Impact of distributed generation on distribution protection and power quality

The impact of distributed generation (DG) on voltage sags in a distribution network depends on the design of the protection system and the coordination between the different protective devices. DG changes the radial nature of distribution systems and affects the performance of the protection system. This paper summarizes the impact of conventional synchronous machine-based DG on the present protection practices for distribution systems, analyzes the effect of small generation units on voltage sags, and discusses the different alternatives for distribution and DG intertie protection design.