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Using electronic coordinated control of governor and blade in the wind integrated hybrid power system, this study evaluated four proposed techniques for minimizing output fluctuations owing to high wind power penetration. Four cases were investigated for simulation analysis in this study. The power system frequency and energy generation were used as indexes to evaluate the best-proposed techniques. The control of all wind turbine blade angles was demonstrated using a constant and variable reference power generating technique. In terms of wind farm output power characteristics, grid frequency fluctuations, and wind farm energy levels, case 2 performed better than other suggested systems (cases 1, 3, and 4). Frequency deviations were kept to a minimum of ±0.2 Hz. The performance of the power system with higher wind power penetration was investigated using a numerical analysis employing a multi-machine power system model. The real wind speed data were recorded on Hokkaido Island, Japan. [ABSTRACT FROM AUTHOR]

To enhance the stability of power system, a power system stabilizer (PSS) is one of the control mechanisms installed in the power plants. A suitable PSS parameters set can help in reducing the power swing. In general, the design of PSS parameters is performed based on a nominal operating condition of the power system. In this paper, a multi‐objective optimization algorithm based on pole placement technique is proposed to find a robust PSS parameters set. The proposed strategy searches for the optimal PSS parameters under multiple operating conditions of the generator. Preliminary simulation results on a single machine infinite bus (SMIB) model show that the proposed PSS parameters design method can further improve the robustness of the overall power systems performance under different types of disturbance. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In recent years, the sub‐/super‐synchronous oscillation (SSO) caused by grid integration of direct‐drive permanent magnet synchronous generators (D‐PMSG) has attracted wide attention. However, most of the existing stability analysis methods are either complex or cannot quantitatively analyze the influence of parameter changes on system stability. To address the problems, this paper proposes a novel stability analysis method for SSO in the D‐PMSG integrated power system based on closed‐loop transfer function poles. Firstly, the impedance modeling method was introduced to analyze the stability of the D‐PMSG power system. Then, a stability criterion was proposed based on the poles of the closed‐loop function. The proposed criterion is simple and has a clear physical background. The real part of the poles represents the damping while the imaginary part of the pole reflects the oscillation frequency. Finally, simulation results verify the accuracy and effectiveness of the proposed method. Moreover, its application in influence factors for quantitative analysis was also validated. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In order to reduce the torsional vibration of the turbo‐generator shaft and improve the stability of the power system, this paper proposed a more stable shafting structure model of Double ended Driving Turbo‐Generator (DDTG) by improving the shafting structure of conventional turbo‐generator set. For DDTG, the mechanical power is supplied symmetrically and synchronously from both ends of the generator. Compared with the conventional Single ended Driving Turbo‐Generator (SDTG), simulation results verify the effectiveness of the proposed shafting structure model, and indicate that DDTG can effectively reduce the torsional vibration of turbo‐generator shafts under the same electrical disturbance. Besides, in order to further suppress the torsional vibration of turbo‐generator shafts and improve the system performance, based on the nonlinear control method with objective holographic feedback, a Coordinated Control law of Excitation and Steam‐Valve (CCESV) is proposed. Under the action of CCESV, the simulation results show that the restraint effect of the DDTG on shafting torsional vibration is more obvious, and the dynamic and static performance of the system can be effectively improved. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In order to improve the transient stability of the coordinated control system of generator excitation and static synchronous compensator (STATCOM), an adaptive backstepping robust coordinated control strategy based on immersive and invariant (I&I) adaptive backstepping control and L2‐gain control is proposed with consideration of the multiple uncertain parameters and external disturbance in the system modeling. The parameter adaptive law and coordination of control law are designed independently. The parameter adaptive laws for the two uncertain parameters: damping coefficient and mechanical power in the system are designed simultaneously by adopting I&I adaptive control method; the L2‐gain control is introduced in the backstepping design to eliminate the effects of the external disturbance on the system transient stability. The results of simulation show that the proposed strategy has strong adaptability to parameter fluctuations and robustness to external disturbances. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

