Global research uses nano- and microparticles to produce innovative insulation for winding insulation, electromobility, anticorona paint, transformer insulation, and bushings. Scientific, multifunctional research on materials provided the engineering data required to design manufacturable insulation. This article overviews the holistic approach needed to successfully develop insulation materials by examining specific insulation systems from recent research.

ABSTRACT This investigation addresses the effect of particulate additives on the electrical breakdown strength of the oil impregnated insulation paper system. The morphological complexity is addressed by converting data from scanning electron microscope images to a data set suitable for numerical simulation analysis. Then, by using the conventional oil‐triggered breakdown assumption, the breakdown strength of the proposed hybrid insulation system was calculated. As a result, it demonstrates that the introduction of particles can redefine the electric field distribution in the hybrid insulation system under study. Consequently, a higher applied voltage is needed for the electrical breakdown to occur in the hybrid system with proper selection and addition of particles. This analysis method builds on the existing understanding of the electrical breakdown phenomena for oil impregnated insulation paper system, explains recent experimental data and supports improvements of material design in the future.

Recent research shows that a five-time enhancement in through-plane thermal conductivity of the oil-paper insulation in transformers can double their life by decreasing hotspot temperatures. This can be achieved by developing novel insulation paper with improved through-plane thermal conductivity without compromising other key paper attributes such as dielectric breakdown strength, tensile strength, and thermal degradation rate. The present study broadens the design space for advanced transformer insulation paper with improved and balanced thermal, mechanical, and dielectric properties by incorporating turbostratic boron nitride (BN) particles. A simulation model based on Scanning Electron Microscopic (SEM) imaging was used to explain the dielectric breakdown strength and through-plane thermal conductivity enhancement of the proposed material. Depending on the material formulation, the proposed BN insulation paper has 2 to 3 times greater through-plane thermal conductivity, 20 %-30 % higher dielectric strength, 25 %-50 % greater tensile strength and approximately 30 % smaller relative permittivity than the commercial insulation paper with similar thermal degradation rates.

Growing energy demands and renewable integration are stressing the aging power grid infrastructure. Lignocellulosic oil-impregnated paper is widely used in power transformers but suffers from critical limitations, such as low dielectric strength, mechanical strength, and thermal conductivity, causing premature transformer failures. Here, we demonstrate a superior electrically insulating oil-impregnated paper design using the naturally anisotropic structure of densified wood veneer to achieve nanosized channels of oil that efficiently disrupt electrical breakdown pathways. The developed oil-impregnated densified wood (ODW) creates aligned cellulose fibers with 166 ± 87-nanometer oil nanochannels, achieving record dielectric strength of 105 kilovolts per millimeter. The structure also delivers a mechanical strength of up to 384 megapascals and a thermal conductivity of 0.33 watts per meter per kelvin, enabling enhanced longevity upon thermal aging tests. The ODW could replace conventional transformer insulation to enhance power transformer performance and improve lifetime. Moreover, its anisotropic oil-filled nanochannel design offers a general strategy for hybrid dielectrics in medium- and high-voltage applications.

Increasing the thermal conductivity of the oil-paper insulation system can significantly extend the thermal life of transformers by enabling effective heat removal, which reduces high temperature-induced insulation degradation. This research shows that the addition of nominally 25 mu m diameter boron nitride particles can achieve sufficient increase in through-plane thermal conductivity of insulation paper to an extent that doubles the transformer thermal life. Importantly, the dielectric breakdown strength can also be enhanced by adding boron nitride particles to the developed insulation paper. Moreover, applying lignin containing cellulose microfibrils into the paper can compensate for the paper strength loss due to the disruption of hydrogen bonding by the addition of BN particles. Building on these findings, we outlined a pathway for a boron nitride-based enhanced insulation system with outstanding through-plane thermal conductivity, enhanced dielectric strength, an appropriate dielectric constant and the needed tensile strength. Additionally, thermal aging experiments showed that the proposed material can have a reasonable thermal life under transformer operating conditions. Overall, this research shows that the mix of thermal, mechanical, and dielectric properties can be successfully tuned to achieve a beneficial insulation system which can significantly enhance the transformer life. As the summary, the proposed material has three times better through-plane thermal conductivity (0.76 W/m center dot K vs. 0.2 W/m center dot K), 23 % higher dielectric strength (84.6 kV/mm vs. 65.3 kV/mm), 35 % greater tensile strength (71.26 N center dot m/g vs. 45.91 N center dot m/g) and 33 % smaller relative permittivity (3.7 vs. 5.5) than the commercial insulation paper with similar thermal degradation rates.

