基于均衡应力分布的高压电缆接头保护装置安全裕度提升方法

Safety Margin Improvement Method of High Voltage Cable Joint Protection Device Based on Equilibrium Stress Distribution

高压电缆接头短路电弧易引发爆炸、失火,造成二次伤害,需加装保护装置。而保护装置结构的不均匀性导致应力分布畸变,出现防爆薄弱环节,针对性地提出了基于均衡应力分布的电缆接头保护装置安全裕度的提升方法。采用爆源等效方式,利用基于温度场、流体场、位移场耦合的有限元计算方法,对保护装置内部短路电弧冲击过程进行仿真计算。以220 kV弹簧收缩泄能方式电缆接头保护装置为计算实例,保护装置内部应力最集中的区域位于端头收缩处,应力畸变率达到24%,端头收缩处的应力导致装置的安全裕度值仅为4.09%。因此认为提升电缆接头保护装置安全裕度的关键在于降低应力畸变率。进而提出了在电缆接头保护装置内侧应力集中区域覆盖陶瓷化硅橡胶高分子复合耐火材料的方法来提升保护装置的安全裕度,经计算选择6 mm厚的材料覆盖内侧应力集中区域,可将装置的应力畸变处的畸变率降至7%,安全裕度值提升至31.81%,使保护装置整体的安全裕度提升至18.18%。与传统提升方法相比,更具针对性,促进设备的轻质化发展,为220 kV高压电缆接头安全设计提供了新的解决思路与方法。

High-voltage cable joint short-circuit arcs can easily cause explosions and fires,resulting in secondary damage,so protective devices need to be installed.The irregular structure of the protection device leads to the deformation of the stress distribution,which becomes the weak link of explosion protection.A method to improve the safety margin of cable joint protection device based on equilibrium stress distribution is proposed.Using the explosion source equivalent method and the finite element calculation method of coupling temperature field,magnetic flux field and displacement field,the simulation calculation of the short-circuit arc impact process in the protection device is carried out.Taking the 220 kV spring contraction energy release method cable joint protection device as a calculation example,the area with the most concentrated stress inside the protective device is located at the end contraction,with a stress distortion rate of 24%,and the stress at the end contraction results in a safety margin value of only 4.09%for the device.It is considered that the key to improve the safety margin of the cable joint protection device is to reduce the stress distortion rate.A method of covering the inner stress concentration area of the cable joint protection device with ceramic silicon rubber polymer composite refractory material is proposed to improve the safety margin of the protection device.After calculation,a material with a thickness of 6 mm is selected to cover the inner stress concentration area,which can reduce the stress of the device.The distortion rate at the stress distortion point is reduced to 7%,and the safety margin value of the protection device is increased to 31.81%,increasing the overall safety margin of the protection device to 18.18%.Compared with the traditional improvement method,it is more targeted,promotes the development of lightweight equipment,and provides new solutions and methods for the safety design of 220kV high-voltage cable joints.