Design of energy‐efficient train speed profiles considering fixed‐block signaling system

In dense traffic railway networks, trains may often slow down or stop between stations owing to previous train delays. If preceding train trajectory can be predicted, energy‐efficient driving can be achieved by suppressing unnecessary speed changes. In this paper, we propose an algorithm to find energy‐efficient driving considering fixed‐block signaling (FBS) system by using dynamic programming (DP). DP is suitable for use because it can optimize the control inputs with discrete and state constraints. In this paper, we discuss energy‐efficient driving by considering a FBS system using some case studies of simulation. In the simulation, we examine a technique to drive an express train in an energy‐efficient way when the preceding local train is running toward the station with passing loops. The results show that the proposed method can derive complex speed profiles for energy‐efficient driving and the train can be operated with a maximum reduced energy consumption of 8.3%.     

Modeling and optimizing energy‐efficient manual driving on high‐speed lines

This paper presents a simulation‐based model for manual driving strategies that will minimize energy consumption for high‐speed trains. Specific characteristics of both high‐speed lines (HSLs) and manual driving strategies are considered in order to obtain achievable designs that can be tested on commercial services. The proposed design model calculates a list of efficient high‐level commands to be systematically executed by the driver on an HSL along the trip. The design is based on a detailed simulation model of the train's motion (taking into account track and train characteristics and operational constraints), combined with a genetic algorithm to select the best driving. Continuous control solution by mathematical optimization is avoided, as it is not an appropriate reference for manual driving in HSL. The validation of the simulation model is focused on running resistance, tractive/braking efficiencies, and consumption of auxiliary equipment, and shows differences between real measurements and simulated results which are lower than 2% both in run time and energy consumption. Finally, a real case is presented in which the proposed model was used to design efficient driving strategies that were subsequently implemented on commercial services along the Spanish HSL Madrid–Barcelona in both directions, measuring average energy savings of 23 and 18%, respectively, when the efficient driving strategies were compared with measured standard manual driving. The future scope will be the application of this model to online recalculation of driving commands. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Optimized Energy‐Saving Speed Profile in Linear‐Motor Railway System

The most striking characteristic of linear‐motor railway system is that the structure consists of a primary and secondary linear induction motor (LIM). The primary side of the LIM is installed in a rolling stock, and the secondary side of LIM is installed on the track. The magnetic attractive vertical force produced by the LIM increases the running resistance since this force is in the same direction as the gravitational force due to which rolling stocks gain weight virtually from the track side of view. In addition, the efficiency of the LIM has different characteristics of efficiency compared with the rotary motor. Previous studies have focused on the design method of LIM to improve motor efficiency and decrease energy consumption. However, it is a well‐known fact that this kind of approach requires hardware renewal which requests large amount of investments. The purpose of this study is to analyze these characteristics of LIM effects and design the optimal speed profile to minimize the energy consumption as a linear‐motor railway system. This smart and economic energy‐saving approach is based on the optimization of speed profiles of the linear‐motor railway system using dynamic programming.     

Energy‐efficient single‐clock‐cycle binary comparator

A new fast low‐power single‐clock‐cycle binary comparator is presented. High speed is assured by using parallel‐prefix architecture, whereas low power is guaranteed by reducing the switching activities of the internal nodes. When implemented with the ST 90 nm 1 V CMOS technology, the proposed circuit exhibits a 4.5 GHz maximum running frequency and 0.77µW/ MHz energy dissipation. Copyright © 2010 John Wiley & Sons, Ltd.     

Energy‐Saving Technologies for Inverter Air Conditioners

Almost all residential air conditioners in Japan are inverter air conditioners in which a permanent magnet synchronous motor (PMSM) is driven by a PWM inverter. The inverter technology can reduce the energy consumption to less than half that of air conditioners driven by a constant‐speed induction motor (IM). This paper reviews the trends and the latest energy‐efficient technologies for the motor and the power converter that achieve considerable energy saving. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Energy‐efficient cooperative localization in mobile WSN

