In response to the demand for voltage sag mitigation devices in the film industry, a super capacitor energy storage DC support device has been developed. The working principle of the super capacitor energy storage DC support device is introduced, and the design of the main circuit and control system is described in detail. The test waveform is also provided. Through test data and field application results, the problem of equipment downtime caused by sag in film enterprises has been well solved, meeting the requirements of continuous production in the film industry.
Aiming at the problem of how to predict the remaining life of railway relay accurately and efficiently,a life prediction method of railway relay based on TPE-Informer model is proposed.Firstly,the electric life test platform of railway relay is built to obtain the degradation data of its whole life cycle,and the characteristic parameters that can reflect its operation state are extracted from it.Secondly,the extracted feature parameters are input into the Informer model for training,and the multi head sparse self-attention mechanism is used to mine the correlation between the states before and after the feature information.Finally,the tree-structured parzen estimator(TPE)is used to optimize the hyper parameters of Informer model to obtain better prediction performance.The experimental platform is used to collect data to verify the model,and the results are compared with the other three deep learning algorithms.The experimental results show that the proposed prediction model has higher prediction accuracy than RNN,LSTM and Informer models,with an average accuracy of 96.52%,small error rate and good stability,which proves the feasibility of the application of the prediction model.
The axially-split phase spherical bearingless flywheel machine (ASP-SBFM) operates mostly in fast charging and discharging conditions. The unique topology design and high power density of the ASP-SBFM can lead to complex machine losses and result in high-temperature rise. This article employs magneto-thermal coupling to perform an accurate analysis of the temperature field distribution of the ASP-SBFM. First, as the heat source for machine temperature rise, the ASP-SBFM losses are analyzed in detail. And the theoretical calculation results agree well with the FEA results. Then, the magneto-thermal coupling method is conducted to obtain the accurate temperature distribution of ASP-SBFM, where both natural cooling and high vacuum conditions are considered. The temperature distribution results can provide a reference for machine heat dissipation design, topology optimization, and machine body material selection.
With the comprehensive promotion of the"dual carbon"goal,the demand for new energy is increasing day by day.It is urgent to promote the coupling and interconnection of railways,new energy,and energy storage,and promote railways'low-carbon and green development.Therefore,a low-carbon economic optimization operation model of high-speed rail new energy hybrid energy storage system is proposed.Firstly,in order to further mobilize the enthusiasm of the railway industry for carbon reduction,the carbon benefits is incorporated into the operating model of the high-speed rail system,and a mathematical model of the hybrid energy storage system composed of vanadium batteries and supercapacitors is established.Then,the Latin hypercube random chance constrained programming method is used to deal with the uncertainty of new energy,an energy management strategy of hybrid energy storage system is proposed,the stop charging and discharging threshold of vanadium battery and the configuration parameters of energy storage capacity are taken as the optimization variables,and the maximum total net benefit of new energy hybrid energy storage system for the high-speed rail system in the whole life cycle is taken as the optimization objective,the adaptive particle swarm optimization algorithm based on Cauchy mutation is used to solve the practical example.Finally,the effectiveness and superiority of the proposed scheme and algorithm are verified through comparison and analysis.
Transmission lines'live working is one of the effective means to ensure the reliable operation of the lines.In order to solve the unsafe problems existing in the implementation of traditional live working.Grounded LIDAR is used to collect point cloud data,and a tile based on the pyramid data structure is employed to complete the storage and calling of the data.The improved bidirectional filtering algorithm is used to quickly distinguish surface features and obtain a 3D model of the site.Considering the characteristics of live working,data reading and query speed,the nearest point search algorithm based on octree is used to calculate the safety distance of each point in the planned path in real time,and the safety of the operation mode is obtained by comparing with the value specified in the regulation,and assist decision-making of the implementation plan.The actual working condition simulation is carried out by taking"the hanging basket swing method"as an example.The experimental results show that the established 3D model can meet the whole process control of the operation,and has achieved practical effect.
The current life assessment of power devices only predicts the lifetime of the devices in continuous operation, and does not take into account the changes of thermal resistance caused by device aging and dust accumulation in the whole life cycle. In order to solve this problem, this paper takes the electric vehicle charging module as the application scene, selects the VIENNA rectifier as the front-stage topology of the 30 kW charging module, and proposes a flexible equivalent thermal model to characterize the aging and dust accumulation of the devices. Considering the influence of the mission profile of the devices working intermittently, the lifetime of the continuous working power devices and the actual intermittent working power devices in different scenarios are predicted respectively.
