Search Results (365)

Taking a typical high-power microwave power supply system as the research object, this paper quantitatively simulates and compares electromagnetic disturbance characteristics under multiple operating conditions, systematically investigates the influence mechanism of the system on EMI, and verifies the proposed simulation model via prototype experiments. Firstly, the typical equipment composition and three operating modes of the system are elaborated. Standardized high-frequency equivalent circuits of thyristors, capacitors, and inductors are established, and parasitic parameters are extracted to construct a system-level high-frequency coupling model. Different from traditional static parasitic extraction and separated field-circuit simulation methods, the proposed global collaborative optimization co-simulation method with voltage-dependent thyristor parasitic model significantly improves EMI prediction accuracy under full-cycle multi-mode operation. Secondly, based on the dynamic device characteristics under resonant charging, energy recovery and energy supplement modes, the generation mechanisms of EMI are clarified with quantitative data. During modeling, the electrical characteristics of thyristor body diodes and inter-electrode capacitances are fully incorporated with reference to actual component parameters. The EMC co-simulation based on CST field-circuit coupling is adopted to collaboratively optimize all parameters, which reduces the approximation error introduced by local modeling and greatly improves simulation accuracy. Combined with simulation and prototype experimental verification, this paper reveals the multi-path EMI coupling mechanism of pulsed power systems. The proposed parasitic parameter-based SPICE modeling and field-circuit co-simulation method can provide quantitative analysis tools and theoretical support for the EMC suppression design of high-power microwave power supplies. Full article

The article is aimed at studying the features of the hot rolling mill CWBRM-1700 of JSC “Qarmet”, which negatively affect the operation of the distribution network of the workshop. Such factors are frequent shock loads of technological mechanisms with high installed capacity of the equipment. Experimental studies of the distribution network of the rolling production on the buses of the 10 kV substation showed that shock loads of synchronous electric drives of roughing stands lead to periodic voltage drops of up to 13% lasting 5–6 s. Mathematical modeling in the MATLAB/Simscape/Electrical environment, the results of which coincide with the data of the experimental study, showed that the most significant factor affecting the quality of electricity are abrupt changes in the reactive power of the synchronous motor from −0.5 to +0.5 MVAR. To solve the problem, it is proposed to use a controlled filter-compensating device. Variants of circuit solutions for such devices are considered. The choice was made in favor of a three-phase adjustable LLC filter with diode–transistor keys. The article develops a method for calculating the electromagnetic parameters of such a filter and establishes that in order to reduce the level of harmonic distortion of voltage, it is necessary to use a triangle connection of the controlled reactive compensator and select the PWM frequency of the transistors, a multiple of the tripled frequency of the power grid. Two options for creating a closed-loop control system for energy modes are studied: a reactive power stabilization system and a voltage stabilization system in a distribution network node, which reduce the duration of transient processes to 0.5 s and reduce the voltage drop in the network node to −4 to + 1% in the first case and to −4 to + 3% in the second, also reducing reactive power consumption to 0.02 MVAR and 0.25 MVAR, respectively. The advantage of a closed-loop control system with voltage stabilization is the ability to use a technically less complex voltage sensor. Full article

The fastest growing waste stream worldwide is represented by Waste from Electrical and Electronic Equipment (WEEE). One of the main critical issues related to the recovery of such waste is the mixed plastic fraction, which is difficult to sort and can contain flame retardants and additives that pose a risk to human health and the environment. This study aims to validate the possibility of using tribo-electrostatic separator technologies to sort plastic polymers (e.g., PP, PA6, PS and PVC) obtained after a size-reduction operation of WEEE. The experimental study was conducted on a 10 kg/h laboratory-scale pilot plant. Several parameters were analysed during the tribo-charging and electrostatic separation processes, including the rotation speed and residence time of the particles in the tribo-charging device as well as electrode voltage, and the distance between the deflectors and the electrodes in the electrostatic separator. The results show that the tribo-electrostatic separation technologies are promising and efficient for plastic waste recycling. In fact, under specific conditions, it is possible to achieve high recovery rates (>70%) and purity levels (>76%) that allow the reintegration of plastic polymers into the economic cycle as a secondary raw material. Full article

