Distributed Generation: impact on Protections and Power Quality

The present energy crisis drives to carry to an extreme the use of all the available energy sources, which need to be connected in their closest point. Traditional electric systems are changing their characteristics. Power quality is one of the aspects modified by the presence of distributed generation (DG), specially respect to harmonics, flicker, voltage sags and overvoltages. The new protection problems of the different parts of the system are explained. The contribution of generators to short circuit currents is analyzed. Philosophy changes are studied, such as: fault current bi-directionality, modification of the protection reach, failures of the overcurrent coordination, etc. It is analyzed the impact of the "islanding operation". It is concluded that DG application offers technical-economic advantages so much to the utility as to the user.