山火条件下的特高压输电线路击穿概率模型研究与分析

特高压输电线路跨越林区、秸秆类农作物,山火的发生会威胁系统运行可靠性和稳定性。综合考虑了山火温度和燃烧产生的碳化小颗粒、灰烬浓烟对输电线路气隙绝缘强度影响,并将山火高度作为气隙击穿电压修正因素,建立了山火条件下的特高压输电线路击穿概率计算模型。仿真结果表明山火条件下特高压相地、相间击穿概率随温度、烟浓度呈现“S”型增长态势;山火高度对相地气隙绝缘强度影响类似于温度因素。且相同山火条件下,特高压相地击穿概率远低于超高压;相同烟浓度下,特高压更易发生相间击穿,但由于相同山火条件下的特高压相间烟浓度更低,其实际相间击穿概率可能低于超高压。

Study and Analysis of Breakdown Probability Model of UHV Transmission Line under Forest Fire Condition

Ultra high voltage(UHV) transmission lines across forest areas and straw crops, and the occurrence of wiforest fire threats the reliability and stability of the power system. Considering the influence of the fire temperature and the carbonized small particles, ashes and smoke on the air gap insulation of transmission line, and the height of wildfires is taken as the correction factor of air gap breakdown voltage, the calculation model of breakdown probability of UHV transmission line under the condition of mountain fire is established then. The simulation results show that the breakdown probability of UHV exhibits a "S" growth pattern with temperature and smoke density. And the effect of fire height on insulation of the air gap is similar to that of temperature. Under the same fire condition, the phase-to-ground breakdown probability of UHV is much lower than that of Extra high voltage(EHV). At the same smoke density, the phase-to-phase breakdown is more likely to occur at UHV. But because of the lower smoke density under the same fire condition, the actual situation may be opposite.