Resonance Overvoltage And Suppression Research Of Electrical Sectioning Overlap Structure

Single-Phase AC25kV is used as traction power supply in electrified railway, in order tobalance the load of power system and ensure that current is get from the power systemsymmetrically, electric split phase device is set up in the boundary of different phases.Electrical split phase structure is widely used in high-speed electrified railway, in most cases,electric split phase is made of the overlap, but some problems are appeared in the application,for instance, over-voltage is produced when the electric locomotive goes through electricalsectioning, which leads to the traction substation’s tripping，the roof insulation’s breakdown，lightning arrestor explosion, and so on. For the transient process that electric locomotive goesthrough the electrical sectioning, the mechanism and suppression method of over-voltage areneeded further research.In this article, for the concrete structure of traction network and electrical sectioningoverlap structure, the dynamic circuit form when the electric locomotive goes through theelectrical sectioning is analyzed. The equivalent higher-order circuit is established,over-voltage on the neutral line is solved by using Runge-Kutta method. Throughelectromagnetic transient simulation software PSCAD/EMTDC, by the coordination andcontrol of switches, the combined simulation model of locomotive-traction network-electricalsectioning is established, the higher-order circuit model and theoretical analysis aredemonstrated by experiment.In order to ensure the type and mechanism of over-voltage when electric locomotivegoes through electric split phase, based on the combined simulation model oflocomotive-traction network-electrical sectioning, for the whole transient process that electriclocomotive goes through the electrical sectioning, the simulation experiment is done. Thevoltage oscillation range and time sequence of neutral section are get, by Latin Hypercubesample-Monte Carlo simulation, the rule of voltage harmonics distribution is get, thereference and experimental basis are provided for over-voltage suppression research.At last, in terms of resonance energy consumption and resonance condition destruction,the method to suppress over-voltage is put forward. When the isolation suppression method of resistance capacity device is installed on electrical sectioning neutral line, the voltageoscillation of neutral line can be weakened effectively; by controlling voltage phase of contactline, ferromagnetic resonance over-voltage can be suppressed effectively. Research resultsshow that: when resistance capacity device is installed on seven-span electrical sectioningneutral line, the maximum over-voltage is reduced to68.10kV, the inhibitory effect is obvious;switching transient voltage and oscillating voltage can be separated by the isolation inhibitmethod of eight-span double neutral segment, and the impact of over-voltage to power supplysystem and locomotive roof insulation can be reduced.