This paper describes a synthetic (because it homologues and superpose various phenomena) and systemic (oriented to system's performance) model for power quality (PQ) assessment. The model proposes an n dimensional electromagnetic "incompatibility" (EMiC) vector, where each vector's component evaluates a PQ phenomena that's independent from the others (in order to assure orthogonality between them) and must be conveniently normalized. By the use of computer simulation is shown that voltage fluctuation's quantification, using IEC's methodology (IEC 61000 standards), and harmonics quantification, using IEEE 519 std., are orthogonal components. The same method is used to show that the magnitude of the vector is proportional to energy supplied outside tolerable operational margins for equipment connected in the evaluation point's vicinity. This methodology offers to electric chain actors (utilities, system operator, consumers and regulator) a tool for assessment capable of establish the quantity of "bad" supplied energy