Beyond overcurrent protection: Distributed generation in the future grid

Protection is a crucial feature of conventional electricity grids, and relies on the well understood principle of detecting elevated currents in the event of a fault. However the future grid is likely to incorporate a significant amount of renewable and other distributed generation, which may affect operation of protection systems. As the type of devices participating in the grid becomes more diverse, the protection environment becomes more complex, and there is a need for smart protection to complement the smart grid. This study reports on practical demonstrations of some of the issues using case studies of distributed generation, both when attached to a distribution feeder and when islanded.