Stator winding is one of the most vulnerable parts in Switched Reluctance Machine (SRM), especially under thermal stresses during frequently changing operation circumstances and susceptible heat dissipation conditions. Thus real-time online thermal monitoring of the stator winding is of great significance to the system protection and lifetime extension of SRM. A sensor-less approach for online thermal monitoring of stator winding of SRM is proposed in this paper, only voltage and current measurements which already exist in the control system are needed to estimate the temperature of stator winding, neither machine parameters nor thermal impedance parameters are required in the scheme. Simulation results under various operating conditions confirm the proposed sensor-less online thermal monitoring approach.
The printed circuit heat exchanger is a typical representative of mini-channel heat exchangers, which are generally applied in many advanced energy and power systems due to their high compactness and efficiency. However, axial heat conduction may significantly decrease efficiency at low mass flow rates, and few studies have focused on enhancing the performance of heat exchangers by reducing axial heat conduction. This study proposes a novel multilayer mini-channel heat exchanger to solve this problem. The axial heat conduction of the new design is reduced by inserting phlogopite layers into the metal sections. The thermal-hydraulic performance of the novel multilayer mini-channel heat exchanger is investigated at different numbers of segments and different mass flow rates using Fluent. The results show that, at low mass flow rate, the performance of the multilayer heat exchanger is superior to that of a traditional heat exchanger. With the increase of heat exchanger segments, the performance of the multilayer heat exchanger is improved. The maximum relative increment in the new heat exchanger efficiency is 1.6%, and the pressure drop is relatively reduced by 12.3%. The difference in performance between the multilayer heat exchanger and the traditional heat exchanger decreases when increasing the mass flow rate. It is recommended that more segments of multilayer heat exchanger should be used for lower mass flow rates to achieve better performance.
In response to energy shortages, uneven distribution, and severe pollution, the global energy structure is rapidly changing. In the dispatching of power systems, the coordinated planning and flexible regulation of virtual power plants play a crucial role. This paper proposes a multi-objective model considering economic efficiency and carbon emissions to study the scheduling of virtual power plants and the proportion of new energy installed capacity. Firstly, the paper optimizes the power system load curve by implementing time-of-use pricing strategies, alleviating the additional pressure on installed capacity caused by demand differences during peak and off-peak periods. Secondly, an improved back propagation neural network method is employed to refine the robust interval, and by integrating feed-back historical data, the adaptive robust control theory is enhanced, thereby improving the system robustness and adaptability. Finally, through specific case analysis and scenario simulation, the paper finds that when the proportion of new energy in the system reaches 60%, it is possible to maximize economic efficiency and minimize carbon emissions while ensuring the stable operation of the virtual power plant.
In wind turbine wake models, Gaussian models depend on multidimensional integration to ascertain the distribution of wake velocity deficits. These integrations, which often involve complex boundary conditions, significantly enhance the complexity of mathematical computations. Due to the difficulty of obtaining analytical solutions, numerical integration methods such as Monte Carlo or other numerical integration techniques are commonly employed. This study presents a three-dimensional wake model (3DJW) for horizontal axis wind turbines, utilizing the Weibull function to simplify wake deficit characterization instead of traditional Gaussian distribution methods. The 3DJW model considers wind shear effects and mass conservation laws to enhance predictions of vertical wake velocities. By integrating incoming wind conditions and turbine parameters, the model efficiently computes downstream wake velocities, improving computational efficiency. To enhance predictions in the ultra-far wake region, an improved three-dimensional Weibull wake model is proposed using the exponential fitting method. Validation through wind tunnel experiments and wind farm data demonstrates the model's accuracy in predicting wake deficits at the hub height, with relative errors in horizontal and vertical profiles mostly within 5% and 3%, respectively. The proposed model enables accurate and rapid calculation of wake velocities at any spatial location downstream, facilitating enhanced energy utilization and reduced costs.
From the perspective of flexible welding robot system design,analyze the structure feature and welding accessibility of winding housing for truck crane and clarify the approach of fixture design.From the perspective of system integration,introduce the system configuration of welding robot system with two work stations,especially present the function and features of the welding robot,the robot peripheral equipment,the welding system and the environmental device.Based on the analysis of performance of the welding robot work station in practical production,it is verified that the welding robot work station,as flexible manufacturing equipment,has been improving the welding quality and productivity of the winding housing,releasing labor intensity and meeting the requirement of mixed-model automatic production.
A new and efficient methodology for optimal reactive power and voltage control of distribution networks with distributed generators based on fuzzy adaptive hybrid particle swarm optimisation (PSO) is proposed. The objective is to minimise comprehensive cost, consisting of power loss and operation cost of transformers and capacitors, and subject to constraints such as minimum and maximum reactive power limits of distributed generators, maximum deviation of bus voltages and maximum allowable daily switching operation number. PSO is used to solve the corresponding mixed integer non‐linear programming problem and the hybrid PSO (HPSO) method, consisting of three PSO variants, is presented. In order to mitigate the local convergence problem, fuzzy adaptive inference is used to improve the searching process and the final fuzzy adaptive inference‐based HPSO is proposed. The proposed algorithm is implemented in VC++ 6.0 program language and the corresponding numerical experiments are finished on the modified version of the IEEE 33‐node distribution system with two newly installed distributed generators and eight newly installed capacitors banks. The numerical results prove that the proposed method can search a more promising control schedule of all transformers, all capacitors and all distributed generators with less time consumption, compared with other listed artificial intelligent methods.
In vehicle dynamics research, a dynamics model is essential, as it provides the basis for the demonstration of early system design of vehicle as well as the verification and optimization of the dynamics performance of the final product. To promote the development of a permanent magnet (PM) Electrodynamic Suspension (EDS) in a maglev train, research was carried out in order to explore a fast dynamics modeling, with suspension system based on two-sided PM. First of all, a halbach array was taken as the object of study, with the analytical solution of its magnetic force obtained by theoretical derivation according to magnet filed and 2D analytical method; then, the magnetic force was discretized into a data matrix of displacement, force, and speed; thirdly, the data matrix was introduced in SIMPACK to establish a magnet-track relationship in scalar form, and a dynamics model of the two-sided PM EDS maglev system was finished by the theory of multi-body dynamics modeling; finally, the proposed modeling was validated by the agreement between theoretical derivation and dynamics model calculation of the heaving frequency and pitching frequency of the frame; at the same time, it was also validated by the agreement of dynamic responses between the modeling by vehicle-track coupled dynamics theory and the dynamic model calculation of the levitation gap and force. According to the established dynamics model, dynamic response of the system at the speed of 600 km/h was calculated, and the feasibility of the two-sided PM EDS maglev train was verified. The simulation speed of model which was established before is 50 times that of the mathematical model by the vehicle-track coupled dynamics, thus providing reference for the future research in this regard.
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