地铁对高压天然气管道杂散电流干扰监测评价

Monitoring and Evaluation of Subway Stray Current Interference on of High-pressure Natural Gas Pipeline

在佛山新近开通的地铁二号线附近的高压天然气管道上,选取9个测点,安装了无线远传监测装置,连续记录各测点的通电电位、断电电位、交流干扰电压和牺牲阳极电流等。结合波形分析和EEMD算法,确立了通电电位、断电电位等与地铁运行频次的关联度。参照国内外标准和相关研究,根据断电电位的偏移情况确定了各测点的干扰风险等级,对现有的阴极保护系统提出了改进建议。研究结果表明,管道受到地铁运行的严重干扰,日间通电电位和断电电位均大幅波动,而夜间均呈现平稳状态。通电电位的正向偏移、负向偏移以及断电电位的正向偏移,均与地铁运行频次高度或显著相关,断电电位的负向偏移与地铁运行频次的相关度较弱,更多取决于阴极保护系统自身的性能。使用EEMD算法考察了通电电位,各分量的合成完整地还原了实测结果,说明EEMD算法可用于深入分析地铁所导致的通电电位波动;分量IMF6与地铁行驶周期的重叠,反映该分量可刻画地铁运行的杂散电流影响。9号测点的干扰风险等级为低级,4号、8号测点的干扰风险等级为中级,其余测点的干扰风险等级为高级,并且除2号、4号、8号、9号测点外的其他测点断电电位都处于正向偏移值≥100 mV的水平。防护措施可考虑加装极性排流器。

On the high-pressure natural gas pipeline near the newly opened Subway Line 2 in Foshan,nine measuring points were selected and wireless remote monitoring devices were installed to continuously record the on-potential,off-potential,AC interference voltage and sacrificial anode current of each measuring point.Combined with waveform analysis and EEMD algorithm,the correlation degree between the on-potential,off-potential,etc.and the subway operation frequency is established.Referring to domestic and foreign standards and relevant research,the interference risk level of each measuring point is determined according to the deviation of off-potential,and suggestions for improving the existing cathodic protection system are put forward.The results show that the pipeline is seriously disturbed by the subway operation,and the on-potential and off-potential fluctuate greatly during the day,while they are all in a stable state at night.The positive offset and negative offset of on-potential and the positive offset of the off-potential are all highly or significantly related to the subway operation frequency.The negative offset of the off-potential is weakly related to the subway operation frequency,which depends more on the performance of the cathodic protection system itself.EEMD algorithm is used to investigate the on-potential,and the synthesis of each component completely restores the measured results,which shows that EEMD algorithm can be used to deeply analyze the on-potential fluctuation caused by subway.The overlap of component IMF6 with subway running cycle reflects that this component can describe the influence of stray current generated by subway operation.The interference risk level of No.9 measuring point is low,the interference risk levels of No.4 and No.8 measuring points are medium,the interference risk levels of other measuring points are high,and the off-potentials of other measuring points except No.2,No.4,No.8 and No.9 measuring points are at the level of positive offset value≥100 mV.Protective measures can consider adding a polar drain.