Toshifumi Ise

• Osaka University

Grid Connected Converters: Modeling, Stability and Control discusses the foundations and core applications of this diverse field, from structure, modeling and dynamic equivalencing through power and microgrids dynamics and stability, before moving on to controller synthesis methodologies for a powerful range of applications. The work opens with phy...

To achieve a more sustainable supply of electricity, consumers are expected to rely increasingly on combinations of various types of power generators. Among them, distributed generators (DGs) utilizing renewable energy sources (RESs) are a promising solution. However, introducing renewable energy based DGs into microgrids (MGs) can reduce the inert...

This chapter addresses some significant aspects in microgrid (MG) planning and management and relevant topics. Several functions such as power prediction of renewable energy sources (RESs), load forecasting, energy storage reserve, peak shaving, reduction of CO2 emissions, and maximization of the use of renewable energy options should be considered...

This chapter addresses the application of robust control in microgrids (MGs), and emphasizes the robust frequency control in islanded MGs. It describes the MG case study and the state-space dynamic model for the first robust control synthesis example. The chapter focuses on the application of H2, H∞, and μ-synthesis robust controls for improving co...

Recently, intelligent system applications have received increasing attention in microgrid (MG) operation, planning, control, and management. This chapter focuses on some application examples of intelligent systems in MG operation and control. It then addresses the most important intelligent control technologies for application in MGs. The chapter d...

This chapter presents an introduction on the recent developments on the microgrids (MGs), and describes the main structure, fundamentals, and concepts of MGs. Generally, an MG is centrally controlled and managed by a microgrid central controller (MGCC) installed at the medium-/low-voltage (MV/LV) substation. The chapter then explains the MG operati...

This chapter first presents a general introduction on emergency control in microgrids (MGs), and then describes the load shedding as the most important and well known emergency control strategy. The MGs are small-scale power grids structured in distribution systems to support the efficiency, reliability, and expandability. On the other hand, using...

This chapter explains a basic virtual synchronous generator (VSG) structure with the main components. The VSG control performance is compared with the well-known droop control performance. It presents small-signal models of VSG and droop control for both stand-alone and synchronous generator-connected modes. Small-signal and state-space models are...

Understanding the dynamics and using appropriate modeling methodologies are significant issues for microgrid (MG) control synthesis and stability analysis. This chapter gives an overview on the recent developments in MG dynamic representation and modeling, a dynamic model for the main grid and connecting components. The main grid is represented as...

This chapter addresses a general overview on the existing technologies and major challenges in microgrid (MG) control. It classifies MG control strategies into four control levels: local, secondary, central and emergency, and global, where the first three levels are associated with the operation of the MG itself, and the fourth level (global contro...

This chapter describes the renewable power generation, and presents the principles for integration of wind power and solar power to the grid. Then, it emphasizes the modeling procedure and control structures of the grid-connected wind and photovoltaic (PV) energy systems. The chapter discusses the problem of the primary energy intermittency is tack...

This chapter presents a statistical approach to assess the impact of wind power variation on the size of primary reserve provided by the wind power generators (WPGs). Renewable power generation capacity has been increasing over the last years due to political incentives for development of low carbon generation. The chapter investigates the implemen...

This chapter proposes the "low-voltage bipolar-type DC microgrids (MG)" that can supply super high-quality power with a three-wire DC distribution line, and presents a DCMG for a residential area. Each house has a cogeneration system (CGS) such as micro-combined heat and power (micro-CHP) unit or gas engine and fuel cell. The output electric power...

A solution toward the microgrid (MG) stability enhancement is to provide virtual inertia, by using the concept of virtual synchronous generator (VSG). This chapter introduces several VSG control schemes to support the MG stability and regulation performance. It addresses an enhanced VSG control to achieve oscillation damping and proper transient ac...

This book discusses relevant microgrid technologies in the context of integrating renewable energy and also addresses challenging issues. The authors summarize long term academic and research outcomes and contributions. In addition, this book is influenced by the authors’ practical experiences on microgrids (MGs), electric network monitoring, and c...

In comparison of the conventional bulk power plants, in which the synchronous machines dominate, the distributed generator (DG) units have either very small or no rotating mass and damping property. With growing the penetration level of DGs, the impact of low inertia and damping effect on the grid stability and dynamic performance increases. A solu...

