Electrified Railway Traction Substation Feeder Protection Research

The microprocessor-based Substation Automation Systems are used widely in power systems with good effect, which evolve with rapidity and reliability of relay protection. As the distinction of traction load from normal electric load, the development of relay protection technique and operation level of traction substation is relatively slow compared to that for normal substations. So substation automation has not been applied widely to traction substations.This thesis researches the feeder protection module of Substation Automation Systems. It analyzes the composition of the traction supply system at first, and the supply style of the traction substation to electric locomotive, and the load characteristic of electrified railway. The traction load have the characteristic of impulsion, mobility, the wide range of current change, the high excitation current, the amount of harmonic current etc. So the principles of feeder protection are different to general transformer substation. According to adaptive principle, this thesis utilizes higher harmonic current to restrain the distance protection and the increasing of current gain protection etc. So its borders of movement may be changed automatically. And the second harmonic is used to block. These have effect to prevent the protection miss operation caused by factors such as excitation current and regenerated load etc. The distance protection adopts quadrangular characteristic. This thesis proposes the movement characteristic to prevent miss operation.This thesis sets up the model of the electric locomotive, simulates the situation of the locomotive's normal running and the production of excitation etc by using PSCAD/EMTDC simulation software. The result confirms the characteristic of the traction load. It simulates the distance and increasing of current gain protection in the situation of normal running and faults. The results are better by improving the characteristic of protection. The Fourier algorithm is carried on, with the union difference algorithm to eliminate the influence of the weak direct current. So it may obtain the good filter characteristic in the situation of normal running and faults. This...