Study of Electromagnetic Influence on the Low-voltage Secondary Cables when Lightning Strikes Thermal Power Plants

When solving the electromagnetic compatibility problem of low-voltage distribution system in thermal power plants, it is found that the current protection specifications for secondary cables in some conventional substations and common civil buildings are not suitable for thermal power plants, and there is a lack of reference standards for lightning protection data of secondary cables in thermal power plants. Therefore, this paper takes Xishui Substation as the research object, uses CDEGS software to build a three-phase low-voltage distribution system combined with the structural characteristics of large-scale ground screen, overhead cable bridge, building group and others of thermal power plants, and completes the modeling of its buildings, grounding grid, transformer and secondary overhead cable bridge. According to the layout of two buildings in the low-voltage distribution system, the overvoltage of the secondary power cable generated when the buildings are struck by lightning is calculated. The results show that the lightning strike will cause great electromagnetic influence on the secondary equipment. This provides data support for the layout design and protection of secondary cables in thermal power plants, and is of great significance for improving the insulation coordination capability of secondary systems.