Search Results (5,042)

To address the challenges of integrating multi-source heterogeneous data, fragmented fault knowledge, and the limited capability of traditional rule engines in recognizing edge cases for ultra-high voltage (UHV) bushing fault diagnosis, this paper proposes a fault identification and decision-making method based on knowledge graph (KG) rule reasoning and inductive graph convolutional network (Inductive GCN). First, a triple-matching strategy is employed to perform entity extraction and relation mining from fault cases, constructing a fault knowledge graph that transforms unstructured fault case texts into a structured knowledge graph. Second, a rule engine based on a multi-source feature rule set is designed, utilizing the entropy weight method and the RETE algorithm to achieve interpretable symbolic reasoning. On this basis, a double-layer inductive graph convolutional network is introduced to learn implicit fault patterns by aggregating topological information from neighboring nodes, and a confidence-driven dynamic weighted fusion strategy is adopted to achieve complementary advantages between the two models. Finally, a large language model is introduced to generate operation and maintenance decision recommendations. Experimental results demonstrate that the proposed method achieves an identification accuracy of 98.1% on a test set of 159 samples, which is 10.7 percentage points higher than that of a single rule engine and 6.9 percentage points higher than that of a single inductive graph convolution network. The standard deviation of accuracy across different test batches is only 0.0029. These results demonstrate the effectiveness and stability of the proposed method, providing a practical technical solution for UHV bushing fault identification. Full article

The increasing penetration of renewable energy has made the transient stability of new power systems a critical concern. Grid-forming (GFM) energy storage can provide voltage and frequency support for renewable energy stations. However, existing studies on the transient stability of GFM converters predominantly consider only the synchronization of a GFM converter with an infinite bus and do not fully account for the effects of renewable-energy injection and LVRT control in remote-grid-connected renewable energy stations. To fill this gap, this paper establishes a transient power-angle stability analysis model for a GFM energy storage system in renewable energy stations connected to a remote grid. Based on the equivalent swing equation and the equal-area criterion, the transient instability mechanisms under different renewable energy source LVRT depths are investigated. The results demonstrate that increasing renewable energy output reduces the transient stability margin of the GFM converter. Furthermore, the system exhibits two distinct transient response modes depending on the renewable energy source LVRT depth: under shallow LVRT depth, the GFM converter accelerates first and then decelerates, whereas under deep LVRT depth, it decelerates first and then exhibits a swing-back oscillation. These findings, validated through time-domain simulations, provide a theoretical basis for understanding the effects of renewable energy output, LVRT control, virtual inertia, and virtual damping on the transient stability of GFM-integrated renewable energy systems. Full article

Photovoltaic (PV) pumping systems offer a sustainable alternative to diesel solutions, yet their nonlinearity, intermittent irradiation, and complex motor-pump dynamics challenge energy extraction and reliability. Currently, these systems predominantly rely on classical Maximum Power Point Tracking (MPPT) algorithms such as Perturb and Observe (P&O) and Incremental Conductance (INC), which suffer from slow convergence, steady-state oscillations, and an inability to track Global MPP (GMPP) under uniform irradiance variation conditions. Furthermore, existing studies typically address MPPT optimization and motor control in isolation, without considering their coupled interaction, and rarely incorporate economic viability assessments. To address these limitations, this paper proposes an innovative control architecture integrating four advanced metaheuristic MPPT techniques, namely the Genetic Algorithm (GA), Gray Wolf Optimizer (GWO), Cuckoo Search (CS) algorithm, and Horse Herd Optimization Algorithm (HOA), with Model Predictive Control (MPC) for a Brushless DC (BLDC) motor-driven pumping system, supplemented by battery storage. Comprehensive simulations were conducted under both constant and variable irradiance profiles (1000 to 500 to 1000 W/m²) to evaluate dynamic performance, tracking accuracy, and system robustness. The results demonstrate that HOA and GWO significantly outperform GA and CS, achieving superior DC bus voltage stability with ripple values below 2.4 V, faster convergence times, reduced electromagnetic torque oscillations, and enhanced MPPT efficiency exceeding 99%. Under variable irradiance, HOA exhibits the fastest stabilization with minimal overshoot and superior disturbance rejection, while GA suffers from severe oscillations and CS displays sawtooth ripple patterns. A techno-economic analysis further confirms the economic viability of the proposed system, with HOA and GWO strategies yielding lower lifecycle costs, extended converter lifespans from 5 to over 12 years, and improved return on investment compared to conventional approaches. This integrated framework offers a robust, efficient, and economically sustainable solution for autonomous PV water pumping applications. Full article