In recent years, introduction of distributed generations and energy storages to residential houses is promoted to solve energy and environmental problems. The distributed generation system with energy storage can be operated in stand-alone operation. In that case, the electrical power is supplied to ac loads in houses by a single-phase 3-wire inver...

The modular multilevel matrix converter (MMMxC) applied to a low frequency ac (LFAC) transmission system is investigated. The LFAC (1 Hz ~ 20 Hz) has some advantages compared to conventional ac and dc transmission systems, such as the increase of current-carrying capacity of power cables due to reduction of capacitive charging current, and better f...

抄録 The capacity of distributed generators (DGs) connected to grid by inverters is growing. The inverters are generally controlled by PLL (Phase Locked Loop) in order to synchronize with power system frequency. It cannot have synchronous power. Power systems will become unstable, if the capacity of inverter type DGs is increased. The concept that in...

This paper presents a basic sensitivity analysis of the conversion losses in a dc microgrid by varying the system parameters. A simple residential apartment with 20 units with a photovoltaic (PV) system is taken for the analysis. The conversion losses are calculated with the measured electricity consumption and the estimated output of the PV system...

The distributed flexible network PV (photovoltaic) system is a kind of dc micro-grid which is composed of several PV generation systems, a battery bank and loads. Controller of each converter takes local information and control the converter autonomously. However, there are several problems like voltage rise in dc link causing loss of maximum power...

Application of a doubly-fed induction generator (DFIG), which is one of variable speed generators, to a gas engine cogeneration system has been investigated. To operate during a blackout as an emergency power supply is one of important roles for the gas engine cogeneration system. However, recent lean-burn and miller-cycle gas engine, which realize...

The role of distributed generations such as photovoltaic, wind-turbines, co-generations are getting more and more important in power systems. Moreover, energy storages such as chemical batteries, electric double layer capacitors and superconducting magnets will play an important role in power systems in near future in order to match supply and dema...

DC microgrids are suitable for a local area power system which includes dc output distributed generations, batteries and dc loads. In this paper, we propose an analysis method for a dc microgrid using hardware-in-the-loop simulation (HILS). In this case, a fast response bidirectional dc voltage source is essential for high accuracy analysis. We dev...

A novel soft-switching inverter with regenerative snubber circuits is proposed. This inverter can be operated in soft-switching condition by simple control, without any additional complicated control. Having a passive clamp circuit, a maximum voltage across main switches is suppressed. In addition, voltage of each dc link capacitor is automatically...

This paper details a Smart Grid Laboratory for the study of modern house distribution systems with multiple energy sources and energy regeneration capability. The laboratory is designed to perform real-time simulation of a realistic distribution system connected to multiple houses. In addition, a real house with typical appliances and power sources...

[Comment from the 2nd author] This is a paper for the model description of an earth system model "MIROC-ESM". The model structure, spin-up strategy, performance of each component etc are displayed. [Formal abstract] An earth system model (MIROC-ESM 2010) is fully described in terms of each model component and their interactions. Results for the C...

For the past few years, hybrid generation systems including solar panel and gas cogeneration have been used for residential houses. Solar panels can generate electronic power at daytime but not at night. But the power consumption of residential houses usually peaks in the evening. The gas engine cogeneration system can generate electronic power wit...

A doubly-fed induction generator (DFIG), which is one of the variable speed generator, applied to a gas engine cogeneration system has been investigated. To operate during a blackout as an emergency power supply is one of important roles for the gas engine cogeneration system. However, the DFIG requires the initial excitation for startup during a b...

An earth system model (MIROC-ESM) is fully described in terms of each model component and their interactions. Results for the CMIP5 (Coupled Model Intercomparison Project phase 5) historical simulation are presented to demonstrate the model's performance from several perspectives: atmosphere, ocean, sea-ice, land-surface, ocean and terrestrial biog...

The power capacity of distributed generators such as photovoltaic and wind turbine is growing, many of distributed generators are connected to a grid by inverters. The inverters are controlled by a PLL (Phase Locked Loop) in order to be synchronized with power system frequency. Power system will become unstable, if the capacity of inverter-connecte...

DC microgrid is an appropriate system to interconnect kinds of dc output sources and to supply high quality power. In this presentation, we show a novel dc distribution voltage control by several dc/dc converters for energy storages considering the stored energies. In an assumed system, electric double layer capacitors (EDLC) are connected to a dc...

