High-voltage System Research Articles

Design of a High-Voltage Miniaturized Control System for Macro Fiber Composites Actuators

Macro Fiber Composites (MFCs) exhibit significant potential in active control applications. These include vibration control for unmanned aerial vehicle wings and helicopter rotors. However, the high-voltage drive requirements of MFCs present challenges. The miniaturization of the controller is a mandatory condition in order not to affect the overall space utilization. Thus, this paper presents a specialized miniaturized high-voltage control system designed specifically for MFC actuators. The proposed system employs a mixed analog-digital modulation method (ADM). This method precisely regulates a discontinuous conduction mode flyback switch-mode power supply operating in current mode. The system achieves an adjustable high-voltage output range of -500 V to 1500 V. The mixed control system consists of several components. These include a switching power supply, a voltage divider circuit, a bleeder circuit, and a digital controller. Additionally, this high-voltage control system integrates with a Simulink software environment. The system is compact and lightweight. It also features high load capacity, high power, and excellent dynamic response. Moreover, it offers real-time control capabilities. Experimental validation on a high-aspect-ratio wing demonstrates that this control system achieves a vibration reduction effect of 65%. The miniaturized control system provides a valuable research base for vibration control studies.

Coordinated optimization of control parameters for suppressing transient overvoltage in wind power DC transmission systems

With the increasing proportion of new energy in power systems, the instability issues of novel power systems become more prominent. This paper addresses the transient overvoltage problem in wind power DC transmission systems by proposing a method for transient overvoltage suppression based on doubly-fed wind turbines, high-voltage DC transmission systems, and SVC control parameter optimization. The electromagnetic transient model of the wind power DC transmission system is combined with intelligent optimization algorithms through joint invocation to achieve coordinated optimization of control parameters. Case studies validate the effectiveness of the proposed model and method. The results indicate that the improved genetic algorithm, SEGA, proposed in this paper, effectively suppresses overvoltage at the grid connection point of wind turbines. Furthermore, by simultaneously applying coordinated control strategies based on DFIG and SVC and optimizing parameters of HVDC, DFIG, and SVC, transient overvoltage phenomena can be effectively eliminated.

Low-voltage DC-DC off-grid PV system: various irradiance studies

The off-grid photovoltaic (OGPV) system, also referred to as a stand-alone power system, generates electricity from solar energy independently of the main electricity grid. However, photovoltaic (PV) modules face limitations in consistently providing the necessary voltage. Thus, a DC-DC converter is employed to adjust the voltage to match the requirements of the load. This paper proposes a detailed analysis of irradiance patterns resembling in-lab and real-world conditions to address the challenge of selecting the optimal DC-DC OGPV system capable of functioning effectively under standard test condition (STC) and dynamic test condition (DTC), respectively. Three proposed irradiance analyses, tailored to different environmental scenarios, aim to identify output performances for DC-DC OGPV system which are aligning with standards set by the International Electrotechnical Commission (IEC) 61727. The DC-DC OGPV system is simulated using MATLAB Simulink. Furthermore, comparative studies involving different PV module types and several switching techniques (pulse generator and maximum power point tracking or MPPT implementations), where findings are instrumental in advancing the development and projection planning for medium to high-voltage OGPV systems, contributing to the global initiative for accessible and sustainable energy solutions aligned with sustainable development goal (SDG 7).

Design and implementation of high voltage DC generation system based on push-pull inverter integrated with Cockcroft-Walton

