Simulation Of Temperature Rise Research Articles

A mechanism-data driven resistance transfer algorithm for lithium-ion batteries and its application to thermal modeling

In this paper, a resistance transfer algorithm (RTA) is proposed to transfer a known battery's resistance data to a new battery, it saves the cost of testing required for thermal modeling. Firstly, the resistance linearization process is derived based on the Arrhenius equation, and a calibration algorithm for the resistance transfer from the reference battery to the target battery is presented. Then, taking the NCM622 battery (50 Ah) as the reference battery, the RTA is performed on an NCM622 battery (51 Ah) to verify the feasibility. Three schemes are compared to explore the appropriate test number of the target battery required for RTA. Subsequently, the RTA is applied to construct the thermal model of the target battery, and the simulation of the NCM622 (51 Ah) battery temperature rise is completed. Finally, RTA is utilized for resistance transfer and temperature rise simulation at different temperatures for four different batteries to further explore the universality. The verification results demonstrate that the proposed RTA can save a significant amount of resistance testing time and the thermal model based on RTA can supply precise temperature rise prediction. In the cost-effective 4-SOC scheme, the number of resistance test points can be reduced by 55 %, the maximum error of the transferred resistance remains within 0.1495 mΩ and the maximum error of the simulated temperature rise at three ambient temperatures stays below 1.727 °C.

Research on temperature rise performance of DC universal disconnect switch at high altitude

Abstract Low Voltage appliances are used more and more widely in high altitude areas, but the research on their temperature rise performance is still insufficient. Aiming at this problem, a high altitude temperature rise simulation model is established and verified by experiment, and the temperature rise performance is studied. Firstly, a DC universal isolation switch with a rated current of 1600A was used as the carrier to build an electro-thermal coupling calculation model of high-altitude temperature rise. Secondly, the temperature rise experiment of the isolation switch in high altitude environment was carried out to verify the effectiveness of the simulation model. Finally, the temperature fields of the DC universal isolation switch at different altitudes are simulated, and the change of convective heat transfer coefficient is calculated, and the temperature rise performance of the isolation switch at high altitudes is analyzed. With the increase of altitude, the temperature rise of the conductor is significantly higher than that of the insulation shell, and the heat dissipation capacity of the aluminum radiator decreases significantly at high altitude. The model and conclusion can provide reference for the use of low voltage electrical apparatus in high altitude environment.

Comparative Study of Simulation of Temperature Rise in Ring Main Unit.

The Ring Main Unit (RMU) is a critical device in power distribution systems used for connecting and distributing electricity. However, due to its compact internal structure and high current load, heat dissipation issues are particularly prominent. To address this problem, this study innovatively proposes a simplified RMU model, employing finite element simulation methods to accurately solve for the ohmic losses of conductors under actual operating conditions and obtain ohmic loss data for various components. This is the first in-depth investigation of the RMU's temperature rise problem using such a comprehensive approach. Subsequently, the temperature field was solved using two different temperature field analysis modules, with a detailed comparison and analysis of the simulation results to identify similarities, differences, and trends in temperature distribution. The results indicate that the temperature field solution model, which considers convective heat transfer, is more accurate and aligns with actual operating conditions. This research provides an innovative approach and practical solutions for the design and optimization of RMUs. Future research can further explore multiphysics coupling analysis methods to address structural design and mandatory validation issues for high and ultra-high voltage RMUs and other electrical equipment, thereby providing important insights for engineering design.

Simulation of temperature rise in low voltage winding of natural oil circulation transformer and analysis of oil flow heat dissipation

Abstract The heat dissipation performance of an oil-immersed transformer is the key to its stable operation. Winding loss is a crucial part of transformer heat loss, and winding heat dissipation greatly influences the rise in transformer temperature. In this paper, depending on the finite element method, the magnetic field distribution of a 66 MVA (225/26.4 kV) natural oil circulation transformer is analyzed, and the DC and eddy current losses of the low voltage winding are calculated. Based on the finite volume method, the temperature field distribution of the low-voltage winding is calculated, and the heat flux distribution of the contact surface between the disc insulation paper and the oil flow is obtained. It is found that there are transition points and extreme points between the upper and lower surface of the disc and the inner and outer surface of the disc, and the heat flux on the upper and lower surface of the disc conductor has obvious alternating oscillation. This study provides direction for further analysis and understanding of the heat dissipation mechanism and structural design of natural oil circulation transformers.

