Research On Insulation Fault Monitoring In AC Floating Ground Electric Power System

AC Floating Ground Electric Power System, witch is also called Neutral Ungrounded power System, is widely used in domestic and foreign shipboard distribution system. With the continuous improvement of modern ships' automation, their power system capacity rises constantly , the electric network becomes more and more complex, and the humidity and temperature condition get worse and worse, which make power system insulation faults quite frequent. Once insulation faults occur, it is quite difficult to find fault point. Therefore strengthening insulation status monitoring, finding insulation status variance timely and excluding faults promptly are the key tasks to guarantee safe operation in shipboard power system. Therefore, it's very important to develop a new insulation supervision device with the function of branch insulation breakdown orientation. At present, there exists many various devices with all kinds of deficiencies orientating branch insulation breakdown of AC Floating Ground Electric Power System. The unavoidable deficiency is that distribution capacitance has an influence on orientating branch breakdown. This dissertation describes double-frequecy methods of testing alterating system insulation breakdown and what kind of detailed breakdown type different methods can test as well as the deficiencies in these methods. As far as the dificencies are concerned, it's suggested that we should eliminate the influence of distribution capacitance by inductance compensation. We have got the maths model and theoretical formula about electric net state afer the supply of inductance through analyzing the insulation status; we also have gained the supply mode and magnitude of inductance compensation which needs consecutive controllable inductance through lots of emulation modes and experiments.