Discharge Tests Research Articles

A Remote Intelligent Check and Discharge Test System for Substation Battery Pack Based on Raspberry Pi

Abstract Regular check and discharge test of the battery pack is an effective means to ensure the normal state of the battery and timely detect outdated batteries. However, conventional manual check and discharge test methods are costly, cumbersome, and inefficient in maintenance. This article introduces a remote intelligent check and discharge test system for a substation battery pack based on Raspberry Pi. The system monitors the battery status in real-time, allowing operators to detect battery faults on time through the front-end management interface. At the same time, remote check and discharge tests can be carried out, greatly ensuring battery safety and solving the shortcomings of conventional manual methods.

Research on discharge characteristics of synthetic ester-paper insulation under power frequency and low frequency

Abstract Synthetic ester insulating oil transformer has broad application prospects in offshore wind power low-frequency power transmission. This paper carried out discharge tests on synthetic ester-paper insulated used sharp plate electrodes at a power frequency of 50 Hz and a low frequency of 17 Hz based on the pulse current method. The research results show that some basic characteristics do not change under 50 Hz and 17 Hz, that is, the discharge is distributed near the voltage peak in a peak shape. The main differences are that the positive peak characteristics at 17 Hz tend to be blurred; the positive maximum discharge amount, and discharge times show an overall downward trend; the phase-resolved partial discharge pattern (PRPD) and the statistical map (n-φ, n-q) have the same overall shape, but different distribution ranges. The test results can be used as a reference for partial discharge pattern identification and insulation design in synthetic ester low-frequency transformers.

Synthesis and electrochemical properties of high entropy titanate powders (La0.2X0.2Ba0.2Sr0.2Y0.2)TiO3 (X = Na or K, Y = Ca or Pb) with perovskite structure

In this paper, four new high entropy titanate powders (La0.2X0.2Ba0.2Sr0.2Y0.2)TiO3 (X = Na or K, Y = Ca or Pb) were successfully synthesized by a sol‒gel strategy. When the pH value of the sol ranged from 3 to 4, it was easier to obtain pure high entropy powders with a perovskite structure. When the calcination temperature was in the range of 700 °C–900 °C, the high entropy powders were more beneficial to form a single solid solution with high XRD diffraction intensity and crystal quality. The as-synthesized powders with uniform distribution of A-position elements had a particle size between 50–120 nm and good dispersibility. The cyclic voltammetry (CV) and galvanostatic charge discharge (GCD) tests showed that these powders had better electrochemical properties and energy storage potential. When the discharge current was 1 A/g, the specific capacitance was higher than 136 F/g, even if the current density was 10 A/g, the specific capacity remained about 60 % of the initial.

Analysis of gap distance of ultra high voltage AC transmission lines in areas with altitude above 2000m

Abstract Research on long-wave front discharge characteristics of lines and long gaps of substation equipment in high-altitude areas needs to be conducted in a systematic manner immediately in order to guarantee the safety and economy of high-altitude UHV lines with respect to external insulation. However, at present, the gap discharge test of transmission lines is mainly carried out in areas below 2000m above sea level. The actual test is challenging to conduct in the high altitude region, and the test data is incomplete. To further confirm the validity of extrapolation of existing altitude test data to high altitude areas, this paper conducts theoretical analysis based on the real test data under standard meteorological conditions provided by GB/T 24842 standard. The altitude correction methods in IEC 60071-2: 2018 and IEC 60060-1: 2010, the m-coefficient method and g-parameter method, are used to correct the lightning impulse, power frequency, and standard switching impulse of AC transmission line gaps. The discharge voltage in areas below 5000m above 2000m is obtained, and several significant discharge characteristic parameters are obtained. Based on the 50% discharge voltage requirements of various voltage types of 1000kV transmission lines, combined with the discharge voltage curves at multiple altitudes, the minimum air gap distance of transmission lines at the altitude of 2000m-5000m is obtained. The comparative analysis of the correction results of the two methods provides a way of thinking for the next step to carry out the true test of UHV AC transmission line gap discharge in higher elevation regions.

Breakdown calculation of zoning tests by positive lightnings

To simulate a natural lightning strike, the breakdown should occur within 1–3 μs in an aircraft lightning zoning test. However, the breakdown voltage–time characteristic of the combined gap is hard to derive because of the complex breakdown process. In this paper, a series of positive lightning impulse discharge tests in a rod electrode–floating aircraft model–plate combined gap were conducted. The leader propagation processes in both sub-gaps were observed using a high-speed camera. The potential of the floating aircraft model was analyzed. We propose a potential calculation model for the floating aircraft during the leader propagation phase. After fitting test data, an empirical formula for the connected streamer plasma was given. Taking that model into account, the calculation result of the average breakdown time of the combined gap has an error of <5.7%.

