Tracking agrivoltaic (TAV) systems represent a significant form of agrivoltaics, which optimize solar energy capture through the dynamic adjustment of photovoltaic (PV) panel tilt angles. However, there is limited research on the effects of TAV systems on the three-dimensional spatial distribution of the light environment within PV arrays and their impacts on agricultural production. Therefore, a comparative experiment was conducted between wheat production under a TAV system and traditional open-field cultivation. Solar radiation intensity sensors were deployed to continuously monitor the dynamic changes in solar radiation under and between the PV panels throughout the entire growth period. Simultaneously, a light environment model for the TAV system was constructed, and the photosynthetic parameters of wheat leaves, as well as yield, were measured. The results indicated that the light environment within the system exhibited significant gradient attenuation, with average light capture rates of 43.2% and 46.1% for the inter-panel and under-panel measurement points, respectively. The model results confirmed that the synergistic adjustment of panel tilt angle and solar altitude angle significantly affected the shading effects, leading to notable spatiotemporal heterogeneity in the light environment during the winter solstice, spring equinox, and summer solstice. This heterogeneity showed as regular variations in shadows and radiation, collectively forming a dynamic light–thermal environment that influences crop growth. Wheat yields under and between the panels decreased by 11.5% and 6.6%, respectively, compared to the open-field control, with yields of 4625.9 kg·hm⁻² and 4883.6 kg·hm⁻². Additionally, the photosynthetic characteristics of the leaves effectively reflected the yield differences. Overall, the comprehensive benefit assessment demonstrates that the TAV system can effectively mitigate the reduction in wheat yield in PV farmlands. This study provides a theoretical basis for optimizing the light environment in AV systems.

Hollow coils with complex structures are very common in electrical equipment and sensors. Additionally, the responses at different frequencies are an important characteristic of the coils. However, it is quite challenging to divide the irregular coils with fine windings (thousands of turns and wire diameter less than 0.2 mm) into meshes using finite element simulation software (FESS), much less perform the simulation calculations, as theoretical derivations are only applicable to coils with specific shapes. This issue presents challenges in designing coils with high-density, multi-turn and irregular structures. Thus, we propose a calculation method for determining the frequency characteristics of hollow coils with such structures. To validate this method, three sets of hollow coils with complex structures and high-density winding were fabricated. These coils included two coupled PCB coils, one coil with thousands of fine turns, and a PCB coil with a complex and were tested using an LCR analyzer with a frequency range of 0 to 2 MHz. The experimental results showed good agreement with numerical calculations.

This study delves into the response characteristics of core grounding current signals in power transformers across different operating conditions, aiming to enhance the accuracy of transformer condition assessment. Existing detection technologies often rely on single-parameter methods, which fall short in providing a comprehensive evaluation of transformer conditions. To address this limitation, this research develops a wideband circuit model based on multi-conductor transmission line theory and backed by experimental validation. The model systematically investigates the response mechanisms of core grounding current to various electrical stresses, including impulse voltages, power-frequency harmonics, and partial discharges. The findings reveal distinct response characteristics of core grounding current under different stresses. Under impulse voltage excitation, the core current exhibits high-frequency oscillatory decay with characteristics linked to voltage waveform parameters. In harmonic conditions, the current spectrum shows linear correspondence with excitation voltages, with no resonance below 1 kHz. Partial discharges induce high-frequency oscillations in the grounding current due to multi-resonant networks formed by distributed winding-core parameters. This study establishes a new theoretical framework for transformer condition assessment based on core grounding current analysis, offering critical insights for optimizing detection technologies and overcoming the limitations of traditional methods.