Research On Wide-area Protection Of Hub Traction Power Supply System

In recent years,Chinese railway construction has developed vigorously,and large scale passenger stations where many main railway lines have been introduced into the intersection emerge continuously.In order to make full use of the power supply capacity,the traction substation near large scale passenger station and its power supply unit form the hub traction power supply system.However,traditional protection measurement and control technology cannot adapt to the complex structure,short lines,and multi-level coordination of the hub traction power supply system.It is difficult to balance selectivity and rapidity of protection,which cannot meet the needs of the development of railway power supply.Firstly,this paper analyzes the structural characteristics of the hub traction power supply system and the deficiencies of the current protection schemes.And the short-circuit faults of transformer,busbar and traction network of the hub traction power supply system are analyzed theoretically.The problem of dead zone existed in the distance protection at AT station in the case of proximal short-circuit in the substation is demonstrated by especially using the AT equivalent circuit that takes into account the leakage reactance of the autotransformer.And the distribution characteristics of the measured impedance and measured current of each node under faults at different locations are derived.Based on the comprehensive information of multiple nodes,it realizes the differentiation of the section and line where the fault occurs.Then the principle and setting of adaptive directional blocking wide-area protection are studied.After the protection is activated in the case of a fault occurred and the blocking signal is not received within the delay,the corresponding circuit breaker trip signal will be sent to remove the fault section while minimizing the scope of power outage.In addition,the action behavior of the protection under special circumstances is analyzed.Then the communication and software design of wide-area protection are studied,which provides a reference for the specific implementation of wide-area protection.Finally,the hub traction power supply system was built on the Matlab/Simulink simulation platform,equipped with a wide-area protection scheme and a traditional protection scheme.And the short-circuit faults are set at different positions of the busbars and traction networks,as well as in the case of annular power supply,protection refusal,circuit breaker failure and voltage transformer disconnected,which verifies the correctness of the wide-area protection of the hub traction power supply system and can solve the problem of selectivity and rapidity.