Influences of the vibration frequency and phase of the core of ultra-high voltage shunt reactors on suspended discharge in oil-paper insulation

Severe vibration of the core of ultra-high voltage (UHV) shunt reactors under operating conditions often leads to the occurrence of suspension electrode, and such a suspended discharge defect will destroy the oil-paper insulation. It is necessary to investigate the influence of vibration on suspended discharge when determining the best operating condition of UHV shunt reactors. The vibration frequency of the suspension electrode and the phase difference between the applied voltage and the vibration are studied by simulation and experiment. The simulation results show that the phase difference between the voltage and the vibration parameters will lead to an increase in the surface maximum field strength. The distortion of the field intensity caused by several typical vibration frequencies of reactor vibration is ranked (in ascending order) thus: 100, 300, 50, and 200 Hz. There is a coupling relationship between the phase difference and the vibration frequency on the suspended discharge, which will lead to an inconsistency between the field intensity and each single factor. The partial discharge test results of the collision between the suspension electrode and the high-voltage electrode show that the discharge generated by vibration at 100 Hz is much higher than that at other frequencies, followed by those at 300 and 50 Hz, and the discharge generated by vibration at 200 Hz is very small. When the phase difference of voltage advance vibration is between 0° and 90°, the quantity of local discharge is large. When the phase difference is between 90° and 180°, the local discharge is small.

Research on the method of air gap clearance selection for bushing at high-altitude areas

Abstract As an important component of the core equipment of the UHV substation, the operation reliability of the bushing is directly related to the safe operation of the main equipment. There are some technical problems in the development of casing in the Sichuan-Chongqing project, such as technical problems at high altitudes and a lack of relevant experience in the correction of air gap and equipment external insulation altitude. Therefore, there is an urgent need to research the selection of gap distance for UHV AC substation bushing electrical characteristics test in high altitude areas. In this paper, based on the standard meteorological conditions and the rod-plate gap switching impulse discharge test data at an altitude of 4300 m, the minimum gap distance of UHV AC substation bushing withstanding 1800 kV and 1950 kV under different methods is obtained. The results show that by comparing the two calculation methods, the minimum distance calculation method of the true test combined with the gap coefficient method avoids the error of altitude correction, and the minimum gap distance is reduced by 7.84%-14.17% compared with the former. The research content can provide a reference for selecting the dry arc distance of the casing. The next step should be to carry out the discharge characteristic test of the true-size electrode at a high altitude, so as to simulate the field situation more realistically and provide more powerful technical support for the project.

Analysis and Treatment of a Partial Discharge Fault in a 220kV Transformer

Abstract Partial discharge test of transformer is one of the most important detection items in the factory test of transformer, which is related to whether the transformer can operate safely and stably. This article will analyze a case of partial discharge exceeding the standard in a 220kV transformer. Based on the joint detection technology of ultrasonic partial discharge and ultra high frequency partial discharge, the defect location will be found. And the structure of the transformer will be researched to identify the cause of the defect. The diagnosis and treatment will be successfully completed. Finally, the conclusion will be verified through finite element analysis. This provides reliable guidance for partial discharge detection and rectification measures in transformers’ production and operation.

Relating state-of-charge to impedance and equivalent circuit parameters in lithium-ion cells: An experimental study

The wide-band impedance of Lithium-ion (Li-ion) batteries has become a focal point for researchers interested in State-of-Charge (SOC) estimation and battery modeling. However, the interplay between SOC, wide-band impedance, and model parameters has not been extensively explored. This paper addresses this gap by investigating how SOC impacts the impedance and Equivalent Circuit Model (ECM) parameters of a Li-ion battery cell through empirical measurements. The study utilizes discharge tests to vary the SOC and employs the Coulomb Counting Method (CCM) to estimate the approximate SOC from the response signals. A novel measurement technique is introduced and applied to determine a cell’s wide-band impedance at different SOC levels. This innovative approach uses a Pseudo-random Impulse Sequence (PRIS) perturbation signal to measure wide-band cell impedance. The collected impedance data is then used to estimate the ECM parameters. Experimental findings reveal an inverse relationship between impedance and SOC. Additionally, the ECM parameters exhibit significant correlation with SOC, particularly in mid- to low-frequency regions. This research highlights that SOC profoundly influences ECM parameters, offering valuable insights into the performance of Li-ion batteries under various conditions.

