A fast busbar protection technique based on travelling wave

Using propagation characteristics of travelling wave, an extra high speed busbar protection technique is proposed. If a fault occurs on the transmission line, the forward and backward travelling waves will be generated. When a fault occurs on the busbar, the detected initial travelling waves on all lines connected to this busbar will come from their backs, which are positive direction travelling waves. When a fault occurs on any one of these lines, the detected initial travelling waves on all healthy lines are positive direction travelling wave, whereas the direction of detected one on faulted line is negative. Utilizing amplitude integral relationship of directional travelling waves within a short time after fault, an algorithm discriminating fault direction is constructed. Analyzing fault directions of all lines, an internal busbar fault can be fast identified from external fault. Main factors influencing busbar protection are simulated and analyzed. Simulation results demonstrate that the proposed technique can fast and reliably discriminate whether the busbar has an internal fault or not. Moreover, its performances are hardly affected by earth fault resistances, fault inception angles and fault types, etc.