Sodium-ion batteries are emerging as credible complements to lithium-ion technology for sustainable, safe, and cost-effective energy storage. This critical review links molecular-scale electrolyte solvation and interphase chemistry to electrode compatibility, full-cell engineering, manufacturing constraints, and commercial viability. Organic liquid, aqueous, ionic-liquid, concentrated, inorganic solid, polymer, and composite electrolytes are compared using transport, stability, processing, and interface criteria. The principal cathode and anode families are then evaluated in terms of practical voltage, reversible capacity, cycling stability, raw-material exposure, manufacturability, and end-of-life implications. A distinctive contribution of this work is the explicit separation of thermodynamic predictions, laboratory measurements, prototype demonstrations, and company-reported targets, together with design rules that connect electrolyte chemistry to cell-level performance. Sodium-ion batteries are unlikely to replace lithium-ion batteries universally, but they can occupy a strategic role where cost, safety, abundance, supply-chain resilience, and circularity outweigh maximum energy density. Full article

The growing share of photovoltaic generation in power grids intensifies the need for converter architectures capable of combining efficient energy conversion, DC-bus stability, and ancillary service provision at the grid coupling point. This paper presents the modeling, implementation, and simulation-based evaluation of a 91 kWp three-phase photovoltaic (PV) system integrated with a battery energy storage system (BESS), developed in the PLECS environment. The proposed architecture comprises three interleaved Boost stages for maximum power point tracking (MPPT), a DC bus regulated at 600 V, three independent bidirectional buck–boost converters for LiFePO${}_4$ bank management, and a two-level three-phase voltage source inverter (VSI) with an LC output filter. The control is organized in cascade voltage–current loops for the DC–DC stages and in vector control within the synchronous reference frame (SRF) for the inverter, with synchronization via SRF-PLL. A C-Script supervisory block integrates the Perturb and Observe (P&O) MPPT algorithm, independent state of charge (SOC) estimation per bank via coulomb counting, and Volt–VAR reactive power reference generation with a dead band of 0.90–1.10 pu. Five scenarios are analyzed for validation: DC-bus regulation under irradiance transients; reactive power support during undervoltage and overvoltage events (0.80–0.85 pu and 1.15–1.20 pu); BESS operation as an active DC-link support element; and PV curtailment with fully charged banks. All five scenarios were additionally corroborated on a Typhoon HIL402 Pro 2 hardware-in-the-loop platform, reproducing the PLECS waveforms within the amplitude and timing resolution of the oscilloscope captures. Across all scenarios, the DC bus is held within $\pm 15$ V (2.5%) of the 600 V reference, with the worst-case transient recovering in 80–100 ms; under a sustained 9 s bidirectional disturbance, redirecting PV surplus to BESS charging in both the undervoltage and overvoltage segments—with no externally imposed active-current limit—keeps the current-vector magnitude $\sqrt{i_d^2+i_q^2}$ below the 335 A rating throughout (≈271 A and ≈242 A, respectively), while the available reactive margin $Q_{disp}$ reaches ≈78– 80 kVAr in both segments and the bank SOC advances by ≈$0.03$ pu; and supervisory curtailment under a sustained overvoltage ride-through with a saturated bank keeps the per-bank SOC dispersion within $4\times {10}^{-5}$ pu while expanding the available reactive margin $Q_{disp}$ from ≈50 to ≈90 kVAr. Full article