Microgrid is one of the new conceptual power systems for smooth installation of many distributed generations (DGs). While most of the microgrids adopt ac distribution as well as conventional power systems, dc microgrids are proposed and researched for the good connection with dc output type sources such as photovoltaic (PV) system, fuel cell, and s...

This paper describes the comparison of circuit configuration of CSC (Current Source Converter) and VSC (Voltage Source Converter) in HVDC (High Voltage DC Transmission) with SMES (Superconducting Magnetic Energy Storage) connection. The purpose of using SMES is to smooth out power fluctuation in one terminal side in order to avoid causing power sys...

The changes of vegetation distribution due to the climate change and anthropogenic land use alternations have great impacts on terrestrial carbon cycles. To examine these impacts, a Spatially Explicit Individual-Based Dynamic Global Vegetation Model (SEIB-DGVM; Sato et al., 2007) was developed. This is a process-based model that can simulate the gr...

Effect of a new parameter of voltage sag, i.e., phase angle jump, on invertors for PV System was surveyed by newly developed Voltage Sag Generator. The generator can reproduce actual voltage sags recorded past, and artificial voltage sag with controlled phase angle jump. It consists of PC, D/A converter and power amplifier. A program generating wav...

DC microgrid is an appropriate system to interconnect dc output sources and to supply high quality power. This paper describes a novel dc distribution voltage control for dc microgrid. We assumed two electric double layer capacitor (EDLC) banks connected to a dc grid through dc/dc converters, and each EDLC converter controls dc distribution voltage...

A high-power bidirectional isolated dual full-bridge dc-dc converter with an active clamp for a electric double layer capacitor (EDLC), which is installed into a dc distribution system, is investigated. This dc-dc converter consists of two full-bridge converters on both low and high voltage sides, a high-frequency transformer, an active clamp switc...

The DC microgrid is a novel power system using DC distribution in order to provide superhigh-quality power. This DC system is suitable for DC-output distributed generation and energy storage. In this research, we assumed one type of DC microgrid for residential houses (apartment house or housing complex). Each residence has a distributed generation...

In this paper, loss of a dc microgrid system for residential complex is compared with loss in an ac system. Each system has a PV system, a gas engine cogeneration and 20 residential houses. The losses are calculated from measured load data and PV output data which was estimated from global solar radiation and temperature of a PV panel. The operatio...

Magnets of the synchrotron which extracts the accelerated beams are excited by a pulse operation power supply, and then the load fluctuation should be a severe problem. An energy storage system, such as superconducting magnetic energy storage (SMES), fly-wheel generator so far, will be required for compensating the pulse electric power, and reducin...

This paper focuses on the stability issue of power hardware-in-the-loop (PHIL) simulation of inductor coupled systems. Main factors which influence the stability of this type system are analyzed and verified through experiments. A method to resolve the instability problem of the PHIL simulation without decreasing the simulation accuracy is also pro...

The Large Helical Device (LHD) is one of the world's largest superconducting systems. It consists of a pair of pool-cooled helical coils, three pairs of forced-flowcooled poloidal coils, nine superconducting bus lines, a helium liquefier and refrigerator of 10-kW class, and six dc power supplies. Its stored magnetic energy reaches 0.8 GJ. Availabil...

This paper describes a novel power control scheme for a three-phase to single-phase matrix converter for a gas engine cogeneration system. This matrix converter has no dc link but a small capacitor for compensation of single-phase power pulsation. The capacitor also contributes to compensate reactive current of a generator. Additionally, modulation...

This paper mainly discusses the accuracy of power hardware-in-the-loop simulation (PHILS) through an example of a boost chopper. A method to evaluate the error of PHILS is presented and verified by both experimental results and offline simulation results of the PHILS of a boost chopper. The factors which affect the accuracy are also discussed and v...

Sensitivity of electro-magnetic contactors for voltage sags is studied by experiments and simulations. An experimental circuit with a semiconductor fault switch that controls the phase angle of system voltage at the initial point of voltage sags is developed. The phase angle is a new parameter for voltage sags. The operating characteristics of the...

