Masafumi Miyatake

In this paper the authors investigated an algorithm optimizing a train speed profile by the Bellman's Dynamic Programming (DP). The DP-based method has substantial advantages of coping with complicated conditions easily, e.g. speed limitation, non-linear tractive effort and running resistance, effects of regenerative electric energy and so on. One of the major drawbacks of DP is that it requires a lot of computation time. If high accuracy of solutions is required, computation time for the optimization will increase. In this paper, the authors introduce the parallel computing technique for DP. The parallel computing technique will shorten computation time sharply and succeed in both raising accuracy of simulation and shortening of computation time. While distance between stations for the profile optimization is 1000m at the longest in our previous work, it will be prolonged significantly, keeping a comparable computation time. In this paper the computation times with and without parallel computing will be compared. DP has a further advantage in its use as a real time control algorithm to which the optimal profile can be easily reconfigured against some disturbances such as signalling. © 2014 WIT Press.

In this paper, the authors proposed the loop microgrid system composed of loads, Superconducting Magnetic Energy Storage (SMES), and renewable energies such as solar and wind generators. The system adjusts the balance of supply and demand in the microgrid by compensating the power fluctuation of renewable energy sources with SMES. The SMES is connected with two independent Current Source Inverters (CSIs) in order to control power flow in the microgrid as well as at the interconnection with the main power system. The aim of this paper is to control power flow at the point of interconnection with the main system and the microgrid. The system was simulated by using PSIM and MATLAB/Simulink. The authors proved that the system can control the power flow as expected..

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Since PV power output depending on the operating voltage and current, PV systems need maximum power point tracker (MPPT). Further, multiple local maximum power points appear in the power-voltage characteristics under partial shading conditions, finding the global MPP using conventional MPPT is a difficult task. To solve this issue, the authors proposed a PSO technique to solve the problems involved in the MPPT. PSO-based MPPT can be used only one pair of sensors and able to control by a single centralized MPPT. These methods resulting in lower cost, higher overall efficiency and simplicity of its implementation. In this paper, the proposed methods, I-PSO, R-PSO and IR-PSO were used to verify their effectiveness on three photovoltaic arrays under different types of the change in insolation conditions through Simulations and demonstration experiments studies for the first time. © 2013 IEEE.

In this paper, the authors proposed a new circuit topology of AC loop microgrid with a Superconducting Magnetic Energy Storage (SMES) and solar and wind generators. The SMES is connected with two converters controlled independently to supply power to different parts of the microgrid. The balance of supply and demand in the microgrid is adjusted by controlling the converters. The aim of this study is to control power flow between the main power system and the microgrid so as to reduce reverse power flow. The authors proved that SMES can control the power flow in the proposed microgrid through the numerical simulation by use of PSIM and MATLAB/Simulink.

Nowadays some nuclear power plant in Japan is shut down due to problem of security in earthquake disaster. Consequently, Japan will encounter a lack of electrical energy in the future if new electrical generation is not constructed. Solar energy is one of appropriate renewable energy for Japan. Solar panel produces electrical energy by using the natural solar radiation from sun. PV Solar farm consists of multiple components, including the photovoltaic modules, mechanical and electrical connections. PV solar farm with grid-connected can directly connect to the existing electricity grid by using inverter circuit toward transformer. In this paper, PV solar farm is utilized as a power generation which injects active power into a Japan east power system. An optimal location and sizing of solar farm by using multiobjective Bees optimization (MBO) is proposed to minimize fuel and emission costs of overall system with considering solar radiation energy in each area. The results show that the proposed method found the optimal position of solar farm with minimum cost of fuel and environmental pollution. © 2013 IEEE.

A train scheduling method to minimize the trip time of passengers under restricted electrical energy is investigated in this paper. This method assumes that the consumed electrical energy of one railway artery, all the vehicles of which are local trains, is restricted to a certain value. The endogenous variables of this method are the running time for each interstation, the consumed energy for each interstation, and the number of vehicles. The solution depends on the Kuhn-Tucker theorem on the constraints of both the number of vehicles and the total amount of consumed energy per unit time. This method enables us to determine the running time for each interstation and the number of vehicles according to the solution, which gives priority to small changes in the running time in interstations over decreasing the number of vehicles. Numerical examples verify the effect of reducing the time increment caused by the restriction in some artery without reducing the number of vehicles. The results also imply that the effect on passengers of each energy-saving method differs for every traffic artery. © 2013 The Institute of Electrical Engineers of Japan.

