In an approach for detecting islanding effect in a power electrical network topology, a computer processor finds, in the power electrical network topology, a point of common coupling between a load and a distributed generation with potential islanding effect as well as a substation supplying power to said point of common coupling; collects operating parameters of the power grid in vicinity of said point of common coupling as well as in vicinity of said substation; determines whether islanding effect exists in said distributed generation and the load in accordance with a variation characteristic of the operating parameters of the power grid in vicinity of said point of common coupling and the operating parameters of the power grid in vicinity of said substation. Higher degree of accuracy and sensitivity of detecting islanding effect is achieved without compromising the energy quality on user side according to embodiments of the present invention.