A HIGH FREQUENCY ISLAND DETECTION APPROACH APPLIED IN SINGLE-PHASE GRID-CONNECTED PV GENERATION SYSTEM

Island detection is a necessary feature of the photovoltaic (PV) generation system. Both passive and active anti-island methods exist. Typically, active methods modify a given parameter, which also affect the shape and quality of the injected current. A new active anti-island approach is proposed in this paper, which is suitable for single-phase grid-connected PV system. First, the output voltage of grid-connected inverter spectrum is investigated to prove feasibility. Second, the equivalent model of grid is proposed, and the frequency response of the voltage of PCC point is also investigated. Then, 1kHz perturbation component current is selected to be injected into the grid current and the diagram of island detection method is also proposed, which mainly consists of a phase detector and magnitude detector. From the experimental results, compared to the low frequency injection, it can be seen that the proposed high frequency injection achieves the goal of anti-island detection and reduce the current distortion to the minimum as well. As a result, this technique has good industrial application prospect.

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