Li1.4Al0.4Ge0.1Ti1.5(PO4)3: A stable solid electrolyte for Li-CO2 batteries

In this study, a solid electrolyte, Li1.4Al0.4Ge0.1Ti1.5(PO4)3 (LAGTP), with a sodium superionic conductor-type crystal structure, was prepared using a facile solution-based method. LAGTP exhibited exceptional ionic conductivity (1.05 × 10−3 S cm−1) and a low activation energy (0.237 eV). The LAGTP pellet was employed as a solid-state electrolyte in a Li-CO2 battery, showcasing charge-discharge characteristics via a reversible electrochemical reaction (4Li+ + 3CO2 ↔ 2Li2CO3 + C). As-synthesized multi-walled carbon nanotubes, drop-cast on carbon cloth, were used as the cathode. The battery underwent 60 cycles with a cut-off capacity of 1000 mAh g−1 at various current densities, and a full-depth charge and discharge test was conducted at 100 mA g−1. During the charge/discharge process, the particle size of the dead lithium increased on the cathode surface, leading to the blockage of active sites for conversion. Post-cycling analyses were performed to elucidate the cathode degradation mechanism. The incorporation of LAGTP significantly enhanced battery cycle life and safety, making it a suitable candidate for use in next-generation, high-performance Li-CO2 batteries.

Accurate Internal Monitoring of Batteries by Embedded Piezoelectric Sensors

AbstractAdvancements in operando techniques have unraveled the complexities of the Electrode Electrolyte Interface (EEI) in electrochemical energy storage devices. However, each technique has inherent limitations, often necessitating adjustments to experimental conditions, which may compromise accuracy. To address this challenge, a novel battery cell design is introduced, integrating piezoelectric sensors with electrochemical analysis for surface‐sensitive operando measurements. This innovative approach aims to overcome conventional limitations by accommodating commercial‐grade battery electrodes within a single body, alongside a piezoelectric sensor. This enables operando electrogravimetric measurements to be realized, and the electrochemistry of a battery to be more faithfully reproduced at the sensor level. A proof of concept is carried out on both Li‐ion (LiFePO4//Graphite) and Na‐ion (Na3V2(PO4)2F3//Hard carbon) systems, utilizing commercially available powder electrodes. In both cases, the results reveal rational mass variations at the sensor level during the cycling of commercial electrodes with mass loadings several orders of magnitude higher, while performing Galvanostatic Charge Discharge (GCD) tests across various C‐rates. This innovative design opens up possibilities for a broader application of operando electrogravimetry within the battery community, to enhance the understanding of EEI behavior and facilitate the development of more efficient energy storage solutions.

Size-adjustable, foldable, and stretchable capacitor with origami and auxetic structure

Stretchable and flexible capacitors offer significant advantages as energy devices for next-generation electronics. In line with the trend for the aforementioned electronic devices, scientists are exploring the development of energy devices using intrinsically stretchable materials to endow geometrical flexibility. However, these materials typically exhibit a positive Poisson’s ratio, which may not be favorable for long-term mechanical stability. In this study, a size-adjustable capacitor is presented, featuring an auxetic and origami structure designed for foldability and stretchability. The combined structural strategy of auxetic and origami allows the device to be folded and stretched without a deterioration in performance. The size of this auxetic capacitor can be modified into five different stages: 100 % and 50 % folded, original, and 50 % and 100 % stretched. To assess the stability of the device under mechanical deformations and long-term usage, multiple characterization tests were conducted, including cyclic voltammetry and charge−discharge tests, demonstrating stable performance under mechanical deformations. This promising size-adjustable capacitor can find applications in a wide range of devices, including wearables and compact electronics.

Effects of Deformation Microstructures on the Electrochemical Properties of Mg-Hg-Ga Alloy Anode

Mg-Hg-Ga alloy is one of the anode materials for seawater-activated batteries. Here, Mg-3.0 wt%Hg-3.0 wt%Ga alloys were prepared by extrusion and rolling and the microstructure of the Mg-3.0 wt%Hg-3.0 wt%Ga alloy after plastic deformation was studied. The effects of deformation microstructures on the discharge properties and corrosion behavior of the alloys were investigated by galvanostatic discharge, potentiodynamic polarization, electrochemical impedance spectra experiments, and Mg/AgCl battery test. The results show that the microstructure of the extruded alloy is uniform, and the corrosion activity and discharge activity of the extruded alloy are relatively weak. Hot rolling deformation refines the grains and promotes the precipitation of the Mg5Ga2 phase distribute more dispersively, which results in faster and more uniform activation of the alloy, thus improving the corrosion activity and discharge activity of the Mg-3.0 wt%Hg-3.0 wt%Ga alloy. The results of galvanostatic discharge in half battery and Mg/AgCl battery discharge tests show that rolling deformation improves the discharge properties of the alloy, and the alloy with 78% rolling reduction has the best discharge performance.