<span lang="EN-US">High-voltage DC generation is essential for industrial, medical, and scientific applications, such as X-ray machines, particle accelerators, and electrostatic precipitators. Existing high-voltage DC generators face challenges such as high cost, complexity, and inefficiency. A simplified and cost-effective solution that can reliably generate high-voltage DC from a low DC power supply is needed. This paper discusses the design and implementation of a high-voltage DC generator with a low-voltage DC power supply input. The generator employs a push-pull inverter to transform the DC 12 V voltage into AC 400 V at a frequency of 20 kHz. A Cockcroft-Walton circuit, comprising a positive and a negative Cockcroft-Walton circuit, then steps up this voltage. The Arduino Nano microcontroller uses pulse width modulation (PWM) signals to control the system. This research aims to provide a reliable and economical high-voltage DC voltage generation system for various applications. We discuss the design process and hardware implementation in detail. We set the target output voltage of this hardware at 10 kV DC. MATLAB/Simulink simulation software verifies the performance of the proposed high-voltage generator, and hardware implementation validates its effectiveness. The proposed high-voltage DC generator's hardware tests successfully produced an output voltage of 14.12 kV DC.</span>

The formative time delay and electron avalanche number distributions for multielectron initiation of streamer breakdown

Electron avalanche statistics were mainly studied with a single electron initiation and there was no mathematical transition reported to the formative time delay distribution. This paper deals with the transition from the electron avalanche number distribution to the formative time delay distribution for multielectron initiation and streamer breakdown mechanism. The goal of the research is a detailed analysis of the formative time delay of electrical breakdown for different applications, such as spark counters, resistive plate chambers, gas-discharge switches, and high voltage systems with gas as an insulator. The electron avalanche number distribution for multielectron initiation is described by negative binomial distribution (NBD). Regarding the newly derived formative time delay distribution, when the number of initiating electrons k is small, the formative time delay distributions are asymmetric with the pronounced right tail. With increasing k, the formative time distributions shift to the shorter formative times and become narrower and higher, more symmetric and Gauss-like. As statistical tests show, for k≳20 the hypothesis that the formative time delay distributions are Gaussians cannot be rejected. As illustrations, the formative time delay distributions in neon and air at low reduced electric field are shown and briefly discussed. The distributions for methylal, ether and methane are presented in order to compare the estimated distribution parameters with available experimental data and to model the measured distributions.

Competing mechanisms of charge-induced electric field distortion and charge-involved neutralization on surface discharge

Charge-induced surface discharge poses a critical risk to the operational reliability of high-voltage direct current gas-insulated equipment and pulsed power system. In this study, we investigate the effects of charge-induced electric field distortion and charge involvement during surface discharge by separately depositing charge spots on two dielectric layers. The results show that deposited positive charges inhibit positive streamer development, whereas negative charges facilitate it, primarily due to electric field distortion induced by deposited charges. Nevertheless, the involvement of deposited charges in streamer development predominantly exhibits a neutralizing effect, exerting an opposite influence on the streamers. This highlights a competitive relationship between deposited charge involvement and electric field distortion. Additionally, the neutralization of deposited charges with electron avalanches reduces the impact of charge-induced electric field distortion, thereby mitigating its effects on discharge.

Influence of Temperature Variability on the Efficacy of Negative Ions in Removing Particulate Matter and Pollutants: An Experimental Database

Cities globally must make urgent decisions to ensure a sustainable future as rising pollution, particularly PM2.5, poses severe health risks like respiratory and heart diseases. PM2.5’s harmful composition also impacts vegetation and the environment. Immediate government intervention is necessary to mitigate these effects. This study tackles the urgent problem of reducing PM2.5 levels in Medellín’s urban and indoor environments, where pollution presents serious health risks. To explore effective solutions, this research provides new data on the interaction between particulate matter from various pollutants and negative ions under different temperature conditions, offering valuable insights into air quality improvement strategies. Using a high-voltage system, ions bind to pollutants, accelerating their removal. Experiments measured temperature, humidity, formaldehyde, volatile organic compounds, negative ions, and PM2.5 in a 40 cm3 chamber across various conditions. Pollutants tested included cigarette smoke, incense, charcoal, and gasoline at two voltage levels and three temperature ranges. The data, available in CSV format, were based on 36,000 samples and repeated tests for reliability. This resource is designed to support studies investigating particulate matter control in urban and indoor environments, as well as to improve our understanding of negative ion-based air purification processes. The data are publicly available and structured in formats compatible with leading data analysis platforms.

