1 results about "Island state" patented technology

The invention discloses a photovoltaic grid-connected island detection method based on zero-sequence current injection. The photovoltaic grid-connected island detection method comprises the steps thatan island detection model is built; iabc flowing out of the DC/AC inverter passes through a transformer and then enters a power grid unit for operation; and if the signal relay acts, information is fed back to the DC/AC inverter, the DC/AC inverter is injected into I(0) at the moment, a zero-sequence current value at the PCC is detected, and if the zero-sequence current value at the PCC exceeds aset threshold value, the island state is judged. According to the photovoltaic grid-connected island detection method, the signal relay is used for sending the signal to the photovoltaic power generation unit, so that the problem of relatively high cost of a communication detection method is avoided; only when an alarm starting signal given by the signal relay is received, zero-sequence current disturbance is injected, so that the problem of large blind area of a passive detection method is avoided, and the influence of the active detection method on the electric energy quality is relieved toa certain extent.