Factors Associated with Low Volumes of Mother's Own Milk at Neonatal Intensive Care Unit Discharge of Very Low Birth Weight Infants-a Cohort Study.

Background: Mother's own milk (MOM) provides health benefits for infants with very low birth weight (VLBW). This study aimed to describe the incidence and factors associated with low volumes of MOM (<50% of total diet volume) at discharge for VLBW infants. Methods: A prospective cohort study of infants with VLBW and gestational age of <30 weeks, who survived to discharge and had no contraindication to MOM. We conducted bivariate analyses to investigate associations with the volume of MOM at discharge, using chi-square, t, and Mann-Whitney tests. All p-value analyses were two-tailed. The variables significantly associated with "low volumes of MOM" entered the multivariable analysis. Univariate and multivariate relative risk (confidence interval [CI] 95%) estimates were obtained from Poisson regression with a robust estimate of variance and controlled by the length of hospital stay. Results: Of 414 infants included and followed until discharge, 32.9% (n = 136) received less than 50% of the total daily volume of MOM. This outcome was associated with gestational age <28 weeks, lower birth weight, multiple births, developing bronchopulmonary dysplasia, and longer lengths of stay. After Poisson regression, low volumes of MOM at discharge were associated only with being born multiples (RR 2.01; CI 95% 1.53-2.64, p < 0.001) and with longer length of stay (RR 1.07; CI 95% 1.01-1.14, p = 0.01). Conclusions: Most VLBW infants were discharged home receiving predominantly MOM. Each neonatal intensive care unit (NICU) should acknowledge which clinical characteristics of mothers and VLBW infants are associated with difficulties maintaining MOM volumes until discharge.

Simulation Analysis of Corona Pulse Propagation along the Line Based on an Actual Transmission Line

Abstract In the partial discharge test of the shunt reactor of the ultra-high voltage transmission line, the corona discharge caused by high voltage interferes with the test. To further study the propagation rules of the corona pulse on the line side in the transmission line during the ultra-high voltage partial discharge test, based on the parameters of an actual transmission line, the ATP-EMTP electromagnetic simulation software was used for modeling. The propagation rules of corona pulses in the transmission line were analyzed in detail through the simulation model. As the propagation distance increases, different frequency components show different degrees of attenuation. The higher the frequency is, the faster it attenuates.

Efficient and stable supercapacitors using rGO/ZnO nanocomposites via wet chemical reaction

The electrochemical behaviorof metal oxide nanoparticles (NPs) can be improved by maximizing the surface area and combining materials with high electrical conductivity. The reduced graphene oxide (rGO) enables to bestow a larger surface area for intercalation and deintercalation as well as shorter paths for ion transfer, lowering ionic resistance. In the current research, hybrid composites of rGO and zinc oxide (ZnO) NPs were successfully synthesized by using a wet chemical method for the application of supercapacitors. The wet chemical technique for industrial-scale nanocomposite synthesis is easy, fast, and cost-effective and requires no specialized equipment. The size, surface morphology, and crystalline structure of the rGO/ZnO nanocomposites were characterized by using FE-SEM, HR-TEM, and XRD, respectively. By using cyclic voltammetry and Galvanostatic charge–discharge tests, it was confirmed that the capacitances of rGO/ZnO composites were significantly enhanced compared to that of pure ZnO NPs. The proposed nanocomposite could achieve significantly enhanced specific capacitance (258 Fg−1) and also, it was able to achieve a longer life cycle with maximum capacitance retention. We expect that this work provides a simple but very effective strategy for the rGO and metal oxide NP composites.

Stable 3D porous N-MXene/NiCo2S4 network with Ni–O atomic bridging for printed hybrid micro-supercapacitors

The vision of “Internet of Everything” marked by wearable and multi-functional microelectronics technology has a profound impact on our lives, and the requirements for micro-supercapacitors (MSCs) are also constantly increasing. Compared to traditional super capacitors, there is still a lack of systematic investigation on regulating the morphology and internal structure of microelectrodes. Herein, we achieved the inkjet printing of intricate structures, a novel 3D N-MXene/NiCo2S4 porous network, and applied it to long-life hybrid MSCs. A new bridging mechanism of Ni atoms and O atoms is demonstrated by XPS. DFT calculations reveal that the O atoms of N-MXene can capture electrons from Ni atoms of NiCo2S4, resulting in charge redistribution in the interfacial region of 3D N-MXene/NiCo2S4, thereby realizing enhanced structural stability of the composite material. Due to the gradual release of active sites within the porous network, its capacitance retention rate can be as high as 99.1 % after 25,000 charge and discharge tests. With a wide voltage window of 1.6 V, a volumetric capacitance of 983.9 F cm−3, and an energy density of 342.4 mWh cm−3, the MSCs perform better than previously reported inkjet-printed MSCs. Our work demonstrates a new strategy to regulate the surface morphology and internal structure of the microelectrodes by high-precision inkjet printing to improve the performance of the MSCs.

