This paper investigates transformer inrush currents during the energisation of arc furnace transformers in electric arc furnace (EAF) power supply systems. The study focuses on an industrial DSP-100 installation operating with harmonic filters and reactive-power compensation equipment. A nonlinear reduced-order lumped-parameter model is formulated using explicit phase-domain relations for the supplying-system equivalent, the furnace-transformer branch, the connected filter/compensation branches, and the nonlinear magnetic circuit. The surviving DSP-100 oscillograms are used as an experimental anchor and for a waveform-level consistency assessment of peak current, inter-phase peak-current variation, and transient decay. Because the original high-resolution recorder export, complete channel documentation, and recorder characteristics are no longer available, this comparison is not presented as a unique experimental validation of the nonlinear saturation law or of the detailed nonsinusoidal inrush waveform. A model-level evaluation framework for controlled pre-magnetization is then formulated using peak inrush current, transient decay time, and an energy-based transient severity index. Relative peak-current error and RMSE are retained as waveform-consistency metrics, while the practical interpretation of the severity index is linked to equipment-specific I²t withstand limits. The experimentally anchored model provides a basis for comparative and sensitivity assessment of controlled pre-magnetization in the DSP-100 operating environment. Prototype-level confirmation of controller performance, nonlinear-waveform fidelity, and the influence on associated compensation and filtering equipment remains a subject of further industrial validation.
With the rapid development of driverless systems technologies, the differences inelectromagnetic exposure levels amongst passengers of different ages have become a researchhotspot in this field. This study focuses on the electromagnetic exposure of adults andchildren inside an electric vehicle caused by positioning antennas of driverless systems.Based on the COMSOL Multiphysics software, an electromagnetic numerical calculationmodel is established, including a vehicle body model, an antenna model, and separate modelsfor an adult and child. Considering the differences in body size and dielectric propertiesbetween adults and children, the finite element method is used to calculate exposure levelsunder the electromagnetic environment generated by the positioning antenna. The resultsreveal that the electromagnetic exposure level in a child’s body is higher than that in anadult due to the former’s smaller body size and higher dielectric parameters. This studyfacilitates the evaluation of the electromagnetic environment of positioning antennas inelectric vehicle driverless systems, provides a basis for improving electromagnetic radiationsafety standards inside electric vehicles, and promotes the rapid development of electricdriverless technologies while ensuring public health and safety.
The paper presents an experimental verification of a method for computing losses in a magnetic core operating in a DC-DC converter with a variable duty cycle, based on losses measured under sinusoidal excitation conditions. The core operating conditions that influence the losses and the method for their measurement are presented. The measurement setup was designed for this research, its basic features are discussed in the paper. The results obtained from the analysis were compared with core loss measurements obtained from the Brockhaus MPG-200 system. The theoretical foundation for core loss calculations and the measurement error analysis are also presented. The discussion of the results takes into account additional factors, such as the effect of working temperature on loss level.
To mitigate grid load fluctuations caused by large-scale electric vehicle (EV) charging while preserving user experience, this paper proposes a satisfaction-aware orderly charging coordination framework. First, based on Kano theory, a comprehensive fitness evaluation model is developed to characterize diverse user charging demands, integrating the grid load peak-to-valley difference, total charging cost, and user satisfaction into a uni-fied scheduling objective. To efficiently solve this complex high-dimensional problem, an improved particle swarm optimization (PSO) approach is employed. By incorporating adaptive inertia weights, asynchronous learning factors, and Lévy flight perturbation, the proposed algorithm enhances global search capability and alleviates premature conver-gence. Simulation results based on the IEEE 33-node distribution system demonstrate the effectiveness of the proposed strategy. Compared with disorderly charging, the proposed method significantly reduces the grid peak-to-valley difference and total charging cost. Meanwhile, the comprehensive user satisfaction is improved and consistently outperforms the conventional PSO method. These results indicate that the proposed strategy effectively balances grid operation and user benefits.
Residual earth-fault indicators installed in medium-voltage overhead feeders operate with fixed pickup thresholds, while the available residual current decreases with feeder distance. As a result, indicator operation becomes progressively less reliable toward remote feeder sections, and deterministic short-circuit analysis alone is insufficient to cha-racterize practical detectability limits. This study investigates distance-dependent detecta-bility of fixed-threshold residual earth-fault indicators using a combined experimental, si-mulation-based, and probabilistic framework. First, the relay–RTU–SCADA event chain is verified through controlled current-injection testing in a 35 kV reserve feeder bay. Second, residual earth-fault current along the 9.4 km Prizreni 1–Zhuri overhead feeder is evaluated using IEC 60909 single-phase-to-earth simulations implemented in DIgSILENT PowerFac-tory. Probabilistic threshold-exceedance analysis is then applied to estimate detection relia-bility as a function of feeder distance. The simulated residual current decreases from 350.577 A near the source substation to 299.793 A at the feeder endpoint. For the deployed 300 A pickup threshold, the detection probability decreases from near-unity values in upst-ream feeder sections to approximately 0.49 at the remote end of the feeder. Additional sen-sitivity analysis shows that fault resistance, uncertainty level, pickup threshold, and feeder electrical length significantly influence practical detectability limits. The results demon-strate that residual earth-fault indication in long feeders should be evaluated as a probabili-stic distance-dependent problem rather than as a purely deterministic threshold-crossing condition. The presented framework provides an engineering basis for evaluating reliability limits and pickup-threshold adequacy in medium-voltage distribution.
