Siting and Sizing of DG Unit to Minimize Loss in Distribution Network in the Presence of DG Generated Harmonics

This paper deals with the problem of optimal siting and sizing of a Distributed Generation (DG) unit in the distribution system in presence of DG-generated harmonics. Minimization of power loss in distribution network is often considered as the most desirable criteria for optimizing the location and size of DG. However, power electronic inverter based DG units inject harmonic currents into the network which in turn, distorts the bus voltages. IEEE Std. 519 has set a permissible limit of 5% on the maximum allowable voltage distortion. The maximum harmonic distortion in bus voltages in a network increases with increase in the size of DG and thus imposes restriction on the DG size at any given bus. Such restriction puts a limit on the amount of reduction in power loss that could have been achievable otherwise. Proper attention should be paid during optimal planning for DG size and location so that the targeted benefit can be maximized within the allowable limit of maximum voltage distortion. In this study, Particle Swarm Optimization (PSO)technique is applied to determine the optimal size of DG at any given bus that maximizes the reduction in power loss within the allowable limit of maximum harmonic distortions in bus voltages. Application of the proposed method on IEEE-33 bus system has been demonstrated by simulation results.