Deep drilling equipment operates under high-load, strong-vibration, intermittent-impact, and variable environmental conditions, which motivate sensing systems that provide low-noise acquisition, synchronized triaxial measurements, local data integrity, and quantitative measurement-chain characterization. This paper presents a Zynq UltraScale+ MPSoC-based triaxial vibration sensing station for deep drilling equipment applications. The modular station integrates conditioned-voltage triaxial accelerometer interfaces, analog signal conditioning, 24-bit simultaneous analog-to-digital conversion, electrical isolation, local solid-state-drive storage, Ethernet/wireless communication, and GPS-disciplined oven-controlled crystal oscillator (OCXO) timing. The programmable logic performs deterministic acquisition, GPS pulse processing, oscillator calibration, and DMA transfer, while the processing system facilitates storage, network communication, device-state management, and host computer interaction. The sensing electronics are evaluated through zero-input noise, an experiment-specific input-amplitude-to-noise ratio, gain linearity, thermal stability, repeatability, and station-to-station local-PPS timing tests. The characterized electronics achieve a mean equivalent input noise of 0.31 microvolts, a test-derived ratio of 135.08 dB, and a mean station-to-station local-PPS falling-edge difference of 0.34 microseconds. A lightweight post-acquisition interpretation workflow using learnable multichannel weighted fusion, a convolutional autoencoder, a training-distribution-based quantile threshold, and an auxiliary classification branch achieves 0.9705 accuracy and 0.9704 F1-score on a public triaxial bearing dataset under the reported protocol. A crane-based experiment evaluates deployment feasibility and the sensing–analysis workflow using controlled operating events and a removable stationary mass disturbance. The results provide an engineering sensing basis for distributed monitoring studies on deep drilling equipment. Full article

Field voltage testing after the maintenance of large converter transformers requires high-voltage response verification while preserving the restored equipment boundary. However, conventional direct voltage application on the grid side usually requires the disconnection of high-voltage leads and auxiliary devices, which may alter the original electrical boundary and increase field disturbance. To address this issue, this study develops an integrated framework with three core contributions: a minimal-lead-disconnection induced-voltage testing topology, a boundary-specific engineering-equivalent parasitic-capacitance model, and a terminal-referred phasor-based power-supply capacity-calibration method. Under the proposed testing topology, single-phase power-frequency excitation is applied on the valve side, and the induced-voltage response is established at the grid-side bushings while some of the restored auxiliary-equipment connections are retained. Considering the parasitic capacitance introduced by valve towers, tubular busbars, grading fittings, and grid-side auxiliary devices under the minimal-lead-disconnection boundary, an engineering equivalent model for extracting the valve-side stray capacitance is developed based on quasi-static electric field theory, geometric-envelope dimensional reduction, and conformal-mapping-based edge correction. The grid-side equivalent capacitance is further obtained using equipment parameters. On this basis, the induced-voltage distribution under the interconnection of multiple converter transformers is analyzed, and a power-supply capacity-calibration method considering the phasor relationship between inductive excitation current and capacitive current is established. Pre-test calculations yield a valve-side stray capacitance of 0.96 nF and a grid-side equivalent capacitance of 1.27 nF. When the grid-side induced voltage of phase C reaches 9.90 kV, the induced voltages of phases A and B are 4.56 kV and 5.14 kV, respectively, while the apparent power calculated from the field-measured RMS voltage and current is 1.34 kVA. The results verify the effectiveness of the proposed method for low-disturbance field testing and portable test-power-supply configuration. Full article

High photovoltaic (PV) penetration in distribution networks can cause significant voltage deviations, making effective voltage regulation a critical issue for distribution system operators. Step voltage regulators (SVRs) provide a cost-effective solution; however, their performance strongly depends on control parameter settings that should account for PV-induced voltage fluctuations. Because installing high-resolution sensors at all PV sites is impractical, this paper proposes a method for determining SVR control parameters using short-term PV output estimation. The proposed approach assumes that only large-capacity PV systems are equipped with high-resolution sensors and estimates the outputs of other PV systems using the inverse distance weighting (IDW) method. Based on historical power flow data and estimated PV outputs, the method determines 48 sets of SVR control parameters for the following day while capturing rapid voltage rises caused by PV fluctuations. Numerical simulations using a practical distribution network model developed from an actual Chubu Electric Power Grid Co., Inc. system demonstrate the effectiveness of the proposed method. The results show that the allowable PV hosting capacity increases by 25% compared with a method without short-term PV output estimation, while the increase in SVR tap operations remains within an acceptable range. Full article

