This paper explores the effects of attaching radiative cooling films at different positions of solar cells in different seasons on their thermoelectric performance through experiments and simulations. The results show that attaching a radiative cooling film on the front side can significantly reduce temperature, but due to the decrease in transmittance, the electrical performance is lost by nearly 70%; while attaching a film on the back side can reduce the average temperature by 5.08 ℃ in summer, and the power is approximately increased by 2%, maintaining a high photoelectric conversion efficiency while effectively reducing the module temperature, In terms of the comprehensive performance of thermal management and power generation efficiency, it performs even better. In summer, the film on the back side has a good cooling effect, and in a low-temperature environment with an average ambient temperature of -10 ℃ in winter, the temperature difference of the module decreases by 0.59 ℃. By reducing the temperature difference, the service life can be extended. At the same time, the radiative cooling effect is affected by irradiance, ambient temperature and wind speed. The cooling effect of attaching a film is more prominent under high temperature and high irradiance conditions, while enhancing convection will weaken its cooling effect.

To address the problem of poor voltage stability of wind-solar-energy storage DC microgrids in distributed renewable energy systems, an optimized nonlinear active disturbance rejection control strategy based on the SAC algorithm （SAC-ADRC） is proposed. Firstly, the wind-solar-energy storage system is modeled with nonlinear ADRC control. Then, the gain parameters of the nonlinear ADRC are reconstructed by using linear/nonlinear ADRC switching to improve its internal parameters which are more difficult to tune and analyze. Finally, the analysis establishes a mechanism for SAC intelligence to learn interactively with the microgrid environment, enabling the adjustment of non-linear ADRC parameters. Comparative analysis using algorithm convergence curves and simulation of various classical working conditions confirms the superiority of the SAC-ADRC control strategy in terms of interference performance. Thus, it is shown that the organic integration of nonlinear ADRC and deep reinforcement learning improves the stability of the microgrid bus voltage.

To explore a new mechanism of frequency response with multi-resource coordination, a day-ahead and intra-day decentralized mutual-aid method of energy and auxiliary services is proposed. Firstly, based on the mutual-aid of energy resources, the framework of multivariate adjusting resources is established including day-ahead and intra-day energy, inertia and primary frequency regulation （PFR）. Secondly, the shared alternating direction method of multiplier（ADMM） is adopted to realize efficient solutions of the model and protect the privacy of mutual-aid subjects, in which the alternating optimization procedure （AOP） is established to address the non-convexity. Finally, a simulation example is given to verify that the proposed method can effectively motivate multiple regulatory resource suppliers to provide inertia and PFR services, which provides a reference for promoting mutual-aid of frequency regulation resources.

To realize the intelligent interconnection and interaction between the intelligent integrated energy system （IES） and the power supply system of rail transit, a synergistic optimization strategy for the hydrogen-containing IES and the power supply system of rail transit is proposed based on the dynamic ladder-type carbon trading mechanism. This strategy can reduce the cost of energy supply and utilization, while enhancing the low-carbon energy supply of the multi-flow coupling system and the low-carbon energy consumption of the rail transit system. Firstly, a dynamic ladder-type carbon trading model is designed based on the level of renewable energy and loads in IES. Secondly, according to the electric and thermal output characteristics of gas turbine （GT） and hydrogen fuel cell （HFC）, the traditional combined heat and power （CHP） unit and hydrogen energy unit are coupled by the Kalina cycle to develop a hydrogen-containing flexible energy supply unit, which can enhance the flexibility of the energy supply. Then, a hydrogen-containing IES collaborative optimization model connecting to the power supply system of rail transit is established to achieve cross-system joint optimization of rail transit energy consumption and multiple heterogeneous energy supply units, fully exploring the low-carbon economic operation potential of the system. Simulation results show that the proposed strategy can effectively balance the low-carbon economy and flexibility of multi-energy system scheduling, which can provide references for the synergistic operation of IES and power supply system of rail transit.

In order to study the high dimensional unsteady flow characteristics in the flow field of supercritical carbon dioxide centrifugal compressor reversed as turbine, the research object is centrifugal compressor reversed as turbine, the CFX flow field analysis software was utilized for numerical simulation, the dynamic mode decomposition（DMD） was performed on the simulated results, and the first four order modes and their corresponding spatio-temporal information are obtained. The analysis results show that the DMD method can decompose the unsteady flow field into modes with distinct energy levels and frequencies, including the basic mode with the highest energy contribution （0 Hz）, the dynamic and static interference mode with the second-highest energy （at the blade passing frequency）, and the high order harmonic characteristics of the dynamic and static interference modes with lower energy contributions（at multiples of the blade passing frequency）; The main characteristics of the basic mode are caused by the geometric parameters of the impeller, the main characteristics of the dynamic and static interference modes are caused by the dynamic and static interference between the impeller and the guide vane, and the high order harmonic characteristics of the dynamic and static interference modes show the subtle flow characteristics in the flow field; Under low-flow conditions, the first order mode exhibits a relative liquid flow angle smaller than the inlet blade angle, leading to flow separation on the pressure side of the blade inlet; Under high-flow conditions, the relative liquid flow angle of the first-order mode exceeds the inlet blade angle, resulting in flow impingement on the pressure side and flow separation on the suction side of the blade inlet. The DMD method can effectively decouple the unsteady flow field within the impeller and extract transient flow characteristics.