A Butterfly Effect: Attack-Induced Heterogeneous Equilibrium Points of High-Voltage DC Systems

A Butterfly Effect: Attack-Induced Heterogeneous Equilibrium Points of High-Voltage DC Systems

Determination of converter parameters for high-voltage electromechanical systems of stationary installations of industrial fans

Purpose. To study the electromagnetic processes in the circuit of the phase rotor of a high-voltage induction motor connected to the network through a step-up converter, to determine the parameters of the converter and their relationship with the voltage gain to ensure the optimal level of energy efficiency of the electromechanical system. Methodology. Methods of theoretical electrical engineering for the construction of a rotor circuit replacement scheme for an induction motor with a step-up converter, methods for solving a system of first-order differential equations, analytical methods. Findings. The expediency of using a converter that combines the rotor circuit of a high-voltage induction motor with the power supply network and provides regulation of the rotor EMF with the recovery of the slip energy of the induction motor rotor to the power supply network has been proved. This will ensure speed control of powerful high-voltage induction motors on the rotor side with an EMF of up to 600 V and significantly reduce the cost of a high-voltage electromechanical system. A methodology for determining the converter gain and the parameters of the rotor circuit of the electromechanical system is proposed, which allows determining the transformation ratio of the matching transformer at the optimal value of the voltage gain. The conditions of trouble-free operation of the inverter at the moment of start-up of the electromechanical system are determined. Achieving these conditions is ensured by determining the delay of the control signal to the power keys of the inverter of a step-up converter. The correlation between the voltage gain and the equivalent resistance of the rotor circuit of the electromechanical system is established. Originality. The ratio of the voltage gain to the equivalent resistance of the rotor circuit of the electromechanical system is established, which will ensure the matching of the rotor EMF with the voltage of the power supply network while maintaining a high level of energy efficiency. Practical value. A methodology for determining the gain and parameters of a step-up converter is proposed, which allows determining the transformation ratio of a matching transformer at the optimal value of the voltage gain. The proposed methodology can be applied to the modelling of complex powerful high-voltage electromechanical systems, especially for stationary installations of industrial fans.

Influence of substrate temperature on plasma-enhanced chemical vapor deposition to improve the surface flashover performance of epoxy resin

Abstract Epoxy resin composites are widely used as insulating and supporting materials in high-voltage power systems due to their excellent mechanical and electrical properties. However, long-term operation under high-voltage direct current induces surface flashover. Plasma enhanced chemical vapor deposition (PECVD) has been shown to effectively improve the surface insulation properties of epoxy resin. However, the influence of substrate temperature on the film composition, stress, morphology, and surface flashover performance remains unclear. This study uses PECVD to treat epoxy resin, enhancing its surface flashover performance. Tetraethoxysilane is used as the precursor to deposit nano-scale SiO x films on the epoxy resin surface. The effects of different substrate temperatures on the surface flashover voltage, physicochemical properties, and mechanical properties of epoxy resin are characterized. The results show that the surface flashover voltage increases and then saturates with increasing substrate temperature, improving by 27.4% at 60 °C compared to untreated samples. The surface roughness of epoxy resin decreases after plasma deposition, while highly oxidized silicon-containing functional groups are introduced. When the substrate temperature increases from 20 °C to 60 °C, the interfacial bonding strength improves by 25.9%. This study provides a simple, efficient, and controllable method to enhance the surface flashover performance of epoxy resin, promoting the application of this technology in engineering practice.

MOF-Derived Nitrogen-Rich Hollow Nanocages as a Sulfur Carrier for High-Voltage Aluminum Sulfur Batteries.