Epoxy resin (EP) has been extensively used in electrical insulation systems because of its favorable adhesion, chemical resistance, thermal stability, and dielectric reliability. Nevertheless, the dense three-dimensional network formed during curing generally gives EP a brittle nature, which restricts its use in insulating components that require both mechanical robustness and long-term reliability. In this work, a hydroxyl-terminated hyperbranched polymer (HBP-OH) was synthesized from itaconic acid (IA) and dipentaerythritol (DPE) through an Ax + By polycondensation route and then incorporated into an anhydride-cured epoxy system as a reactive toughening component. The influence of HBP-OH on the structure, mechanical behavior, dielectric response, and DC breakdown strength of the resulting HBP-OH/EP composites was systematically evaluated. The results demonstrate that HBP-OH effectively improves the mechanical performance of EP. At an HBP-OH loading of 9 wt%, the tensile strength increased from 15.00 MPa for pure EP to 33.27 MPa, while the elongation at break and flexural strength reached 6.5% and 88 MPa, respectively. Meanwhile, only a slight reduction in DC breakdown strength was observed at the optimal HBP-OH content. These results indicate that the proposed hyperbranched-polymer modification strategy can improve the toughness and strength of epoxy resin while retaining its dielectric and insulation performance, providing a feasible approach for developing epoxy insulating materials for high-voltage electrical equipment. Full article

This paper presents a low-cost embedded monitoring system for real-time RMS voltage and RMS current acquisition in three-phase electrical networks. The proposed architecture is based on distributed Arduino Nano acquisition nodes equipped with ACS712 Hall-effect current sensors and isolated voltage transformers, while a Raspberry Pi 4 Model B is used as a centralized data acquisition and processing unit through the I²C communication protocol. The embedded acquisition nodes implement timer-controlled analog signal sampling using the internal 10-bit ADC of the ATmega328P microcontroller, allowing real-time acquisition of electrical waveforms for RMS computation. Unlike conventional low-cost IoT electrical monitoring systems focused mainly on basic parameter visualization and wireless communication, the proposed platform emphasizes synchronized three-phase RMS monitoring and experimental validation accuracy under real operating conditions. The proposed monitoring architecture is experimentally benchmarked against a FLUKE 435 professional power quality analyser used as a high-accuracy reference instrument. Experimental results demonstrate that the proposed low-cost embedded architecture can provide RMS voltage and RMS current measurements with acceptable accuracy for educational applications, experimental electrical platforms, and distributed IoT-based monitoring systems. The presented system does not aim to implement a fully IEC 61000-4-30-compliant power quality analyser but rather to validate the feasibility of low-cost embedded RMS monitoring architectures for real-time electrical applications. Full article

Oil-immersed power transformers and high voltage reactors may experience abnormal mechanical vibration during operation, especially under complex electromagnetic and load conditions. Such vibration can induce periodic pressure fluctuations in narrow oil–paper gaps, promoting bubble formation, collapse, and associated characteristic gas production. Since characteristic gases are important indicators for insulation condition assessment, vibration-induced gas generation may affect the interpretation of dissolved gas analysis and fault diagnosis. However, the gas production behavior and underlying mechanism of oil–paper insulation under combined mechanical vibration and electric field stress remain insufficiently understood. In this work, an equivalent oil–paper gap model was developed to experimentally investigate the effects of vibration parameters and electric field strength on gas generation under vibration–electric field coupling. The bubble collapse dynamics under vibration were further analyzed using a modified Rayleigh–Plesset (R-P) equation. Results indicate that the localized high-temperature region produced during bubble collapse in the positive-pressure phase of vibration initiates pyrolysis of insulating oil and paper, generating characteristic gases including H₂, CO, CO₂, CH₄, C₂H₄, C₂H₆, and C₂H₂, among which CO₂, CO, H₂, C₂H₄, and CH₄ are the dominant components under test conditions. At low electric field strength (before partial discharge inception), the additional pressure contributed by electrostatic forces intensifies bubble collapse, increasing the concentrations of H₂, CO_x, and THC by 15.9%, 7.6%, and 29.8%, respectively. At high electric field strength (after partial discharge inception), discharge-induced decomposition of oil and paper further increases the concentrations of H₂, CO_x, and THC by approximately 47.7%, 30.0%, and 44.9%, respectively. These findings provide theoretical and data support for evaluating insulation conditions and understanding failure mechanisms in oil-immersed power equipment subjected to vibration. Full article

