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.

Fortunately, Japan's big cities have embraced electrified railways as a major method of transportation since the early 20th century. According to the results of Japanese government research, electric railways convey more than 90% of the total person trips of the whole railway system, which carries about 30% of all the person trips in Japan (with the remainder carried 54% by car, 7% by bus, and 7% by air). Thus, we can consider the electric railway to be one of the backbone technologies of Japanese life.

Two methods currently exist to evaluate degradations in arresters in Shinkansen substations. One method uses a surge current counter device to count the number of strokes of lightning. However, surge current counter devices sometimes pick up small switching surge of changeover switches, which are not deterioration to the arrester. The other method is to measure normal leakage current of arrester. This method though is potentially unreliable because the leakage current is strongly affected by the feeding voltage harmonics. A deterioration diagnosis device was thus designed with functions to suppress unwanted small surge current counts and provide accurate measurements of the leakage current in the target arrester. This paper describes various field measurement results, the principle underlying the developed deterioration diagnosis device and a new method for extracting the resistive current in the arrester from the overall measured leakage current.

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.

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Most Shinkansen substations in Japan receive their electric power supply for traction from extra-high voltage systems. "Modified-Woodbridge connection" transformers have been used for this since 1972; however, these have a rather complicated structure. As such, studies were carried out to develop a new type of transformer, which had the same functions, but was simpler. The transformer has been coined the "roof-delta connection" transformer since it has both roof and delta windings. Test results from a prototype of this transformer revealed that it could be used in AC traction feeding systems. This paper describes the fundamental characteristics of the roof-delta connection transformer and results from tests.

Recently, electromagnetic environments and electromagnetic compatibility (EMC) in relation to electrical equipment have become important issues. In 2008, the European Union established the EN 50500 standard, which provides measurement and calculation methods for determining magnetic fields emitted from electrical equipment on railways. The major frequency components of the electric and magnetic fields generated from such equipment are in the low range, such as D.C., 16.7 Hz, 50 Hz, 60 Hz and their low-order harmonics. According to the EN 50500 standard, magnetic fields are dominant around this kind of equipment. This paper describes the physical characteristics and analytical methods of low-frequency magnetic fields emitted from electrical equipment in railway substations, and proposes abatement measures and model substation designs based on the above results.

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.

In AC electric railways, three-phase voltage is changed into the single-phase circuit of two circuits with the Scott-connected transformer. If unbalancing of the load between single-phase circuits becomes large, voltage fluctuation becomes large on the three-phase side. Railway static power conditioner (RPC) was developed for the purpose of controlling voltage fluctuation on the three-phase side. 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. In this way, the two self-commutated inverters can act as a static var compensator (SVC) to compensate for the reactive power and as an active power accommodator from one feeding bus to another.20 MVA/60 kV RPCs started commercial operation in 2002 at each two substations on the newly extended Tohoku Shinkansen for compensating voltage fluctuation on the three-phase side caused by traction loads, absorbing harmonic current. 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, and handle the exciting rush current of transformers, as well as compensate for harmonics successfully. (c) 2007 Wiley Periodicals, Inc.

This paper reports on the basic configuration of the railway static power conditioner (RPC), a static voltage compensator for AC electric railways. 20 MVA / 60 kV RPCs started commercial operation in 2002 at each substations on the newly extended Tohoku Shinkansen. The results of operational test 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 succcessfully controlled by the RPCs.

Energy storage media have been remarkably developed in recent years to constitute an energy storage system. Electric double-layer capacitors can be rapidly charged and discharged and offer a long life time, high efficiency and maintenance free/low pollution features. Charge and discharge tests of a prototype energy storage system at DC 400V were carried out and found that it provides a stable power supply system for DC electric railways. On the other hand, a hybrid system to apply different energy storage media in parallel according to the load pattern may be effective. We carried out fundamental tests about different energy storage media and a hybrid system at DC 75V.

At substations or sectioning posts of Shinkansen, a pair of single-phase power sources are provided in different phase. When a Shinkansen car passes the boundary between the two power sources, the changeover section (about 1km long) with a pair of vacuum changeover switches the power sources for the car instantly. There were no ways to detect the flashover of vacuum switch used as a changeover switch before, so we wasted a long time sometimes to specify the fault reason. We analyzed the fault current carefully, to find the facts: When the changeover switches are normal, a current flows through only one switch. When the fault occurs on a changeover switch with no cars in the changeover section, fault current flows through both switches to make the currents in the two switches the same. When a fault occurs on a changeover switch with a car in the changeover section, both fault current and load current flow. In this situation the currents in the two switches are different. Then we have developed a new type protective relay for Shinkansen changeover switches based upon the facts. This relay has a pair of over current detectors with a pair of optical current transformers to detect the current in each changeover switch. When it detects the over current of both switches, it can judge that a flashover has occurred in one of the changeover switches.

