环氧绝缘材料在脉冲热应力下的暂态温度分布研究

发布时间：2019-03-13 09:50

【摘要】：饱和电抗器是HVDC换流阀的核心保护元件,换流阀周期性的导通与关断使饱和电抗器绝缘长期承受周期性脉冲电热应力的联合作用,快速冲击热应力可能使环氧树脂材料更易出现局部微观结构破坏,导致绝缘性能下降。目前对饱和电抗器环氧树脂材料周期性脉冲热应力及其引起的绝缘老化机理尚不清楚,这成为影响高压直流输电可靠性的潜在威胁。基于对饱和电抗器工况及发热原因进行深入调研和分析,得出铜损发热由于水冷系统散热可忽略不计,而铁芯与环氧紧密贴合的结构使铁损发热成为了电抗器内部绝缘的主要热应力源,铁芯发热为周期性脉冲特性,极难计算及进行内部测量。因此本文利用微秒脉冲电流和电热合金形成阻性发热,以相同波形电功率代替铁损功率,提出一种微秒级脉冲热源模拟方法,简化了仿真计算的同时也能在实验室条件下稳定测量。基于以上探知,本文将重点对饱和电抗器环氧树脂材料的热应力分布计算与快速瞬态温度测量两个问题进行了研究。1)采用基于JMAG-Designer的有限元分析软件,建立脉冲功率发热模型,可实现对材料内部us量级瞬态温度分布规律的仿真计算。2)对国内外快速测温方法和传感器技术进行了系统研究,选定光纤分离式红外测温仪和光纤光栅分别作为瞬时和长时测温传感器,并进行对比实验,建立了基于IGA740-LO光纤分离式红外快速测温平台,温度测量响应速度可达6us～9us;3)以冲击电流发生器作为电源,Cr20Ni80镍铬电热合金扁带作为电阻模拟热源,对距离热源不同位置的环氧材料瞬态温度变化进行了实验研究,实验结果表明环氧各点温度变化曲线与仿真曲线趋势相同、响应时间相同,温度峰值误差较小,实测和仿真保持了良好一致性。本文的研究为饱和电抗器环氧树脂绝缘材料在周期性脉冲电热应力联合作用下的老化机理和寿命预测奠定了坚实的基础。
[Abstract]:Saturation reactor is the core protection element of HVDC converter valve. The periodic conduction and turn-off of the valve make the insulation of saturated reactor endure the combined action of periodic pulse electrothermal stress for a long time. Rapid impact thermal stress may make epoxy resin materials more vulnerable to local microstructure damage, resulting in a decline in insulation properties. At present, the periodic pulse thermal stress of epoxy resin materials for saturated reactor and the mechanism of insulation aging are not clear, which has become a potential threat to the reliability of HVDC transmission. Based on the in-depth investigation and analysis of the working conditions and heating causes of the saturated reactor, it is concluded that the copper loss heating is negligible due to the heat dissipation of the water-cooled system. The structure of the iron core and epoxy makes the iron loss heating become the main heat stress source of the internal insulation of the reactor. The core heating is periodic pulse characteristic, so it is very difficult to calculate and carry out the internal measurement. Therefore, a micro-second pulse heat source simulation method is proposed in this paper, which uses the micro-second pulse current and electrothermal alloy to form resistive heating, and replaces the iron loss power with the same waveform electric power. It simplifies the simulation calculation and can also be measured stably under laboratory conditions. Based on the above findings, this paper focuses on the calculation of thermal stress distribution and rapid transient temperature measurement of epoxy resin materials for saturated reactor. 1) the finite element analysis software based on JMAG-Designer is adopted. A pulse power heating model can be established to simulate and calculate the transient temperature distribution of us order in the material. 2) the rapid temperature measurement method and sensor technology at home and abroad are systematically studied. The fiber separation infrared thermometer and fiber grating are selected as instantaneous and long-term temperature sensors, respectively. A fast infrared temperature measurement platform based on IGA740-LO fiber separation is established, and the response speed of temperature measurement is up to 6 us ~ 9 us. 3) using the impulse current generator as the power source and the Cr20Ni80 Ni-Cr alloy flat strip as the resistance simulation heat source, the transient temperature variation of epoxy materials at different locations from the heat source was experimentally studied. The experimental results show that the temperature variation curve of each point of epoxy is the same as the simulation curve, the response time is the same, the temperature peak error is small, and the measurement and simulation are in good agreement. The study in this paper lays a solid foundation for the aging mechanism and life prediction of saturated reactor epoxy resin insulation materials under the combined action of periodic pulse electrothermal stress.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM21

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