A Comprehensive Approach to Investigate RMU Temperature Rise Problem

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<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Air</td>
			<td>/</td>
			<td>/</td>
			<td>Conventional gases</td>
		</tr>
		<tr>
			<td>Aluminum</td>
			<td>/</td>
			<td>/</td>
			<td>Alloy Materials</td>
		</tr>
		<tr>
			<td>Copper</td>
			<td>/</td>
			<td>/</td>
			<td>Alloy Materials</td>
		</tr>
		<tr>
			<td>Icepak</td>
			<td>ANSYS company</td>
			<td>ANSYS 2021R1</td>
			<td>A CFD thermal simulation software</td>
		</tr>
		<tr>
			<td>PC hosting</td>
			<td>/</td>
			<td>12th Generation Intel(R) Core(TM) i5-13500F CPU</td>
			<td>Host computer equipment</td>
		</tr>
		<tr>
			<td>SolidWorks</td>
			<td>Subsidiary of Dassault Systemes</td>
			<td>SolidWorks2021</td>
			<td>An engineering software drawing tool</td>
		</tr>
		<tr>
			<td>Steady-state thermal</td>
			<td>ANSYS company</td>
			<td>ANSYS 2021R1</td>
			<td>A thermal simulation solution tool</td>
		</tr>
	</tbody>
</table>

comparative study of simulation of temperature rise in ring main unit

The ring main unit is a group of high-voltage switchgear mounted in a steel metal cabinet or made of assembled spaced ring network power supply unit of electrical equipment. The overall structure of the load switch and conductive circuit consists of the conductive circuit, which includes a number of components comprising the main core of the ring unit. However, due to its compact internal structure, the ring main unit faces challenges in heat dissipation. This can lead to thermal deformation and aging when operating for extended periods in high-temperature environments. These issues not only affect the service life of the unit but also impact its insulating properties, posing safety risks. In particular, equipment damage and electrical accidents become more likely, posing significant safety hazards.
Within different research areas, scholars have conducted a series of studies on the temperature rise of overhead line switchgear and analyzed various factors affecting the temperature distribution1. In Polykrati et al.2, a mathematical model for the estimation of the temperature rise of components installed on the distribution network during a short-circuit fault is presented. The model was applied to the common disconnecting switches of the network, and the characteristics of the results were plotted according to the different forms of the asymmetrical part of the short-circuit current waveform and the initial value of the short-circuit DC current component. Guan et al., on the other hand, have taken into account the contact resistance and electromagnetic repulsion by building an equivalent contact bridge to simulate the contact interface and further analyzed the electromagnetic-thermal coupling field and temperature rise experiment3. In addition, the researchers investigated the temperature field and thermal stress distribution of the dynamic and static contacts inside the ring main unit by finite element simulation, which provided a basis for the study of circuit breaker life4. Finally, Mueller et al. have focused on the geometrical characteristics of heat sinks and evaluated the effects of material selection, total surface area, temperature uniformity, and maximum surface temperature on thermal performance5. These studies provide valuable insights and methods to improve switchgear performance and reliability, reduce temperature rise, and extend equipment life. Wang et al. proposed a MiNET Deep Learning Model (MDLM) in the UPIOT environment with the purpose of detecting fault diagnosis of electrical ring cabinets, which was validated to have an identification accuracy of 99.1%, which is significantly higher than that of other methods6. Lei et al. studied the thermal performance of a GIS busbar in a steady state using the magneto-fluid-thermal coupling analysis method, thereby optimizing the conductor and tank diameter based on the temperature rise simulation results7. Ouerdani et al. used the RMU temperature rise simulation model to determine the temperature rise at critical locations inside it, thereby fixing the duration of the maximum overload for the components inside the RMU accordingly8. Zheng et al. described a conventional rectangular busbar in a model of high-current switchgear by building a two-dimensional model and applying the finite element method (FEM) for electromagnetic field calculations. It enabled them to obtain the distribution of bus conductor current density and power loss. An irregular busbar was designed after considering the effects of proximity effect and skin effect. This irregular busbar design improved the performance of conventional rectangular busbar9.
As for the aspect of using the icepak simulation, Wang et al. carried out a temperature rise simulation through vortex field, airflow field, and temperature field theories and found that the temperature rise of the ring main unit was more serious under natural convection. They successfully reduced the temperature rise level by adding forced air cooling and making improvements to the internal contact structure10. Zhu et al.11 used the icepak to simulate a thermal model in order to compare the effect of the presence of thermal vias on the PCB and the presence of heat sinks on the temperature of the power devices. Finally, the theoretical analysis is compared with the simulation results to verify the correctness of the theoretical analysis. Mao et al.12 studied the temperature and internal airflow distribution under summer operating conditions by thermal simulation based on the CAE software in the icepak simulation. The problem of how to improve the cooling efficiency and control the temperature rise of multiple silver-plated contacts is given, and the temperature and internal airflow contours captured in the simulation will lay the foundation for the design of the cooling scheme for the six silver-plated contacts mounted in the sealing unit. Conversely, in the use of a steady-state thermal module, Zhang13 Modeling methods are discussed for solving the thermal network of a high-pressure bushing using an alternative transient procedure. Test and simulation results are in good agreement with the thermal steady state and transient states of the bushing. The transient results are then used to evaluate the bushing overload capacity. Vaimann et al.14 developed and analyzed an analytical thermal model of a synchronous reluctance motor for predicting the temperature of its different components and the set total parameter thermal network.
With the continuous advancement of research on electrical equipment such as ring main units, conventional temperature rise tests, and production methods are relatively inefficient. Therefore, by utilizing finite element technology combined with offline tests, not only the design cost issues are addressed, but adjustments and optimizations can be promptly made to real-world problems based on simulations. Based on the research progress mentioned above, the use of ANSYS Icepak and Steady-state thermal coupling for comparative analysis is rarely mentioned. Therefore, the protocol describes the mechanism research of finite elements, uses numerical and morphological combinations to establish a finite element temperature rise simulation model for the enclosure, and discusses the finite element temperature rise simulation model based on the results of the two analytical modules by comparing the results of the two simulation modules. Through the comparison between the two simulation modules, we will get the characteristics of the temperature rise trend of the ring main unit and find the most applicable method so as to provide the necessary basis and research ideas for a strategy to mitigate the temperature rise of the ring main unit.