With the rapid development of recycling and secondary utilization of end-of-life battery materials, it is crucial to clarify the impact of full-lifecycle degradation on the thermal safety limits of lithium-ion batteries. This study focuses on a 16 Ah NCM613|graphite pouch battery. First, it analyzes the evolution of capacity decay, thickness expansion, and internal resistance during cycling at room temperature (25 °C) and high temperature (45 °C). Furthermore, an adiabatic accelerated calorimeter (ARC) is employed to investigate the influence of different states of health (SOH) levels (95% and 85%) on the battery’s thermal runaway characteristics. The findings indicate that, macroscopically, batteries in all states follow similar voltage–temperature failure pathways, with mass loss rates confined to a narrow range of approximately 16%, emphasizing the low catastrophic potential of mid-nickel chemistry. However, the microscopic kinetic mechanisms exhibit significant anisotropy: although thickness and internal resistance display no apparent abrupt increase during the late stage of room temperature aging, the capacity exhibits a highly nonlinear plunge behavior. The severe internal lithium plating side reaction triggered by this phenomenon causes the self-heating onset temperature to drop rapidly from 130.0 °C in the fresh state to 79.7 °C. Concurrently, the activation energy of the exothermic side reaction, fitted using a simplified Arrhenius equation, exhibits a non-monotonic variation with aging progress. In the early stages of aging at 95% SOH, due to high temperatures promoting more significant growth of the interfacial film or moderate film formation at room temperature enhancing interfacial thermal stability, the activation energies for both aged batteries increase, and the energy barrier at high temperatures is slightly higher than at room temperature; however, during the deep aging stage at 85% SOH, due to the degradation of active material components and the emergence of lithium plating characteristics, the energy barrier significantly decreases, with high-temperature-aged batteries exhibiting a greater reduction, highlighting the cumulative negative impact of prolonged high-temperature exposure on thermal safety. The research provides a core scientific basis for establishing a battery safety early warning and dynamic health management system covering the entire lifecycle. 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 rapid integration of Distributed Generation (DG) units is transforming traditional passive radial distribution networks into active grids with bidirectional power flow. Determining the optimal allocation and physical hosting capacity of DG units is essential for maintaining grid stability while maximizing technical gains. This study presents a multi-objective optimization framework using empirical peak-load field data from an active medium-voltage distribution network in Türkiye. A custom Particle Swarm Optimization (PSO) algorithm was developed in MATLAB to simultaneously minimize active and reactive power losses while improving the Voltage Deviation Index (VDI). The baseline network model and load flow calculations established in DIgSILENT PowerFactory were rigorously cross-validated with MATPOWER, demonstrating complete mathematical agreement with a negligible deviation (<0.001%). Simulation results under both capacity-constrained ($10 \mathrm{MW}$ limit) and unconstrained Hosting Capacity Discovery scenarios demonstrate that single-objective optimization causes negative trade-offs across other operational metrics. Conversely, multi-objective hybrid approaches provide a balanced, globally common optimum operating point best suited to the grid’s natural electrical structure, consistently identifying a reliable ultimate hosting capacity threshold of $21.78 \mathrm{MW}$ at Busbar 4. These findings offer a concrete, empirical decision-support framework for active distribution network planning and modernization. Full article

The increasing complexity of modern power distribution systems, through rising demand, integration of distributed generation, and the scaling of electric vehicles, requires improved demand-side management strategies for effective and reliable operation. This study presents a DSM framework that integrates EV load coordination, DG placement, and load shifting techniques to achieve both economic and reliability improvements in distribution networks. The proposed approach is implemented on the IEEE 33-bus and Cairo 59-bus networks to capture practical operating conditions with higher loading and multiple laterals. The methodology is used to reschedule commercial loads while prioritizing cost minimization and maintaining system constraints. EV load charging demand and DG units are optimally allocated to support voltage stability and reduce power losses. Reliability performance was evaluated using the Customer Total Average Interruption Duration Index, using interruption frequency and duration. The results show that the integrated DSM approach significantly reduces operational cost, peak demand, and energy losses while enhancing system operational cost and reliability. The coordinated interaction between EVs, DGs, and flexible loads proves effective in maintaining a balance between economic efficiency and reliable power delivery. This work highlights the potential of broad sustainability-oriented DSM strategies in supporting the transition toward smarter and more sustainable distribution systems. This ensures that electricity is available to all the consumers at all times just by tweaking the usage pattern of the commercial consumers slightly. This will ensure lesser power losses in the system and better utilization of the available energy thereby creating a sustainable power distribution for the connected consumers. This work aligns with SDG 7 (Affordable and Clean Energy) and SDG 11 (Sustainable Cities and Communities). Full article

