For the accumulator filled with phase change material thermal conductivity is low, heat storage time is long and other shortcomings, this paper establishes the concentric triplex tube regenerative heat exchanger builtin intermittent twisted fin model, the use of Fluent software for the melting process of the internal phase change material for the threedimensional unsteady numerical simulation of the structure of the structure of the different twisted fin number and the degree of twisted degree, analyze the phase change material liquid phase rate, the average temperature, the amount of heat storage and the average heat storage rate rule of law with time. Simulation results show that in this paper, compared with the triplex tube regenerative heat exchanger within the research parameters, with the increase of the degree of twist, the complete melting time is gradually shortened, when the twist rate is 2.5, the complete melting time can be reduced by up to 33.1%, with the increase in the number of twisted fins can also shorten the complete melting time, when the number of twisted fins is 4 complete melting time can be reduced by a maximum of 25.6%. The inclusion of intermittent twisted fin significantly shortens the complete melting time of the phase change material and enhances the heat storage capacity, which helps to improve the comprehensive heat storage performance of the triplex tube regenerative heat exchanger.

SeriesResonant ThreePortConverter (SRTPC) applies the traditional phase shifting control strategy when the port voltage mismatch which has the problems of large reflow power and small soft switching range, and this paper will propose a reflux power optimization method based on the phaseshifting plus duty cycle (PWM) control strategy. The complex power model of SRTPC is given by fundamental analysis method and phasor method, and the optimal control strategy of the converter when the reactive power is zero is given and the optimal control variable is solved through the analysis of the SRTPC reactive power (reflux power) model under the premise of ensuring the transmission of certain active power. Furthermore, the conditions for realizing soft switching under the optimized control strategy are further analyzed, and the soft switching range under the two control modes is compared. Finally, the Matlab/Simulink simulation results show that compared with the traditional phase shift control strategy, the SRTPC reflow power under the optimized control strategy has a smaller reflux power, a wider soft switching range, and higher efficiency under the condition of port voltage mismatch.

When the doublyfed machine is connected to the grid, it can support or raise the frequency of the grid by compensating the active power, but the rotor speed decreases quickly and is not controllable, the time of active power compensation and frequency support is limited, and the stability of motor can not be guaranteed. This paper presents a frequency support technique for doublyfed machine (DFIG) phase modulation system with flywheel energy storage based on virtual synchronization control and dynamic speed limit. Firstly, the flywheel is hung on the rotor shaft of the doubly fed machine to increase the inertia of the system, and the mechanical energy storage, and delay the rotor speed decline rate in the process of frequency drop. Secondly, when the frequency of power grid drops, the realtime compensation of active power is carried out by means of virtual synchronization control strategy, and the compensation time of active power is regulated on demand based on the dynamic control of the lower speed limit of rotor. Finally, the validity of the proposed frequency support technology is verified by Matlab/Simulink simulating.

In order to improve the accuracy of ultrashortterm power prediction of wind turbines, this paper proposes a CNNBiLSTM ultrashortterm power prediction method considering the health status of wind turbines and dual attention mechanism. Firstly, considering the influence of the interaction between the environmental factors and the components of the wind turbine on the output power of the wind turbine, he relative error of the normal operation of each component of the wind turbine is used as the deterioration degree of the monitoring index. Secondly, the fuzzy comprehensive evaluation method assesses the health of wind turbines, and the historical data set is categorized based on the evaluation results. Finally, the dual attention mechanism CNN BiLSTM model is used to construct an ultrashortterm power prediction model for the classified data set. The experimental results show that the RMSE and MAE considering the health status of wind turbines are reduced by 17.3% and 20.5% respectively compared with the RSME and MSE without considering the health status of wind turbines.

In transmission lines, due to the influence of line impedance, it is difficult for energy storage power station systems to allocate power reasonably according to capacity. In order to better promote the stable operation of black start, this article proposes a battery power distribution scheme for energy storage power plants based on improved Virtual Synchronous Generator (VSG). This scheme first introduces virtual impedance to eliminate bus voltage fluctuations caused by line impedance, in order to improve the accuracy of power allocation in energy storage power station systems; Then, in response to the problem of uneven power distribution among multiple energy storage units in parallel in an energy storage power station due to the influence of line impedance, the power transmission and circulating characteristics of multiple energy storage devices in parallel were analyzed to continuously improve the black start system. Finally, experimental analysis was conducted using Matlab/Simulink and semi simulation platforms to verify the effectiveness of the proposed strategy, which can improve the stability and economy of system operation.

Aiming at the unbalanced load that the wind turbine is subjected to when it operates above the rated wind speed, an independent pitch control strategy that combines the Radial Basis Function (RBF) neural network and Model Predictive Control (MPC) is proposed. A meanperiod statespace model suitable for controller design is established by means of wind turbine dynamics equations and coordinate transformations. On the basis of Kalman state observer, the model predictive control is used to adjust the pitch angle of the wind turbine instantaneously and the RBF controller to suppress the loads, and then the required independent pitch controller is designed. Taking the NERL 5 MW wind turbine platform as an example, the load characteristics of the independent pitch control strategies based on Proportional Integral (PI), MPC, and MPCRBF are analysed under turbulent winds, as well as their operating characteristics. Simulation results indicate that the method can reduce the load efficiently, improve the operating life of the wind turbine, and have a better suppression effect on the power fluctuation.

