Research On Lightning Protection Of LV Device In Substation

Lightning is one of the key factors that do harm to the safe and stable function of power system. If lightning damage occurs in substations, huge block would be caused out in a large area, and lots of trouble would be brought to social production and daily life. So it requires that lightning protection should be reliable. Presently, the lightning protection measures of high voltage system are perfect, while the low voltage system mainly consists of plenty of electronic, micro-electronic, etc LV devices, which make the withstanding voltage standard fairly low. So when lightning wave invades into LV devices, it is easy to bring on malfunction or breakdown puncture, which affects security and stability of power system seriously. So it's necessary to do a research on LV devices'lightning protection. This thesis consists of three parts:In the first part, the formation of lightning and the main approaches of lightning from primary system invading into secondary system are analyzed. Mathematics models on lightning invading into secondary system through power source line and through arrester into grounding grid are established respectively. Meanwhile, this thesis analyzes the effect by lightning to the secondary system theoretically.In the second part, lightning mainly invades into secondary LV devices by power source system. This paper proposes a new device on lightning inhibiting, and based on theoretical study and ATP simulation, it's obvious that the amplitude of lightning is half of before, with nice suppressing lightning effects. Subsequently, step assort of multi-Step is analyzed by simulation, and the best fitted effect is discussed, which can availably solve the lightning problem in power source of substation.In the last part, it discusses interference on LV device by grounding line, when lightning current diffuses through the grounding grid. First the ATP simulation model on grounding grid is established, and the influence on ground potential by lightning is analyzed. Then discussion is made on the main reasons that cause grounding potential interference, and effective measures to inhibit ground potential are proposed.