Protection Scheme For Electrical Conversion Equipment Of Continuous Cophase Power Supply System

The structure of electric traction power supply system and its single-phase load result in problems of negative sequence, reactive power, harmonics and crossing neutral sections, which seriously influence the development of railway high-speed and overloading. The continuous cophase power supply system based on electrical conversion equipment can eliminate negative sequence, compensate reactive power and achieve smaller harmonic distortion, not only fundamentally solve the power quality of traction power supply system, also eliminate neutral sections of the traction network, and is an ideal form of traction power supply.First, based on the introduction of cophase power supply system of the two single-phase converters, the composition and implementation of continuous cophase power supply system are discussed, the principle of feeder voltage regulation and capacity optimization are analyzed, the structure and transformation principle of static power converter are studied, and a feasible program of the main structure of traction substation under continuous cophase power supply system is proposed.The control of static power converter can be resolved into the control of three-phase rectifier and single-phase inverter, in the paper the establishment of mathematical model and control system design of the three-phase rectifier and single-phase inverter are discussed, then the correctness and feasibility of the control strategy are simulated and analyzed.Afterwards, a variety of possible fault to electrical conversion equipment are analyzed, and the influences of static power converter on three-phase rectifier transformers, single-phase stet-up transformer and feeder protection are discussed. Then, a set of protection scheme for electrical conversion equipment is presented, which can satisfy the selectivity of protection, furthermore, a corresponding protection scheme for three-phase rectifier transformer, single-phase stet-up transformer and static power converter is set.Finally, under MATLAB/Simulink continuous cophase power supply system is modeled, the operation behaviors of continuous cophase power supply system is simulated and analyzed in many conditions, such as pure active load operation, rectifier load operation, no-load operation, load changing operation, low-voltage side fault of three-phase rectifier transformers, static power converter fault and traction line fault. Simulation results show the feasibility of continuous cophase power supply system and the correctness of protection scheme for electrical conversion equipment.