A new method of detecting PV Grid-connected Inverter Islanding based on the frequency variation

When the grid occurred fault, it is important for PV Grid-connected Inverter to detect the Islanding accurately and quickly. In order to achieve target much better, we will introduce a new method based on the frequency variation in detecting the Islanding. According to the traditional ways, there are some defects when the load is special. With the old method Active Frequency Drift(AFD) can not detect the Islanding. But the new rule that we will introduce could discover the Islanding much more accurately and quickly when frequency does not pass the limit value. The simulink test proves that the new method can detect the Islangding within 0.04 second and reduce the blind spot effectively, even in the most adverse conditions.