过程复杂、保守性强等缺点。针对以上问题，本文通过推导逆变器输出电压与输出电流的关系，建立n台逆变器并联系统的戴维南模型，提出一种高效阻抗分析方案。该方法以逆变器线路阻抗最小的节点作为系统稳定情况最恶劣的判别节点，通过绘制该节点处源载阻抗比函数的奈氏曲线可以准确分析出孤岛微电网中的高频稳定性问题。与现有阻抗判据方法相比，该方法具有分析过程高效简洁、判断次数少、保守性弱等优点。理论分析与仿真结果验证传输线路对系统高频稳定性的影响及本文所提高效阻抗分析方案的正确性与有效性。

英文摘要：

Different length of line impedances will lead high-frequency stability due to the fast response of the inner loops and the interactions among paralleled inverters. Middlebrook impedance analysis method was considered as an efficient method to analyze the high-frequency stability, but it has the disadvantages of complex analysis procedure and serious conservation. Therefore, Thevenin model of N-paralleled inverters was built by deducing the relation of its output voltage and current. A high efficient impedance analysis method is proposed in this paper. High-frequency stability can be analyzed by using the proposed method which takes the smallest inverter line impedance in the node as the worst case all over the system. And then the Nyqnist plots of the worst case is analyzed. Efficient analysis procedure, less judgments and weak conservation are maintained in proposed method compared to Middlebrook impedance analysis method. The feasibility of the proposed method and the effects of impedance on high-frequency stability are verified by the analysis and simulations.