Evaluation Model for the Scope of DC Interference Generated by Stray Currents in Light Rail Systems

Abstract

Electrochemical corrosion caused by stray currents reduces the lifespan of buried gas pipelines and the safety of light rail systems. Determining the scope of stray current corrosion will help prevent the corrosion of existing buried pipelines and provide an effective reference for new pipeline siting. In response to this problem, in this paper the surface potential gradient was used to evaluate the scope of stray current corrosion. First, an analytical model for the scope of the stray current corrosion combined with distributed parameters and the electric field generated by a point current source was put forward. Second, exemplary calculations were conducted based on the proposed model. Sensitivity of the potential gradient was analyzed with an example of the transition resistance, and the dynamic distribution of surface potential gradient under different locomotive operation modes was also analyzed in time-domain. Finally, the scope was evaluated at four different intervals with the parameters from the field test to judge whether the protective measures need to be taken in areas with buried pipelines and light rail systems nearby or not.

Stray Current Protection and Monitoring Systems: Characteristic Quantities, Assessment of Performance and Verification

“…When only TPSs are equipped with track voltage measurement points, not only are such points quite sparse (separated, e.g., by 2–4 km) but readings are taken in front of the TPS, where the track voltage change is the least (the track resistance from the power supply point is minimal), with an arguable representativeness and comprehensiveness of such track voltage monitoring. This is also confirmed by [ 4 ], Figure 3 , where the maximum stray current (at train position) is minimal when the train passes in front of the TPS. When VLDs are located at all stations (e.g., for electrical safety reasons), then the density of the measurement points is increased and track voltage is monitored about every 0.6–1.2 km.…”

“…(3) Output noise not specified. (4) Uncertainty mainly influenced by the offset temperature coefficient. (5) The "rated insulation voltage 50 Vrms" statement in probe datasheet [35]…”

“…Corrosion induced by stray current (SC) is a significant problem of electrified transportation systems (ETSs) and has attracted a lot of attention, especially for systems operated at dc, such as light railways, metros and rapid transit in general: general system analysis [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ] including design optimization and defects [ 8 , 9 ], impact on buried conductive pipes [ 10 , 11 ], with both deterministic and stochastic approaches [ 12 , 13 ]. A marginal impact may be expected also for ac railways [ 14 , 15 ], but the lower intensity of the traction current and the lesser impact of ac on the chemical mechanism of corrosion make it a less relevant problem.…”

Corrosion and stray currents at urban track infrastructure

“…If a vehicle moves at uniform speed or decelerates without the possibility for regenerative braking (return of electricity to the supply grid using engine as generator during braking activity [16]), its electricity consumption will be minimum, and hence stray currents will also be minimum. On the other hand, the consumption of electricity increases with acceleration, which will result in higher stray current values [17,18]. When a vehicle accelerates, the quantity of stray currents will also depend on vehicle acceleration rate, i.e.…”

“…In floating system, during return of electricity from the vehicle to the electrical substation, the electric voltage in the rail will appear as positive as the soil in near the rail vehicle, and negative in the vicinity of the electrical substation. The distribution of voltage along the rails will define points where stray currents will occur [17,18]. GRAĐEVINAR 72 (2020) 7, 593-606 Katarina Vranešić, Stjepan Lakušić, Marijana Serdar…”