Late-onset dyshormonogenic goitrous hypothyroidism due to a homozygous mutation of the SLC26A7 gene: a case report

BackgroundIn this study, we used targeted next-generation sequencing (NGS) to investigate the genetic basis of congenital hypothyroidism (CH) in a 19-year-old Tunisian man who presented with severe hypothyroidism and goiter.Case presentationThe propositus reported the appearance of goiter when he was 18. Importantly, he did not show signs of mental retardation, and his growth was proportionate. A partial organification defect was detected through the perchlorate-induced iodide discharge test. NGS identified a novel homozygous mutation in exon 18 of the SLC26A7 gene (P628Qfs*11), which encodes for a new iodide transporter. This variant is predicted to result in a truncated protein. Notably, the patient's euthyroid brother was heterozygous for the same mutation. No renal acid–base abnormalities were found and the administration of 1 mg of iodine failed to correct hypothyroidism.ConclusionsWe described the first case of goitrous CH due to a homozygous mutation of the SLC26A7 gene diagnosed during late adolescence.

Preparation and Capacitive Properties of Ni-Doped Zinc Cobaltate/Carbon Fiber Composite Porous Mesh Materials

Nickel-element-doped zinc cobaltate/carbon fiber composites (Ni-ZnCo2O4/CF) were prepared on carbon cloth (made of a combination of carbon fibers) conductive substrates using a simple ambient stirring method combined with heat treatment. Characterization tests of the materials revealed that the prepared products were porous Ni-ZnCo2O4/CF mesh structures. This porous network structure increases the surface area of the material and helps shorten the diffusion path of ions and electrons. The samples were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) methods to investigate the effect of Ni elemental doping on the stability of the materials. The results show that there are no other impurity peaks and no other impurity elements in the Ni-ZnCo2O4/CF electrode material, which indicates that the sample purity is high. Meanwhile, the electrochemical properties of Ni-ZnCo2O4/CF electrode materials were studied. Under the condition of 15 A·g−1, the specific capacitance of Ni-ZnCo2O4/CF electrode material is 1470 F·g−1, and after 100 cycles, its specific capacity reaches 1456 F·g−1, which is 99.0% of the specific capacity of 1470 F·g−1, indicating that the electrode material has good stability. In addition, we assembled asymmetric supercapacitors (Ni-ZnCo2O4/CF//CNTs) with Ni-ZnCo2O4/CF as the positive material and carbon nanotubes (CNTs) as the negative material. In the cyclic stability experiment of Ni-ZnCo2O4/CF/CNTs devices, when the current density was 1 A·g−1, the specific capacitance was 182 F·g−1. After 10,000 cyclic charge–discharge tests, the specific capacity became 167 F·g−1, which was basically unchanged compared with the initial specific capacity, reaching 91.8%. It shows that it has higher charge–discharge performance and higher cycle stability.

Highly efficient electric-thermal conversion of Silver/PVP composites for micro initiators by direct ink writing

Traditional film initiator fabrication techniques were limited by material and process constraints, resulting in restricted ignition capability, durability issues, and complexity in manufacturing. In this study, Metal/polymer composite materials were applied in film initiators in order to enhance the mechanical properties, longevity, and thermal attributes. Silver/polyvinylpyrrolidone composite film bridge (SPB) initiators were fabricated by direct ink writing (DIW). By adjusting the silver loading level and sintering temperature in the Ag nanoparticles/polyvinylpyrrolidone (Ag NPs/PVP) ink formulation, precise control over the structure and resistivity of the SPB was achieved. Compared to single silver film bridge (SFB) initiators prepared by magnetron sputtering (MS), SPBs demonstrated superior heating performance, higher current carrying capacity, and energy utilization under constant current excitation. In capacitor discharge tests, SPBs exhibited superior electric explosion characteristics and plasma properties, with a 25.53% higher energy utilization efficiency compared to SFBs. The peak plasma electron temperature of SPBs reached 7610 K, which was 1065 K higher than that of SFBs. This makes Silver/polyvinylpyrrolidone composite highly promising practical alternatives for high-efficiency, stable, and reliable ignition processes, with potential widespread applications in the aerospace field.