Allowable DG penetration level considering harmonic distortions

The interconnection of distributed generation (DG) requires careful study with respect to selecting both the best DG location and the size of the DG unit. The DG installation at the distribution level injects harmonics, and thus may lead to significant power quality problems. In this paper, the impact of DG penetration level and DG location is evaluated by considering the power quality limits of IEEE Standard 519-1992. The nonlinear optimization problem is formulated with size of DG being a positive real number to be optimized and solved using particle swarm optimization. The optimization algorithm is integrated with the harmonic power flow algorithm to calculate the values of the system operating point and harmonic components. The formulated approach is tested on an IEEE 18-bus radial distribution system and the results show that the consideration of harmonics during DG interconnection studies is essential to avoid associated power quality problems.