Design and implementation of an energy‐efficient protocol is one of the main challenges in wireless sensor networks (WSNs). In terms of localization, both energy efficiency and accuracy must be addressed to achieve the final goals of localization. In mobile sensor nodes, where battery power is the most hardware resource limitation, accurate localization needs to be extremely energy efficient. In this work, a virtual multiple‐input multiple‐output (VMIMO) technique is deployed to tackle the problems of getting more energy efficiency and higher accuracy simultaneously.In this case, the optimum selection of the number of transceiver nodes can be obtained with the lowest possible total energy consumption, localization error, and speed of nodes. In addition, VMIMO decreases the power of transmitters, and therefore will lead to the reduction of destructive effects of electromagnetic sensitivity (EMS) on the body. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Energy‐saving Technologies for Automobiles

Since entering the 21st century, we have been facing a globally urgent need for all nations, without exception, to deal with environmental concerns such as global warming and energy issues arising from the depletion of fossil fuels. As a countermeasure, next‐generation vehicles for a recycling‐based society that are energy‐efficient, compact, light, low‐cost and reliable need to spread in the society. In this study, we will explain the basic philosophy of how to approach next‐generation energy‐saving technologies for automobiles, the current status and technological issues of internal combustion engines (ICE), hybrid electric vehicles (HEVs), electric vehicles (EVs), and fuel cell vehicles (FCVs) with the latest examples. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Automatic Train Operation Using Autonomic Prediction of Train Runs

In this paper, we present an automatic train control method adaptable to disturbed train traffic conditions. The proposed method presumes transmission of detected time of a home track clearance to trains approaching the station by employing equipment of Digital ATC (Automatic Train Control). Using the information, each train controls its acceleration by a method that consists of two approaches. First, by setting a designated restricted speed, the train controls its running time to arrive at the next station in accordance with predicted delay. Second, the train predicts the time at which it will reach the current braking profile generated by Digital ATC, along with the time when the braking profile transits ahead. By comparing them, the train correctly chooses the coasting drive mode in advance to avoid deceleration due to the current braking profile. We evaluated the effectiveness of the proposed method regarding driving conditions, energy consumption, and reduction of delays by simulation. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(3): 65–73, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.10020/eej.21080     

Design of Optimal Coasting Speed for MRT Systems Using ANN Models

An artificial neural network (ANN) has been proposed in this paper to determine the optimal coasting speed of train operation for the Kaohsiung Mass Rapid Transit (KMRT) system to achieve the cost minimization of energy consumption and passenger traveling time. A train performance simulation (TPS) is applied to solve the energy consumption and the traveling time required to complete the journey between stations with various riderships to create the data set for ANN training. The ANN model for the determination of the optimal coasting speed is then derived by performing the ANN training. To demonstrate the effectiveness of the proposed ANN model, the annual ridership forecast of the KMRT system over the project concession period from 2007 to 2035 has been used to determine the optimal coasting speed of train sets for each study year according to the distance between stations and the passenger ridership. The power consumption profile of train sets and the traveling time of passengers have been solved by TPS to verify the reduction of social cost for KMRT system operation with the optimal coasting speed derived.      

A novel method to improve low‐voltage ride‐through capability of wind turbine generators

With increasing penetration of wind farms, power grids have responded by developing specific grid codes to maintain their stability. One of the main grid codes is the low‐voltage ride‐through (LVRT) capability, which requires the wind generator to remain connected when the grid voltage sags for a certain time period. A wind farm with squirrel cage induction generators suffers this LVRT problem the most because of their direct connection to the grid and reactive power consumption. In this paper, a new method is proposed to solve this problem by shunt‐connecting a motor‐driven mechanical load to the cage wind generator. For driving mechanical loads, the induction motor is most widely used in industries. This paper studies the terminal voltage holding effect of an induction machine during grid voltage sag due to the magnetic flux holding effect and the saturation characteristic. Taking advantage of this effect, the induction motor that is used for driving mechanical load is then proposed to improve the LVRT capability of wind turbine generators. Furthermore, the change of the rotating speed or slip of the induction machine is found to have a great impact on improving the LVRT. By adding some inertia to the motor‐driven mechanical load, an enhanced voltage holding effect, and therefore LVRT improvement, is expected for the wind farm. Both simulation and experimental results prove the effectiveness of the proposed method. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A high‐speed reclosing method to improve the stability in a power system

