Characteristic signal frequency selection method based on identification system impedance detection island

The invention discloses a characteristic signal frequency selection method for detecting an island based on identification system impedance. The method comprises the following steps: establishing a power grid model; obtaining measured impedance in a grid-connected mode and an island mode according to the power grid model; selecting the frequency of the characteristic signal according to the impedance; on the basis of analyzing the impedance-frequency characteristics of each element of the system, the impedance-frequency characteristics of a grid-connected point during grid-connected and off-grid operation of the system are obtained, and a specific characteristic frequency selection basis is provided for a harmonic impedance measurement island detection method according to the impedance-frequency characteristics, so that the sensitivity and reliability of island detection are improved. 本发明公开了一种基于识别系统阻抗检测孤岛的特征信号频率选择方法，包括如下步骤：建立电网模型；根据电网模型得到并网模式下和孤岛模式下的测量阻抗；根据阻抗选择特征信号的频率；在分析系统各元件阻抗-频率特性的基础上，得到系统在并、离网运行时并网点的阻抗-频率