This paper presents a new Maximum Power Point Tracking (MPPT) method of a Photovoltaic (PV) array based on the Binary-Search Technique and the Ripple Correlation Control (RCC) using the DC voltage and power ripples caused by a converter. The Binary-Search technique makes the operating point to converge to the MPP in a short time with simple calculation process. The proposal to combine the Binary-Search and RCC techniques enables the convergence to the MPP more accurately and quickly. The theoretical analysis and design principle of the proposed method are described in detail. Demonstrated by simulations on MATLAB/Simulink and experimental studies are presented. In addition, by comparing total output energy for the conventional Perturb and Observation (P&O) method under the same conditions, the effectiveness of the proposed method are shown.

The authors proposed a comprehensive mathematical formulation as a linear/nonlinear programme for considering energy-saving train scheduling. The formulation is to optimize running time for each section between stations with fixing total time between origin and destination of a train. The original fundamental manner of optimization named "identical incremental energy consumption" was introduced. The model was extended and applied to a simple railway line model with six stations and five interstations. It could be solved with a general-purpose optimization library on a PC. The result showed that optimal condition and energy saving effect could be evaluated easily. Several percent of energy was saved by the optimization process. © 2012 WIT Press.

Although rail transportation is conventionally considered to be environmentallyfriendly, currently research is being carried out globally to find ways to improve energy-saving in rail transportation. Development of an energy management system for railways and new transport systems including the BRT (Bus Rapid Transit) system has begun. The railway energy management system manages and controls the use of energy for transportation as well as train operation. An EE (energy efficient) train traffic control system is being developed in order to reduce energy consumption in train traffic operation. This system is mainly useful for urban railways. The control system reduces consumed running energy by assigning several seconds of the scheduled margin times at platforms to inter-stations. While taking care about delay of the trains, the control system adjusts the arrival-and-departure time at stations without making passenger aware of the difference from the usual. The following methods can be considered in utilization 1) drivers judge and lengthen the running time appropriately according to the train operation condition of routes 2) the ground operation control device grasps train traffic conditions and decides the arrival time at the next station and then orders the time to each train using a ground-vehicle transmission system, while drivers operate according to the guidance by the on-board driving assistance equipment 3) trains run with automatic train operation equipment according to the order from the ground operation control device. By computer simulation for typical urban transport lines, the evaluation of an EE train traffic control algorithm was carried out. As a result, it was confirmed that a 5% reduction of energy consumed is expected by assigning 5 seconds on average to the margin included in station stoppage time to the running time between stations. © 2012 WIT Press.

The authors propose microgrid system combining photovoltaic (PV), wind turbine (WT) and Superconducting Magnetic Energy Storage (SMES). In the microgrid system, not to have a big influence on the main grid, it is necessary to make power supplying from the grid stable and lessen power flowing to the grid. The aim of this paper is to shave peak power from the main grid and to control power flow in the loop power system by introducing the microgrid with SMES. Two thyristor rectifiers control SMES I/O power to match load demand and PV/WT supply power. We prove that two rectifiers can control SMES and proposed microgrid system has little influence on the grid. The system was simulated by using MATLAB/Simulink.

Now, electric railway which is higher transport efficiency, punctuality, safety and rapidity than other transportation is developing in traffic society. Furthermore, the streetcar which is closer than a railway and more environmental than bus is attracted attention in an aging society. Light Rail Transit (LRT) called next generation type streetcar has low-floor vehicles which is easy to get on and off, and is introduced in many cities. Furthermore, it is possible to use energy storage for the main power supply of LRT by technological advancement of electrical storage device, and movement toward realization of catenary free LRT is becoming active. So, this research aimed at realizing energy-saving operation by changing the running time and charging time while catenary free LRT runs in the catenary free section. As a result of performing a simulation at MATLAB, in charging briskly at each station, consumption energy increases as running time becomes short. In this case, the increase in the charge loss by charge time becoming short is very small compared with the influence which running time has on consumption energy. Moreover, when the case where charge became impossible among 4 stations in some sections was assumed, 1.07% of consumption energy reduction was possible by charging to the capacitor voltage appropriate for the condition instead of full charge.

