In this work is described the way in which a virtual laboratory was developed to simulate the individual and combined effect of a great variety of Power Quality phenomena, implementing in same the algorithms to evaluate the impact of these phenomena in a user, from the levels of Electromagnetic Compatibility (EMC) defined internationally. The laboratory was developed under the software PSCAD -Power System Computer Aided Design-. The implemented algorithms allow to establish the indicators Total Harmonic Distortion (THD), that measures the effect of the nonlinear loads, and the indicator Short Term P erceptibility (P ST ) that measures the severity of the voltage fluctuations due loads and phenomena where it varies the power demand. As fluctuating loads the simulation includes faults, large induction motors and capacitors bank switching. In order to cause distortions of the waveform, rectifying bridges for loads in DC were modeled. With this tool it’s possible to generated multiplicity of cases in which the topology of the network can be arbitrarily modified, and the severity of the generated phenomena can be user defined and inclusively appear of a random way in the time. Finally an analysis of the results obtained when the evaluation models previously mentioned were put under on approval.