Realization of Current Protection in Distribution Network with Distributed Generation

The traditional distribution network is usually a passive and radial network. The current protections are planned, designed and set according to the radial network. With the connection of distributed generations (DGs), the former radial distribution network becomes a linking network where sources and loads are spread all over. The power flowing and short-circuit current in the network will be changed by the fundamental changes of the distribution network When there is a short-circuit fault occurred in the network with DG, it may cause the current protections failure to operate or misoperate. Meanwhile, it may cause the neighboring current protections loss coordination and selectivity which will extent the fault range. Considering the existed protection devices in the present network, large changes can´t be made for the newly added DGs. A new realization of current protection is provided in this paper. Regulating the settings and adding fewest devices are based on unchanged protection range and sensitivity according to the location and capacity of DG.