Multiple photovoltaic (PV) modules feeding a common load is the most common form of power distribution used in solar PV systems. In such systems, providing individual maximum power point tracking (MPPT) schemes for each of the PV modules increases the cost. Furthermore, its v-i characteristic exhibits multiple local maximum power points (MPPs) during partial shading, making it difficult to find the global MPP using conventional single-stage (CSS) tracking. To overcome this difficulty, the authors propose a novel MPPT algorithm by introducing a particle swarm optimization (PSO) technique. The proposed algorithm uses only one pair of sensors to control multiple PV arrays, thereby resulting in lower cost, higher overall efficiency, and simplicity with respect to its implementation. The validity of the proposed algorithm is demonstrated through experimental studies. In addition, a detailed performance comparison with conventional fixed voltage, hill climbing, and Fibonacci search MPPT schemes are presented. Algorithm robustness was verified for several complicated partial shading conditions, and in all cases this method took about 2 s to find the global MPP.

In this paper, the author proposes a simple comprehensive mathematical formulation for considering energy-saving train scheduling. The formulation is to optimize running time for each section between stations with fixing total time between origin and destination of a train. The model was demonstrated numerically with a simple railway line model with four stations and three sections. The result showed that optimal condition and energy saving effect could be evaluated easily. © 2011 The Institute of Electrical Engineers of Japan.

Eco-driving technique for Electric Vehicle (EV) is investigated in this paper. Many works on EV were reported however they did not deal with the eco-driving from the viewpoint of theoretical study. The authors have developed the energy-saving driving technique so-called "eco-driving" based on the dynamic programming (DP). Optimal speed profile of an EV, which minimizes the amount of total energy consumption has been decided under fixed origin and destination, running time, and road condition. DP algorithm can deal with such complicated conditions and also can derive the optimal solution. Using the proposed method, simulations were implemented in some cases. Especially the authors paid attention to the road with traffic signals and simulated it without increase of calculation time. © 2011 IEEE.

An effective PSO (Particle Swarm Optimization) of MPPT (Maximum Power Point Tracking) control method for photovoltaic(PV) power generation system was proposed in the past paper. In this paper, the authors propose the parameter tuning method of the controller based on an adjusting rule in order to extract power as large as possible under various insolation conditions with partial shading. In the result, PSO control makes PV output power increased. © 2011 IEEE.

Photovoltaic (PV) generation systems need maximum power point tracker because the PV power output depends on the operating voltage and current. Further, multiple local maximum power points (MPPs) appear in the power-voltage characteristics under partial shading conditions, hence finding the global MPP using conventional MPPT techniques is a difficult task. To overcome this difficulty, the authors improved MPPT algorithm by introducing a Particle Swarm Optimization (PSO) technique. PSO's feature is it uses only one pair of sensors to control and has extensibility in a multiple dimension. In this paper, the authors tried to verify the extensibility of the improved method, Initialization and Repulsion PSO (IR-PSO) in multiple photovoltaic arrays under various types of change in insolation and partial shading conditions. Thereby, these methods resulting in lower cost, higher overall efficiency and simplicity of its implementation. IR-PSO method was verified through simulation and experimental studies. The detailed performance comparisons with other methods, Initialization PSO (I-PSO), Repulsion PSO (R-PSO), are presented. © 2011 IEEE.

