The design of secure and reliable microgrids (MGs)
increasingly relies on the extensive deployment of power
electronic converter–based technologies. As these
converters introduce harmonic distortion, accurate harmonic
assessment is essential to ensure compliance with
power‑quality standards in future MGs. This paper advances
previous work by extending a nonlinear programming
(NLP)–based decoupled harmonic load flow (DHLF) method for
accurate harmonic analysis in MG environments. The proposed
approach eliminates the need for explicit inversion of
harmonic admittance matrices while maintaining high
computational accuracy. Its performance is evaluated on the
Enhanced IEEE 33‑bus test system under varying nonlinear
loads and time‑dependent DER outputs. Comparative analysis
with the DHLF implementation in DIgSILENT demonstrates
strong accuracy and improved numerical efficiency.

Under harsh transient situations, contemporary protection
relays necessitate the accurate and swift estimation of
phasors. The prior CCHDF filter was limited by DFT
techniques and utilized the Biunivocal Frequency
Relationship of Phasors (BFRP). The Modified Covariance
Method (MCM) is a sophisticated autoregressive spectral
estimator offered as a substitute for spectral estimation
in this study. This method improves the estimation of
frequency, magnitude, and phase in challenging conditions.
The initial algorithm's structure is preserved by the
resulting MC-CCHDF (Modified Covariance CCHDF) filter,
which provides enhanced accuracy and a faster convergence
rate with harmonics and noise that are closely spaced.

This paper presents the design of the grounding system for
a transition tower connecting two overhead transmission
lines (OHLs) and two underground cable lines (UCLs). The
tower is in an urban area, and space constraints
significantly constrain the layout of the grounding system.
At the same time, the strict safety requirements must be
satisfied. Ground potential rise (GPR), as well as touch
and step voltages, are calculated, and their surface
distributions around the tower are analyzed. Calculations
are performed using the single-phase short-circuit current
reduction factor for OHLs and UCLs. The grounding system of
the transition tower is dimensioned in accordance with IEEE
Std. 80 to ensure compliance with the prescribed safety
criteria.

Silicon solar cells are subject to degradation over time
due to imperfections formed in the crystal structure by
high-energy photon interactions. These imperfections lead
to macroscopic aging effects such as reduced efficiency,
open-circuit voltage, and short-circuit current. Since
real-time aging tests are impractical due to time and cost
constraints, as well as rapid technological advancements,
this paper proposes an accelerated aging method based on
artificial degradation using high-energy electromagnetic
(gamma) and particle (neutron) radiation. Key cell
parameters, including series resistance, open-circuit
voltage, short-circuit current, and efficiency, were
monitored and compared to known real-time aging data. To
analyze performance degradation over the time, pairs time -
current density at the maximum power point, are formed
based on the data collected through experiments. The
results enabled the definition of conditions for
correlating accelerated tests with actual long-term aging,
offering a valuable tool for reliability assessment and
design optimization of photovoltaic technologies.

The increasing penetration of electric vehicles (EVs)
poses new challenges for distribution and low voltage
networks,
particularly regarding power quality. This paper presents a
comprehensive analysis of the impact of EV charging on
distribution and low voltage system performance, focusing
on a 50
kW DC fast charger. Real-world measurements were conducted,
and a detailed simulation model of the charger was developed
in Simulink to evaluate the effects of EV charging on
voltage
stability, harmonic distortion, and overall power quality in
low- and medium-voltage networks. The research within this
paper was conducted for the purpose of future development of
optimization models for the analyzed field. This paper
highlights
the significant influence of power electronic converters
used in
EV chargers and emphasizes the need for strategic planning
and
mitigation techniques to ensure reliable and high-quality
power
supply during large-scale EV integration.

The paper presents a design of a modular device
for power control of smart agricultural systems, with
special
attention to the issue of power stabilization for
agricultural
devices (sprayers, pumps and sensors). The designed modular
hybrid device is intended for power management in smart
agriculture systems. The key problems that the paper solves
are unstable power supply due to poor access to the electric
grid in rural areas; Volatilities in power provided by solar
panels due to meteorological factors; Potential
implementation
of a hybrid power supply that combines electric grid and
solar energy power sources with optimization and better
energy
efficiency. The system serves not only for power supply, but
also for smart management of fertilization and irrigation,
which
potentially achieves energy autonomy and increases the
efficiency
of agricultural production. The paper complements existing
contemporary literature by focusing on infrastructural
specifics
and offers a practical engineering response to the
challenges of
smart agriculture in the area of power and digitalization.

This paper presents an active power decoupling
(APD) method for single-phase photovoltaic (PV)
transformerless
converters utilizing a front-end multilevel flying
capacitor (FCML)
converter. While conventional APD techniques often rely on
less
efficient auxiliary circuits, the implemented multilevel
topology
inherently improves overall system efficiency. The
multivariable
control strategy is systematically designed by first
deriving a
dynamic Thevenin equivalent model of the PV panel at the
Maximum Power Point (MPP) across varying solar irradiances
to
define parameters across the operating range. The control
plant
model is then established via Small-Signal Analysis,
alongside a
dynamic flying capacitor voltage reference, derived from
energy
balance equations. A limitation of conventional approaches
is
addressed where standard PI controllers fail to maintain
wide
range stability and ensure error-free tracking of
sinusoidal voltage
references. Consequently, an upgraded control scheme is
introduced using a proportional-resonant (PR) controller
for the
voltage loop and employing a lead compensator for the
current
loop, complete with a dedicated parameter tuning
methodology.
The output stage inverter control is also outlined to
ensure stable
grid connection and robust common DC link disturbance
handling.
Simulations in MATLAB/Simulink validate the proposed
algorithm’s stability and dynamic response throughout the
defined
PV operating range. Finally, an analytical figure of merit
demonstrates that the proposed control implementation
achieves a
reduction in passive component volume compared to
conventional
strategies without APD.