Temperature rise simulation and thermal strain study of ring main unit

The internal structure of the Ring Main Unit is compact, the gap between the components is limited, and the heat dissipation performance is poor. Working in a high temperature environment for a long time will lead to structural deformation and aging, which will affect the service life and insulation performance, and may even lead to electrical accidents. In order to better solve such problems, this study uses the finite element multi-physics coupling simulation model. According to the characteristics of the Ring Main Unit, the internal components and the body are simplified, the calculation amount is reduced and the simulation accuracy is improved. In ANSYS Workbench, through the coupling calculation of steady-state heat and transient heat, the temperature distribution of the Ring Main Unit circuit under the condition of external temperature is obtained. The temperature change and distribution are further used for the thermal stress and strain analysis of the structural field to obtain the thermal strain distribution map of the conductive circuit under the influence of temperature, which provides theoretical support for the internal structure design of the new Ring Main Unit.

An elastoplastic mechanical-thermal model for temperature rise simulation of two-dimensional triaxially braided composites under quasi-static loads

An elastoplastic mechanical-thermal model for temperature rise simulation of two-dimensional triaxially braided composites under quasi-static loads

Power transformer overload risk evaluation based on temperature rise simulation and fuzzy analytic hierarchy process

The evaluation of transformer overload risk and operational safety is a systematic process. Selecting an appropriate method to accurately assess its overload operation risk is an urgent need for flexible control and safe and reliable operation of power systems. According to the thermal characteristics and state of the transformer, a method for evaluating the overload risk of transformers with improved accuracy based on temperature rise simulation calculation combined with the Fuzzy Analytic Hierarchy Process (FAHP) is proposed. The weights are calculated by fuzzy set theory and FAHP, and the overload risk of the transformer is finally determined. The method comprehensively considers the possible information conflict between the working condition data and the thermal characteristics of the structure itself, and the calculation results are accurate and the process is clear. The calculation results after substituting the actual data show that the method can accurately evaluate the overload risk and operational risk of the transformer. This method is beneficial to identify the relative importance of transformer overload risk factors, calculate transformer overload risk coefficients, and formulate transformer risk control methods.

Use of Cement Hydration Heat as Heating Resource in Curing of Precast Concrete - Temperature Rise Simulation

In the present paper, the effects of the thermal insulation layer on the temperature field of concrete board and further on the development of mechanical properties of the concrete are investigated by a temperature field model that takes cement hydration heat into account. In the modeling, factors that may influence the development of temperature in the board, including the thickness of the insulating polystyrene foam board, concrete strength, and casting seasons are considered. The effect of temperature rise on the mechanical properties of the concrete is evaluated through a model of degrees of cement hydration and compressive strength of concrete. The results show that the temperature inside the concrete board is greatly increased after placing a thermal insulation layer on the surface of the concrete after casting. More uniform temperature distribution along the slab thickness is observed compared to that without the thermal insulation layer. Temperature rise inside concrete board can greatly speed up cement hydration and the development of concrete strength. Curing with a reasonable thermal insulation layer allows the heat of cement hydration to be used effectively to increase the strength of concrete and to realize demoulding around 24 hours after casting.

Study on the Measurement of the On-Site Overvoltage and Internal Temperature Rise Simulation of the EMU Arrester

In order to analyze the explosion accidents of the CRH5 EMU roof arrester in recent years, an internal temperature measuring platform based on fluorescence fiber was established, and the temperature distribution characteristics under the continuous operating voltage and high-current impulse were analyzed. The test results show that passing section overvoltage and steep impulse overvoltage have higher amplitudes, while high-harmonic overvoltage has a lower amplitude but a longer duration. The maximum temperature rise of the arrester was 5.2 °C under 34 kV for 3 h. The surface temperature of the valve plate column was high in the middle and low on both sides; the maximum temperature difference at different positions was only 2.2 °C. The maximum temperature of the valve plate column rose to 97.6 °C under 105 times of the high-current impulse, and the maximum temperature difference at different positions reached 33.8 °C. Then, the actual overvoltage of the arrester in operation was measured and analyzed statistically, and the arrester simulation model was established. The temperature characteristics of the normal arrester and the arrester with the electric tree were studied under the actual typical overvoltage, and the influence of air velocity on the internal temperature rise was analyzed. The simulation results show that, due to the low amplitude and small current of high-harmonic overvoltage, the internal temperature rise of the normal and defective arresters was very small. Under the effects of passing section overvoltage and steep impulse overvoltage, the internal temperature of the normal arrester can reach 36.57 °C and 241 °C, and the arrester with the electric tree defect can reach 44.75 °C and 536 °C, respectively. The air velocity has little effect on the internal temperature rise of the arrester. Passing section overvoltage and steep impulse overvoltage occur frequently and have an obvious influence on the internal temperature rise of the arrester, so the roof overvoltage of the EMU is an important reason for the arrester burst.

