| The multi-level high voltage inverter with unit series has the advantages of relatively mature technology,wide application range,convenient fault handling,and simple equipment modification,etc.Currently,its market share is relatively high.However,this type of inverter has a complex topology and a large number of components,which leads to numerous failure factors,especially in the harsh working environment of humidity,high temperature,dust,etc.The failure rate increases significantly.It leads to energy waste and affects the safe and stable operation of the unit.In severe cases,it will cause downtime and even endanger the safety of personnel and equipment.How to improve the reliability of inverter operation has become one of the key research areas of enterprises.In this paper,the research status at home and abroad of the fault handling,reliability improvement,reliability theory and QC group research methods for high-voltage inverter has been firstly studied.Then the Z power plant was taken as an example,the occurrence of different types of faults was counted and the fault tree analysis tool was used to study the reliability improvement methods.This paper focus on the optimization of the equipment operation and maintenance program and the improvement of the structure of the equipment,which provides a reference for quicker and more convenient maintenance of the inverter.In this paper,the improvement of inverter operation reliability and stability is achieved through the optimization of operation and maintenance methods and structural improvement.By means of the analysis method related to QC group activities,each type of fault is analyzed,improved and verified,so as to analyze and solve problems more comprehensively and improve efficiency.In the aspect of operation and maintenance optimization,the management and maintenance of the cooling fan was strengthened and its control logic was improved,the internal parameter setting and configuration management and the life management of the capacitor was strengthened,so the power unit failure was reduced.Component life management account was established to ensure good spare condition,the equipment failure was reduced.The frequency of daily inspections was increased,indoor humidity was reduced,the possibility of equipment failure caused by moisture was controled.The power distribution and management of the plant power system was strengthened,in order to reduce the probability of equipment failure due to abnormal voltage.In terms of structural improvement.By allocating dual power supplies for air conditioner in inverter room,improving the temperature protection logic of power unit,and adding the temperature alarm function for inverter room,the control of inverter ambient temperature was enhanced and the equipment failure rate due to high ambient temperature was reduced.By adding a pre-charging circuit,the power supply of the inverter was reduced,especially when starting up after long-term shutdown or replacing long-term backup power unit.By improving the fixing method of voltage divider resistor,the condensation was avoided to reduce the moisture impact on the reliable operation of inverter.This paper describes how to indirectly monitor the state of capacitors and proposes a method of finding power unit faults based on the elimination method,which provides a reference for quicker and more convenient inverter maintenance.After verification,the inverter failure rate is reduced from 5 times per month to 1 time every six months,the system reliability is increased from 98.69%to 99.95%,and the operation reliability and stability are improved to a certain extent.It is verified that the O&M optimization and structural improvement methods proposed and summarized in this paper are feasible,can reduce the overall cost to a certain extent,and have the value of promotion and use. |
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