有限元法应用于电缆终端应力锥缺陷分析

Analysis of Faults on Cable Terminal Stress Cone Based on Finite Element Method

为了研究电缆终端应力锥出现缺陷时,高压静电场的分布和数值大小,采用有限元法,计算了加载110kV恒定电压于电力电缆上时,其终端的静电场分布与数值。当电缆附件预制式应力锥内侧出现凹陷时,凹陷处电缆表面与应力锥内侧不能完全密合,将形成由电介质填充的腔体。针对该现象,按照凹陷可能出现的位置和形状建立多个模型,然后计算110kV恒定电压下该模型电场强度的数值大小和电场分布,着重分析了凹陷周围的电场畸变。最后比较不同模型仿真结果表明小尺寸较大尺寸凹陷的场强大,畸变更严重,凹内介质为硅脂较空气时场强小。预制式应力锥内侧缺陷的存在,可能对电力设备安全运行造成危害。

The electric-field intensity around the power cable terminal is computed based on the finite element method when the power cable is loaded on the 110kV constant voltage source. If there are depressions on the inner flank of the pre-fabrieated stress cone, the surface of the power cable can not contact with the inner flank of the stress cone closely and the depression would cause the cavity that would be filled with the electrolyte. So the materials＂ characteristic changes suddenly on the space and the distribution of materials＂ dielectric constants are discontinuous on its mathematical model. The phenomenon could cause the local electrical field distorted and the electric-field intensity increasing sharp. It is ruinous for the insulation materials when the local electrical field is distorted for the intensity exceeding the dielectric strength possibly. Therefore, to analyze the electric-field distortion around the depressions, mathematical models are established according to the depressions and the distribution of the electric-field intensity on the models is computed when loaded on the 110kV constant voltage source. At last, the maximum intensity values from the different models are compared, and the potential harm of the depression to the safe operation of electrical equipment is analyzed.