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.

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Microgrid is one of the solutions to supply stable electrical power with a large amount of intermittent renewable sources. However, efficiency of DGs and ESSs in microgrid might drop to a lower value because of microgrid operation, and there is a possibility that the convenience of a consumer may be spoiled. This paper shows a load forecast method and an optimized operation planning for DGs and ESSs in microgird to solve this problem. It is possible to estimate high accuracy electrical load by using a pattern data of power consumption not including power consumption of heat sources and an operation planning of the heat sources which run according to heat load prediction. The operation planning of DGs and ESSs consider direct-current characteristics of ESSs. As a result, error of SOC between planning and real-time operation decreases.

The installation of renewable energy sources based generators such as photovoltaic cells and wind turbines require energy storage systems(ESSs) to control power fluctuation. ESSs, however, are quite expensive. In order to reduce the necessary capacity of ESSs for microgrid applications, the control of heat pumps is researched. In this research, basic characteristic of a heat pump's power consumption is measured experimentally by use of heat pump chiller unit used in real building. Using the measured characteristic, a method to reduce the energy capacity of ESS is proposed and studied. The capacity reduction of ESS that can be achieved by use of heat pump control and the effect of control on temperature were calculated using simulations.

When a microgrid is operated in the islanding mode, the operator must satisfy the power quality demand by compensating the active and reactive power using several types of distributed power generation (DG) systems. In this paper, a method to stabilize the system frequency fluctuations and voltage fluctuations of the islanding microgrid is suggested. Extending the suggested “combined cascade control method” which can realize the power compensation without interferences between several types of DGs, “hybrid control” strucuture is proposed and negative effects of control and measurement signal delays on a control are reduced. Moreover, a control of the state of charge (SoC) of energy storage devices is added. For the stabilization of the system voltage, the energy storage is driven by “STATCOM model control”. Experiments have been carried out to confirm the effects of these methods by use of the model microgrid system, and satisfying results were received.

The hybrid control system, which is a combination of cascade control and local control, is proposed as a method to compensate power fluctuations caused by load and renewable energy sources in a microgrid with distributed power generation systems(DGs). The use of energy storage system(ESS) such as EDLC facilitates power compensation. However, since the energy capacities of these components are limited, the contol of their state of charge(SoC) is necessary.In this paper, a new method to control ESS's SoC which would enable power compensation with less energy capacity and with less effect to the compensation result is proposed. This method uses the feature of the cascade control that faster DG's reference is dependant on slower DG's output.The new method is implemented on EDLC in the model microgrid and its effectivity is verified by a simulation and a experiment. The result of the simulation and experiment in islanding mode is also reported in the paper.

The micro-grid has been operating at institute of technology of Shimizu Corporation since July, 2006. Main generators are two gas engine CHP (Combined Heat and Power) systems which rated output are 350kW and 90kW. Two power storage devices, a secondary battery and an electric double layer capacitor, are also installed to compensate rapid load fluctuation. This paper proposes an islanding operation control technique for these equipments using an integrated central control by central control server and an autonomous control of electric double layer capacitor. It is possible seamless operation transition between grid-connecting operation and islanding operation because condition signal of circuit breaker has transmitted to each generator at 30 milliseconds. We have verified validity of the developed control method by using the micro-grid. As the results of 50 times transition experiments, frequency fluctuation target (within 0.2 Hz) has been satisfied with probability 99.9% and voltage fluctuation target (within 10%) has been satisfied with probability 100.0%.

The hybrid control system, which is a combination of cascade control and local control, is proposed as a method to compensate power fluctuations caused by load and renewable energy sources in a microgrid using distributed power generation systems(DGs). When energy storage system(ESS) such as EDLC is used in the microgrid to compensate power fluctuations, its state of charge(SoC) should be controlled. In this paper, a new method to control ESS's SoC which would enable power compensation with less energy capacity and with less effect to the compensation result is proposed. This method uses the feature of the cascade control that faster DG's reference is dependent on slower DG's output. The new method is implemented on EDLC in the model microgrid and its effectivity is verified by a simulation and a experiment. The result of the simulation and experiment is also reported in the paper.

The scope of the paper is to reveal the strange behavior of Direct Torque Controlled (DTC) drives resulting from the nonlinearity of hysteresis comparators. A piecewise-defined, non-stroboscopic, discrete-time Poincare¿ map can be constructed for the system which takes into account the fast switching operations of the Voltage Source Converter (VSC). The evolution of the stator flux linkage and the electric torque within the hysteresis loops are determined from switch to switch. The movement of the two controlled state variables exhibits periodic, subharmonic, chaotic and intermittent chaotic states along a special series of border collision bifurcations induced by discontinuity of the Poincare¿ mapping function. In order to give a better insight into these bifurcations, a one-dimensional piecewise linear discontinuous iterated map is developed and analyzed.