With the depletion of resources in flat terrain, the site selection for wind farms is gradually shifting towards complex terrains. Complex terrain presents geographical conditions distinct from flat terrain, the undulating topography leads to intricate flow patterns, and the wind characteristics in complex terrains are also different. Therefore, studying the distribution patterns of flow fields in complex terrain is significant for micrositing of wind farms and wind power prediction. This paper, based on the opensource software OpenFOAM, establishes geometric and numerical simulation models for complex terrain. It investigates and analyzes grids, boundary conditions, and turbulence models suitable for complex terrain. The reliability of the numerical model for complex terrain is compared and analyzed using real measurement data from the Askervein mountain. The paper solves the flow field distribution for typical complex terrains such as isolated peaks, plateaus, and peak clusters, studying the impact of slope and height on the flow fields in different terrains. The research reveals that different terrains satisfy the Reynolds number independence principle. In isolated peak topography, the influence of slope becomes more pronounced in the lee zone behind the mountain as the slope increases. Plateau terrain is more affected by changes in height. For peak cluster topography, the flow field development remains consistent under varying slopes and heights, with height having a greater impact compared to slope. The provided distribution ranges of flow field characteristic values in this paper can serve as a reference for wind farm micrositing and wind power prediction in complex terrain.

The low energy consumption and mild storage and transportation conditions of the clathratebased solid natural gas technology make it a key factor in promoting the development of the natural gas industry. However, the slow hydrate formation kinetics has hindered its application. This article explores the formation laws of methane hydrates supported by porous media (activated carbon and quartz sand) under the action of 1,3dioxolane. It analyzes the hydration efficiency in different systems, evaluates the synergistic and antagonistic effects of 1,3dioxolane and porous media on hydrate growth, and clarifies the influence of the pore structure. The results show that: under high pressure, the adsorption of 1,3dioxolane by the pore structure of activated carbon leads to an antagonistic effect between the two, resulting in poor hydration efficiency. Moreover, as the initial pressure and the concentration of 1,3dioxolane increase, the antagonistic effect intensifies. Under low pressure, there is a synergistic effect between 1,3dioxolane and activated carbon. The hydration efficiency is affected by pressure. The free 1,3dioxolane enhances the formation of methane hydrates and increases the gas storage capacity of hydrates. 1,3Dioxolane enhances the formation of hydrates in the quartz sand system. However, the rapidly growing hydrates limit the conversion of internal water, making this enhancement effect achieve the best performance when the initial pressure is 5 MPa.

Steam methane reforming membrane reactor removes hydrogen through a hydrogen selective permeation membrane, which can promote the forward movement of the reaction, improve methane conversion rate with reduced reaction temperature, and achieve thermochemical storage under mediumtemperature of trough solar collector. However, the characteristics of multiphysical field coupling in the reactor are complex, and the influence of operating parameters on the performance of the reactor needs to be further investigated. The steam methane steam reforming reaction in the membrane reactor driven by solar at mid temperature was taken as the research object in this paper. The multiphysics coupling model of fluid flow, heat/mass transfer and chemical reactions in the reactor was established by using ANSYS FLUENT, and the effects of the key operating parameters (i.e., inlet mass flow rate, temperature, reaction pressure, water to carbon ratio and permeation pressure) on the reactor chemical and thermodynamic performances were studied. The results show that the methane conversion rate and energy efficiency are negatively correlated with the inlet flow rate. The conversion rate of methane is positively correlated with reaction temperature. The energy efficiency first increases and then decreases with the increase of temperature, existing a peak value. When the inlet flow rate is low, the methane conversion rate and energy efficiency increase with the increase of the reaction pressure, while the methane conversion rate and energy efficiency decrease with the increase of reaction pressure when the inlet flow rate is high. The increase of the water to carbon ratio can significantly improve the chemical reaction performance but reduce the energy efficiency. The lower the pressure on the permeation side, the better the reactor performance. The research results are of great significance for highgrade solar thermal utilization.

The study elucidated the relationship between anaerobic digestion gas production efficiency and temperature and hydraulic retention time (HRT) using synthetic glucose wastewater as a substrate. Gas production under different temperatures (37,55 °C) and HRTs (25, 30, 50 d) was compared. The results indicated that the hydrolysis rate of glucose was higher at thermophilic temperature than at mesophilic temperature. However, volatile fatty acids, especially propionic acid, tended to accumulate at thermophilic temperature. Additionally, Methanomicrobiaes and Methanosarcinales were enriched at both moderate and high temperatures, suggesting the presence of pathways for methane production from acetic acid and acetate oxidation at both temperatures, with the acetate oxidation pathway exhibiting greater environmental resilience. The recommended optimal fermentation conditions for treating heavy glucosecontaining wastewater through anaerobic digestion are 37 °C and an HRT of 30 days.