*2.3. Electricity Network Model*

The electricity network model is based on a typical network supply to a town and its surrounding areas. The model consists of a primary substation, MV feeders, MV to LV distribution substation and other associated equipment. The primary substation is outdoor and air insulated which steps down the voltage from 38 kV to 10.47 kV and is equipped with two units of 5 Mega Volt Amp (MVA) transformers, the on-load tap changers of the 5 MVA transformers automatically regulates and controls the target voltage of 10.7 kV. The stepped down voltage (10.47 kV) is distributed from substation to the 10.47 kV to 0.400 kV substation via feeder circuits [32] Figure 1.

**Figure 1.** Primary substation single line diagram [32].

The feeder circuit C15 from the primary substation has a total circuit length of 40 km with a mix of overhead lines and underground cables. The project is assumed to be located to the south of the primary substation and main town centre [32] Figure 2.

**Figure 2.** Feeder circuit C15 and location of the project [32].

The transition of the feeder circuit C15 from overhead line to underground cable takes place 5.9 km from the primary substation via spur connection and the underground cable is connected to distribution substation which is located at the edge of the existing project housing estate, where voltage is further stepped down from 10.47 kV to 0.400 kV using a 630 kVA transformer. The LV (0.400 kV) is further distributed using six LV underground cables to 11 street pillars. Over the entire network model, the number of units connected to each phase were balanced with 22 units connected to phase-1, 23 units connected to phase-2 and 23 units connected to phase-3 [32]. At all the 11 load points the solar PV system were connected by each unit.
