计算±1100 kV特高压直流输电线路对埋地油气管线磁感应影响的快速二阶差分方法

A Fast Second-order Difference Method for Calculating Magnetic Inductive Influence of ±1100 kV HVDC Transmission Line on Buried Oil/Gas Pipeline

高压直流输电线路发生极导线对地短路时,导线和地线中电流由于电磁感应在邻近埋地油气金属管道产生纵向感应电动势,造成对管线磁感应危险影响。±1100 kV高压直流输电线路由于线路长,与金属管线交叉邻近的情况复杂,对评估方法的精度和效率有更高的要求。为定量评估危险影响的程度,提出一种采用二阶有限差分技术求解管道中的感应电流和对地电压的新计算方案,其对场线耦合传输线方程中内点采用有限差分技术离散,对管道端部,结合边界条件确定了相应的准确离散格式。通过与已有结果的对比,数值算例表明文中方法的正确性;同时,由于文中方法是二阶精度的,计算结果准确,计算效率高,为快速计算高压直流输电线路的磁感应危险影响提供了基础,可应用于特高压/高压直流输电线路对邻近埋地金属管线危险影响的评估。

When HVDC transmission line is short-circuited to ground,the current in pole conductor and ground line generates a induced longitudinal electromotive force in adjacent buried oil/gas metal pipeline due to electromagnetic induction,causing a dangerous influence on the pipeline.±1100 kV HVDC transmission line has higher requirement for accuracy and efficiency of evaluation method because of its longer line and more complicated situation at intersection of metal pipelines.In order to quantitatively assess hazardous impact,this paper proposes a new calculation scheme for solving the induced current and the ground voltage in the pipeline using finite difference technique.The internal points of the field-line coupled transmission line equation are discretized using finite difference technique.The terminal points of the pipeline,combined with boundary conditions,are expressed with corresponding exact discrete format.By comparing with existing results,numerical examples show correctness of the method.At the same time,because the method is of second-order accuracy,the calculation results are accurate and the calculation efficiency is high.This method provides a basis for quickly calculating the magnetic induction hazard of HVDC transmission lines,and can be applied to evaluation of the hazardous impact of UHVDC/HVDC transmission lines on adjacent buried metal pipelines.