A single-phase ground fault of the AC substation will cause electrical interference to the adjacent pipeline, mainly reflected in the touch voltage, step voltage, and coating breakdown voltage of the pipeline exceed the safety threshold. In order to evaluate the electrical interference effect of an AC substation on adjacent pipelines, the numerical simulation method is used to calculate the relevant safety parameters of the pipeline during the single-phase ground fault of the substation. For the case of touch voltage of the pipeline exceeding the safety threshold, the mitigation methods have been obtained by the software calculation. The specific mitigation method is to connect the pipeline to the grounding of the valve room through the solid state decoupler, and then set the gradient mitigation line in parallel with the pipeline near the substation.
A substation is a place where the power system converts voltage and current and receives and distributes electric energy. When a phase line is abnormally connected to another phase line or ground, a large amount of current will flow into the ground through the grounding bed of the substation. In such case, if metal structures exist such as buried pipelines near the substation, the pipelines often withstand serious electrical interference 1, which causes stray current corrosion of the pipelines 2 and other safety problems. The pipelines are affected by inductive coupling and resistive coupling on a position near the grounding electrode of the substation, instant high current pulse arising from fault current or lightning current discharge may cause damages to external anti-corrosion coating and even pipeline metal, auxiliary equipment and discharge protection devices 3. The extent of damages is dependent on the distance between the pipeline and the grounding body of the substation, magnitude of the fault current or lightning current, duration, soil resistivity, pipeline parameters and factors 4. Therefore, in some cases where a specific pipeline is disturbed by the substation, we need to determine the degree of influence of the substation on the pipeline through specific analysis and calculation.
