Research On Fault Current Limiter Of Power System

The short circuit fault is one of the most dangerous and frequent faults in power system. Once it happens, the short circuit current level will become very high within half a period. With the development of power systems, the short circuit capacity becomes a serious limiting factor to it. In order to reduce the damage to the Power system, a protection system to limit the short circuit current to a safe level as quickly as possible is required.With the development of power electronics technology, solid-switch due to its quickness, permitting many times of operation, simple control, low cost and small size is considered to be a practical protection device for Power System in the future. Based on the advantage of the solid-switch, many fault current limiters' with solid-state switch have been proposed. Fault current limiters with series compensation which could limit the fault current and also make compensation is more flexible and practical when compared to the others.A new type of fault current limiter is studied. It is composed of a reactor and in series with a compensation capacitor, which is paralleled with a by-pass reactor controlled by a GTO pair. The fault current limiter operates in two modes, in normal conditions, it is used as a compensation capacitor, in fault conditions, the GTO pair quickly switches on to get the by-pass reactor in operation to limit the current. First, the topology of the fault current limiter is proposed together with the principle and characteristic of the fault current limiter, second, the design method of fault current limiter's parameters is presented, finally, the basic units of the fault current limiter are introduced.To test the performance of the fault current limiters, A Model of a distribution network and a model of one machine-infinity bus system is established by the software which is MATLAB, in which some short circuit faults are simulated, eventually, current waves and voltage waves are obtained. Simulation results show the fault current limiter is effective in limiting the fault current and improving the voltage.To improve the stability of the system, fuzzy controller which is based on fuzzy control theory is designed for controlling the GTO, simulation results show the system performance can be improved successfully.