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High-speed rail power supply systems
Published in Andrzej Żurkowski, High-Speed Rail in Poland, 2018
DC power supply system has been used since the dawn of an electric traction contact system (Figure 10.4). The variant 3 kV DC adopted in Italy or Poland, allows train operation in the range from 220 km/h to 250 km/h, power output of 6–8 MW [4, 12, 14]. Larger loads (vehicle output and traffic density as in Italy), however, cause significant voltage drops and large load currents, which require an increase in the cross-section of a contact line conductor (up to over 600 mm2 copper), smaller distances between substations (as little as 10–12 km), higher installed power in substations (above 10 MW). This forces an increase in investment outlays and is costly in operation. In addition, increased load and generation of harmonics result in the necessity to move the point of common coupling of a substation to the electric power grid at the high voltage level. So a single-stage transformation (as 110/1.3/1.3 kV in Poland) is applied to feed the rectifier set in a traction substation. Attempts were taken to increase voltage to 6–18 kV DC in a contact line; the major issue was of breaking the fault currents, which caused resignation of practical usability of such voltages. Legend to Figure 10.4HV – high voltage;MV – medium voltage;TrPr – transformer of rectifier unit;Pr – rectifier,Tr 1st – power supply with single-stage HV transformation.
A novel measurement approach based on wideband excitation for frequency-coupling admittances of train converter
Published in International Journal of Rail Transportation, 2022
Haidong Tao, Xiaojuan Zhu, Haitao Hu, Jiameng Yu, Zhengyou He
Among the frequency-coupling stability issues of the railway power supply system, the high-frequency especially more than half the 4QC switching frequency stability problem is frequently reported [16–18]. For instance, in March 2018, the catenary voltage in Deyang traction substation, China, experienced high-frequency instability near 1650 Hz, resulting in the breakdown of five lightning arresters. The following year, in November, the catenary voltage in Jingbian East traction substation, China, experienced high-frequency instability near 950 Hz, resulting in the breakdown of 14 lightning arresters. It is feasible to evaluate the high-frequency stability issues based on the impedance-matching analysis [19], where the sampling frequency-coupling admittances (SFCAs) of train 4QC play a vital role in the analysis [4–8]. However, the impedance modelling above half 4QC switching frequency is complicated since switching modulation as well as A/D sampling involve multiple coupling harmonics. There is no DC steady-state operation point [15,20]. The common state space average modelling method may not be appropriate in the high frequency [8]. Additionally, the control system of actual 4QC is characterized as a black box or a grey box. These unfavourable factors lead great challenges to the high-frequency modelling of 4QC. As such, it is elementary to measure the SFCAs of train 4QC for verifying the theoretical model and assessing the stability performance in the high frequency. Nevertheless, the measurement of SFCAs also faces two challenges.
Optimal energy management of a DC power traction system in an urban electric railway network with dogleg method
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Xiaojuan Hu, Shan Zhou, Tie Chen, Mohammad Ghiasi
Where, is the output voltage of the traction substation (V);represents the output current of the traction substation (A). As we considered the regenerative power from braking vehicle (s) and the amount of energy received at the start of the traction motor and train movement, is the regenerative energy from braking vehicle, and is the amount of energy received at the start of the traction motor, where in this study we assume that . When the position of the running vehicle varies, every discrete power could be calculated and obtained, and the consumption of electrical power and energy loss could be computed using integration of all discrete power points which is given in equation (8).
Rail potential control with train diagram optimization in multitrain DC traction power system
Published in International Journal of Rail Transportation, 2021
Chengqian Zhu, Guifu Du, Yawen Ding, Weiguo Huang, Jun Wang, Mingdi Fan, Zhongkui Zhu
At present, DC traction power system widely uses the running rails as the backflow conductor in the system [1,2]. Because of the resistance of the rails, there is a certain potential between the rails and earth, which is called rail potential [3]. Part of the current in the rails will flow to the earth, forming stray current [4]. Excessive rail potential and stray current will endanger the safety of passengers and the equipment [5,6]. Under normal operation conditions, the rail potential should be controlled within 90 V [7]. Over Voltage Protection Devices (OVPDs) are usually installed at each traction substation (TSS). If the rail potential on the OVPD exceeds the safety limit of 90 V, OVPD will be triggered to connect the rails to earth, so as to control the rail potential [8].