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

Chapter 6. Hardware Implementation
The ultimate validation of the control capabilities is a successful series of tests carried on a
hardware level. Steady state and dynamic analysis can give many insights on the performance of
the control, but it is only after realizing a scaled down version of a microgrid that it is possible to
assess the actual quality of the design.
The details of the hardware setup that implements the proof-of-concept for the microgrid will be
given in this chapter.
6.1 Basic System
A scaled down version of a microgrid has been reproduced in the lab to test microsource
operation and control. This system incorporates the typical components that can be found in a
local load center: there is one transformer that connects to the utility system and a radial network
with feeders that delivers the electric power to all the loads. Figure 6.1 shows the network
configuration. The point of delivery of power from the main grid is at 480 V, while inside the
system all the loads and the feeders are operating at 208 V. The microsources generate power at
the voltage level of 480 V appropriately lowered to the network voltage by a separate
transformer. On the inverter side of the transformer there is a low pass LC filter to smooth out
the voltage waveform. In series to the filter there is an inductance to allow for power transfers.
There are two load centers located near the two microsources and another load electrically
installed between the two units: this allows to test the power sharing during operation in island
mode.
Utility System
208 V
Static Switch
4 wire Cable,
75 yd
4 wire Cable,
25 yd
4 wire
Cable
Load
Load
480 V
Load
MS 1
MS 2
Figure 6.1 Single Phase Test System Diagram.
The three phase passive loads are connected at star and are purely resistive, while the cables
consisting of four conductors, three phases and a neutral, that run in parallel from a bus to the
next, representing the feeder.
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