To explore the synergistic optimization effect of electric heat pump and gas heat pump,a regional comprehensive energy system(RIES)economic dispatch method for the coordinated operation of multi-source heat pump systems is proposed.Firstly,a comparative exposition of the technical characteristics of electric heat pump and gas heat pump is conducted.Based on the energy hub,various energy flows of the system under the multi energy complementary operating conditions of electric heat pump and gas heat pump are analyzed.Secondly,based on the price advantages of electricity and gas energy,electric heat pump is used for electric cold energy coupling during peak electricity periods,and gas cooling is replaced by gas heat pump during peak electricity prices to improve the peak valley characteristics and operating costs of the system's electricity load.Finally,a collaborative optimization dispatch model for electric heat pump and gas heat pump is established with the optimal system cost,and solved by using CPLEX software.The calculation example shows that the coordinated operation of electric heat pump and gas heat pump can fully leverage the advantages to reduce the operating cost of the system and optimize the interaction power fluctuation of the interconnection line.Moreover,the proposed method has good environmental benefits.
In order to solve the problem of soil heat imbalance caused by the uneven operation time of ground source heat pump in winter and summer,an optimal scheduling method of regional integrated energy system considering the balance of heat discharged from soil was proposed.First,according to the operating characteristics of ground source heat pump in winter and summer,the annual heat imbalance rate of soil is calculated.Secondly,increase the use time of ground source heat pump in the cooling season to increase the heat output from the soil,so as to ensure the heat balance of ground source heat pump throughout the year.Finally,a double-layer optimization model is constructed.The upper model optimally arranges the output of ground source heat pump based on the system operating cost in winter.The lower model optimizes the output of ground source heat pump based on the system's optimal benefit in summer,taking into account constraints such as the soil heat extraction and emission balance.Simulation examples show that the proposed method effectively solves the problem of soil thermal imbalance and improves system energy efficiency.
The interaction of internal wakes in wind farms affects the inflow wind speed of downstream wind turbines.To reduce the impact of wake effects on the power generation of floating wind farms,a yaw optimization control strategy of floating wind farms considering wake effects is proposed.A Gaussian curl mixed wake model is established for the specificities of the wake recovery speed changes and the impact on the wake of downstream units under yaw conditions.Considering the influence of yaw conditions on the blade displacement,the blade root load,and platform motion,a range of unit yaw angles is set as a constraint condition.Using the least squares SLSQP optimization algorithm,the optimal yaw angle and power generation of each unit in the wind farm are obtained with the maximum overall power generation as the objective function and the yaw angle as the optimization variable.The simulation results show that the proposed control strategy can effectively improve the overall power generation of the wind farm.
Molded case circuit breakers(MCCB)below 125 A are main force in the field of MCCBs.The main way to integrate and improve them is to elevate 63 A and 100 A products to 125 A with short circuit breaking being the main difficulty.It is possible to preliminarily increase its breaking capacity through gas producing materials.Quantified data analysis can be conducted on the condition of the arc extinguishing chamber's grid segments through the measurement and analysis of grid voltage.The simulation of electromagnetic force is used to optimize the magnetic field of the contact part.By improving the design,the new 125A product can replace the original product and meet the performance requirements while reducing the cost of the main product.
In view of the large initial investment of park micro-grid and the uncertainty of distributed power generation,in order to fully explore and quantitatively evaluate the economic benefits of micro-grid operation,a micro-grid economic operation evaluation method based on probabilistic income analysis algorithm is proposed.In this algorithm,the uncertainty of micro-grid investment income is quantified from the perspective of income probability distribution,the resource uncertainty and prediction uncertainty are fully considered,the uncertainty models of load and photovoltaic output are established,and a large number of random scenarios are generated.By using Monte Carlo method to analyze the micro-grid monthly income,the corresponding income probability distribution curve is generated to realize the quantification of micro-grid uncertain income.The calculation results show that the method can compare the benefits of different micro-grid configuration parameters,and provide a scientific basis for the investment decision of park micro-grid.
The temperature rise to a certain extent restricts the miniaturization and lightweight development of automobile relays.It is particularly important to analyze the temperature field of automobile relays to improve their heat resistance.The computational fluid dynamics(CFD)simulation tool based on heat conduction differential equations,fluid motion control equations,and radiation heat transfer equations is used to propose a temperature field simulation method for automobile relays based on fluid structure coupling.Using the proposed method the temperature field distribution of a certain automobile relay under different environmental temperatures and load current levels are obtained.The proportion of heat dissipation through conduction,convection,and radiation is calculated.the heat dissipation law of the relay and coil under different environmental temperatures and load current levels is analyzed,which can lay a foundation for the subsequent thermal design and temperature rise optimization of automobile relays.