This paper presents a characterization of series arc faults based on experimental results obtained from a megawatt-level dc microgrid system. Series arc faults have garnered considerable attention because they can cause fires in photovoltaic systems and are not detected or isolated by legacy protection technology. Unlike the lower-power arc faults commonly reported in the photovoltaic literature, high-power series arc faults exhibit distinct behavior. Specifically, the elevated temperatures resulting from higher current levels increase plasma conductivity. At short air gaps, this conductive plasma remains stable, behaving as a linear series impedance; however, as the air gap widens, the arc becomes increasingly unstable, becoming nonlinear due to elevated pressures and thermally driven convection. The unstable nature of high-power arcs, combined with the significant circuit inductance introduced by large conductors, strongly influences the arc's voltage and current characteristics. Furthermore, the stable plasma observed at shorter air gaps lacks the high-frequency components typically present in low-power dc arcs, rendering conventional detection methods ineffective. The proposed series arc fault model demonstrates strong agreement with the experimental results and supports the development of advanced protection schemes tailored for high-power dc microgrids

Degradation of insulation paper is a key contributor to the failure of power transformers. Insulation degradation accelerates at elevated temperatures, which highlights the potential for better thermal management to prolong life. While several studies have analyzed the benefits of high thermal conductivity oil for reducing temperatures inside a transformer, this study is an initial assessment of the benefits of high thermal conductivity paper on transformer life. Blending particulates with cellulosic fibers offers a pathway for high thermal conductivity paper (with good dielectric properties), which can reduce internal temperatures. Presently, life extensions that can be achieved by the use of such thermally conducting papers were estimated, with the thermal conductivity of the paper being the key parameter under study. The analytical-numerical thermal model used in this study was validated against experimental measurements in a distribution transformer, adding confidence to the utility of the model. This model was then used to provide estimates of hot-spot temperature reduction resulting from the use of papers with higher thermal conductivity than baseline. Transformer life was predicted conventionally by tracking the degree of polymerization of paper over time, based on an Arrhenius model. Results indicate that increasing the thermal conductivity of paper from 0.2 W/mK (baseline) to 1 W/mK reduces the hot spot temperature by 10°C. While degradation significantly depends on the moisture and oxygen content, the model shows that such a temperature reduction can increase life for all conditions, by as much as a factor of three.

This paper presents experimental findings on the behavior of series arc faults within an MW-level DC microgrid when an inverter drive with variable frequency control and protective functions powers an induction motor. The experiments show that the series arc faults quenches when the inverter drive controlled for specific functions is in the circuit. The hypothesis points to the protective feature implemented in the inverter control against detrimental transients caused by a sudden loss of the DC source. The inverter supplies power to an induction motor rated at 75 HP (55.95 kW) and 460 V. The results demonstrate a promising approach to mitigate series arc faults by leveraging conventional inverters commonly found in DC microgrids.

Future electric transportation systems are expected to employ electrical power trains with higher operating voltage and power density. Therefore, compact and reliable insulation systems are important, since they influence the system integration, thermal resistance, and parasitic inductance. In this paper, experiments and analysis show behavior which are not observed with mechanically produced holes before. A boundary element analysis of the electric field distribution around the voids reveals why these new observations are identified in voids with relatively sharp corners. The electric field computation shows conditions under which there is electric field enhancement at the void periphery. This drives the partial discharge (PD) activity and the erosion growth away from the center of the voids.

A growing hydrogen economy requires new hydrogen distribution infrastructure to link geographically distributed hubs of supply and demand. The Hydrogen Optimization with Deployment of Infrastructure (HOwDI) Model helps meet this requirement. The model is a spatially resolved optimization framework that determines location-specific hydrogen production and distribution infrastructure to cost-optimally meet a specified location-based demand. While these results are useful in understanding hydrogen infrastructure development, there is uncertainty in some costs that the model uses for inputs. Thus, the project team took the modeling effort a step further and developed a Monte Carlo methodology to help manage uncertainties. Seven scenarios were run using existing infrastructure and new demand in Texas exploring different policy and tax approaches. The inclusion of tax credits increased the percentage of runs that could deliver hydrogen at <$4/kg from 31% to 77% and decreased the average dispensed cost from $4.35/kg to $3.55/kg. However, even with tax credits there are still some runs where unabated SMR is deployed to meet new demand as the low-carbon production options are not competitive. Every scenario, except for the zero-carbon scenario (without tax credits), resulted in at least 20% of the runs meeting the $4/kg dispensed fuel cost target. This indicates that multiple pathways exist to deliver $4/kg hydrogen.

When an elevated risk is anticipated for a microgrid, such as adverse weather conditions, live line repairs, potential acts of sabotage, or public events with the crowds close to the overhead lines launching fireworks or objects into the air, there is a benefit to transitioning the system's operational strategy from the traditional ‘economical’ approach to a ‘resilient’ one. The resilient dispatch represents an operational mode that is employed selectively and temporarily in response to heightened risk conditions and is tailored to enhance the microgrid's ability to withstand and recover from failures, ensuring operational continuity. In conventional synchronous -generator-based microgrids, the P/Q dispatch of the generators is controllable and one can leverage this property to set up any required steady state condition. This research developed an approach to optimize the steady-state conditions of synchronous generator-based microgrids with the primary objective of enhancing fault tolerance. By strategically configuring the system's operating condition, the microgrid can respond more effectively and reliably to disturbances, including faults and other sudden load changes. The results of this study, using simulations and analysis, show the potential benefits of this approach. Microgrids adopting the resilient steady state exhibit enhanced stability, reduced vulnerability to faults, and increased reliability for continuous operation.