Aluminum-sulfur batteries (ASBs) are emerging as promising energy storage systems due to their safety, low cost, and high theoretical capacity. However, it remains a challenge to overcome voltage hysteresis and short cycle life in the sulfur/Al2S3 conversion reaction, which hinders the development of ASBs. Here, we studied a high-voltage ASB system based on sulfur oxidation in an AlCl3/urea electrolyte. Nitrogen-doped hollow nanocages (HNCs) synthesized from MOF precursors were rationally designed as sulfur/carbon composite electrodes (S@HNC), and the impact of the nitrogen species on the electrochemical performance of sulfur electrodes was systematically investigated. The S@HNC-900 achieved efficient conversion at 1.9 V, delivering a stable capacity of 197.3 mA h g-1 and a Coulombic efficiency of 93.28% after 100 cycles. Furthermore, the S@HNC-900 electrode exhibited exceptional rate capacity and 800th long-term cycling stability, retaining a capacity of 87.1 mA h g-1 at 500 mA g-1. Ex situ XPS and XRD characterizations elucidated the redox mechanism, revealing a four-electron transfer process (S/AlSCl7) at the S@HNC-900 electrode. Density functional theory calculations demonstrated that pyridinic nitrogen-enriched HNC-900 significantly enhanced the sulfur conversion reaction and facilitated the adsorption of sulfur intermediates (SCl3+) on the carbon interface. This work provides critical insights into the high-voltage sulfur redox mechanism and establishes a foundation for the rational design of carbon-based electrocatalysts for the enhancement of ASB performance.

Research on Ultra-Fast Transient Overvoltage Characteristics of Electric Locomotive

Operating overvoltage occurs when the pantograph or main breaker of an electric locomotive is operated, which is prone to causing insulation failure of high-voltage equipment. The HXD1 electric locomotive is taken as the research object in this paper to explore the characteristics and influencing factors of operating overvoltage. Under pantograph lifting, main breaker closing, main breaker opening, and pantograph dropping, operating overvoltage waveform in the high-voltage system is recorded by a high-speed oscilloscope and resistance–capacitance voltage divider to analyze the overvoltage characteristics and distribution law. Tested data show that the amplitude of operating overvoltage is in the range of 80 to 330 kV with ultra-high steepness, which is similar to the Very Fast Transient Overvoltage (VFTO) in power systems. The maximum overvoltage during the entire test occurred during the main breaker closing and its amplitude is 328.60 kV with a steepness of 4.21 × 104 kV/μs. The max overvoltage of the other operations (pantograph lifting, main breaker opening, and pantograph dropping) are 280.60 kV, 194.73 kV, and 305.56 kV with ultra-high steepness. High-amplitude overvoltage is predominantly located at the pantograph, while the low-amplitude sort is mainly observed around other high-voltage equipment. The result indicates that operating overvoltage belongs to ultra-fast transient overvoltage and its amplitude and steepness are higher than existing research.

Narrowband-UVB-emitting gadolinium-doped yttrium oxide nanofilm on xenon excimer lamp for phototherapy

The continuous utilization of ultraviolet (UV) light sources within both academic and industrial contexts necessitates the imperative advancement of alternative UV sources to replace hazardous mercury lamps. Herein, we proposed a mercury-free narrowband UVB (NB-UVB)-emitting device from Y2O3:Gd3+ nanofilm on a tubular quartz substrate. The nanofilm is fabricated utilizing the spin-coating sol-gel precursor technique and is subsequently synthesized via a high-annealing temperature solid-state reaction. This synthesis resulted in the formation of a single-phase cubical structure of Y2O3 characterized by a crack-free morphology. The NB-UVB radiative output with a peak at 315 nm is generated through vacuum UV-induced photoluminescence originating from the emission of Xe excimer, which subsequently excites the Gd3+ luminescent centers incorporated within the Y2O3 host matrix. Moreover, in a high-voltage bipolar power system operating at 19 kV and 19 kHz, the device exhibited an NB-UVB radiance output of 1.34 mW, accompanied by a power efficiency of 0.02 %, whilst preserving exceptional temporal performance. Thus, this investigation introduces an innovative perspective on a mercury-free NB-UVB-emitting device, thereby promoting further exploration into the application of UV radiation sources derived from excimer lamp technology.

