The task of determining the voltages induced on a pipeline by the electromagnetic field of power lines is significantly complex and requires taking into account a number of factors, such as: operating mode of the influencing line; approach trajectory; the nature of the grounding of the metal structure; the length of the approach area and the conductivity of soils on it. The goal of the research presented in this article was to develop computer models of long-distance ultra-high voltage (UHV) power transmission lines to provide comprehensive modeling of power flows and calculating electromagnetic interference effects on extended steel structures. In developing the models, we employed the methods based on the use of the phase frame of reference and equivalent lattice circuits with a fully connected topology. The simulations were carried out for a 1,150 kV UHV transmission line with a length of 900 km, each phase of which was formed by eight AC-330 wires. Simulations were performed using the software package Fazonord. Along with power flow calculations and determination of the voltages created by the 1,150 kV long-distance transmission line on the pipeline, we simulated electromagnetic fields, taking into account the impact exerted by the grounded steel structure. The following modes were considered: normal with loads at the receiving end of 300 + j200 MVA per phase; emergency, caused by single-phase and two-phase short circuits; single-phase with loads 80+ j50 MVA per phase. The results of modeling a long-distance 1,150 kV transmission line with receiving end loads of 300 + j 200 MVA per phase led to the following conclusions: in the case of a normal power flow with balanced loads at individual points of the structure the levels of induced voltages did not exceed the allowable limit of 60 V; in the case of two-phase and single-phase short-circuit power flows the maximum induced voltages also did not exceed the 1,000 V limit set by the regulatory document. When phase B is disconnected at the starting end of the power line, the induced voltages on the pipeline increase 3.12 times and at the point with coordinate x = 50 km exceed the permissible value; in this case, the currents flowing through the pipe increase more than three times, which can lead to malfunctions in the pipeline protection system against electrochemical corrosion. The models presented in the paper can be put into practice when planning the measures to ensure the electrical safety of technicians working at the pipeline sections located in the areas that are subject to electromagnetic interference effects of transmission lines. Based on them, it is possible to reasonably select measures to ensure the safety of personnel servicing the structure, as well as to develop methods and means of protection against corrosion. The application scope of the technique developed covers the cases where a transmission line and a pipeline run in close proximity following a complex trajectory that includes parallel and oblique segments. Based on the presented digital models, it is possible to reasonably select measures to ensure the safety of personnel servicing the structure, as well as develop methods and means of protection against corrosion.