To address the difficulty of effectively sensing weakly distorted electric fields generated during the early stage of insulation degradation in power equipment, this paper proposes a miniaturized high-sensitivity multilayer flexible electric field sensor optimized using an improved GOOSE algorithm. First, based on the electric field coupling mechanism, the enhancement effect of the flexible arc-shaped structure on local distorted electric fields is analyzed, and an equivalent model that discretizes the flexible curved surface into parallel-plate micro-elements is established. Furthermore, a multilayer sensor equivalent circuit model considering the effects of parasitic capacitance and conductive ink electrode resistance is developed, and the relationship between sensor sensitivity and structural parameters is derived. Subsequently, an electric field–circuit-coupled simulation model is established in COMSOL Multiphysics to systematically investigate the influence of parameters such as electrode layer number, electrode thickness, dielectric layer thickness, and electrode side length on the output response. The results show that the multilayer structure can effectively improve the equivalent sensing capacitance and electric field coupling capability, while the electrode thickness and dielectric layer thickness exhibit significant nonlinear effects on the output voltage. To achieve the coordinated optimization of high sensitivity and miniaturization, Tent chaotic mapping initialization and nonlinear dynamic adaptive inertia weight are introduced to improve the traditional GOOSE algorithm, and a multi-objective optimization model is constructed with the objectives of maximizing the output voltage and minimizing the electrode area. The optimization results indicate that the improved GOOSE algorithm achieves faster convergence and better optimization stability. Among the Pareto solution sets with different electrode layer numbers, the seven-layer structure exhibits the best size–performance trade-off. The final optimized design achieves an electrode area of only 1.746 mm² and an output voltage of 2.565 × 10⁻⁶ V. These results demonstrate that the proposed multilayer flexible structure and improved GOOSE optimization method can significantly enhance the response capability to weak electric fields while maintaining device miniaturization, providing a new sensor design concept and optimization approach for non-contact detection of early-stage insulation degradation in power equipment. Full article

To address the challenges of insufficient multi-time-scale complementarity, imbalanced energy storage lifespan evaluation, and difficulties in high-dimensional non-convex optimization during the coordinated dispatch of low-voltage distribution areas, this paper proposes a multi-objective optimal dispatch strategy coordinating heterogeneous flexible loads and energy storage. Specifically, a multi-resource coordinated regulation framework comprising energy storage, electric vehicles (EVs), and inverter air conditioners (IACs) is constructed to deeply exploit the long- and short-term physical response potential of heterogeneous resources. Furthermore, a lightweight non-linear energy storage lifespan evaluation model compatible with long-horizon day-ahead optimization is proposed to guide the system to circumvent high-frequency micro-cycles, thereby reducing equipment degradation costs without altering physical configurations. Finally, a multi-objective optimization and posteriori objective fuzzy algorithm is proposed to tackle operational economy, grid stability, and energy storage lifespan, accurately restoring the genuine Pareto non-dominated boundaries. Experimental results demonstrate that the proposed strategy consistently outputs an optimal compromise scheme for the energy management system (EMS) that reconciles the core interests of multiple stakeholders. Full article

Gas-insulated switchgears (GISs) and gas-insulated transmission lines (GILs) are essential for large-capacity power transmission in demanding environments, such as high drops, large spans, and heavy pollution. As the core components providing both electrical insulation and mechanical support, ultra-high voltage (UHV) epoxy-based insulators often suffer from high internal residual stress. This issue, compounded by a lack of reliable detection methods, frequently results in equipment being commissioned with hidden defects. To address this, this review first examines the formation mechanisms of curing deformation and residual stress in oversized insulators based on cure kinetics and thermo-chemical coupling models. Subsequently, it provides a comprehensive summary of current residual stress measurement techniques, comparing the applicability and limitations of embedded sensors, direct mechanical measurements, and indirect non-destructive testing (NDT) methods. Finally, by coupling residual stress with filler sedimentation, the stress distribution patterns and mechanical reliability of epoxy-based insulators across different life-cycle stages are analyzed. These insights offer valuable theoretical references for the structural design, process optimization, and performance evaluation of oversized epoxy-based insulators, ultimately contributing to the intrinsic safety of UHV power equipment. Full article

