Research And Implementation Of Control Strategy Of Grid-side Converter In Hybrid EMU

Grid-side converter is the core part of Electric Multiple Units(EMU) traction power supply system for energy exchange.therefore, there are high standards and demands for its security and stability. The article relying on the key project, which is called the research on key technology and manufacture of typical prototype for Hybrid EMU, of National Technology Support Program for the 12th Five-year Plan. And the research and implementation of the key control technology and related applications strategy for network side converter were conducted in the traction converter developed by our research group and the prototype vehicles of hybrid EMU.First of all, based on the analysis of topologies of grid-side converter in CRH series EMU and depending on design requirements and performance indicators, double two-level topology was selected for the grid-side converter of Hybrid EMU. The computing standards and selection basis for electrical parameters of main circuit was also given.Next, the basic working principle, modulation method and mathematical model of synchronously rotating coordinate system for single-phase PWM rectifier of grid-side converter were introduced. On this basis, the improved PI control based on semi-decoupling, the PR control based on semi-decoupling, general dq-decoupling control and new dq-decoupling control with fast virtual axis algorithm were described in this paper. And the analysis of the causes of the double frequency pulsations in dq-axis current was revealed. Naturally, the characteristics of methods described above were discussed and compared in matlab system simulation. Finally, the new dq-decoupling control method, which has a good dynamic and static performance, was determined as the control strategy of grid-side converter in hybrid EMU. This kind of method could control active and reactive power individually and deal with grid voltage fluctuations and other conditions effectively. In addition, multiplexed phase shift control technology was applied so that harmonic components in grid current could be suppressed as possible.And then, application strategy of grid-side converter in hybrid EMU was studied. The system protection strategy, the new passing phase separations strategy for three conditions and the coping strategy for short-term interruption of line voltage were proposed.Finally, numerous waveforms and analysis of high-power experiments, which were conducted in the prototype vehicles of hybrid EMU and the ground traction chain test platform.The scientific and feasibility of related theory in the article was verified.