The optimal operation of railway systems minimizing total energy consumption is discussed in this paper Firstly, some measures of finding energy-saving train speed profiles are outlined After the characteristics that should be considered in optimizing train operation are clarified. complete optimization based on optimal control theory is reviewed Then basic formulations are summarized taking into account most of the difficult characteristics peculiar to railway systems Three methods of solving the formulation. dynamic programming (DP). gradient method. and sequential quadratic programming (SQP). are introduced The last two methods can also control the state of charge (SOC) of the energy storage devices By showing some numerical results of simulations. the significance of solving not only optimal speed profiles but also optimal SOC profiles oh energy storage are emphasized. because the numerical results are beyond the conventional qualitative studies Rutile scope for applying the methods to real-time optimal control is also mentioned (C) 2010 Institute of Electrical Engineers of Japan Published by John Wiley & Sons, Inc

The optimal operation of a rail vehicle with onboard energy storage device minimizing energy consumption in catenary free mode is discussed in this paper. The Electric Double Layer Capacitor (EDLC) is assumed as an energy storage device because of its high power density, long lifetime and quick charge/discharge. The proposed method can determine the optimal acceleration/deceleration at each sampling point under fixed running time between stations taking state of charge of the EDLC into account. The model can be used for planning train schedule and evaluation of energy consumption. Using the methods, simulations for a Light Rail Vehicle (LRV) were implemented in some cases. From the simulation results, optimal distribution of running time through two sections with quick charging at the intermidiate station is clarified. The trend of optimal solutions such as values of control inputs and energy consumption is finally discussed qualitatively. ©2010 IEEE.

This paper proposes a three-phase four wire current-controlled Voltage Source Inverter (CC-VSI) for both harmonic mitigation and PV energy extraction. For harmonic mitigation, the CC-VSI works as a grid current-controlling shunt active power filter. Then, the PV array is coupled to the DC bus of the CC-VSI. The MPPT controller employs the Fibonacci search method. The output of MPPT controller is a DC voltage that determines the DC-bus voltage according to the PV maximum power. From computer simulation, the CC-VSI can effectively compensate for harmonics as well as deliver PV power to the grid. ©2010 IEEE.

The optimal operation of rail vehicle minimizing total energy consumption is discussed in this paper. In recent years, the energy storage devices have enough energy and power density to use in trains as on-board energy storage. The on-board storage can assist the acceleration/deceleration of the train and may decrease energy consumption. Many works on the application of the energy storage devices to trains were reported, however, they did not deal enough with the optimality of the control of the devices. The authors pointed out that the charging/discharging command and vehicle speed profile should be optimized together based on the optimality analysis. The authors have developed the mathematical model based on a general optimization technique, sequential quadratic programming. The proposed method can determine the optimal acceleration/deceleration and current commands at every sampling point under fixed conditions of transfer time and distance. Using the proposed method, simulations were implemented in some cases. The electric double layer capacitor (EDLC) is assumed as an energy storage device in our study, because of its high power density etc. The trend of optimal solutions such as values of control inputs and energy consumption is finally discussed. (C) 2009 Institute of Electrical Engineers of' Japan. Published by John Wiley & Sons, Inc.

This article proposes a hybrid energy system combining solar photovoltaic and wind turbine as a small-scale alternative source of electrical energy where conventional generation is not practical. A simple and cost-effective control technique has been proposed for maximum power point tracking from the photovoltaic array and wind turbine under varying climatic conditions without measuring the irradiance of the photovoltaic or the wind speed. The proposed system is attractive because of its simplicity, ease of control, and low cost. A complete description of the proposed hybrid system, along with detailed simulation results that ascertain its feasibility, are given to demonstrate the availability of the proposed system in this article. Simulation of the hybrid system under investigation was carried out using PSIM software.

The optimal operation of a rail vehicle with on-board energy storage device minimizing energy consumption in catenary free mode is discussed in this paper. The Electric Double Layer Capacitor (EDLC) is assumed as an energy storage device because of its high power density, long lifetime and quick charge/discharge. The proposed method can determine the optimal acceleration/deceleration at each sampling point under fixed running time between stations taking state of charge of the EDLC into account. The model can be used for planning train schedule and evaluation of energy consumption. Using the methods, simulations for a LRV were implemented in some cases. From the first simulation, the relation between running time and energy consumption and impact of running time on the optimal acceleration/deceleration are derived numerically. From the second simulation, optimal distribution of running time through two sections without quick charging is clarified. The trend of optimal solutions such as values of control inputs and energy consumption is finally discussed qualitatively.

