| With the advantages in equipment start-up,speed adjustment,energy saving,the inverter is widely used in the important auxiliary equipment of thermal power plant.Therefore,in the voltage drop accident,due to the sensitivity of the inverter to voltage fluctuations and lack of low voltage crossing capacity and trip,resulting in the main fuel tripping of the furnace,the crew tripping,the power grid safety and enterprise economic benefits have a serious impact.That is to say,this thesis focuses on the low voltage ride through capability of inverter of coal feeder system is necessary.This thesis aims at an in-depth analysis of the problems of the coal machine inverter tripping and unit tripping in the power grid voltage drop accident atone coal-fired power plant,which shows that the current coal-fired power plant to the coal machine system lack of low voltage ride through capability.This thesis conducts a comparative analysis of the existing scheme of voltage protection tripping for coal converter inverters.In addition,the scheme of low voltage ride through capability of coal feeder is modified in the thesis.Based on the technical transformation scheme,the low voltage ride through device is installed and debugged on the spot,focusing on the implementation of the function of the device,and it is found that the function and protection provided by the device can fully meet the needs of the normal operation of the equipment.On account of the simulation of plant voltage temporary drop fault condition and MFT action chain test,the results show that the low voltage ride through device to provide power support to the coal machine inverter DC bus,can make the coal machine inverter have enough to deal with the low voltage crossing capacity of the plant voltage temporarily dropped.Meanwhile,it also provides relevant reference for the research of low voltage ride through capability transformation of the important auxiliary inverter of similar thermal generator sets. |
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