Control and Design of Microgrid Components - Power Systems ...

Utility
System
480 V
Z1
T1
Static Switch
208 V
Z2
Z3
Z4
T2
T3
480 V
480 V
L1 L2
L3 L4
L5
MS
1
MS
2
Figure 6.3 Single Phase Laboratory Circuit Diagram.
Each microsource is connected to the feeder by a series of low pass LC filter, an inductor and a
transformer. The 208V low side of the transformer is connected at wye with the neutral cable
connected the fourth wire inside the system. The 480V high side of this transformer is on the
microsource side where there is a 3 wire system. The supply voltage from the utility is also at
480V, while the rest of the microgrid operates at 208V.
Every component of the network is described in detail in the following paragraphs.
6.2.1 Transformers
This section describes the transformers used in the systems. The transformer that is used to
connect with the utility system has larger ratings than the transformer used to interface with the
microsource. The two microsources are twin systems, therefore their transformers will be
identical.
Transformer T1
Nameplate Data:
75 KVA, 480/208
Δ/Y with neutral connected to the 4 th wire, but not grounded
5% Impedance, X/R = 1
74