Single-phase To Three-phase Converter In House-service Power Supply Of Traction Substation

In the traction substation,the non-traction load is mainly powered by a power transformer connecting to the 10kV power line or traction network.There are a large range of voltage fluctuations,complex harmonic content,current pollution and other serious power quality issues in the single-phase power obtained from the traction network.Therefore,it is very important to study the high quality power from the traction network as the non-traction load power,and it is a great significance for the safe and stable operation of the railway power.In this paper,the house-service power supply of traction substation is used as the research background,and a single-phase to three-phase converter is put forward to replace the existing power transformer,which makes compensation for the harmonic and reactive power and transfer active power to the inverter side.It is greatly improved the power quality of power supply.At the same time,the main circuit,control system and modulation strategy of the single-phase to three-phase converter is deeply studied in theory,simulation and experimentFirstly,the mathematical model of single-phase to three-phase converter is established,and the working principle of single-phase converter and three-phase converter is introduced.The harmonic current detection principle of single-phase circuit is deduced from the principle of harmonic current detection of three-phase circuit.The two harmonic current detection algorithms of instantaneous reactive power principle and active and reactive decoupling principle in the single phase active power filter are studied emphatically.This paper compares the difference between the two algorithms in the case of the same main circuit parameters and control strategy.The results show that the compensation result of the two harmonic current detection algorithms are basically the same in the case of relatively good voltage on the network side.Compared with the harmonic current algorithm based on the instantaneous reactive power principle,the harmonic current detection algorithm based on active and reactive decoupling has not calculated the process of instantaneous active and instantaneous reactive power,so the computation time in each cycle is greatly reduced,the dynamic response time is shortened correspondingly and the overshoot is increased in the dc-side.Secondly,the harmonic compensation and power transfer of the single-phase to three-phase converter are studied by the simulation software platform.The system response on network side,DC side and inverter output of single-phase to three-phase converter is studied on the condition of network voltage rise,decrease and mutation.Under the condition of increasing the compensation current,the compensation effect is more obvious than using the active power filter alone.The inverter can provide a stable voltage source for the load,so that the load is working properly.The single-phase to three-phase converter has a controllable output,a good dynamic and static performance,a fast response for the load change.Finally,the FPGA-based low-power experimental platform is built,which further proves that the single-phase to three-phase converter designed in this paper can not only compensate the power quality of the network side,but also transmit the active power to the three-phase inverter.And the good dynamic response and high reliability is verified in the experiment,which completes the harmonic compensation and the intermediate DC voltage stabilization in a short period of time.