This paper deals with Maximum Power Point Tracking (MPPT) control of photovoltaic generators. Photovoltaic (PV) generation systems need maximum power point tracker because the PV power output depends on the operating terminal voltage and current. Further, the PV array exhibits two or more MPP's under partial shading condition and hence finding the MPP using conventional techniques is a difficult task. To overcome the difficulty, finding the MPP, the authors improve the MPPT with Particle Swarm Optimization (PSO) technique by adding a kind of "repulsion term" to the equation of PSO algorithm. The term enables to improve the response to various types of insolation change. This results in lower cost, higher overall efficiency and also the algorithm is simple. The improved PSO-MPPT algorithm is verified through simulative and experimental studies. It is proved this algorithm is superior to the original PSO-MPPT methods by evaluating generated power and electrical energy.

This paper focuses on the implementation of a three-phase four wire current-controlled Voltage Source Inverter (CC-VSI) as both power quality improvement and PV energy extraction. For power quality improvement, the CC-VSI works as a grid current-controller shunt active power filter. Then, the PV array supported by the Hill Climbing type of a MPPT controller is coupled to the DC bus of the CC-VSI. The output of MPPT controller is a DC voltage that determines the DC-bus voltage according to the PV maximum power. The system has been tested using computer simulation.

In this paper a hybrid energy system combining variable speed wind turbine, solar photovoltaic and fuel cell generation systems is presented to supply continuous power to residential power applications as stand-alone loads. The wind and photovoltaic systems are used as main energy sources while the fuel cell is used as secondary or back-up energy source. Three individual dc-dc boost converters are used to control the power flow to the load. A simple and cost effective control with dc-dc converters is used for maximum power point tracking and hence maximum power extracting from the wind turbine and the solar photovoltaic systems. The hybrid system is sized to power a typical 2 kW/150 V dc load as telecommunication power plants or ac residential power applications in isolated islands continuously throughout the year. The results show that even when the sun and wind are not available; the system is reliable and available and it can supply high-quality power to the load. The simulation results which proved the accuracy of the proposed controllers are given to demonstrate the availability of the proposed system in this paper. Also, a complete description of the management and control system is presented. (C) 2008 Elsevier Ltd. All rights reserved.

In this paper, a novel strategy of maximum power point tracking is presented for photovoltaic power generation systems based on Fibonacci search algorithm to realize simple control system to track the real maximum power point even under non-uniform or for rapidly changing insolation conditions. The Fibonacci search technique was modified in order to apply to time-variant P-V characteristics of the PV array. It is proved experimentally and through simulation results that the algorithm has good performances and very fast response even for partial shaded PV modules. The proposed technique can be applied to various types of PV power conditioners including dc-dc and dc-ac converters. It can be commonly used instead of the conventional MPPT techniques. This method requires neither the measurement of temperature and insolation level nor prior knowledge about the model of the used photovoltaic panel. The proposed method can track the global maximum power point in most cases by doing a wide-range search and more power can be extracted with partial shaded PV modules as compared to the other methods. Simulation and experimental results are presented to prove the feasibility of the proposed technique. (c) 2007 Elsevier B.V. All rights reserved.

The optimal operation of rail vehicle with on-board energy storage device minimizing total energy consumption is discussed in this paper. Until now, not enough research deals with the optimal control of the devices. The authors have developed the mathematical model based on a general optimization technique. In our study, the electric double layer capacitor (EDLC) is assumed as an energy storage device, because of its high power density etc. The proposed method can determine the optimal acceleration/deceleration and current commands at every sampling point under fixed conditions of transfer time and distance. The authors have also modified it for applying to catenary free operation. Using the proposed methods, simulations were implemented in some cases. The trend of optimal solutions such as values of control inputs and energy consumption is finally discussed.

