隧道电缆系统电气稳态特性及降损措施

Electrical steady-state characteristics and loss reduction measures of tunnel cable system

为了分析隧道内电缆系统在特殊环境下的稳态特性及降损措施,构建了包含回流电缆阻抗和导纳元素的隧道电缆系统单位长度下的串联阻抗矩阵和并联导纳矩阵。通过Laurent级数展开建立微元段隧道电缆系统节点导纳矩阵,基于级联算法并考虑到长距离电缆系统接地节点的存在得到电缆系统金属护套环流及感应电压分布。在隧道电缆系统交叉互联节点处引入串联阻抗,通过阻抗幅值和相角的配合降低功率损耗。研究结果表明,输电电缆系统交叉互联段护套电压最大可达128.13 V,护套环流最大可达35.63 A,并验证了矩阵解析算法的准确性和有效性。通过阻抗幅值与相角的配合可有效降低功率损耗,当交叉互联系统串联阻抗小于2Ω时,其相角选择60°为最优;当选用的串联阻抗大于2Ω时,其相角选择90°为最优,为隧道电缆系统降损措施提供了计算参考和工程应用依据。

To analyze the steady-state characteristics and loss reduction measures of cable systems within tunnels in special environments,series impedance matrix and shunt admittance matrix of tunnel-cable system formulas including the impedance and admittance elements of the earth continuity cable were derived.The admittance matrix of the non-decoupled node of the micro-element tunnel cable system was established by Laurent series expansion,and the circulating current in the metal sheath and induced voltage were analyzed based on the cascading algorithm which was considered the existence of grounding nodes in the long-distance cable system.Proper coordination between the amplitude and phase angle of series impedance at the cross-bonded joint can effectively reduce the power loss of the cable system.The research findings indicate that the maximum induced sheath voltage appears at the cable cross-bonded joint and is 128.13 V,with a maximum sheath current of 35.63 A,validating accuracy and effectiveness of the matrix analytical algorithm.Effective reduction of power losses can be achieved through the coordinated use of impedance magnitudes and phase angles.When the impedance is less than 2Ω,the optimal phase angle is 60°,whereas if the impedance is greater than 2Ω,the optimal phase angle should be 90°.This study provides computational references and engineering application foundations for the loss reduction measures of tunnel cable system.