一种低谐波畸变量的快速主动移频式孤岛检测方法

孤岛检测是并网逆变器必备的一种功能。针对传统主动移频(Active Frequency Drift, AFD)孤岛检测法存在的检测时间较长和检测盲区(Nondetection Zone, NDZ) 较大的问题，提出一种新型的AFD孤岛检测法。通过在原始电流参考波形中注入接近余弦的扰动波形，使参考波形在产生孤岛检测所需无功功率相同时，能有效减小对电能质量的影响。对参考波形进行数值分解，分析该方法的THD与Q/P之间关系以及NDZ分布情况，并与传统AFD法进行比较。仿真结果表明，该方法具有检测时间更短和NDZ更小，同时对电能质量影响小的特点。

An improved active frequency drift islanding detection method with lower total harmonic distortion

Anti-islanding detection is a mandatory function of grid-connected inverters. This paper proposes a novel active frequency drift (AFD) islanding detection method to solve the problems of the classic AFD method, such as longer detection time and larger non-detection zone (NDZ). In the proposed AFD method, an approximating cosine disturbance current waveform is injected into the original reference current waveform, so that there is less side influence on power quality when the reactive power generated by reference current waveform equals. This paper analyzes the relationship between the total harmonic distortion (THD) and Q/P and the distribution of NDZ in the proposed method through the value decomposition of the proposed reference current waveform, and compares the new method with the classic AFD method. The simulation results show the proposed method has shorter detection time, smaller NDZ and less influence on power quality.