As a consequence of the increasing contingent of distributed energy resources (DER) in low and medium voltage networks the complexity concerning control, network protection and operation grows significantly. Excessive growth of distributed generation (DG) disturbs the radial structure and changes the fault current flowing in different branches. These changes disturb the existing protection plant and lead to miss coordination between protection devices.

In order to avoid unwanted operation and failure of protection systems, this dissertation will focus on the development of advanced distribution network protection systems. It will define flexible schemes for distribution network protection and grid interconnection protection of DG units. These new protection schemes should include capacity of dealing with fault-ride-through of installed DG units without loss of selectivity in the detection of faults in the local grid. This feature is especially important when dealing with large scale integration of DG in order not to affect the operation of the overall distribution system. Furthermore, in order to ensure a successful operation of the different protection relays, some pre-defined settings may need to be changed taking into account operating conditions such as the topology configuration of the network and the output of the DG units at that given instant. In this case, the possibility of commuting between different sets of parameters must be deployed.