IEEE PES T&D Conference & Exposition 2022 - 101

or kVA component proportional to a processed feeder current
measurement may be added to the total mitigation command
to further enhance the mitigation.
Minimizing Steady State Reactive Power
Output for Voltage Control
ANSI standards allow operation of the distribution system
at +/−5% of the rated voltage. Hence, when tight control of
voltage by the power quality compensator is not necessary,
overall system efficiency may be improved by utilizing a
large dead-band and using the compensator's capability to
operate exactly at the edge of the dead-band. This operating
point would be close to where the rest of the power system is,
thereby minimizing the amount of current draw and losses.
The compensator can be set up so that AVR action increases
steeply as the system voltage leaves the dead-band and gets
further away. When flicker control is enabled, the steady-state
voltage operation is moved into the dead-band to allow voltage
fluctuations on both sides.
Validation Process of the Power
Quality Compensator
Before installing the power quality compensator in the field,
each control mode goes through extensive simulation and
laboratory testing. The following highlights the process of
validating the flicker mitigation control mode using only
voltage feedback before field testing.
Simulation Setup
Control modes design and simulation were performed using
traditional computer control simulation programs and hardware-in-the-loop
(HIL) simulation techniques to minimize
design time and full power validation in a test lab. The HIL
system used to validate the compensator's control aspects is
shown in Figure 3.
The simulation system is a Typhoon HIL 604 (middle
unit in Figure 3), which compiles a designed grid configuration
into an array of field-programmable gate arrays and
will emulate the feedback of measurement devices typically
connected to the compensator's application controller.
The bottom unit consists of the controllers and hardware
interconnections for the compensator converters, with two
converters housed in this unit. The application controller,
shown on the top, therefore sees no difference between a
lab or field installation and the emulated grid and converter
feedback. Development engineers can then use the system
the same way it will be deployed in the field. This allows
for responses and control actions to be quickly developed
and fine-tuned for real-world application. Using the HIL
emulation system, development engineers can operate the
compensator controller using the system's human-machine
interface and operation screens to diagnose and fix operational
issues much earlier in the development plan than in
the laboratory or field. This approach also allows the engineers
to perform these tests safely.
April 2022 Show Issue
Flicker Mitigation Simulation Validation
To validate the compensator's flicker mitigation control
algorithm, multiple test cases were run in the HIL system. In
each test case, a baseline fluctuation waveform was injected
into the system, then the flicker mitigation was enabled, and
the voltage was compared to the baseline. An example of the
baseline fluctuation superimposed on a 60Hz voltage waveform
is shown in Figure 4.
This shows the top envelope of a 60Hz voltage waveform
experiencing a cyclic voltage fluctuation at a frequency of
2Hz. The zoomed-in portion in red shows the voltage fluctuation
amplitude at the top envelope of the sinusoid. A heavy
momentary load, such as an arc welder, can cause this type
of operation on a distribution grid where the valleys correspond
to a moment of high current draw.
An example of a test case with the comparison of the
baseline and the power quality compensator with flicker
enabled is shown in Figure 5.
The baseline case in this test is the same as shown in
Figure 4, modified to only show the total voltage magnitude,
which shows a voltage amplitude swing of approximately
3.5% (0.0035pu) at 2Hz. It is shown as the blue signal in the
top subplot of Figure 5. This signal was then run through
a MATLAB Simulink IEC 61000-4-15 flicker meter
to
achieve the instantaneous flicker perceptibility factor in blue
in the bottom subplot of Figure 4. When this instantaneous
flicker waveform was extended to 10m, and the MATLAB
figure 3. Hardware-in-the-loop testing rack.
ieee power & energy magazine
101
IEEE PES T&D Conference & Exposition 2022

Table of Contents for the Digital Edition of IEEE PES T&D Conference & Exposition 2022