This paper proposes a high‐speed reclosing operating method to improve the stability in a power system. The proposed method calculates the reclosing time, taking a standard case in which the reclosing is not done using the generator phase angle δ, and the angular velocity ω, and the field system voltage ed′. Also, the execution of reclosing time is calculated, while taking into consideration the acceleration/deceleration energy of the generator during a fault. It can be expected that δ is suppressed by this optimum reclosing operation. Therefore, the system stability can be expected to improve by carrying out high‐speed reclosing when a fault occurs. At present, it has been set at a value which seems to be optimal considering various problems in the reclosing time. However, in those methods, the system stability improvement effect cannot be expected. It was demonstrated that the high‐speed reclosing method serves to depress δ in the computer simulation. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 147(2): 13–21, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10317     

同步电动机起动大负载时的优化控制分析

在同步电动机的驱动控制中,矢量控制方法得到广泛应用,对于无刷励磁同步电动机,常采用定子磁链定向的控制方案,但这样并不能使电机的输出转矩最大。从能量（功率）角度进行分析,得出了在３种状态下,应如何对定子电流＾→ｉｓ进行控制的各表达式;特别是在书籍转子位置（ｄ轴）时,定子电流＾→ｉｓ应超前它的角度α角。按中文的方法进行控制,对加快电机的起动过程,节省电能均有其意义。     

A 5‐GHz energy‐efficient tunable pulse generator for ultra‐wideband applications using a variable attenuator for pulse shaping

A new energy‐efficient tunable pulse generator is presented in this paper using 0.13‐µm CMOS technology for short‐range high‐data‐rate 3.1–10.6 GHz ultra‐wideband applications. A ring oscillator consisting of current‐starved CMOS inverters is quickly switched on and off for the duration of the pulse, and the amplitude envelope is shaped with a variable passive CMOS attenuator. The variable passive attenuator is controlled using an impulse that is created by a low‐power glitch generator (CMOS NOR gate). The glitch generator combines the falling edge of the clock and its delayed inverse, allowing the duration of the impulse to be changed over a wide range (500–900 ps) by varying the delay between the edges. The pulses generated with this technique can provide a sharp frequency roll off with high out‐of‐band rejection to help meet the Federal Communications Commission mask. The entire circuit operates in switched mode with a low average power consumption of less than 3.8 mW at 910 MHz pulse repetition frequency or below 4.2 pJ of energy per pulse. It occupies a total area of 725 × 600 µm² including bonding pads and decoupling capacitors, and the active circuit area is only 360 × 200 µm². Copyright © 2011 John Wiley & Sons, Ltd.     

Stabilization analysis of commercial‐scale subsonic diagonal‐type MHD generator considering loading conditions

In previous research on subsonic diagonal‐type MHD generators, the authors have proposed a conceptual design with relatively low Mach number in order to stabilize the MHD generator of commercial scale and have shown that the MHD generator works stably under constant‐current loading condition. In the present paper, effects of loading conditions on stability of the MHD generator are examined. A channel‐length scale linear stability analysis and time‐dependent calculations are carried out, where both gasdynamical boundary conditions and loading condition are taken into account. These analyses show that the MHD generator behaves stably under various loading conditions such as constant‐voltage loading condition and ohmic loading condition. Then the stability of the MHD generator connected with an ac power system is also analyzed by time‐dependent calculations. The analysis shows that the MHD generator stably provides the rated power to the ac power line. © 1999 Scripta Technica, Electr Eng Jpn, 128(4): 16–24, 1999     

Autonomous decentralized voltage profile control of super‐distributed energy system using multi‐agent technology

A super‐distributed energy system is a future energy system in which a large part of its demand is fed by a huge number of distributed generators. At one time some nodes in the super‐distributed energy system behave as load, whereas at other times they behave as generator—the characteristic of each node depends on the customers' decision. In such situation, it is very difficult to regulate the voltage profile over the system due to the complexity of power flows. This paper proposes a novel control method of distributed generators that can achieve autonomous decentralized voltage profile regulation by using multi‐agent technology. The proposed multi‐agent system employs two types of agent: a control agent and a mobile agent. Control agents generate or consume reactive power to regulate the voltage profile of neighboring nodes and mobile agents transmit the information necessary for VQ‐control among the control agents. The proposed control method is tested through numerical simulations. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(4): 43–52, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20484     

