Low-amplitude direct lightning hazard assessment and warning method for distribution network

A low-amplitude direct lightning hazard assessment and warning method for a distribution network, comprising the following steps:

• Step 1:
• counting a maximum grounding resistance Rch, a tower nominal height h and a tower span d of each line in a distribution network, wherein these values are input into corresponding data of each tower in a distribution network lightning detection system;
• Step 2:
• counting insulator models and a lightning impulse withstand voltage Uset for each line in the distribution network, wherein these values are input into the corresponding data of each tower in the distribution network lightning detection system;
• Step 3:
• calculating a grounding shunt coefficient β for each tower, wherein this value is input into the corresponding data of each tower in the distribution network lightning detection system;
• Step 4:
• detecting, by the distribution network lightning detection system, a cloud-to-ground lightning in real time, wherein if the cloud-to-ground lightning is located at a small distance from a tower, the cloud-to-ground lightning is classified as a direct lightning, and calculating an overvoltage U at a top of the tower;
• and
• Step 5:
• if U≥Uset, a degree of hazard is serious, and the distribution network lightning detection system issues a warning;
• if U<Uset, the degree of hazard is small and no warning is needed.