Simulation of Steady‐State Temperature Rise of Electric Heating Field of Wireless Sensor Circuit Fault Current Trigger

This article analyzes the structure of the wireless sensor circuit, considering the balance of power consumption, integration, area, noise, etc., and adopts a radio frequency wireless sensor circuit with a low‐IF structure. Through the analysis and comparison of traditional analog current trigger and digital current trigger structure, the feed‐forward current trigger structure is selected, which is composed of received signal strength indicator (RSSI) and variable gain amplifier (VGA), which achieves low power consumption, fast stabilization time, and wide dynamic range design. The received signal strength indicator adopts the form of approximate logarithmic amplifier, five‐stage double feedback loop structure, and realizes lower power consumption. In order to prevent the load current trigger from entering the speed saturation zone, a gain unit structure in which the superimposed current trigger is connected to the NMOS tube as the load is proposed. The test results show that the circuit has a good power consumption performance (1 mW) and at the same time 56.8 dB/m sensitivity. In this paper, through the analysis of the current trigger system and the analysis and comparison of the existing variable gain amplifiers, the variable gain amplifier structure composed of the folded wireless sensing unit and the index control unit is adopted. In order to reduce the power consumption of the circuit and increase the output swing, a structure in which the two‐stage folding wireless sensor unit shares the controlled voltage‐to‐current part of the circuit is proposed. Aiming at the design requirements of the system, this article discussed in detail the architecture of the entire temperature measurement node and the design parameters of the chip and completed the overall architecture design of the chip. The simulation results of the steady‐state temperature rise of the electric heating field show that the circuit has achieved an input dynamic adjustment range of more than 60 dB, the maximum power consumption is 1 mW, and the linearity error is less than 0.5 dB. The designed automatic gain control circuit is implemented in SMIC 0.18 cape CMOS process. The simulation results of the steady‐state temperature rise of the electric heating field show that the circuit has a 56 dB input dynamic adjustment range within a linear error of 1.25 dB, and the time constant is 7.55 ms, and power consumption is 2.84 mW. Through the steady‐state temperature rise simulation and test results of the electric heating field, the correctness of the design is verified and it meets the system requirements.

Soil resistivity modeling for temperature rise calculating of HVDC deep-well earth electrode

Deep-well DC earthing electrode occupied much smaller area than the traditional one, which greatly reduce the difficulty of site selection. However, due to the extremely high current density at the end of linear earthing electrode, temperature rise has become an important factor restricting the development of deep-well earthing technology. In order to evaluate the heating situation of deep-well earthing electrode in an accurate way, this paper carried out the field temperature rise test of deep-well earthing electrode, and the error between the temperature rise result calculated by the wide-area soil resistivity model obtained by conventional measurement methods are analyzed. It was found that the local soil resistivity near the deep-well earthing electrode determines the temperature rise characteristic. Based on the fitting results of the apparent resistivity logging, a local soil resistivity modeling method suitable for deep-well earthing electrode temperature rise calculation is proposed, and the deep-well earthing electrode temperature rise calculation model considering temperature characteristics of water-saturated underground medium and local soil model is established. The calculation result of this model is used to compare with the field measured data of the temperature rise in actual projects, and the maximum temperature error is found to be 5.5 °C. The trend of electrode temperature rise is in good agreement with the test results, which explains the special phenomenon of high temperature rise in low resistance layer. Project cases prove the effectiveness and accuracy of the soil modeling and temperature rise simulation method proposed in this paper.

