Ningning Li

With the development of semiconductor technology, the increasing number of power electronic converters and nonlinear loads has further exacerbated power-quality issues in the grid. To address this, this paper presents an improved DC-side voltage control strategy for UPQC, aiming to enhance power quality under complex conditions. First, an adaptive filter is integrated into the linear active disturbance rejection control (LADRC) to address control accuracy issues caused by noise and parameter variations. To solve the voltage sag problem resulting from the filter, the effects of fixed-step and various variable-step algorithms within the filter are analyzed, and the optimal control strategy is identified. Simulation results demonstrate that the proposed arctangent function-based variable step-size algorithm (VAV-LADRC) strategy effectively improves the UPQC system’s performance in mitigating voltage sags, swells, and harmonics under dynamic load changes, enhancing the stability of the DC-side voltage. To further validate the generalizability of the method, a co-simulation of a photovoltaic power-generation system with the UPQC is conducted, simulating variations in solar irradiance. The results show that the proposed method maintains excellent control performance under complex conditions, providing a better practical solution for the efficient use of green energy.

With the growth of the global population, energy demand continues to rise, making cross-regional energy transportation less viable as a sustainable solution. As a result, the construction of facilities for agriculture in cold regions has become increasingly important in the development of modern agriculture. However, cold region facility agriculture faces significant energy and environmental challenges, necessitating the advancement and application of energy saving technologies. This study addresses the high energy consumption in cold region facility agriculture by experimentally evaluating the integrated effects of geothermal heat pumps, solar collectors, intelligent light control systems, LED plant lamps, and smart ventilation systems in saving energy. The focus is on analyzing the technical adaptability and economic feasibility of these technologies under extremely cold conditions in Heilongjiang. The research findings indicate an overall energy saving rate of 17.8%, with energy savings in heating, lighting, and ventilation systems being 17.6%, 18.6%, and 17.4%, respectively. Economic analysis shows that geothermal heat pumps and high efficiency insulation materials have a short investment payback period and are suitable for widespread adoption, while solar collectors and intelligent light control systems are more appropriate for long-term application. This study demonstrates that intelligent and integrated energy saving technologies have significant potential in cold region facility agriculture, providing both data support and technical references for the efficient, low-carbon development of agriculture in cold climates. This study not only provides scientific evidence for the sustainable development of cold region facility agriculture but also highlights the practical implications of these technologies for reducing energy consumption and promoting low-carbon agriculture.