在双极高压直流(high voltage direct current,HVDC)系统中,气体绝缘金属封闭开关设备(gas-insulated switchgears,GIS)可能承受交-直流混合电压.为了提高盆式绝缘子的沿面耐电性能,该文提出了基于多维功能梯度材料(multi-dimensional functionally-graded material,MFGM)的绝缘子交、直流电场协同优化方法,制备了兼具体介电常数梯度材料(ε-functionally gradient materials,ε-FGM)和表面非线性电导材料(surface nonlinear conductivity materials,SNCM)的MFGM绝缘子,并在直流、交流和交-直流混合电压下开展电场仿真计算与沿面闪络测试.结果表明:直流电压下MFGM 绝缘子的凸面中心区域积聚同极性表面电荷,而周围区域积聚异极性表面电荷,使高压三结合点处的电场强度较常规绝缘子降低25%,沿面闪络电压提升约14.5%;交流电压下,MFGM 绝缘子的沿面电场畸变较常规绝缘子降低 21%,沿面闪络电压提升约 18%;交-直流混合电压下,MFGM 绝缘子可同时降低暂、稳态电场分量,沿面闪络电压提升约 12.7%.MFGM 绝缘子满足暂、稳态工况下的沿面电场协同优化需求,在高压直流气体绝缘装备中具有很好的应用前景.
Electric Field Relaxation and Surface Flashover Suppression Under AC/DC Voltages by Functionally Graded Spacer for HVDC GIS
In bipolar high voltage direct current(HVDC)systems,gas-insulated switchgears(GIS)may be subjected to AC-DC mixed voltages.To improve the insulation performance of the basin spacer,this paper proposes a collaborative optimization method for AC and DC electric fields based on the multi-dimensional functionally-graded material(MFGM).A kind of spacer,combining the bulk-permittivity graded materials(ε-FGM)and the surface nonlinear conductivity materials(SNCM),is fabricated,and the electric field simulation and the flashover voltage test under AC,DC and AC-DC mixed voltages are conducted.Results show that:under the DC voltage,homopolar surface charges accumulate in the central region of the convex surface of the MFGM spacer while heteropolar surface charges accumulate in the surrounding area,thus reducing the electric field strength at the HV triple junction point by 25%and increasing the flashover voltage by 14.5%compared to the conventional spacer.Under the AC voltage,the electric field distortion of the MFGM spacer is decreased by 21%and the flashover voltage is raised about 18%.Under the AC-DC mixed voltage,the flashover voltage of the MFGM spacer is raised by about 12.7%.The MFGM spacer meets the requirements of electric field relaxation under both stationary and transient conditions,and it has a promising application prospect in HVDC gas-insulated apparatuses.
high voltage direct currentbasin spacerfunctionally graded materialselectric field relaxationflashover voltage
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