Limitations in the Application of Computer Simulations of Temperature Rise of Completely New Designs of MV Metal Enclosed Switchgear

Temperature rise simulation deals with different physical domains describing heat generation and heat dissipation effects. Cigre working group A3.36 has conducted a study on temperature rise simulation of switchgear for distribution and transmission level. The working group built up new, manufacturer independent devices. Members of the working group simulated the temperature rise in advance to the tests, which were performed at laboratories of universities, as independent parties. In order to assess the simulation accuracy, the simulation results are compared to each other and to the measured results. This paper summarizes the main findings from the medium voltage device. The study has shown that when simulating the temperature rise on a completely new design, with reliable input values of contact resistances and emissivity coefficients, an accuracy of about 25% could be expected. Primary reason seems to be based on the complexity of simulating the heat dissipation mechanisms. To get a more accurate result, verification and validation is needed in order to adjust the parameters determining the heat dissipation. This study has also illustrated that it requires good knowledge (especially of the radiation) in order to adjust these parameters properly.

A Novel Modularizing Design Method of 10 kV High Voltage Switchgear for Live Maintenance

Due to imperfect manufacturing technology, design defects and environmental impact, the failure rate of 10 kV switchgear is very high. For this reason, based on taken present situation of traditional switchgear and the current technical requirements for switchgear into account, a new reliable and safe modular high voltage switchgear design method is presented in this paper, which can reduce the failure rate of switchgear and improve the reliability of power supply. The electric field and temperature rise simulation model are established to check the reasonability and validity. By using the finite element software, the simulation results show that the design in this paper has a maximum temperature rise of 55 K for the main cabinet and a maximum temperature rise of 45 K for the deputy cabinet, which is far below the international standard of 70 K. The areas where the partial discharge is likely to occur within the switchgear are places such as the connection between bus-bar and cabinet, bus-bar joint and bus-bar corner. In order to avoid potential dangers, the discharge point must be located in time to prevent insulation fault of electrical equipment of the high voltage switchgear. The simulation results demonstrate that the design method in this paper greatly improve the reliability of switchgear and meets the demands of power system.

Characteristic Analysis and Temperature Rise Calculation of PMSM Under Different Power Supply Modes

In the servo system, the performance of the permanent magnet synchronous motor (PMSM) is affected by the controller. Based on the software interface technology, this paper establishes a cosimulation system of PMSM finite element model and control system, and compares the operating characteristics of the motor under sine wave power supply and inverter power supply. On this basis, the loss and temperature rise of the motor under two power supply modes are calculated. Finally, the temperature rise simulation results are compared with the prototype measurements. The results show that the temperature rise calculation result of the motor when the inverter is powered in the simulation model is very close to the measured result of the prototype.

A Data-Driven Residential Transformer Overloading Risk Assessment Method

Residential transformer population is a critical type of asset that many electric utility companies have been attempting to manage proactively and effectively to reduce unexpected failures and life losses that are often caused by transformer overloading. Within the typical power asset portfolio, the residential transformer asset is often large in population, having lowest reliability design, lacking transformer loading data and susceptible to customer loading behaviors such as adoption of distributed energy resources and electric vehicles. On the bright side, the availability of more residential operation data along with the advancement of data analytics techniques have provided a new path to further our understanding of local residential transformer overloading risks statistically. This research developed a new data-driven method to combine clustering analysis and the simulation of transformer temperature rise and insulation life loss to quantitatively and statistically assess the overloading risk of residential transformer population in one area and suggest proper risk management measures according to the assessment results. Case studies from an actual Canadian utility company have been presented and discussed in detail to demonstrate the applicability and usefulness of the proposed method.

Temperature Rise Simulation of Medium Voltage Cubicle Type Gas Insulated Switch-Gear Based on Coupling of Multi-Physical Fields

Usage of Cubicle type Gas-Insulator Switch-gear (C-GIS) is gradually increasing in power system. During the operation of C-GIS, long-term excessive temperature rise leads to degeneration of insulation and mechanical property, which may finally leads to fatal accidents. In order to analyze the temperature distribution of the C-GIS, the model of a 40.5 kV medium voltage SF 6 insulated C-GIS has been established and simulations based on electromagnetic-fluid-temperature coupling are carried out. In the simulations, eddy-current filed is solved by ansys-multiphysics to obtain the heat generation inside the C-GIS. In order to improve calculation accuracy, the contact resistance is taken into consideration and the physical characteristics of SF 6 gas are considered to be related to the temperature. First, simulations with and without surrounding air environment considered are carried out and the results are compared. The type test of temperature rise is also conducted to verify the simulation results. The simulation results are found out in agreement with experimental results. Second, in order to reduce the temperature rise and improve the design of C-GIS, recommendations are put forward. The influence of the cooling system and surrounding barriers is analyzed by numerical simulation.