Fluorinated functional groups enhanced composite in-situ gel electrolytes for high voltage cathode of quasi solid-state lithium battery

Gel electrolyte is an ideal system for improving the cycling stability and safety of lithium metal battery. However, traditional gel system with acrylic ester system is still not suitable for high-voltage battery system limited by its intrinsic structure and unstable interface. The polymer structures with -CF3 modified acrylic ester are proposed to improve the stability of both structure and interface in high-voltage battery systems. The LiF-rich anode-electrolyte interface assisted by fluorine contained in-situ gel electrolyte ensures stable cycling of lithium anode. The quasi-solid state lithium battery assembled with the LiFePO4 can still achieve a capacity retention rate of 81.2 % after 900 cycles at a rate of 1 C. Furthermore, the uniform organic cathode-electrolyte interface constructed by crosslinked -CF3 modified polymer effectively inhibits the corrosion of HF on the cathode material. The interaction between the anion and solvent molecules prevents the continuous decomposition reaction of the electrolyte on the surface of the LiCoO2 cathode at high voltage, which guarantees LiCoO2 battery can still achieve a capacity retention rate of 82.1 % after 500 cycles at a voltage of 4.45V. Design of fluorine contained in-situ polymer gel electrolyte could promote the development of quasi solid-state battery in practical industrial application.

Transient stability enhancement of Beles to Bahir Dar transmission line using adaptive neuro-fuzzy-based unified power flow controller

A power system is a complex, nonlinear, and dynamic system, with operating parameters that change over time. Because of the complexity of big load lines and faults, high-voltage transmission power systems are usually vulnerable to transient instability concerns, resulting in power losses and increased voltage variation. This issue has the potential to cause catastrophic events such as cascade failure or widespread blackouts. This problem affects Ethiopia's high-voltage transmission power grid in the northwest area. Because of the increased demand for electrical energy, transmission lines' maximum carrying capacity should be enhanced to maintain a secure and uninterrupted power supply to consumers. To address the problem, ANFIS-based UPFC is used for high-voltage transmission lines. This device was chosen as the ideal alternative due to its capacity to rapidly correct reactive power on high-voltage transmission networks. The PSO algorithm was used to determine the best location for the UPFC. The ANFIS controller receives voltage error and rate of change of voltage error as inputs. Seventy percentage of the retrieved data are used for ANFIS training and 30% for ANFIS testing. To show the performance of the proposed controller, three-phase ground faults are used from a severity perspective. When a three-phase ground fault occurs at the midpoint of the Beles to Bahir Dar transmission line, for instance, the settling time of rotor angle deviation, rotor speed, rotor speed deviation, and output active power of synchronous generators using ANFIS-based UPFC is reduced by 70.58%, 37.75%, 37.75%, and 43.75%, respectively, compared to a system without UPFC. At peak load, PI-based UPFC and ANFIS-based UPFC reduce active power loss by 51.25% and 71.50%, respectively, compared to a system without UPFC on the Beles to Bahir Dar transmission line. In terms of percentage overshoot and settling time, ANFIS-based UPFC outperforms PI-based UPFC for transient stability enhancement.

Research on the monitoring system for induced voltage and ground current of 27.5 kV cable sheath in railways

PurposeThe purpose of this study is to address the deficiency in safety monitoring technology for 27.5 kV high-voltage cables within the railway traction power supply by analyzing the grounding methods employed in high-speed railways and developing an effective monitoring solution.Design/methodology/approachThrough establishing a mathematical model of induced potential in the cable sheath and analyzing its influencing factors, the principle of grounding current monitoring is proposed. Furthermore, the accuracy of data collection and alarm function of the monitoring equipment were verified through laboratory simulation experiments. Finally, through practical application in the traction substation of the railway bureau on site, a large amount of data were collected to verify the stability and reliability of the monitoring system in actual environments.FindingsThe experimental results show that the designed monitoring system can effectively monitor the grounding current of high-voltage cables and respond promptly to changes in cable insulation status. The system performs excellently in terms of data collection accuracy, real-time performance and reliability of alarm functions. In addition, the on-site trial results further confirm the accuracy and reliability of the monitoring system in practical applications, providing strong technical support for the safe operation of high-speed railway traction power supply systems.Originality/valueThis study innovatively develops a 27.5kV high-voltage cable grounding current monitoring system, which provides a new technical means for evaluating the insulation status of cables by accurately measuring the grounding current. The design, experimental verification and application of this system in high-speed railway traction power supply systems have demonstrated significant academic value and practical significance, contributing innovative solutions to the field of railway power supply safety monitoring.

