The Distributed Protection And Fault Location Based On The Power Supply Segmention Of Traction Network

The traction network is a large system which placed in the natural environment and affected by lightning disturbance, high winds, bird damage, so the traction network has various problems in the operation. How to detect and isolate the faults of traction network timely and accurately and guarantee the trouble-free interval normal is particularly important. Faults anywhere on the traction network once happened will cause the entire power supply arm under the existing protect devices. So it has large-scale power outages and poor reliability. A distributed protection system of the electrified railway traction network based on the power supply segmentation is described in this paper. It uses current differential protection to realize the fault isolation timely and accurately based on traction network segmentation. The power outage is reduced and power supply reliability is improved. The power outage is narrowed down to a supply zone instead of the entire supply arm. This approach is better real-time and is not affected by the number of segmentation.This paper first described the distributed protection system based on power supply segmentation of the electrified railway traction network. The traction network power supply segmentation and differential protection criterion started by low voltage are defined. The simulation models of traction network and control module are established.The main factors of the current differential protection such as the capacitive current, current transformer saturation and model differences are studied. The current and voltage start values of differential protection is determined of electrified railway traction network. By the way of Setting short-circuit faults of different types and different locations and counting the breakers status to test the rapidity and selectivity of the protection.Finally the port impedance on short circuit of traction network are calculated and the relationship lines between the short-circuit impedance and short circuit distance are simulated. The fault location method is determined based on the voltage and current of the segmentation on both sides of the fault.This method is used to realize fault location based on short-circuit test data of a whole parallel AT traction network in Shanxi Province. The results showed that the method has high measurement accuracy.