This paper presents a modular photovoltaic system (MPVS) that uses a chain-link-type multilevel converter (CLMC). In large-scale PV generating systems, the DC power supply is generally composed of a large number of PV panels. Hence, losses are caused by differences in the maximum power point at each PV panel. An MPVS has been proposed to address th...

For the past few years, a hybrid generation system including solar panel and gas engine cogeneration is being introduced into residential houses. Solar panels can generate electric power at daytime; meanwhile, it cannot generate electric power at night time. But the power consumption of residential houses usually peaks in the evening. The gas engin...

DC microgrid is suitable for dc output type distributed generations and energy storages. In this paper, dc microgrid for residential houses is described. Electrical power through dc distribution line (± 170 V) can be converted into some proper ac or dc voltages by converters placed near loads. Each house has a cogeneration system such as gas engin...

Application of a three-phase to single-phase matrix converter (MC) to a 1 kW household gas engine cogeneration system is investigated from the viewpoint that the MC can improve the efficiency of a synchronous generator with power factor control and reduce the converter losses by using reverse blocking devices. Since the MC connects a three-phase ge...

A method of controlling voltage profile in distribution line with many distributed generations (DGs) using distributed-series compensator (D-SC) is proposed. These DGs are assumed to be clustered photovoltaics (PVs) which are installed at residential area. A large power injected by PVs may result in reverse power flow from PVs to main source, which...

This paper proposes a method to stabilize a power hardware-in-the-loop (PHIL) simulation of inductor coupled systems, in which real time simulator causes instability due to the introduced time delay of the system. The configuration of the PHIL simulation is described and the focused issue is the instability problem of the PHIL simulation. The cause...

The ongoing anthropogenic climate change is immensely altering structure and function of the terrestrial biosphere, including forest ecosystems. In turn, the changing ecosystems have a strong potential to modify the climate through changes in biogeochemical cycles (e.g., C storage) and biophysics (e.g., albedo and hydrological cycling). Forest ecos...

DC microgrid is a novel power system using dc distribution in order to provide a super high quality power. This dc system is suitable for dc output type distributed generations and energy storages. In this research, we assumed one type of the dc microgrids for residential houses (apartment house or housing complex). Each residence has a distributed...

DC microgrid is a novel power system using dc distribution in order to provide a super high quality power. This system is suitable for dc output type distributed generations and energy storages. The dc power can be converted to the proper ac or dc voltages for the consumers by converters placed near loads, and these converters do not require transf...

Application of a three-phase to single-phase matrix converter for a 1 kW household gas engine cogeneration system is proposed. The matrix converter connects a three-phase permanent magnet synchronous generator of the cogeneration system to single-phase utility. Application of the matrix converter has the following advantages: (a) the generator effi...

The “DC Micro-grid” is a novel power system using DC distribution in order to provide superhigh-quality electric power. The DC distribution system is suitable for DC output distributed generation techniques such as photovoltaic and fuel cells, and energy storage forms such as batteries and electric double-layer capacitors. The power is distributed...

Power supply for the large-scale accelerator magnets draws a large amount of power from the utility network. For an example, the new proton accelerator complex for high intensity beam (Japan Particle Accelerator Research Complex, J-PARC) is under construction at the Tokai campus of Japan Atomic Energy Agency (JAEA) as a joint project between KEK an...

Connecting Distributed Generations (DGs) into distribution system has presented challenge of controlling voltage profile in distribution system. The presence of DGs makes voltage profile non-uniform and may result in large voltage fluctuation and over-voltage at loads. Therefore, there is need for strict limitation on power injected by DGs. This pa...

The LHD is a fusion plasma experimental device and it has six dc power supplies to excite three sets of superconducting helical coils and three sets of superconducting poloidal coils. Although the basic operation of an LHD experiment is performed under the dc magnetic field, some experiments require dynamic control of the magnetic field. For the dy...

“DC Micro-grid" is a novel power system using dc distribution in order to provide a super high quality electric power. The dc distribution system is suitable for dc output type distributed generations such as photovoltaic and fuel cells, and energy storages such as batteries and electric double layer capacitors. Power is distributed through dc dist...

Connecting distributed generations (DGs) into distribution system has presented a challenge of controlling voltage profile in distribution system. In the presence of DGs, voltage profile of distribution system becomes non-uniform and may result in large voltage fluctuation at loads. Therefore, there is need for strict limitation on power injected b...

