Challenges and solutions for MV and LV protection in grids with large amount of distributed generation – a final report from the German research project ProFuDis

Abstract

The ongoing installation of distributed generation (DG) in low- (LV) and medium-voltage (MV) grids might be prospectively limited by restrictions of today's protection systems due to the DG's impact onto the system's fault behaviour. Investigations show that today's DG shares do not yet lead to protection malfunctions. A reasonable future increase of the share of DG and the increasing complexity of the grids will partially pose protection-challenges in the near future though. Therefore, detailed protection planning becomes increasingly important in the future, using enhanced calculation, modelling and evaluation approaches, as developed within the project Protection for Future Distribution Systems (ProFuDiS). While the future protection-challenges in German MV grids can widely be solved using altered parametrisation and application of the present digital protection devices, the usage of classical NH fuses for LV grid protection will be possible for most, but not all grids any more. While sufficient, but rather complex digital protection approaches are already available, the development of innovative, more cost-efficient solutions for LV protection should be carried on. Additionally more precise regulations for the fault behaviour of DG should be stated to allow effective protection planning and reliable and realistic fault simulation.