Evaluation Engineering - 25

POWER SUPPLIES/LOADS

TEST SOLUTION TARGETS V2G
by Takemi Iguchi
	 In recent years, problems that affect
the stable operation of grids, such as
voltage fluctuations and the generation
of surplus power from solar and other
renewable-energy power sources, have
become prominent. In order to stabilize
the grid, it is necessary to adjust the
power generation.
V2G (vehicle to grid) technology provides a way to adjust the grid to suppress
fluctuations by utilizing EV batteries.
Also, peak power can be shifted by storing
surplus power and supplying it when demand reaches its peak. V2G is expected to
be one of the technologies that can solve
the problems of renewable-energy power
generation.
By using V2G technology to control
charging/discharging of multiple EVs,
V2G can be used as a resource for a VPP
(Virtual Power Plant). Because a VPP
can balance power and demand without
establishing large-scale power-plant infrastructure, its use has been studied in
several countries, and empirical and commercialization studies are underway. As
renewable-energy power generation, including solar power generation, increases,
VPP construction using V2G is expected
to expand in the future.
This article describes a test solution
for V2G.
With V2G, power is supplied from
the vehicle to the power grid. The power
output from the vehicle is controlled
on the grid side and is expected to be
used for the frequency adjustment
and demand adjustment of the power
system. Figure 1 shows the simulation
of the power grid for onboard charger
evaluation.
Since a general switching-type AC
power supply cannot sink current, a resistive load device for discharging has
traditionally been required to verify the
operation during regeneration. The use a
grid simulator capable of 4-quadrant operation eliminates the need for discharge
resistors. In addition, because energy is
not consumed as heat by the resistors but

Figure 1. Power-grid simulation
for onboard-charger evaluation.

instead is regenerated to the grid, power
consumption can be reduced.
A programmable power supply able
to serve as a grid simulator (such as the
one shown in Figure 2) can provide full
4-quadrant operation with regeneration
of up to 100% of the output power. The
voltage, phase angle, waveform, and impedance can be changed for each phase.
It offers power-line disturbance simulation (voltage dips, short interruptions,
and voltage variations) and supports
testing in accordance with IEC610004-11.1 It offers arbitrary and harmonic
waveform generation and features an
isolated analog programmable interface
with each phase. It is also easily used in
a hardware-in-the-loop (HIL) system.
Bidirectional-type onboard chargers
require functional testing of tripping
requirements and ride-through requirements in accordance with IEEE
1547-2018.2 They are designed
to meet all bulk system

needs and power-system reliability and
power-distribution-system reliability
needs. By using a grid simulator, it is possible to easily create an environment for
performing the required tests.

Figure 2. PCR-WE/
WE2 Series AC/DC
programmable power
supplies.

DECEMBER 2019 EVALUATIONENGINEERING.COM

25
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