<div style="text-align:justify;"> Generalized S-transform is a time-frequency analysis method which has higher resolution than S-transform. It can precisely extract the time-amplitude characteristics o...<div style="text-align:justify;"> Generalized S-transform is a time-frequency analysis method which has higher resolution than S-transform. It can precisely extract the time-amplitude characteristics of different frequency components in the signal. In this paper, a novel protection method for VSC-HVDC (Voltage source converter based high voltage DC) based on Generalized S-transform is proposed. Firstly, extracting frequency component of fault current by Generalized S-transform and using mutation point of high frequency to determine the fault time. Secondly, using the zero-frequency component of fault current to eliminate disturbances. Finally, the polarity of sudden change currents in the two terminals is employed to discriminate the internal and external faults. Simulations in PSCAD/EMTDC and MATLAB show that the proposed method can distinguish faults accurately and effectively. </div>展开更多
In order to reduce the magnetically electromotive force of railway signal cables, combined with the basic engineering conditions for setting the interval grounding round steel, it is recommended to ground the signal c...In order to reduce the magnetically electromotive force of railway signal cables, combined with the basic engineering conditions for setting the interval grounding round steel, it is recommended to ground the signal cables at both ends. It is necessary to further increase the grounding measures to reduce the value of the magnetically induced electromotive force when the distance is km. At the same time, the signal cable should be installed as far away from the catenary as possible in the engineering design stage. For this reason, when the train is running in the shield tunnel, the protection of the signal cable also puts forward an objective requirement that is different from the DC power supply project. This paper investigates this.展开更多
文摘<div style="text-align:justify;"> Generalized S-transform is a time-frequency analysis method which has higher resolution than S-transform. It can precisely extract the time-amplitude characteristics of different frequency components in the signal. In this paper, a novel protection method for VSC-HVDC (Voltage source converter based high voltage DC) based on Generalized S-transform is proposed. Firstly, extracting frequency component of fault current by Generalized S-transform and using mutation point of high frequency to determine the fault time. Secondly, using the zero-frequency component of fault current to eliminate disturbances. Finally, the polarity of sudden change currents in the two terminals is employed to discriminate the internal and external faults. Simulations in PSCAD/EMTDC and MATLAB show that the proposed method can distinguish faults accurately and effectively. </div>
文摘In order to reduce the magnetically electromotive force of railway signal cables, combined with the basic engineering conditions for setting the interval grounding round steel, it is recommended to ground the signal cables at both ends. It is necessary to further increase the grounding measures to reduce the value of the magnetically induced electromotive force when the distance is km. At the same time, the signal cable should be installed as far away from the catenary as possible in the engineering design stage. For this reason, when the train is running in the shield tunnel, the protection of the signal cable also puts forward an objective requirement that is different from the DC power supply project. This paper investigates this.