Optimum Methods of Thermal-Fluid Numerical Simulation for Switchgear

Thermal-fluid coupled calculation is an effective way to simulate the temperature rise and heat dissipation process of switchgear. But there are still problems such as huge calculation and low accuracy need to be solved. This paper discusses the optimization methods of the thermal-fluid coupled field for the switchgear from grid controlling, boundary conditions, and heat source calculation. First, the mesh adaption method based on posterior error estimation is proposed to achieve efficient mesh refinement with less redundancy. The final mesh size is only 32.3% of that obtained with the traditional global-refining method. Then, an external flow model is built to obtain the convective heat transfer coefficient of the enclosure, replacing the process of artificial choosing. The results show that the convective heat transfer coefficient at the enclosure under natural convection is 0.4 W/(m 2 ·°C) ~1.4 W/(m 2 ·°C). Afterwards the eddy current field is used to solve the heat generation in the switchgear. The heat sources are coupled to the thermal-fluid calculation so that the influence of current non-uniformity, contact heat, and eddy loss is considered. At last, the methods are applied to the steady-state temperature rise simulation of KYN28A-12kV/630A switchgear and the results are compared with the test data. The maximum relative error between simulation and experimental results is 3.43%, which proves the validity of the mentioned methods.

Simulation of temperature rise within a rolling tire by using FE analysis

A simulation method is proposed to predict temperature rise within a dynamic rolling tire. The friction heat from tire-road contact and the internal heat generated by hysteresis loss caused by rubber deformation are considered in the simulation model. A systematic process was developed to calculate the heat generation rate by using dissipated energy, and it was applied to the simulation model by establishing user subroutines. An axial tensile test was conducted for the rubber specimen, and the obtained stress-strain curve was applied to the simulation model based on the first-invariant Marlow model. The reliability of the simulation method was verified by comparing the tensile simulation and test results. A simplified 3D finite element tire model was developed, and simulations were performed in dynamic rolling conditions. Heat was generated because of friction and internal deformation. The temperature distribution within the tire, which was derived using the model, indicates that the proposed simulation method is reliable.

An LCC-C Compensated Wireless Charging System for Implantable Cardiac Pacemakers: Theory, Experiment, and Safety Evaluation

The technique of wireless power transfer (WPT) via magnetic coupling resonance provides a way to transfer power wirelessly to cardiac pacemakers from external source. For wireless charging system to be used in clinical environment, this paper gives priority consideration to three technical difficulties, i.e., implantation, efficiency, and safety. The LCC-C compensation topology for pacemaker wireless charger is presented, where only one secondary side resonance capacitor needs to be implanted, and resonance compensation parameters are derived. The compensation network can make the WPT system operate at stable resonance and high efficiency. The prototype of the wireless charging system for implantable cardiac pacemaker is developed, where a thin flexible receiving unit was designed to effectively shield eddy currents in the pacemaker shell. The experiments of wireless charging through pork tissues reveal that 3.072-W power can be received from a 3.919-W power source at 300 kHz, reaching a rather high WPT efficiency of 78.4%, such that the charging is fast, i.e., the 1050 mA·h, 4.2-V Li-ion battery voltage increases from 3.98 (80% residual capacity) to 4.2 V within only 27 min, and only 3.3 °C maximum temperature rise of the pork is in safe limits. The feasibility and safety of the charging system were further evaluated by simulations of specific absorption rate and temperature rise in human tissues and electromagnetic fields in the pacemaker case.

Numerical Simulation and Field Test of the Transient Temperature Rise of HVdc Grounding Electrodes

This paper investigates the temperature rise of vertical/horizontal high-voltage direct current (HVdc) grounding electrodes by simulations and field tests. Based on a field-circuit coupling current distribution model and a three dimensional (3-D) finite element model, a comprehensive methodology is proposed to analyze the transient temperature rise. Since soil resistivity varies with temperature around the electrodes, the temperature-dependent soil resistivity is tested, and then approximated by an empirical formula. Moreover, two practical tests are implemented to validate the simulation model. By ignoring the underground water fluctuations, the calculation results match test results nicely, which demonstrates that the terminal effect of the vertical electrode significantly affects the temperature distribution. But for a horizontal grounding electrode, the current distribution is more uniform than the vertical one. This study provides valuable references for design of HVdc grounding electrodes.