Study of Islanding Behavior of a Grid-Connected Photovoltaic System Equipped with a Feed-Forward Control Scheme

One of the main issues related to the integration of Distributed Generation (DG) in the utility grid is safety. The protection schemes of distribution systems are usually designed under the assumption that power flows from distribution system to end users. If a fault takes place and a breaker opens, all circuits downstream will be deenergized. However, this is not the case when a DG is used, and it is possible that an Island with power generation and consumption is created, thus raising concerns with respect to equipment and personnel safety. During islanding, a portion of the utility system which contains both load and generation is isolated from the remainder of the system and continues to operate, a condition that is not desirable. Therefore, a DG interfaced with the utility system must be equipped with an anti-islanding scheme to ensure personnel safety and acceptable power quality. Performance of an anti-islanding scheme is usually evaluated by inspecting the corresponding Non Detection Zone (NDZ). It has been reported in past studies that DG's control scheme has an impact on the NDZ. This paper studies the impact of control structure on NDZ is studied in a grid-connected PV system equipped with a feed-forward control scheme.