Author Spotlight: Simulation and Analysis of the Temperature Rise of Ring Main Unit Equipment

دراسة مقارنة لمحاكاة ارتفاع درجة الحرارة في الوحدة الرئيسية الحلقية

The Ring Main Unit (RMU) is a critical device in power distribution systems used for connecting and distributing electricity. However, due to its compact ...

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Comparative Study of Simulation of Temperature Rise in Ring Main Unit

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747 Views.  Wenzhou University. يتناول بحثنا محاكاة وتحليل ارتفاع درجة حرارة معدات الوحدة الرئيسية الحلقية . من خلال مقارنة تحليلين لدرجة الحرارة ، الوحدة ، اشتقنا ارتفاع درجة حرارة الوحدة الرئيسية الحلقية لسيناريوهات مختلفة. كان Aspect أكثر ملاءمة لنقل القطيع وكانت الدراسات في ذلك الصي?...

Video: Author Spotlight: Simulation and Analysis of the Temperature Rise of Ring Main Unit Equipment

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.

This paper addresses the temperature rise problem of the ring main unit by establishing a simplified model and conducting a comparative analysis in two temperature field-solving modules.

Comparing Two Temperature Field-Solving Modules to Address the Temperature Rise Problem of the Ring Main Unit

Begin the protocol by setting up the ice pack model. To do so, right click on the selected component, click edit, and then go to properties to set the material for both the surface and solid materials. First, set the material properties by designating all circuit solid materials with surfaces using copper polished surface as copper pure.For the panel components, select Aluminium606 1-T6 material with a surface coating of Paint-AL surface having an emissivity of 0.35. Select the model, and click on set in the edit menu. Then, choose multi-level meshing level to adjust the mesh settings.Set the external cabinet and all boundaries to a mesh level of two. For all other components, set the mesh level to three. Finally, open mesh control and click generate to create the mesh.Import the geometric model of the temperature field enclosure, established using the design software for meshing. Determine the grid size to balance efficiency and accuracy. For solution setup, set the directions of the solution domain cabinet to opening.In the software, select problem step. Under basic parameters, check the surface to surface radiation model. Choose zero equation for turbulent flow regime, select the gravity option for natural convection, and set the ambient temperature to 20 degrees Celsius.In the file settings, choose volumetric heat losses for EM mapping, and select all objects shown to complete the loss settings. To set up the steady state thermal model, maintain the displayed material properties in the material settings. By clicking on thermal load generation, generate the ohmic losses, resulting from the eddy current field simulation analysis in the steady state thermal module.Click on the convective temperature value and set it to 20 degrees Celsius, with a convective coefficient of five watt per square meter Celsius applied to the inner walls of the cabinet, components, and external cabinet. Apply the settings and click on the generate option to generate a cloud map of the temperature distribution. Set the output to solve for temperature by clicking on solve and output results.Compare the temperature values obtained from the steady state thermal temperature field solving module with those from the ice pack temperature field solution module.