Research On The Power Electronic Magnetically Controlled Reactor And It's Inrush Current Suppression

Power electronic magnetically controlled reactors(PEMCRs)are core components to realize soft starting of high voltage large motors.They are playing increasingly important roles in transportation fields such as rail transit,ports,docks,tunnels,ships,and other industrial fields.The in-depth research on PEMCRs and their closing inrush current suppression is the basis for the smooth starting of high-voltage large motors,the stable operation of power system,and the extension of the service life of PEMCRs.The research results have important theoretical and practical engineering significance.In order to solve the over current problem caused by high voltage large motors connected to the power grid and improve the overall performance of the soft starting devices based on the PEMCRs,the research on the scientific issues related to PEMCRs including mathematical modeling methods,inrush current suppression methods and ontology design methods is carried out.The main work and research results of this thesis are as follows:Firstly,to solve the problem that traditional magnetically controlled reactors(MCRs)are not suitable for soft starting of high-voltage large motors due to the withstand voltage of power electronic devices,a topology structure of the PEMCR is integratedly and innovatively proposed to softly start high voltage large motors.The topological structures of single-winding and multi-winding PEMCRs are designed and their working principles are analyzed.The consistency of the working principle and reactance conversion mechanism of them is clarified.Mathematical models of IGBT-type and thyristor-type PEMCRs are established and their impedance transformation mechanisms are analyzed.A two-port network modeling method is proposed to deal with the problem that the mathematical modeling of the PEMCR depends on the power electronic impedance conversion circuit on the secondary winding side and the analysis of the impedance transformation mechanism requires complex theoretical derivation and lengthy calculation.The general mathematical model of the PEMCR is constructed and its impedance transformation mechanism is studied.It is revealed that controlling the current of the secondary winding of the PEMCR can continuously and smoothly adjust impedance values of the primary winding.The research result is the foundation for the study of inrush current suppression methods,the design methods and multiphysics coupling analysis of PEMCRs.Secondly,the inrush current suppression methods under no-load and with load working state are proposed to decrease the serious inrush current generated when the PEMCR is switched to the power grid.When the PEMCR is connected to the power grid without load,in order to deal with the problem that the traditional method needs to add additional closing resistance,a method of controlling the switching angle of the PEMCR is proposed to suppress the inrush current.Phase angle control law is revealed.When the PEMCR is connected to the power grid with a load,the reactive power dynamic compensation strategy is proposed to suppress the inrush current,because controlling the switching phase angle cannot achieve the offset of the bias and the remanence.The calculation method of reactive power compensation amount and dynamic compensation method are studied.The simulation models of the PEMCR switched to the power grid under no-load and with load state are established respectively,and the effectiveness of the inrush current suppression method is verified.The simulation results show that the inrush current can be suppressed within2 times of the rated current of the PEMCR,and the inrush current suppression effect is obvious.Thirdly,aiming at the problem that traditional reactor design mostly adopts empirical method and manual calculation is more complicated,a set of PEMCR ontology design method is proposed,including iron core structure design method,winding design method,main reactance calculation method,and leakage reactance calculation methods,etc.The computer-aided design software is developed.It is proposed that the inrush current suppression can effectively reduce the vibration,noise and temperature rise generated by the PEMCR when switched to operation state.The electromagnetic models,structural mechanics models,acoustic models and the three-dimensional flow-temperature field coupling models of the PEMCR are constructed using the finite element simulation software COMSOL.The simulation results show that the inrush current suppression can suppress the noise within 66 d B,and the temperature rise is restricted within 54 K,which meets the relevant national standards for Class A power equipment.Lastly,a soft starting device test platform based on the PEMCR is constructed.The successfully developed 20000 k W/10 k V PEMCR is applied to softly start a19000 k W/10 k V high voltage large motor in a steel plant,and the experiments that the test platform switched to the grid are carried out.The experimental results show that when the PEMCR is connected to the power grid with a high voltage large motor,the starting current is less than twice the rated current of the motor,and the voltage drop of the grid voltage is less than 5%.It can effectively suppress the over-current caused by shock loads such as high voltage large motors connected to the power grid.There isn't inrush current during starting.The starting current curve is smooth,and the test platform has good starting performance.The research on the technology of the PEMCR and its inrush current suppression has been completed.It has conducted beneficial explorations in theoretical research,computer-aided design,computer simulation and test platform construction.The research results give insights on the theoretical and technical study for the design of the PEMCRs and the development of soft starting devices based on PEMCRs.