High-voltage vacuum circuit breakers are critical switching devices in power systems, and their reliable condition assessment is essential for safe operation and maintenance decision-making. However, breaker abnormalities are often reflected by heterogeneous operation-related evidence, and existing methods based on single-source measurements or generic feature fusion may weaken source-specific diagnostic roles and limit the recognition of compound abnormal conditions. To address this problem, this paper proposes the Physics-Guided Multi-Source State Assessment Network (PMSA-Net), a reliability-aware framework that integrates mechanical motion, opening- and closing-position limit events, and infrared thermography. Source-specific encoders first extract dynamic, end-position, and thermal representations. Reliability-aware Asymmetric Selective Interaction (RASI) then calibrates primary and auxiliary evidence, using mechanical motion as the operational context and the other sources as complementary constraints. Thermal Frequency-aware Selective Modulation (TFSM) stabilizes the low-frequency thermal field and enhances high-frequency hotspot responses. Task-conditioned evidence allocation jointly predicts state category, travel anomaly, limit-event consistency, thermal risk, and overall risk. On a laboratory-simulated benchmark covering 15 operating conditions, PMSA-Net achieved $90.18\pm 0.36\%$ state-category accuracy and an $80.00\pm 0.50\%$ overall-risk macro-F1 score over five independent runs. Under cross-source abnormalities, it exceeded the variational-fusion baseline by 2.59 and 3.05 percentage points on these metrics, respectively. These results indicate that reliability-aware calibration improves multi-task assessment of compound breaker abnormalities. Full article

This paper presents a bandgap-referenced current-mode vertical-cavity surface-emitting laser (VCSEL) driver for short-range light detection and ranging (LiDAR) sensor applications. To improve current stability under process, voltage, and temperature (PVT) variations, the proposed driver employs a bandgap-referenced bias generation scheme combined with a current-mode modulation architecture. The driver was implemented in a 0.18 µm CMOS process and occupies a compact core area of 350 × 100 µm². Post-layout simulation results show that the proposed circuit maintains a bias current of approximately 2 mA and a modulation current of approximately 10 mA across PVT corners. The fabricated chip was measured using a 50 Ω termination, and the measured output voltage swing was approximately 495 mV_pp, corresponding to a modulation current of 9.9 mA_pp. Hence, the proposed current-mode VCSEL driver provides a potential solution as a compact, low-power, stable LiDAR sensor transmitter. Full article

The practical deployment of aqueous zinc-ion batteries (AZIBs) is critically limited by uneven Zn²⁺ flux, uncontrolled dendrite growth, and concurrent parasitic reactions—notably the hydrogen evolution reaction (HER) and anode corrosion—arising from interfacial and kinetic instability during repeated plating/stripping cycles. These issues originate at the zinc anode–electrolyte interface, underscoring the necessity of advanced interfacial engineering. Here, we report a surface-confined polyphenol-derived interphase formed on zinc foil through a 1 min dip treatment in a dilute aqueous solution of a commercial tea polyphenol (TP) mixture (0.02 M); after rinsing and drying, the modified electrode is cycled in a conventional electrolyte to which no TP is deliberately added. This interphase promotes more homogeneous nucleation behaviour through coordination between phenolic oxygen-containing moieties and Zn²⁺, improves electrolyte contact homogeneity and perturbs the local water structure to mitigate water-mediated parasitic reactions. The TP-derived surface modification creates a substantially altered interfacial charging environment (Cdl = 47.25 vs. 16.83 µF cm⁻² for bare Zn) that facilitates more uniform zinc deposition. Symmetric cells with TP@Zn anodes demonstrated exceptional cycling stability exceeding 4000 h at 1 mA cm⁻² and 1 mAh cm⁻² (bare Zn fails within ~240 h under identical conditions), while TP@Zn//V₂O₅ full cells retained 56.2% capacity after 300 cycles at 0.5 A g⁻¹ with a higher median discharge voltage than bare Zn cells, substantially outperforming the latter (31.1% retention). Density functional theory calculations using the selected cluster models yield a markedly more negative electronic interaction energy for Zn²⁺ with an EGCG model ligand (−10.97 eV) than with H₂O (−4.49 eV), qualitatively supporting preferential coordination of Zn²⁺ by phenolic oxygen sites. This work presents a green, facile and potentially scalable interfacial regulation strategy and advances the understanding of natural polyphenols as pre-formed surface conditioners for highly reversible metal anodes. Full article

