A Review of Islanding Detection Methods for Biogas-Based Distributed Generation Systems

Due to the characteristics of combining energy generation with waste management, the use of distributed generation (DG) systems, based on biogas, has received special attention among renewable resources. On the other hand, the DG connection brings up the possibility of an equipment to keep feeding a part of the distribution grid comprising DG and local load in a condition known as unwanted islanding. Regarding this, along the years, concerns have been reported related to the safety of utilities staff, power quality issues, reclosers misoperation and DG damage risk. To prevent it, in Brazil, the utilities provide standards stating that, in case of unwanted islanding, the DG must be disconnected from the utility grid. Once the biogas based generation is usually performed applying synchronous machines as DG, its ability to keep running in islanding conditions poses special challenges to this task. In this chapter, a review over the techniques applied for islanding detection with synchronous machines is done, as well as an analysis of the Brazilian standards requirements. The working principle and setup procedure of the mandatory methods are evaluated, pointing up, new challenges over islanding detection with synchronous machines.