Electrical steady-state characteristics and loss reduction measures of tunnel cable system
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 de-rived.The admittance matrix of the non-decoupled node of the micro-element tunnel cable system was es-tablished 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 im-pedance 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 ma-trix 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 2 Ω,the optimal phase an-gle is 60°,whereas if the impedance is greater than 2 Ω,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.
tunnel-cable systemLaurent series expansionnodal admittance matrixinduced voltagesheath circulationloss reduction strategy