The system approach to placement of transformer substations in the UPSS is developed. The mathematical and geometrical modeling of TS service areas in view of correct hexagons is made. The practical calculating of dependences of service areas and radiuses from load density for 110/10 kV transformer substations is made. The model-templates to placement TS of any voltages in the city territory are developed and theoretical expressions for calculations of geometrical sizes are received. The calculation program Microsoft EXCEL and the graphic computer program AutoCAD are offered to automate the process of arranging the service area at Masterplan on the city. The developed method makes it possible to get a rational decision on the development of energy supply circuits of the city in the early stages of the design under conditions of incomplete and uncertain information.