A method for effective utilization of power distribution apparatus in an industrial park by looping distribution lines is proposed. The proposed method uses a series type Back-To-Back (BTB) converter in loop distribution line. This method solves the problem of heavily-loaded and lightly-loaded lines condition in distribution line autonomously. The...

``DC Micro-grid'' is a novel power system using dc distribution in order to provide super high quality electric power. The power is distributed through dc distribution line and converted to required ac or dc voltages by converters placed near loads. The load side converters do not need transformers by choosing proper distributed dc voltage (±170V)....

A novel main circuit topology of transformer-less series voltage sag compensator is proposed. The sagged voltages are compensated by half bridge inverters, which are directly connected in series with the residual voltages and are charged by the residual line-to-line voltages. The proposed compensator can compensate symmetrical three-phase sags down...

Power supply for the large scale accelerator magnets draws a large amount of power from the utility network. For example, the pulse power amplitude and the dissipation power of J-PARC 50 GeV synchrotron magnet power are estimated to be about 170 MW and 30 MW, respectively. Superconducting magnetic energy storage (SMES) is one of candidates to compe...

A dc loop type distribution system using an HTS cable is proposed as one of promising future power systems with many distributed generations. Applying the HTS dc cable can overcome the drawback to normal conducting medium-voltage large-current systems, which is large power loss in the cables, as well as the drawback to ac systems, which is the ac l...

Improvement of the efficiency of a 1 kW household type gas engine cogeneration system is investigated. We propose two approaches. One is the power factor control of the synchronous generator by using an IGBT rectifier instead of a diode rectifier to improve the generator efficiency. This approach enables us to reduce the copper losses in the genera...

DC micro-grid is a novel super high quality electric power system. The power is transmitted through dc distribution line and converted to required ac or dc voltages by converters placed near loads. Those load side converters do not need transformers by choosing proper dc distribution voltage (plusmn170 V). The dc power line is composed of 3 wires:...

A method for minimizing circulating current and balancing power transformer in loop distribution line of an industrial park is proposed. The proposed method uses a series type back-to-back (BTB) converter in loop distribution line of industrial park. Loop distribution line is formed by tying end of two radial lines by a looping wire. Looping wire h...

The state-of-the-art Intelligent Power Modules (IPMs) have been reviewed in the beginning of this paper along with a brief overview of its history and the purpose of its development. In the following part, the paper reviews the key IPM concept and the technologies that supported its evolution as a major power electronics component family so far. Th...

To increase the efficiency of a gas engine cogeneration system (GECS), a matrix converter is proposed to converter the generator output to utility directly. To investigate the interaction between the matrix converter and the GECS, the system needs to be validated before realization, so a real-time simulation will be executed about the Gas Engine Ge...

The LHD contains six sets of large-scale superconducting coils and six dc power supplies to charge them. In its usual operation, the current regulator installed in the power supplies controls the coil currents. This paper focuses on an open-loop control of the current controller, which has no current feedback. The electrical parameters that are est...

In stand-alone photovoltaic (PV) systems, when the battery is fully charged, the excess generated power is wasted. To solve the problems of wasted excess power, a distributed flexible network photovoltaic (DFNPV) system is studied. It incorporates many PV subsystems each consisting of PV panel, DC/DC converter, and load, and are connected to each o...

"DC micro-grid" is the novel power system using dc distribution in order to provide super high quality power. The dc distribution system is suitable for dc output type distributed generations such as photovoltaic and fuel cells, and energy storages such as secondary batteries and electric double layer capacitors. Moreover, dc distributed power is c...

The Large Helical Device (LHD) is an experimental facility for fusion plasma using a large scale mutually coupled superconducting coil system and it is now operating at the National Institute for Fusion Science. This paper introduces the design and the operation results of the dc power systems to drive these coils. First, the outline of the LHD and...

A new proton accelerator complex for a high intensity beam (Japan Particle Accelerator Research Complex-J-PARC) is under construction at the Tokai campus of Japan Atomic Energy Research Institute as a joint project between KEK and JAERI. The accelerator complex is composed of a 600 MeV linac, a 3 GeV rapid cycling synchrotron, and a 50 GeV main syn...

