高压直流GIL盆式绝缘子非线性电导参数优化

直流气体绝缘输电管道(direct current gas insulated lines,DC-GIL)电场分布受温度梯度、运行电压、金属微粒等诸多因素影响,具有非常大的不确定性,给绝缘设计和运行稳定性带来挑战。非线性电导材料能够自适应地调控直流设备电场分布,有望突破DC-GIL绝缘子设计瓶颈。为了兼顾电场调节作用和损耗特性,建立100 kV直流GIL仿真模型,对比研究运行工况下传统绝缘子、表层电导非线性(surface nonlinear conductivity,SNC)绝缘子和体电导非线性(bulk nonlinear conductivity,BNC)绝缘子的电场分布及损耗功率。通过分析非线性电导(nonlinear conductivity,NC)参数对气固沿面电场调控作用和损耗特性的影响规律,发现SNC绝缘子的电场畸变率先随着欧姆区电导率和非线性系数的增大而快速下降,而后趋于平稳。理想情况下,SNC绝缘子的NC参数应处于电场调节作用的"饱和临界线",且欧姆区电导率最低。而BNC绝缘子的电场调节作用仅依赖于非线性系数,降低欧姆区电导率可降低绝缘子功率损耗。缩比绝缘子实验结果证实了SNC绝缘子非线性参数直接影响DC-GIL沿面闪络电压。

Parameter Optimization of Nonlinear Conductivity Spacer for HVDC GIL

The electric field distribution of direct current gas insulated lines(DC-GIL) significantly depends on the temperature gradient,applied voltage,metal particle,etc.,the uncertainty of which brings huge challenge to the design and reliability.Nonlinear conductivity materials are expected to break the bottleneck through intelligently regulating DC electric field distribution.A simplified 100 kV DC-GIL model was built to calculate the electric field distributions and loss powers of the conventional,the surface nonlinear conductivity(SNC) and the bulk nonlinear conductivity(BNC) spacers.Moreover,the effect of nonlinear conductivity(NC) parameters on the electric field distributions and loss powers of spacers were investigated.The electric field distortion rate of the SNC spacer declines rapidly with increasing the ohmic conductivity and the nonlinear coefficient in the "descending zone",and then reaches the "stationary zone".The NC parameters of an ideal SNC spacer should be on the borderline between the "descending zone" and "stationary zone",and the ohmic conductivity should be reduced to the most extent.The electric field regulating effect of the BNC spacer only relies on the nonlinear coefficient.Flashover test results of the downsized spacers prove the strong relationship between the nonlinear parameters of SNC spacers and surface flashover voltage.