In this paper, a traveling wave based fault location method is proposed for distribution networks. Before fault occurs, an intrinsic distance difference matrix (IDDM) is established based on the characteristics of traveling wave propagation and the topology of distribution network. After the fault, the initial fault traveling wave signals are decomposed into several intrinsic mode function (IMF) signals by variational mode decomposition (VMD), and the first IMF signal is analyzed by teager energy operator (TEO) to determine the arriving time of initial fault traveling waves. According to the double-ended traveling wave method and the arrival time of traveling wave at all recorders, a fault distance difference matrix (FDDM) is built. By comparing the difference between IDDM and FDDM, a fault branch determination matrix (FBDM) and the lateral index Q are used to locate the fault. The effectiveness of the proposed method is verified via EMTP/ATP simulations. Results show that the proposed method has a high fault location accuracy, and does not need that all terminals of lines are installed traveling wave recorders.

Aiming at the fault states of split pins in the catenary fastening devices of high-speed railway, such as missing, loosening and improper installation, a method for detecting defects of split pins is proposed. Firstly, split pins are localized by a two-stage positioning method based on the improved YOLOV3 algorithm. The first stage is used to localize five joint components on catenary support devices and the second stage is applied to locate the split pins in the joint component images. Then, the deeplabv3+ algorithm is implemented for semantic segmentation on split pin images. Finally, split pins are classified based on semantic segmentation images in accordance with split pins’ semantic information of head, body and tail. In order to verify the adaptability and accuracy of the proposed method, the catenary support devices images in multi high-speed railway lines and multi environments were tested. Meanwhile, our algorithm is compared with other deep learning algorithm. The results show that the proposed method has a higher accuracy in detecting defects of split pins, which can guarantee the stable operation of catenary support devices.

In this paper, a system with series hybrid converter and shunt active converter (SHC&SAC) for compensation in co-phase high-speed electric railways is proposed. Unlike the general power flow conditioners, the dc-links of the two converters are separated, and therefore, the two converters can operate independently. Just by taking the advantage of the reactive power generation ability and novel connection of SHC&SAC, the grid-side power factor can be improved and negative-sequence current can be suppressed, especially on the cases of high-speed trains. Besides, because of the capacitor in SHC, the active capacity of SHC is significantly lower than that of SAC. To obtain a good current tracking performance, the passive control method, which is based on the dissipation characteristic of resistor, is adopted for controlling converters. And finally, the effectiveness of the system is verified by simulation and experimental results.

Chinaâ™s railway is experiencing a restructuring from taking fossil fuels as leading resources to electrical energy with renewable energy sources (RESs). As a major consumer of energy, the railway system with RESs integration in China is discussed in this paper, and the relevant applications have been summarized and analyzed. At the same time, the development situations have not yet reached the expected target at present, and China is selecting the route for technical, investment, managerial, market and incentive policy approaches to exploit RESs potential for intelligent railway applications. Furthermore, the next-generation intelligent electrified railway with RESs is proposed and investigated, and the relevant core technologies, systems and incentive policies are summarized and elaborated. Referring to advanced experiences from other countries, the characteristics and objectives of railway energy management system based RESs are also obtained. Based on high-proportion of RESs integration, a win-win situation for railway system and RESs is expected in both economy and environment in China in the future.

The inner winding of the power transformer is subjected to uniform compressive stress in the radial direction during the short circuit, which makes circular radial stability a crucial component of reliability. The radial stability evaluation system currently needs more state characteristic judgment quantity considering the manufacturing deviations(MD) and assembly gaps. Thus, there is a significant deviation in the transformer design, which seriously endangers the operation safety of the power system. This paper proposes an improved radial buckling analysis method (IRBAM) to investigate the circular radial stability of inner winding. The IRBAM is implemented by defining two characteristic parameters: equivalent flexibility and MD. Besides, the relative change ratio of impedance (RCRI) is proposed as the buckling judgment for ending each short-circuit test. The destructive short-circuit tested transformer is designed with the rated power of 50 MVA and the high-voltage (HV) rated voltage of 110 kV. Then, 73 cumulative short-circuit tests are performed until impedance exceeds the permissible value based on the judgment. Finally, it is verified that IRBAM can effectively match the winding failure modes by comparing the buckling phenomena and calculation results. Further, the IRBAM can provide a reference for similar designs and verification with more minor deviations.

To improve the power quality of dc traction power supply system (DC-TPSS), a magnetic-integrated multi-pulse rectifier trans-former (MI-MPRT) with a tight impedance equalizing strategy is proposed in this paper. The configuration and winding-arrangement of MI-MPRT are introduced, and by integrating multiple windings on a same iron core, the volume and cost of proposed transformer can be decreased significantly. Cooperated with staggered winding-arrangement, a tight impedance equalizing strategy is proposed to optimize the winding thickness and insulation distance comprehensively, and MI-MPRT would be designed in a minimum axial dimension, with equalizing short-circuit impedance of each winding. A high-power prototype is manufactured, and the efficiency and effectively of prototype are verified by the transformer standard test. In addition, the DC-TPSS based MI-MPRT is implemented, and the experiment results validate that the power quality of new system can be im-proved significantly by harmonic elimination, circulation-currents suppression and dc-voltage ripple restraint. Both the theoretical and experimental results indicate that the proposed MI-MPRT is suitable for power quality improvement and industrial application in DC-TPSS.