Taking a horizontal pendulum wave energy converter （WEC） based on a spiral spring-flywheel power take-off （PTO） system as research object, considering the spring stiffness and flywheel moment of inertia as variables, a fully coupled numerical model of the WEC is constructed to investigate energy acquisition under multiple degrees of freedom through model test and numerical simulation. The research shows that installing a spiral spring-flywheel PTO can enhance the stability of energy acquisition and increase the power generation bandwidth of the WEC. Under regular wave conditions, the standard deviation of power is positively correlated with the spring stiffness and negatively correlated with the flywheel moment of inertia, with this phenomenon being more pronounced near the resonance period.

To investigate the dynamic response of the multi-bucket jacket foundation of offshore wind turbines under storm surge load, this paper conducts a series of 1 g model tests using the motor servo random dynamic loading equipment. Then, the influence of different depth-to-diameter ratios of the suction bucket on the soil and structure is further investigated through numerical simulations. The results indicate that the extreme horizontal displacement of the structure rises as wind speed increases under storm surge conditions, and the amplification coefficient of horizontal displacement follows a trend of “increasing initially before decreasing”. The peak value of the Fourier amplitude spectrum for the nacelle position acceleration increases with the load, while the peak frequency exhibits a pattern of “decreasing first and then increasing”. As the depth-to-diameter ratio of the suction bucket increases, both the extreme horizontal displacement and the amplification of the structures coefficient corresponding decrease. A depth-to-diameter ratio of L/D= 0.5 is the least favorable, as it cannot withstand storm surge loads. The difference between depth-to-diameter ratios of 1.0 and 1.5 is negligible. Taking into account reliability and economy, a depth-to-diameter ratio of 1.0 is the optimal type. Different depth-to-diameter ratios also have the influence onthe rotation center of the SBJ foundation.

To meet the inertia requirements of different voltage levels and dynamic operating conditions, this paper proposes an inertial fusion control technology of multi-voltage-level DC microgrid. Initially, a model of a multi-voltage-level DC microgrid is established, and the inertia characteristics of various levels of DC systems are analyzed. Subsequently, aiming to maximize inertia in each system level, the paper considers the involvement of battery storage and renewable energy side converters connected to the system bus. These are engaged in inertia regulation through increased output current feed-forward control and grouped adaptive control. Meanwhile, the low-voltage side use inertia control based on observation compensation with converters connected to their load side to suppress fluctuations. This approach allows converters with inertia regulation capabilities to participate in the graded fusion of inertia in the DC microgrid and designs the inertia parameters for each end. Finally, a multi-voltage-level DC microgrid hardware-in-the-loop simulation platform is constructed to validate the effectiveness of this control strategy.

Conventional infrared reflective layers often struggle with thermal instability at high temperatures or insufficient infrared reflectivity, limiting their practical applications. In this study, we employed a microalloying approach to enhance film performance by incorporating tantalum （Ta） into silver （Ag） films via magnetron sputtering. The reflective spectra, crystal structure, and surface morphology of the films were systematically analyzed. The results indicate that Ta doping effectively inhibites the preferred growth of the Ag（111） crystal plane. Furthermore, high-vacuum thermal stability tests at 600 ℃ confirm that the AgTa infrared reflective coatings retain excellent optical and structural stability, even under elevated temperatures.

The cascaded H-bridge topology exhibits distinct advantages in the field of photovoltaic （PV） power generation with its modular design, smaller filtering inductance, and simplified layout. However, the three-phase cascaded H-bridge inevitably inherits the inherent issue of the single-phase full-bridge inverter, namely, double-line frequency voltage ripple on the DC-link. This issue leads to an output voltage deviation of photovoltaic array from its maximum power point, thereby reducing the power generation efficiency of system. To address this issue, this paper presents an innovative control method based on adaptive third-harmonic injection, which effectively avoids over-modulation risks under varying power factor angles. The method can calculate the optimal third-harmonic injection based on the real-time operating conditions of the system, thereby achieving optimal suppression of DC-link voltage ripple. Finally, a full-scale experimental platform is constructed, and experimental results confirm the effectiveness and feasibility of the proposed method.