Only the future load of supply area is ascertained that the strategic variables including the substation location and capacity electric lines " route and style switchers " setting up and time when to bring into service can be forecasted 只有确定了配电网供电区域内各小区的未来负荷,才能对变电站的位置、容量,线路的路径、型号,开关设备的装设及其投入时间等决策变量进行规划。