The defective products of AC contactor emit abnormal electro-magnetic noise after the coil is energized,which exceeds the specified noise value.According to the characteristics of AC contactor sound signal,a method combining maximum correlation kurtosis deconvolution(MCKD)algorithm and envelope spectrum analysis is proposed to extract the fault frequency and realize the abnormal vibration noise fault diagnosis of AC contactor.Firstly,the collected original signal is filtered by a band-pass filter to reduce noise interference.Then,the optimal MCKD parameters are searched by the particle swarm optimization algorithm.The signal is deconvolved to enhance the periodic pulse in the signal.The signal processed by the MCKD algorithm is used to obtain the envelope spectrum through Hilbert transform,and the fault frequency amplitude factor is used as the criterion to determine whether the AC contactors is faulty.The actual test of AC contactor shows that the method can effectively diagnose the abnormal noise of AC contactor.
The 60Si2Mn contact sheet of bridge contact in the circuit breaker experiences abnormal fracture under the static state.A detailed analysis is conducted on the microstructure and fracture morphology of the contact sheet using methods such as the macroscopic examination,the metallographic analysis,and the fracture analysis.A finite element model is established to simulate and analyze the stress situation of the contact sheet in using.The results show that the microstructure of the contact film is normal.The fracture morphology is mainly brittle fracture.The maximum stress value at the notch of the contact sheet is 1 818 MPa.Through the finite element analysis,the contact sheet with no notches and decreasing the length of the inner teeth by 4 mm is recommended to reduce the overall stress of the contact sheet.
GaN devices are widely used in totem-pole bridgeless PFC circuits due to their excellent switching performance.In the inductor current critical continuous mode(CRM),Totem-Pole bridgeless PFC can achieve soft switching of the switching tube across the full input voltage range through the reasonable control.In view of the problem of complex control timing for the control mode based on the traditional current zero-crossing detection(ZCD)circuit,a soft switching control strategy based on the current state detection circuit is proposed to reduce the complexity of control.The design pressure of the EMI filter is reduced by adopting an interleaved parallel structure,and the power inductances of the two-phase circuit are integrated by using decoupling magnetic integration technology.Finally,a 3 000 W GaN-based interleaved bridgeless totem-pole PFC rectifier is built.The effectiveness of the proposed circuit design scheme is verified by experiments.
Aiming at the problems of difficult fault line selection and slow detection for the small and medium current grounded systems in distribution networks,a multi criterion fusion method for line selection of small current single-phase ground fault based on convolutional neural networks(CNN),Fourier transform and wavelet packet decomposition is proposed.CNN is applied to the problem of line selection for small current single-phase ground fault.Some components of the zero-sequence current of each line after processing are taken as input,and the fault line is taken as output.After a large amount of data training,the mathematical model of the fault line is obtained.When the new fault data is input into the model,the fault lines can be selected based on the mapping relationship.Finally,the feasibility of the proposed method is verified by the simulation using MATLAB/Simulink.
The causes of the turn off peak voltage of power devices in diode clamped three-level converters is analyzed.The various methods of suppressing the turn off peak voltage in engineering is discussed.Then,the matters needing attention in the use of commonly used peak voltage absorbing circuits is emphatically analyzed.The analysis results show that when the traditional RCD voltage peak absorption circuit is applied to three-level circuits,there is a problem of generated instantaneous short circuit currents if the dead time is insufficient during state transition,which poses a threat to the power circuit.Therefore,it is more appropriate to use a simplified RC absorption circuit.Finally,the above analysis is verified by simulation.
A non-contact voltage regulating and stabilizing power supply for medical equipment without the need for the conductive slip rings is designed to address the issue of wear and tear on the rotating side of medical equipment that requires direct current power supply.By utilizing the electrical isolation characteristics and voltage gain characteristics of LLC,a circuit with complete isolation of the primary and secondary sides and relative rotation is designed and implemented.Through experiments,the non-contact voltage regulation and stabilization is achieved,which can provide a feasible approach for the power supply of this type of equipment.
Hermetically sealed electromagnetic relay(HSER)used in aviation and aerospace have high requirements for long-term on-load reliability.Accelerated degradation test is usually used to predict reliable life.In the multi-stress accelerated degradation test,the failure mechanism of HSER must be consistent,otherwise the product life prediction will have a large deviation.Therefore,the study on the failure mechanism consistency of accelerated degradation test is of great significance to improve the accuracy of reliable life prediction of HSER.Firstly,based on the principle of likelihood ratio detection,a consistency criterion is proposed to design an accelerated degradation test for a typical HSER.The test data is analyzed,and the consistency is checked by the criterion.After obtaining a consistency conclusion,the destructive physical experiments are carried out to analyze the degradation of the permanent magnet and spring.The effectiveness of the proposed criterion is verified.
研究继电器个体的可靠性具有重要意义,有必要对继电器进行寿命预测.由于传统预测方法的建模过分依赖于设备的领域知识,故将深度学习应用于寿命预测领域.首先概述了继电器的贮存失效机理,其次介绍了继电器剩余使用寿命预测的研究现状,接着分析了深度学习的几种常见模型方法及其特点,最后对深度学习应用于剩余使用寿命预测进行展望.
