Reviewing of anti-islanding protection

Distributed generation (DG) has grown over the years mainly due to environmental issues. DG are many varieties and sizes. This article presents an approach to some of this techniques, pointing out their advantages and disadvantages. The arrival of these new generation sources allowed greater variety in sources of energy, however this brought problems of control, protection, operation of the electrical system, reliability and energy quality. Of these problems the unintentional islanding is the most dangerous problem in DG. An islanding occurs due to intentional or unintentional disconnection of DG network. If the utility grid is disconnected from the distribution grid (i.e. as a consequence of a short circuit) an unintentional island is formed and of great importance that the DG is disconnected from the utility grid, may cause risks to consumers and the utility. Due to its undesired effect, there are many techniques that have emerged to solve this problem. These techniques are divided into: remote techniques, are communication-based methods; and local techniques, which can be passive or active techniques.