A Novel Co-Phase Power Supply System for Electrified Railway Based on V Type Connection Traction Transformer

Abstract

Power quality and neutral section are two technical problems that hinder the development of electrified railway to high-speed and heavy railway. The co-phase power supply technology is one of the best ways to solve these two technical problems. At present, a V type connection traction transformer is widely used in a power frequency single-phase AC traction power supply system, especially in high-speed railway. In this paper, a new type of co-phase power supply system for electrified railway based on V type connection traction transformer is proposed. One single-phase winding in the V type connection traction transformer is used as main power supply channel, and three ports are used as compensation ports. Neutral section is no longer set with traction substation, and the train is continuously powered through. The independent single-phase Static Var Generators (SVGs) are used to compensate the three-phase imbalance caused by single-phase traction load. When necessary, the power factor can be improved at the same time. The principle, structure, control strategy, and capacity configuration of the technical scheme are analyzed in this paper, and the effectiveness of the scheme is verified by using the measured data of electrified railway. The advantage of this scheme lies in the universal applicability of the V type connection traction transformer, and the flexibility of the SVG device.

Traction power substation balance and losses estimation in AC railways using a power transfer device through Monte Carlo analysis

“…The railway power conditioner system (RPC) is employed in conjunction with V/V transformers and offers very good performance regarding 3-phase power balancing and power factor correction [10,23,24]. Similarly, the co-phase system [25][26][27][28] , has similar characteristics in terms of an optimized 3-phase interface. Maintaining the objective of guaranteeing a high level of power quality at the 3-phase supply, additional solutions are employed, e.g.…”

Using C‐type filter with partial compensation method for capacity reduction of hybrid power quality conditioner in co‐phase traction power system

“…Therefore, the total compensation currents are considerably reduced in the PC method using the C-type filter, resulting in a maximum reduction of 25.68% compared to the conventional system, i.e. from 13.78 to 10.24 MVA, as shown in Table 4 In addition, referring to (22), i cb plays a pivotal role to determine the three-phase grid currents. As shown in Table 5 as i cb increases, the grid currents would be increased as well.…”

“…When the HPQC operates in the PC method, secondary currents of the V/v transformer are as follows [28]: (22) where i ca_PC and i cb_PC are compensation currents of the PC method, respectively. According to Figure 5b x describes the amount of the load active current compensated by the HPQC.…”

“…Considering (35), the i ca_PC is decreased while there is no change in i cb_PC so that the load active current remains constant. Therefore, concerning (22), it is evident that grid-side currents will also remain constant. Besides, θ cb_PC and θ cb_FC can also be calculated as follows:…”

“…Although the passive solutions are affordable and straightforward, using them individually is impractical for dynamic traction loads and system variations. Therefore, active compensators such as static VAR compensator (SVC) [22,23] and static synchronous compensator (STATCOM) [24] were studied in electrified railway systems. However, despite reactive power injection, these devices are unable to compensate for current unbalance, low PF and harmonics simultaneously.…”