1. A method for analyzing quality of electrical energy in a three-phase electric power system to determine absence or presence of disturbance in the three-phase electric power system, the method comprising: measuring a set of electrical quantities, the set including one electrical quantity per phase; generating, by processing circuitry of an analyzing device, a space vector, which is a time-dependent complex number, from an instantaneous three-dimensional transformation of the set of measured electrical quantities, the space vector being generated over a sliding window; and determining, by the processing circuitry, according to the generated space vector, a set including at least one parameter representative of the quality of the electrical energy in the three-phase electric power system to determine the absence or the presence of disturbance in the three-phase electric power system, the at least one parameter including a parameter representative of voltage flicker.