中文摘要：

采用滑模频率偏移（slide-mode frequency shift,SMS）法、Sandia频率偏移（sandiafrequency shift,SFS）法检测孤岛时,并网逆变器存在相位检测延时,会对孤岛检测盲区的精度产生一定的影响。为克服这一问题,在前期工作的基础上改变下垂锁相环的扰动参数,进而提出改进的频率偏移孤岛检测方法（islanding detection method,IDM）。推导了3种孤岛检测方法在电网频率突变、电网频率偏离额定值2种情况下逆变器并网基准电流的表达式,分析了各自的谐波含量,在具有相同孤岛检测盲区的情况下所提IDM性能最优。仿真结果验证了理论分析的正确性。

英文摘要：

Phase detection delay affectsaccuracy of islanding non-detection zone（NDZ） if grid-connected inverter is controlled with SMS or SFS IDM. In order to overcome this shortcoming, this paper presents a novel islanding detection method（IDM） using frequency drooping phase-lock loop（FD-PLL）. Reference current functions of grid-connected inverters controlled with three different IDMs, are deduced in abrupt change condition and stable state of utility grid frequency.Harmonic contents in reference currents are analyzed respectively. After comparison, it isconcluded that inverter controlled with FD-PLL IDMhas the best performance. Simulation and experiment results verified validity of theoretical analysis.