Energy storage is increasingly important for ensuring power quality and reliability, serving high power and transient loads, and load leveling. There is broad interest in exploring the use of flywheels, which offer an alternative to other forms of energy storage with inherent limitations of power or energy density and concerns with safety or material sourcing. To achieve high power and energy densities, operation at high speed and the use of composite materials is essential. However, composites present unique challenges in their design and manufacture. A suite of design tools, characterization methods, and assembly processes have been developed to produce composite structural components and flywheels that are robust and mechanically stable over a long lifetime. The design approaches developed can limit energy release in the event of an outer composite banding failure and avoid a cascading failure. Containment strategies have been successfully demonstrated.

Photovoltaic systems provide electrical power with reduced emissions at competitive costs compared to legacy systems. A low or medium voltage dc distribution system is usually used for solar integration. In dc systems, parallel and series arc faults are a safety concern. Thus, reliable and timely detection and mitigation of arc faults are critical. DC arc detection methods typically use time or frequency spectrum variations of the circuit current or voltage to differentiate the arcing event from other system events. Since practical systems include power electronics and maximum-power-point tracking, any detection scheme must perform robustly in the electrical environment that these components establish in the dc power system. A capacitor placed in parallel with the main system is an effective sensor for series arc fault detection and localization applicable in this complex electrical environment. This article shows that the analysis of the amplitude, polarity, and spectrum characteristics of the capacitor current and voltage resulting from perturbations caused by the arc provides an effective method to identify and localize faults. The detection accuracy of the proposed approach is 98.3% and the localization accuracy rate is 100% for the correctly detected faults.

Partial discharge (PD) is a phenomenon often occurring in insulation system defects (cavities), which can significantly affect life and reliability. While broad knowledge on PD phenomenology of high-frequency transformers (HFT) has been achieved under ac sinusoidal voltage, much less work has been done to infer PD behavior under emerging high frequency pulsewidth modulation (PWM) operation conditions. An impediment has been the limited appropriate test equipment. A recently developed novel ±5 kV GaN-based high-frequency PWM supply with controllable dV/dt , voltage level and frequency has been developed. This article explores the application of these measurements to the testing of materials in this electrical environment. Two commonly used windings for HFT were tested under different applied voltage magnitudes, frequencies, and slew rates. According to the test results, at high frequency (up to 50 kHz) the electric field generated by space charge deposited by PD occurring during previous PWM pulses plays an important role in PD behavior. The frequency dependent permittivity of the insulation material can also affect PD measurement results.

We are enlightened by problems to solve and ideas, which sometimes last until we understand and then switch off too soon.We try to capture entanglements of a much more complex phenomenology than the bits we can understand and make use for the advancement of science and technology.Frustration is the partner of our life, but lights and dreams make us struggle to keep the light alive.Catching fireflies is our dream and our doom.

Series arc faults are challenging to detect in low-voltage dc (LVDC) distribution systems because, unlike other fault types, series arc faults result in only small changes in the current and voltage waveforms. Though there have been several approaches proposed to detect series arc faults, each approach has its requirements and limitations. A step change in the current and voltage waveforms at the arc inception is one of the characteristic signatures of these faults that can be extracted without requiring one to sample the waveforms at a very high frequency. This characteristic feature is utilized to present a novel approach based on voltage differential protection to detect series arc faults in LVDC systems. The proposed method is demonstrated using an embedded controller and experimental data that emulate a hardware-in-the-loop (HIL) test environment. The successful detection of series arc faults on two sets of series arc fault experimental data validated the approach. The results presented also illustrate the computational feasibility in implementing the approach in a real-time environment using an embedded controller. In addition, the paper discusses the robustness of the approach to load changes and loss of time synchronization between measurements at the two terminals of the line.

This research focuses on establishing a secure data communication system among power electronic converters connected to a common voltage bus in a dc microgrid. As a proof-of-concept, a buck and two boost dc-dc converters, sharing a 24 V dc bus, have been used for simulation in Matlab® Simulink®. Digital bits are generated at 10 kbps rate at the three converters which are modulated by frequency shift-keying (FSK) algorithm using three different frequency bands with two distinct frequencies to represent bits ‘0’ and ‘1’. Active band-pass filters are used to accurately extract useful data signal from the dc voltage waveform for the three communication channels having different frequency bands. A chaotic dynamic system is adopted for each power converter to encrypt and decrypt the data stream. The encrypted data in the communication channel is secure unless the attacker can perfectly synchronize with the chaotic dynamic system, which is very unlikely. Data in various frequency bands can be simultaneously demodulated and decrypted at the receiver with very good accuracy. The simulation result suggests that the bit-error-ratio (BER) is less than 0.01% even during system transients such as load change and/or due to transition between on-off states of other power converter(s).