Power Quality Studies in the Presence of DG

Utility restructuring, technology evolution, and an expanding electricity market are providing the impetus for distributed generation to become an important energy option in the new millennium. Islanding occurs when a portion of the utility system that contains both load and distributed resources remains energized while isolated from the remainder of the utility system. Based on the operating conditions and several other criteria, islanding can cause both positive and negative impacts. Islanding increases the likelihood that DG sources may be allowed to subject the island to out of range voltage and frequency conditions during its existence. So, it is necessary to effectively study the islanding operation in view of various aspects. Hence, this paper is concerned with power quality issues such as harmonic analysis and voltage sags for the operation of distributed generation systems (DGs) in the stand-alone mode of operation. Simulations have been carried on the IEEE 13-bus system using the PSCAD/EMTDC software in time domain using two different types of DGs in both the grid-connected and the stand-alone modes