At substations of Shinkansen, three-phase power received from the utility power system is converted into a pair of single phase power sources with different phases. When a Shinkansen car passes the boundary of two power sources with different phases, the power source for Shinkansen instantly switches from one to the other. Vacuum switches have been used as changeover switches so far. It takes about 300 msec for switching. By this system, Shinkansen cars can pass the boundary of two power sources under powering.Generally speaking, when a vacuum switch is closed at a voltage-phase of 90°, the inrush current into transformer will become small. On the other hand, although the power from substation is not supplied to Shinkansen at no-voltage of power source switching at the changeover section, counter electromotive force by auxiliary motor appears on the main transformer on the car. Due to the counter electromotive force, it is difficult to suppress the inrush current into the main transformer by the conventional vacuum switch. In contrast, the use of static switch such as semiconductor device can decrease the exciting inrush current into the transformer of Shinkansen car, when the turn-on timing of changeover switch is controlled. We investigated the control method for suppressing the exciting inrush current into transformer when a static switch is used as a changeover switch instead of vacuum switch. To verify the control method, we built and tested a mini model to simulate a changeover switch.

The feeding transformer for AC electric railways converts three-phase electric power into a pair of single-phase electric power supplies for driving electric cars. To prevent the fluctuation of three-phase voltage, however, a single phase feeding suits car depots. Authors have developed a single-phase feeding power conditioner (SFC) for unbalanced voltage compensation. This paper describes the principle and test results of using SFC. SFC is made of a scalene Scott-connected feeding transformer and a pair of self-commutated inverters, which connect the secondary side of a transformer and are coupled with the DC side capacitor. Each inverter operates independently in order to control reactive power. On the other hand, SFC controls active power from larger to small load phase circuits via the DC capacitor to keep the active power balanced.

RPC (Railway Static Power Conditioner) is a static voltage compensator to avoid a voltage fluctuation of 3-phase power grid under an AC electric railway load. Normally, in Japan, 3-phase electric power is transferred to paired directional single-phase feeding circuits. At a substation, RPC links directional feeding circuits using two self-commutated inverters and RPC accommodates and active power of these circuits to balance 3-phase power and compensates a reactive power to regulate a 3-phase voltage fluctuation. At a sectioning post, it can reduce voltage drop using a reactive power. Also, it can act as an active filter to compensate harmonics. This paper reports on the successful results of tests using a small model of RPC and dummy loads such as thyristor phase controlled car.

In this paper, the authors describe the basic configuration of an RPC (Railway Static Power Conditioner), its compensation principles and successful test results (using a small model of RPC). An ac electric railway is placed under a rapidly changing single-phase load. To avoid a voltage fluctuation under single-phase loads, electric power is received from a large source. At a feeding substation, three-phase electric power is transformed into two kinds of directional single-phase feeding electric power. The authors have already proposed a static voltage compensator for the ac electric railway, called “RPC.” The RPC links a pair of feeding circuits, using two self-commutated inverters. At the substation, the RPC accommodates an active power in the directional pair of feeding circuits to balance three-phase power, and possess a reactive power to regulate a three-phase voltage fluctuation. At a sectioning post, it can compensate for voltage drop using reactive power. It can also act as an active filter to compensate for harmonics. The authors have made a small model (220 V, 20 kVA) of the RPC, and report on the test results obtained using this small model under various conditions. The results indicate that the RPC can accommodate single phase loads, such as transformers and thyristors, can handle an exciter rush current from a transformer, can compensate for harmonics, and so on.

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.

There are two major feeding systems for over 200 km/h of train speed: single phase AC feeding system and DC feeding system. Many lines with high speed around the world use single phase AC feeding system which has been found to be superior to other systems. However, it is possible to use high voltage DC feeding system if it is cheaper than AC. In this case, feeding voltage of the DC feeding system is required to be from 3 kV to 8 kV to be applied for high speed trains. Also, DC feeding system will be more suitable in case of adoption of the third rail system for over 200 km/h high speed.

In this paper we propose a new train communications network (TCN) system for processing instrumentation data collected between vehicles that have a very rapid data rate.Now there are many TCN for communication available to control devices in a train, which have a data rate of 10k-1Mbps (bits per second). But we need a faster data rate for instumentation data, when we conduct a track test of MAGLEV (Magnetic Levitation Vehicle). In this case, we handle several hundreds of sensors on the train and collect synchronized data for structure analysis and vehicle dynamics analysis after the test.We have developed a new TCN system for collecting synchronized instrumentation data consisting of a huge digital data-recorder and an optical-fiber train bus. This system treats a data rate of 32Mbps. And we have developed all devices, protocol, optical-module, optical-connectors and so on.