The crisis of traditional fuels in the world has become the main reason behind the search on renewable energy resources. Therefore, the researchers become interested with distributed generation (DG) and how to connect them with the main power network to achieve the maximum benefit from these resources. But before connecting these resources with the main grid on the low voltage level, worst case scenario that could occurs must be analyzed first. This paper introduces a procedure to study the effect of the DG units on distribution systems during the short circuit. This effect is measured in terms of fault current and voltage total harmonic distortion. The main objective of this paper is to determine the maximum DG penetration that can be adopted in distribution system without degrading the system performance or change the protection design or coordination. The European technical standard and IEEE-1547 standard are used to compare the results obtained.
General purpose Alternative Transients Program (ATP) version of Electromagnetic Transient Program (EMTP) is used to accomplish the above goals. IEEE 13 node test feeder distribution system is used in this work.