The micro-grid has been operating at institute of technology of Shimizu Corporation since July, 2006. Main generators are two gas engine CHP systems which capacity are 350kW and 90kW. Two power storage devices, secondary battery and electric double layer capacitor, are also installed to compensate rapid load fluctuation. In this paper, load demand is analyzed by using frequency analysis and this sampling interval is decided by probability distribution of power transition. DG systems' characteristics such as frequency response, fuel efficiency and frequency stabilization capability are also assessed. Capacity of DG Systems in the Micro-grid is evaluated by results of load demand analysis and DG systems' characteristics assessment.

The authors have been carrying out a preliminary study on the design of microgrid. Designing microgrid includes selection and capacity determination of power supply devices according to their response characteristics, efficiency and initial cost, and development of methods for integrated control to maintain power quality and efficiency. Both design and control methods depend on conditions of loads, for which microgrid is installed. In this paper, design methods of microgrid, such as power demand analysis, response characteristics measurement of power sources and fuel efficiency measurement of engine-generators, and integrated control methods for power sources are proposed, along with experimental results for a prototype of microgrid.

The paper is concerned with new resonant converter configurations, belonging to the previously published dual channel dc-dc converter family. On one hand, the new configurations solve a significant shortcoming of the original ones, namely, the output midpoint potential was floating in comparison with the input midpoint. This caused a high-frequency oscillation of the output midpoint, often significantly limiting the application fields. Common ground can be used at the input and output sides at the new configurations. In addition, two of the new topologies also include electrical isolation, performed by an isolating high-frequency transformer. This property is often necessary in order to fulfill the strict industrial requirements against the power converters.

The source of nonlinearity are the hysteresis comparators and dependence of switchings on state variables in direct torque controlled (DTC) induction machines (IM). The nonlinearity generates some strange operation states. They are revealed, analyzed by bifurcation diagram and recurrence plots both in motoring and generating operations.

Copyright © 2007 Railway Technical Research Institute. All rights reserved. Reproduction in whole or part without permission is prohibited. Printed in Japan. Brightening the Future of Railways Using New Technologies Eisuke MASADA ........................................................................................ 115 Publishing English Digests of Design and Maintenance Standards for Railway Structures and Commentaries Kenichi KOJIMA ........................................................................................ 116

A power control method to compensate power fluctuation of the load in the micro grid systems is proposed and discussed. Active power responses of several kinds of distributed power generation systems (DGs) such as gas engine, micro gas turbine etc., energy storage system, and load fluctuation of a site have been measured. Based on the measurements, coordinate control system for several kinds of DGs has been constructed. Simulation and experiments have been carried out with small-scale micro grid model system. It is shown that the load fluctuation has been compensated by the proposed method.

The paper is concerned with the stability analysis of a feedback controlled resonant dual channel buck converter. The output voltage is controlled by using constant frequency PWM and PI controller. The analysis is based on the eigenvalues of the Jacobian matrix of the Poincare map function (PMF). After small perturbation determining the deviations of the state variables from the periodic trajectory, the Jacobian matrix is calculated without the need to determine the PMF itself. The introduction of the so-called auxiliary state vector greatly facilitates the calculation. Calculation and simulation results included helps the design of the control loop

清水建設(株)技術研究所に、マイクログリッドの考えを取り入れた小規模マイクログリッド試験設備を構築し、分散型電源の出力協調運転により有効電力の負荷変動分を供給可能な電源システムを志向し開発を進めている。分散型電源の種類はガスエンジン、マイクロガスタービン、鉛蓄電池、太陽光発電である。出力協調制御の考えは、緩やかな応答特性を有するマイクロガスタービンを可能な範囲で負荷追従させ、追従しきれない負荷変動をガスエンジンに負荷追従をさせる。さらにガスエンジンが追従できない負荷変動については最も速い応答特性を有する鉛蓄電池に補償させるものである。この応答特性を活用した出力協調制御を実証した。

A Propulsion Trade Study was conducted as part of the Colorado Maglev Project of FTA’s Urban Maglev Technology Development Program to identify and evaluate prospective linear motor designs that could potentially meet the system performance requirements of the Colorado Dept. of Transportation (CDOT) Project, and be applicable to other urban maglev transit corridors. The study focused primarily on the performance of the linear induction motor (LIM) propulsion system of the Chubu HSST (CHSST) that had been selected as the baseline technology for that project. Potential near-term improvements and modifications to that propulsion system have been considered and appear feasible. This report compares the relative advantages and disadvantages of that linear induction motor and mature linear synchronous motor options for urban and suburban maglev transit systems. 1 Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94-AL85000.