IEEE Electrification Magazine - March 2020 - 57

2017, before commissioning of the site. Meanwhile, performance tests were conducted to demonstrate the system
performance with multiple DER combinations: 1) system
black start, 2) voltage and frequency performance (30-min
load profile), 3) dynamic system response, 4) synchronization to existing voltage source, 5) utility transition mode, 6)
grid simulator transition mode, 7) power-flow control, 8)
unbalanced load, and 9) power quality. The performance
tests conducted in early 2017, leading to various insightful
results; hence, some voltage, frequency, and mode-transition tests under performance tests are presented.
The performance tests were designed to ensure that
the controllers and EMS were operating as designed and
were able to control assets under various configurations
and scenarios. These tests facilitate evaluations of the integration of multiple assets for various load profiles and
renewable sources. Sixteen voltage and frequency performance tests were identified and designed. The voltage and
frequency ride-through settings based on IEEE Standard
1547.4 were applied to the main relay at the PCC. Since
there are ongoing efforts to develop testing procedures for
microgrid controls, the performance test results should
help in the development of industry standards. In this article, the results of three voltage and frequency performance
tests and one mode-transition case are presented.

project Phase I in Northern Ontario with roof-top solar PV
systems in an isolated microgrid (Arriaga et al. 2017).
In this case, since the renewable penetration level is
relatively low compared to the load, ES is not required. The
diesel generator, load bank, PV simulator, and PV inverters
were connected to the microgrid bus. The PV system was
in MPPT control mode, and the diesel generator was in
isochronous mode. Figure 5 depicts the active power of
the diesel generator, PV system, and load as well as the
system voltage and frequency over a 30-min period. The
diesel generator is the only grid-forming asset in this case.
Since there are no large step changes in the load and PV,
the diesel generator can regulate the frequency and voltage within the allowable range. If there is a large step
change in the load, it can lead to system instability due to
the low inertia of the system.

High Renewable Penetration
In Test B, the diesel generator, load bank, PV simulator,
wind simulator, and BESS were connected to the
microgrid bus. The PV system was in MPPT mode, the
diesel generator was in isochronous mode, the wind
simulator was in PQ mode, and the BESS was in droop
mode. The EMS in isolated mode was enabled to coordinate the DERs and BESS, achieving high renewable energy penetration while maintaining system stability.
The objective of the test was to demonstrate the performance of the control system in the high renewable energy penetration levels.
Figure 6 shows the P of the diesel generator, PV, wind,
BESS, and load as well as the system voltage and frequency over a 30-min period. The load profile included
three short-term and long-term step changes to assess
the control system performance. The first step change is

Low Renewable Penetration
Test A was designed for the operation of a microgrid in
islanded mode with low PV penetration levels. The objective of this test was to evaluate the voltage and frequency performance with low PV level and load step changes. This test
enables assessments to be made of the typical deployment
of renewables in remote communities with low renewable
energy penetration, as in the case of the Fort Severn

Genset
PV
BESS

-50

Frequency (Hz)

-100

Load
Load

P (kW)

78
76
74

200 400 600 800 1,000 1,200 1,400 1,600 1,800
Time (s)
(a)

60.2

604

60.1

602

Voltage (V)

P (kW)

60
59.9
59.8

200 400 600 800 1,000 1,200 1,400 1,600 1,800
Time (s)
(b)

600
598
596

200 400 600 800 1,000 1,200 1,400 1,600 1,800
Time (s)
(c)

200 400 600 800 1,000 1,200 1,400 1,600 1,800
Time (s)
(d)

Figure 5. The Test A results. The (a) active power of the diesel generator and PV system, (b) load, (c) frequency, and (d) voltage over a 30-min
period. Genset: diesel generator system.

IEEE Elec trific ation Magazine / MARCH 2 0 2 0

IEEE Electrification Magazine - March 2020

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