A compact solid-state high repetition rate trigger based on a spiral generator.

The trigger generator made with a spiral generator (SG) has the advantages of light weight, compact structure, and low cost and has promising applications in the pulsed power field. This paper introduces a compact solid-state high-voltage pulse trigger system based on an improved SG, which has improved repetition rate and lowered the demands for semiconductor switches' maximum current and current rise rate when compared with previous studies. The improvement is achieved by winding outward an additional layer of the passive layer and low-voltage metal strip, which realizes a significant reduction of the peak current and current rise rate of the discharge switch. The final dimension of the trigger is 25 × 10 × 10cm3, excluding the power supply. An experiment carried out in single shot mode shows that the peak value of the output pulse can reach 50kV with a leading edge of 57ns. Repetitive experiments were carried out up to 1kHz, with the peak voltage of the output pulse being 30.5kV, the leading edge being 48ns, and the jitter being 0.84ns. Finally, the generator is used to trigger a gas switch, and it works stably and reliably.

Localization of partial electrical discharges using compressive spherical frequency-difference beamforming.

Accurate localization of partial electrical discharges is essential for the diagnosis of high-voltage systems. The current study achieves this by employing an acoustic sensor array and a beamforming approach. The occurrence of a partial discharge is accompanied by the emission of high-frequency sounds in the ultrasonic range, making localization a challenging task requiring many sensors to avoid spatial aliasing. Compressive frequency-difference beamforming, as previously proposed, can be effective in addressing this issue. We expand the method to include near-field localization by utilizing a spherical wave and propose a two-step normalization process. This eliminates the bias associated with nonplanar waves and standardizes the field variables, thereby preserving only the phase and relative amplitude information. A distributed algorithm based on the alternating direction multiplier method is used to solve the associated convex optimization problem. The proposed method is demonstrated using simulated and experimental data.

Assessment of Quasi-Stationary Power Quality Phenomena in DC Power Systems

The adoption of dc architectures for electricity distribution has been increasingly considered to reduce the number of energy conversions and to exploit their inherent ability to cope with peaks in energy supply and demand. Furthermore, dc systems have been commonly and widely adopted for high-voltage transmission systems and public transport for many years. Despite this, the Power Quality (PQ) assessment in dc power networks is still unstandardized. In the scientific literature, various indices have been proposed for the quantification of dc PQ. However, not all the aspects encountered in practical applications are adequately accounted for, and their effects regarding the impact on the measurement results are not fully analysed. This paper focuses on signal processing for the analysis of PQ of dc networks in stationary or quasi-stationary conditions aimed at compatibility level assessment. The influence quantities that affect the measurement results of the most commonly adopted procedures for determining the PQ index determination are identified and modelled, and their impact is analytically calculated. Advanced signal processing methods, suitable to be adopted in standards for dc PQ compatibility level surveys, are proposed to improve the accuracy and reliability of results. The rationality and effectiveness of the proposed procedures are shown with analytical calculations and in real measurement situations.

Research on Maintenance Capability Standards for Drive Motor Systems of New Energy Vehicles

Developing industry recognized industry standards within the qualification framework is the benchmark for learning outcomes transformation. Based on the study of general competency standards, this article takes the maintenance competency requirements of new energy vehicle drive motor systems as a case study, and conducts a detailed analysis of the requirements for this module in vocational education undergraduate education for secondary and higher vocational schools. Finally, the vocational skill level standard for "electric vehicle high-voltage system evaluation and maintenance" is revised and preliminarily verified.