Tetsuo Uzuka

A static voltage fluctuation compensator for AC electric railway

This paper reports on the basic configuration of the railway static power conditioner (RPC), a static voltage compensator for AC electric railways. An RPC is comprised of a pair of self-commutated PWM inverters. These inverters connect the main phase and teaser feeding buses, coupled with a DC side capacitor such as a back-to-back (BTB) converter. 20 MVA / 60 kV RPCs started commercial operation in 2002 at each substation on the newly extended Tohoku Shinkansen. The results of operational testing indicate that an RPC can accommodate single-phase loads such as those of PWM-controlled Shinkansen and thyristor phase-controlled Shinkansen, handle the exciting rush current of transformers, as well as compensate for harmonics. The voltage fluctuations on the three-phase side were successfully controlled by the RPCs.

New type of feeding transformer for AC railway traction system

At Shinkansen substations in Japan that receive electric power from an extra-high voltage system, we have been using modified Woodbridge connected transformers for traction power supply since the inauguration of the Sanyo Shinkansen, which commenced commercial operations in March 1972. However, this transformer is of a rather complicated structure. Therefore, we studied a new type of transformer, equipped with equal functions, however a simpler mechanism as compared with a conventional one. We termed the transformer a roof-delta connected transformer since it has a roof-winding and a delta-winding. The roof-delta connected transformer expectable to decrease costs by reducing quantity of winding. We fabricated roof-delta connected transformers for trial at 66kV-voltage. We performed various tests including measurement of neutral phase current. Test results revealed that this transformer is applicable to the used in AC traction feeding system. The first practical roof-delta connected transformer is going to be installed at a new Shinkansen substation constructed by JRTT. JR East is also planning at present to install them at existing Tohoku and Joetsu Shinkansen substations for their renewal. This paper describes the fundamental characteristics of the roof-delta connected transformer and the test results.

Trends in high-speed railways and the implications on power electronics and power devices

High Speed Rail (HSR) are expanding rapidly in the whole world in this decade. Almost all the high-speed trains are fed by high-voltage and are equipped with several large motors. In addition, High-speed trains have a strict restriction for both mass and size. Thus, HSR needs power semiconductors that can handle high-voltage and giant current. In addition, EMC problems become larger in these days, thus higher speed of switching is expected. From simple silicon diodes in 1960s, thyristors, GTO thyristors, IGBTs and until new wide gap devices such like SiC and GaN, the progress of power semiconductor and cooling system directly pulls the performance of high-speed rolling stock. In some cases, fixed installations for HSR are equipped with flexible AC transmission systems (FACTS) such as static VAR compensators (SVC), also.

High Speed Rail Awaits the next Breakthrough of Power Semiconductors

High Speed Rail (HSR) is expanding rapidly in the whole world in this decade. Almost all the high-speed trains are fed by high-voltage AC and are equipped with several large motors. In addition, High-speed trains have a strict restriction for both mass and size. Thus, HSR needs power semiconductors that can handle high-voltage and giant current. In addition, EMC problems become larger in these days, thus higher speed of switching is expected. From simple silicon diodes in 1960s, thyristors, GTO thyristors, IGBTs and until new wide gap devices such like SiC, the progress of power semiconductor and cooling system directly pulls the performance of high-speed rolling stock. In some cases, fixed installations for HSR are equipped with flexible AC transmission systems (FACTS) such as static VAR compensators (SVC), also.