Power-quality resilience is an important component of sustainable industrial electricity use, as voltage sag events can cause production interruptions, equipment damage, and inefficient allocation of mitigation costs and benefits among stakeholders. However, high initial investment costs and the lack of a viable commercial operation scheme have hindered the large-scale deployment of mitigation devices. To support sustainable power-quality governance, this study proposes an integrated framework that connects the technical compensation performance of the mitigation device with the economic foundation of a tripartite commercial operation model. First, an adaptive switching compensation strategy dynamically shifts between different modes based on the real-time voltage sag depth, establishing a mapping relationship with avoided-loss benefits. Then, a bi-level Nash bargaining model is constructed to allocate costs and benefits among the government, the enterprise, and the user, deriving closed-form analytical solutions for both the upper- and lower-level games. Through pilot operations at a large public service facility, economic losses of 480,000 CNY caused by a single voltage sag can be effectively avoided. Meanwhile, under the proposed scheme, all three parties achieve positive net present values. Compared to the user self-funding mode, the user’s NPV increases by 21.9%. Furthermore, unlike bilateral or equal-sharing alternatives, the Nash bargaining solution ensures all parties remain within the strong feasible region. The government and enterprise recover their costs within 4.14 and 6.20 years, respectively. These results indicate that the proposed framework can enhance the economic sustainability of power-sensitive users, encourage shared public–private investment in power-quality improvement, and support more resilient and efficient industrial electricity use. Full article

This paper presents a risk-averse information-gap decision theory (IGDT)-based day-ahead scheduling framework for active distribution networks with high penetration of inverter-interfaced resources. The proposed day-ahead strategy coordinates active and reactive power scheduling in an active distribution network comprising renewable generation, diesel units, demand-side management, electric vehicle charging stations, and energy-storage-equipped soft open points. The corresponding deterministic operating condition is then used as the reference state for uncertainty analysis. The scheduling problem is formulated as a mixed-integer nonlinear programming (MINLP) model considering network operating constraints and voltage-dependent load characteristics. Uncertainty associated with load demand and renewable generation is addressed using the IGDT risk-averse approach to quantify admissible uncertainty. The proposed methodology is implemented on a modified IEEE 33 bus distribution system considering deterministic operation, load-demand uncertainty, renewable-generation uncertainty, and simultaneous uncertainty in both load demand and renewable generation. The optimization model is developed in GAMS and solved using the DICOPT solver. The simulation results demonstrate the capability of the proposed framework to accommodate simultaneous load-demand and renewable-generation uncertainty within a predefined operating-cost threshold while maintaining secure network operation. Full article

During coal mine fracturing operations, real-time monitoring of the vibration frequency of the drilling assembly is crucial for assessing crack development, optimizing fracturing parameters, and ensuring the safety of downhole equipment. However, traditional active vibration sensors are limited by their reliance on external power supplies in the complex environment of underground mining, reducing their operational efficiency and effectiveness. Accordingly, a self-powered Z-shaped vibration sensor based on hybrid triboelectric and electromagnetic mechanisms was developed for monitoring coal mine fracturing drilling. This sensor utilizes the vibrations of the drilling tool to induce frictional electric pulse signals that correspond to the vibration frequency, enabling simultaneous vibration monitoring and energy generation. Experimental results demonstrate the stable performance of the proposed sensor under thermal conditions up to 150 °C and moisture levels reaching 90% relative humidity. The proposed sensor exhibits an operating frequency range of 0 to 11 Hz, with the measurement deviation constrained within a 5% threshold. Under optimal impedance matching, the triboelectric and electromagnetic units deliver peak power outputs of 0.04 mW and 110.5 mW when connected to external loads of 10⁸ Ω and 3.3 × 10² Ω respectively. The proposed hybrid self-powered sensor uses the high-amplitude pulsed voltage signals generated by the TENG unit for vibration frequency identification, while the EMG unit harvests mechanical energy from low-frequency vibrations, thereby enhancing the self-powered capability of the sensor for underground vibration monitoring in coal-mine hydraulic fracturing drilling. Full article