Optimal siting and sizing of DG units for a MV network going through voltage transition

Integration of distributed generation (DG) units in Croatia started in 2007 when a package of subordinate legislation promoting the use of renewable energy was issued. Since then planners of the Croatian Distribution System Operator (DSO) have faced numerous challenges and problems in planning and operation of distribution networks. In recent years, due to the massive inrush of DG units on random locations with random output power, it became very interesting to observe how their location and size affects the reduction of distribution network (DN) losses. In this paper the DG allocation problem is demonstrated for the case of simultaneous connection of different types of DG units on a medium voltage (MV) feeder undertaking voltage transition from 10 to 20 kV. The financial savings which derive from the reduction of power losses are calculated for a future planning period, and the load growth is also taken into consideration.