The optimal operation of rail vehicle minimizing total energy consumption is discussed in this paper. Many works on the application of the energy storage devices to trains were reported, however, they did not deal enough with the optimality of the control of the devices. The authors have developed the mathematical model based on a general optimization technique, Sequential Quadratic Programming. The proposed method can determine the optimal acceleration/deceleration and current commands at every sampling point under fixed conditions of transfer time and distance. Using the proposed method, simulations were implemented in some cases. The electric double layer capacitor (EDLC) is assumed as an energy storage device in our study, because of its high power density etc. The trend of optimal solutions such as values of control inputs and energy consumption is finally discussed.

The optimal operation of rail vehicle with on-board energy storage device minimizing total energy consumption is discussed in this paper. Until now, not enough research deals with the optimal control of the devices. The authors have developed the mathematical model based on a general optimization technique. In our study, the electric double layer capacitor (EDLC) is assumed as an energy storage device, because of its high power density etc. The proposed method can determine the optimal acceleration/deceleration and current commands at every sampling point under fixed conditions of transfer time and distance. The authors have also modified it for applying to catenary free operation. Using the proposed methods, simulations were implemented in some cases. The trend of optimal solutions such as values of control inputs and energy consumption is finally discussed.

An algorithm optimizing total energy consumption of multiple inverter train operation considering DC feeding circuit is investigated in this paper. The proposed mathematical formulation can deal with several characteristics of trains, especially the effect of regenerative braking system. The developed optimization algorithm based on the gradient method is applicable to solve the formulated problems. The algorithm is ready to apply practical large-scale problems. The formulation and algorithm enables us to discuss energy-saving operation quantitatively. Several numerical analyses are demonstrated to verify the reliability and validity of the proposed method and clarify the energy-saving operation for two trains. The results shows that train speed profiles and control inputs strongly depend on the phase of departure times. The proposed algorithm can reduce energy consumption by 4.2 similar to 17.9% from that based on the conventional operation rule. These results indicates that the numerical analyses are significant to realize energy-saving operation.

This paper deals with maximum power point tracking control of photovoltaic generators. Photovoltaic generation systems need maximum power point tracker because the PV power output depends on the operating terminal voltage and current. Further, the PV array exhibits two or more MPP's under partial shading condition and hence finding the MPP using conventional techniques is a difficult task. To overcome the difficulty, finding the MPP, the authors have proposed a novel MPPT algorithm by introducing Particle Swarm Optimization technique. Further, the proposed algorithm uses only one pair of sensors to control multiple PV arrays. This results in lower cost, higher overall efficiency and also the algorithm is simple. Proposed MPPT algorithm is verified through experimental studies. Several partial shading conditions were tested and in all these cases the algorithm takes about one second to reach the global MPP. The reachability to MPP is good in both shading and unshading.

An algorithm optimizing total energy consumption of multiple inverter train operation considering DC feeding circuit is investigated in this paper. The proposed mathematical formulation can deal with several characteristics of trains, especially the effect of regenerative braking system. The developed optimization algorithm based on the gradient method is applicable to solve the formulated problems. The algorithm is ready to apply practical large-scale problems. The formulation and algorithm enables us to discuss energy-saving operation quantitatively. Several numerical analyses are demonstrated to verify the reliability and validity of the proposed method and clarify the energy-saving operation for two trains. The results shows that train speed profiles and control inputs strongly depend on the phase of departure times. The proposed algorithm can reduce energy consumption by 4.2 similar to 17.9% from that based on the conventional operation rule. These results indicates that the numerical analyses are significant to realize energy-saving operation. Furthermore, it is also demonstrated that the method can be applied to the optimal voltage control of a substation.

Recently, a new generation of ac-ac single-phase and three-phase power converters with more commutations per half cycle has been proposed for ac power or ac voltage conditioning due to the increasing availability and power capability of high frequency controlled-on and off power semiconductor switching devices. This paper presents a novel simple circuit topology of symmetrical PWM ac line conditioning circuit for three phase power systems. The converter topology uses a minimal number of controlled power semiconductor switches and features buck voltage capability. This ac-ac power converter is seen to be an ac voltage regulator with output voltage range of 0-1 p.u. with reasonable current and voltage waveforms. The operating principle and the operation modes of the proposed three-phase direct ac-ac power and voltage conditioner are described and evaluated through a design example based on analytical expression and simulation results.