Energy‐saving house utilizing photovoltaic system

To study the efficient use of the housing and photovoltaic, we constructed housing which has adequate airtightness, adequate heat insulating efficiency, concrete floors, multiple window glasses for seasonal weather changes, and much more safety. We built a house in which two people can live (160 m²) and which needs only 4.9 kW of energy. We did data analysis while they were actually living there. As a result, we could create a comfortable environment in which to live, keeping the temperature in summer between 28.5 and 30 °C and the humidity 50% (moisture removal) and the temperature in winter between 22 and 24 °C and the humidity 50% (moisture addition). Because overdrying of the air was restricted, dew condensation was prevented. Of 4240 kWh, 2940 kWh (70%) became surplus electric power and the rest (30%) was consumed for a comfortable living environment. It was demonstrated that we could save 42% of electric power expenses compared with that of general housing (4‐person household, 160 m²) and that we could reduce by more than 60% the cooling and heating capacity. © 2000 Scripta Technica, Electr Eng Jpn, 130(4): 45–57, 2000     

现代水平轴三叶片风力发电机转速控制的优化

提供一种选择适合项目风况下的风力机,并找到风力机运行在最佳性能的方法,通过此方法提高风能的利用效率,实现风电厂投资收益最大化。通过研究风力机发电机转速、风速、最佳叶尖速比和发电机功率之间的关系,使用实际运行数据推算在运风机最佳叶尖速比,找到使风力机运行在该最佳叶尖速比的发电机转速-功率控制曲线。使用该曲线对风力机的发电机转速控制器进行优化,从而使风力机在更宽的发电机转速范围内,运行在最佳叶尖速比下,获取最大风能。使用该方法,结合真实风力发电厂案例,通过对在运机组的运行数据的分析,优化其发电机转速控制策略,最终达到了提升风力机发电量的目的,验证了该方法的可行性。该方法也可作为对风力机选型评估的参考。     

Optimal current control methods of a non‐salient pole hybrid field‐synchronous motor for energy‐efficient and wide speed‐range operation

This paper proposes new practical optimal current control methods for a newly emerging class of non‐salient pole synchronous motors with hybrid rotor fields by both permanent magnet and winding. In practical situations with limited voltage, the extensively used permanent magnet synchronous motor hardly achieves an ideal performance that allows simultaneously both low‐speed high‐torque and wide speed‐range operations, due to its constant magnet field. Hybrid field synchronous motors (HFSM) have recently emerged to achieve ideal performance as practical motors with controllable hybrid rotor field. For HFSM, the same torque can be produced by a variety of currents due to nonlinearity between torque and currents. Consequently, appropriate determination of a set of stator and rotor current commands plays a key role in achieving possible energy‐efficient and wide speed‐range operation. Proposed methods determine the current commands corresponding to a given torque command such that total winding copper loss due to stator and rotor currents can be minimized if the exact solution exists; the best approximate torque can be produced if no exact solution exists. The determined current commands are optimal in the sense of energy efficiency or degree of approximation in wide speed‐range operation under voltage limit. New real‐time recursive algorithms searching the optimal current solution are also given. The proposed methods are analytical but practical, and their usefulness is verified through experiments. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(1): 70–83, 2006; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20156     

百万千瓦级超超临界汽轮发电机试验站拖动系统的方案选择

百万千瓦级超超临界汽轮发电机试验站拖动系统的选择既应满足最大容量等级汽轮发电机的拖动要求,同时也应尽量满足各种不同容量等级的汽轮发电机试验时的能源节约要求。拖动系统不仅要满足汽轮发电机的起动要求,同时也应保证汽轮发电机紧急时刻的安全刹车。拖动系统采用两台异步电动机联合运行方案,6MW异步电机由变频器供电,用于被试汽轮发电机的起动、制动,11MW异步电机挂网运行与6MW异步电机联合拖动,共同承担短路试验的负荷。     

基于功率动态分配的自动驾驶机车牵引电机节能控制

为了降低大功率机车牵引电机运行能耗,提出了一种基于牵引功率动态分配的机车牵引电机节能控制方法。首先,结合现场运行数据,建立牵引电机效率与其发挥牵引力及运行速度间的数学模型。然后,利用机车自动驾驶系统规划的区间速度及牵引力运行曲线,基于所建立的数学模型对不同牵引力分配策略下综合牵引电机能耗指标等进行计算,并选择最小化目标函数值的牵引力功率分配方案,控制机车各轴牵引力输出。最后,基于HX D 1型自动驾驶机车现场某条线路各区间运行数据,对所提方法进行仿真分析,验证了该方法的有效性。