The large leakage current of the roof arrester caused by the high‐frequency resonant overvoltage on the high‐speed train occurs intermittently,which will cause the arrester to overheat locally.In this work,the overh...The large leakage current of the roof arrester caused by the high‐frequency resonant overvoltage on the high‐speed train occurs intermittently,which will cause the arrester to overheat locally.In this work,the overheating issue of the arrester under Ultra Harmonics Overvoltage is studied.Then,the relationship between the active power and the voltage(including amplitude and frequency)of the arrester is investigated,and the impact mechanism of the harmonic voltage on the overheating fault of the arrester is analysed based on experiments in this work.It is found that the total leakage current of the arrester is proportional to the amplitude and frequency of the applied voltage.The internal resistance of the arrester is independent of the amplitude of the voltage,but it will decrease with the increase of the frequency.The main reason that leads to thermal breakdown of the arrester valve under high‐frequency harmonic voltage is the heating power elevation of the arrester valve.The research study can provide theoretical basis and data support for the design,type selection and monitoring of the high‐speed train roof arrester.展开更多
A new type of piecewise negative stiffness(NS)mechanism is designed and the relationship between the force and displacement is studied.At first,the prototype of the piecewise NS mechanism is established,and the stiffn...A new type of piecewise negative stiffness(NS)mechanism is designed and the relationship between the force and displacement is studied.At first,the prototype of the piecewise NS mechanism is established,and the stiffness characteristic of this mechanism is analyzed.Then,the piecewise NS mechanism is applied to dynamic vibration absorber(DVA)system to establish a dynamic model with the piecewise linearity.The differential motion equations are derived according to Newton's law of mechanics.The approximate analytical solution and the amplitude frequency curve of the system with the piecewise NS are obtained by means of the averaging method.The correctness of the analytical solution is proved by comparing with the numerical solution.In the end,the comparisons with two other traditional DVAs show that the system in this paper has better vibration reduction effect under the condition of harmonic excitation and random excitation.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(2021JBM025)the National Natural Science Foundation of China(51907003).
文摘The large leakage current of the roof arrester caused by the high‐frequency resonant overvoltage on the high‐speed train occurs intermittently,which will cause the arrester to overheat locally.In this work,the overheating issue of the arrester under Ultra Harmonics Overvoltage is studied.Then,the relationship between the active power and the voltage(including amplitude and frequency)of the arrester is investigated,and the impact mechanism of the harmonic voltage on the overheating fault of the arrester is analysed based on experiments in this work.It is found that the total leakage current of the arrester is proportional to the amplitude and frequency of the applied voltage.The internal resistance of the arrester is independent of the amplitude of the voltage,but it will decrease with the increase of the frequency.The main reason that leads to thermal breakdown of the arrester valve under high‐frequency harmonic voltage is the heating power elevation of the arrester valve.The research study can provide theoretical basis and data support for the design,type selection and monitoring of the high‐speed train roof arrester.
基金The authors are grateful to the support by National Natural Science Foundation of China(No.U1934201 and 11772206).
文摘A new type of piecewise negative stiffness(NS)mechanism is designed and the relationship between the force and displacement is studied.At first,the prototype of the piecewise NS mechanism is established,and the stiffness characteristic of this mechanism is analyzed.Then,the piecewise NS mechanism is applied to dynamic vibration absorber(DVA)system to establish a dynamic model with the piecewise linearity.The differential motion equations are derived according to Newton's law of mechanics.The approximate analytical solution and the amplitude frequency curve of the system with the piecewise NS are obtained by means of the averaging method.The correctness of the analytical solution is proved by comparing with the numerical solution.In the end,the comparisons with two other traditional DVAs show that the system in this paper has better vibration reduction effect under the condition of harmonic excitation and random excitation.
