Feeder K1

Description

Fig. 1. Feeder K1 feeder map showing existing 1 MW PV System

The second feeder (K1), located in the southeastern US, was selected because a 1 MW customer-owned PV system is serviced by the feeder. In addition, EPRI had a working relationship with both the local utility as well as the PV site owner, thus giving EPRI access to the PV site for monitor installation.

This particular 13-kV feeder supplies energy to approximately 500 commercial and residential class customers. Total peak load on the feeder is approximately 6 MW, supplied via 28 total circuit miles of primary line. Voltage regulation along the feeder is provided via the substation load tap changer (LTC), as well as a single capacitor bank located approximately mid-feeder. This circuit does not contain any feeder regulators.

As shown in Fig. 1, the purple lines represent the feeder (solid lines are 3-phase; dotted lines are single phase). The substation is located in the southwest corner of the feeder (noted by the green triangle). The feeder extends about 2.7 miles east and 2.5 miles north of the substation, representing a 6.8 mi2 geographic area.

The 1-MW customer-owned PV system is located 2 circuit miles northeast of the substation. EPRI is currently monitoring the 1-MW PV system and a single-module reference unit onsite.

Sample Results

Fig. 2 shows the feeder voltage profile without the 1-MW PV system as a function of distance from the substation. Each color represents a separate phase, while the solid lines represent primary voltages and the hashed lines represent secondary voltages. As expected, due to customer load along the feeder, the voltage is reduced as the distance from the substation increases (x-axis is distance from the distribution substation). Without feeder regulators, the end-line voltages remain well above the acceptable threshold of 0.95 pu (note that the ANSI C84.1 acceptable range of 0.95 - 1.05 pu is shown as red horizontal lines). After applying the “voltage change” test with the existing 1-MW PV system, feeder voltages remain within the ANSI limits.

Fig. 2. Feeder Voltage Profile without PV (Solid: Primary, Hashed: Secondary)