Bao Yanyan, Liu Kang, Wen Dingjun, Li Yifan, Wang Hao, Zhang Hongliang
College of Electrical Engineering and Information Engineering, Lanzhou University of Technology, Lanzhou, China.
Electric Power Research Institute of State Grid Gansu Electric Power Company, Lanzhou, China.
Math Biosci Eng. 2023 May 15;20(7):12056-12075. doi: 10.3934/mbe.2023536.
The ultra-high voltage (UHV) AC/DC grid can provide a platform for sustainable power worldwide. To improve the bus voltage quality of the UHV AC system, AC filters are frequently switched into the UHV grid through circuit breakers with pre-insertion resistors. The pre-insertion resistors suppress inrush currents and operate over-voltage during switching. In this paper, we establish a macro and micro model of the pre-insertion resistor based on its temperature coefficient and micro-morphology. We simulate and analyze its electric-thermal coupling characteristics under standard closing and short-circuit faults. After the simulation model and physical comparison analysis, we find that under a usual closing surge, the electric field distribution of the pre-insertion resistor is uniform and undergoes a slight rise in temperature. However, under a short circuit fault, the temperature rise is drastic and exceeds the maximum allowable temperature, causing glassy melt in some parts of the resistor. Considering the volume ratio of each component of the resistor, a two-dimensional cross-sectional simulation model of the resistor is established to simulate the electric-thermal characteristics of the microstructure of the resistor, and insinuates that the current is concentrated in the carbon channel. That is mainly due to the uneven distribution of carbon material and may lead the local temperature to exceed the maximum allowable temperature and damage the resistor.
特高压交直流电网可为全球可持续电力提供一个平台。为提高特高压交流系统的母线电压质量，交流滤波器常通过带预插入电阻器的断路器接入特高压电网。预插入电阻器可抑制合闸涌流并在开关操作时抑制操作过电压。在本文中，我们基于预插入电阻器的温度系数和微观形貌建立了其宏观和微观模型。我们对其在标准合闸和短路故障情况下的电热耦合特性进行了仿真和分析。通过仿真模型与实物对比分析，我们发现，在通常的合闸冲击下，预插入电阻器的电场分布均匀，温度略有上升。然而，在短路故障情况下，温度急剧上升且超过最大允许温度，导致电阻器部分区域出现玻璃态熔体。考虑到电阻器各部件的体积比，建立了电阻器的二维横截面仿真模型，以模拟电阻器微观结构的电热特性，并表明电流集中在碳通道中。这主要是由于碳材料分布不均，可能导致局部温度超过最大允许温度并损坏电阻器。