Although the weak-grid stability of grid-following inverters has been widely studied, traditional SCR-based assessment mainly describes grid strength and does not directly quantify the minimum SCR required for stable operation under a specified active-power command. This paper uses a critical-SCR-oriented operating-boundary evaluation to compare the control-dependent dynamic stability requirement with the physical steady-state feasibility limit. It proposes a channel-specific impedance-reshaping extension that retains the PLL-related q-q and d-q compensation paths and adds a voltage-loop-related q-d compensation path. The added path reduces the control-induced dynamic critical SCR, thereby allowing stable operation at lower SCR than with the original control structure. Firstly, the steady-state critical SCR is derived from the steady-state power-transfer relation under a specified active-power command to define the physical feasibility lower bound, and the dynamic critical SCR is identified using a scanning procedure based on the generalized Nyquist criterion. The resulting control-induced SCR gap quantifies the additional grid-strength requirement introduced by the control dynamics. Secondly, a simplified d-q admittance representation is used to relate established PLL-related and voltage-loop-related coupling effects to the corresponding compensation paths. Thirdly, the proposed channel-specific impedance-reshaping design is used to mitigate these effects while retaining the selected voltage-loop bandwidth, and an anti-drift correction is further introduced to improve implementation robustness. Frequency-domain analysis and time-domain simulations validate the dynamic critical-SCR evaluation, while hardware-in-the-loop experiments demonstrate the real-time operation of the proposed controller. The results show that it moves the dynamic critical-SCR boundary close to the steady-state physical boundary and improves the weak-grid stability margin. The hardware-in-the-loop results further confirm bounded operation under SCR and frequency steps. Full article

Grid-following (GFL) renewable energy stations may experience phase-locked loop (PLL)-dominated small-disturbance synchronization instability in weak grids, while grid-forming (GFM) devices can improve the damping of this mode. However, most current studies directly approximate GFM as an ideal voltage source without providing rigorous proof. There is also a lack of in-depth analysis on how the parameters of GFM affect its enhancement effect on the small disturbance synchronization stability of GFL. To address this gap, this paper establishes an ordinary differential equation model of the GFL/GFM hybrid system and proposes a fourth-order polynomial approximate root method suitable for polynomials with two pairs of weakly damped conjugate complex roots. Based on this method, the approximated form of the PLL damping is given, and the effect of the inertia time constant, damping coefficient, and capacity of a virtual synchronous generator (VSG) on the PLL mode damping was analyzed analytically. Moreover, it was proven that VSG with a certain level of inertia can play a role close to the ideal voltage source in improving the small disturbance synchronization stability of GFL. Finally, an electromagnetic transient simulation model was established on MATLAB/Simulink, and these conclusions were verified. Full article

This paper presents the mathematical modeling, numerical implementation, and experimental validation of a decoupling control algorithm for a five-port multiport modular active bridge (MMAB) converter in DC microgrid applications. Based on an analytically derived generalized state-space framework of the MMAB topology, a matrix-based method for suppressing non-linear mutual cross-couplings among individual ports is proposed. The study addresses parametric uncertainties within the system matrix caused by parasitic bus inductances; by formulating a linear system of equations solved via the numerical least-squares method, the equivalent parameter identification error was reduced from over 18% to a valid threshold. The decoupling performance and dynamic responsiveness of the closed-loop system were experimentally verified on a dual-core TMS320F28379D digital signal processor. The experimental results demonstrate that the proposed algorithm effectively isolates transient step-load perturbations, maintaining voltage stability on adjacent undisturbed ports within a strict deviation of less than $+0.51\%$ and achieving a recovery time below 5 ms. Furthermore, the real-time execution of the online Jacobian matrix inversion via the Newton–Raphson method confirms the computational feasibility and convergence of the iterative approach under tight sampling periods. The obtained results provide a robust, experimentally validated foundation for advanced algebraic and numerical control strategies in high-stability multiport power conversion systems. Full article