This paper proposes a modified converter for use in photovoltaic system. In the modified converter, the voltage ratio of output to input is equal to that of the general boost converter. The difference between the two converters is the configuration of output terminal. Therefore, the working voltage of an output capacitor and the value of its capaci...

In this paper, the voltage sag compensation by parallel type compensator with series inductor is presented. The parallel type compensator injects the current into the system so that the voltage across the series inductor can instantaneously compensate the voltage at the load. The three types of current injection control schemes are explained, analy...

This paper presents a new multilevel pulse width-modulation (PWM) inverter scheme for the use of stand-alone photovoltaic systems. It consists of a PWM inverter, an assembly of LEVEL inverters, generating staircase output voltages, and cascaded transformers. To produce high-quality output voltage waves, it synthesizes a large number of output volta...

The introduction of Distributed Flexible Network Photovoltaic (DFNPV) system is going towards solving the shortcomings of stand-alone systems in remote areas. Three types of configurations of DFNPV system are studied: star, loop, and mesh. Each configuration has many subsystems, which are assumed to have the similar characteristics and location, an...

In this paper, the voltage sag compensation using series type SMES (Superconducting Magnetic Energy Storage) with open-circuit protection is proposed. The voltage sags and momentary interruptions during the fault occurred can be mitigated. For open-circuit protection, the faulted incoming line is disconnected and the new current path is made. The c...

From the viewpoint of high quality output voltage generation in a residential photovoltaic system, a multilevel inverter employing cascaded transformers can become a good substitute for the conventional pulse width modulated inverters and other multilevel counterparts. However, to obtain more sinusoidal output voltage waves, it should increase the...

In this paper, the novel standby mode operation of series type SMES (Superconducting Magnetic Energy Storage) for voltage sag compensation is presented. In the proposed control scheme for standby mode, the power losses are minimized and voltage drop is mitigated. The series type SMES is bypassed during the normal weather. During the adverse weather...

A new circuit of parallel type voltage sag compensator is proposed in this paper. The proposed voltage sag compensator can reduce the necessary capacity of the energy storage capacitor for compensation by boost type power factor correction rectifier charging the capacitor during a voltage sag. As a result the proposed system can reduce the size and...

A new multilevel PWM inverter is presented to improve the system characteristic of a prior 11-level shaped PWM inverter scheme. In appearance, it consists of three full-bridge modules and three cascaded transformers; therefore, the configuration of the proposed multilevel PWM inverter is equal to that of the prior one. Only the turn-ratio of a tran...

This paper describes a control scheme of fault current limiter by series voltage injection. The current limiter proposed in this study is based on the use of a SMES-based series-connected voltage sag compensator, which has been previously studied by the authors, for controlling fault current caused by short circuit on the load side. An algorithm fo...

DC-DC quasi-resonant converters (QRCs) have a highly nonlinear and time-varying behavior as well as other types of DC-DC resonant converters such as conventional and multi-resonant converters. Changing in operating conditions, mainly due to variation in load and line disturbance, leads to significant changes on system dynamics so that desired perfo...

A voltage sag compensating system using a micro-SMES is presented. Based on the previous works, we have carried out experiments for voltage sag compensation on the laboratory-built system to validate the proposed minimum energy injection voltage sag compensation algorithm. In order to improve the compensating performance of the system, two-degree o...

A novel control strategy for active filters, employing quasi-instantaneous positive sequence extraction of utility voltage, can be useful in harmonic polluted and/or imbalanced utility voltage. In this paper, the authors examined its transient response, its performance under the change of fundamental frequency of utility voltage and its performance...

The LHD is a fusion experimental facility using a large-scale superconducting coil system. The coil system includes six sets of superconducting coils, and six DC power supplies are used to charge them. For the current controllers of these power supplies, high accuracy of current control, fast response and robustness of the system are required. This...

In this paper, a general robust control synthesis framework is proposed for DC-DC quasi-resonant converters (QRCs) in order to achieve both stability and desired performance, such as reduced sensitivity to load variations, desired disturbance rejection, reduced output impedance and attenuated transfer from input to output. The μ-analysis is used to...

Toward solving the shortcomings of stand-alone power systems in remote areas, a flexible network photovoltaic system with two subsystems is proposed. To execute the transfer power control, a flexible network PV system is assumed, where all subsystems have the same characteristics and loads sharing excess power. In this fashion, this study describes...