Today worldwide distributed generation (DG) takes a very important role in the operation of distributed electric power systems. However, the existence of distributed generation may have impacts on different topics, such as fault currents, fault protection, coordination schemes or fault location. If there is short-circuit in the system, the presence of one or more distributed generators can affect the fault current levels, the monitoring of voltages and currents at the substation. The main supply generation will not have to inject as much power to the line because of the DG and, therefore, voltages and currents at the substation will be different from the ones that would be measured without DG .