At present, there are mainly two kinds of transaction modes in the power market: bilateral negotiation mode and centralized bidding mode. Bilateral negotiation mode means users' purchases power directly from power plants, whereas centralized bidding mode means power plants and power users conduct power transactions through a Power Trading Center. This paper adopts evolutionary game theory to model this mechanism and explores the behavioral patterns of different entities at equilibrium. This paper is organized as follows. First, we build an evolutionary game model of this mechanism. Then, we discuss the existence and stability of equilibrium outcomes. Furthermore, we compare the equilibrium results under different conditions. We find that different market supply‐demand conditions lead to different equilibrium outcomes. Besides, we find that the bilateral negotiation mode does not necessarily improve the overall profit of the power market. When the demand exceeds the supply in the centralized bidding market, introducing the bilateral negotiation mode would reduce the overall market profit. In addition, the increase of the bidding heterogeneity leads to the increase of profits of power plants in the market. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The problem of shafting torsional vibrations has been increasingly emerging due to the increasing capacity of turbo‐generator and the complexity of power grid. Therefore, how to reduce the torsional vibration of the turbo‐generator shaft and improve the stability of the power system has become the focus of our research. First, in order to solve the problem and alleviate the torsional vibrations of turbo‐generator shafts, this paper proposed a new shafting structure model of Double‐ended Driving and Dual‐Excited Turbo‐Generator set (DDDETG). A static excitation mode is used for the excitation of the DDDETG and the mechanical power is supplied symmetrically and synchronously from both ends of the generator rotor. Then, in order to improve the output characteristic of the generator and further suppress the torsional vibrations of the turbo‐generator shafts, combined with the nonlinear control design method of partial feedback linearization, a Multi‐Index Nonlinear Coordinated Control (MINCC) strategy for the double‐ended driving and dual‐excited turbo‐generator is proposed to ensure good dynamic and static state performances of each state in the system. Finally, the simulation results on a single‐machine infinite bus system demonstrate the effectiveness of the proposed control strategy. In addition, this paper compares the performance of DDDETG and the traditional Single‐ended Drive and Single‐Excited Turbo Generator (SDSETG), the simulation results show that the restraint effect of the DDDETG structure on shafting torsional vibrations is more obvious under the proposed control strategy. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The integrated power system (IPS) with pulse load involves the dynamic processes of millisecond‐level switching period and second‐level pulse period. The characteristics of this kind of multicycle dynamic process cause much difficulty in analyzing system stability. For this reason, this paper presents a multicycle coupling mathematical model of the IPS with pulse load and proposes an algorithm based on the state variables for analyzing the sensitivity of the preceding switching period which can rapidly and accurately calculate the periodic orbit and stability margin of the system. Considering a little change in the system state variables under small disturbance, this paper uses the pulse‐period average model to simplify the calculation. The simulation analysis shows that the pulse‐period average model has the same stability margin with the multicycle coupling model. The critical pulse power calculated by the above models is 5.5 and 17 kW when the constant power is 20 and 14 kW respectively, which is consistent with the time domain simulation. It may provide technical support for the stability analysis of the IPS with pulse load. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The stability of a power system has always been of concern. Now, wide‐area measurement systems are used widely. In this paper, we focus on supplementary turbine/governor control to enhance the stability of a power system with wide‐area measurement information. An H∞ supplementary turbine/governor controller based on the multi‐agent method is introduced to enhance power system stability. First, the synchronous generator is modeled as a second‐order agent. The information of communication topology and power network topology are used to build the system model and the controller design. Then, a linear output feedback controller is adopted. With a suitable Lyapunov function and by solving the linear matrix inequality, the parameters of the controller are tuned by the H∞ synthesis method. Finally, numerical simulations are presented on a Western Systems Coordinating Council three‐generator nine‐bus power system, validating the proposed design. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Based on the topology and working principle of a distributed power flow controller (DPFC) and using the principle of linear superposition, in this article, an equivalent circuit of DPFC is constructed, and a mathematical model for the dynamic energy exchange of the third harmonic between DPFC series and shunt converters is derived, considering the energy constraint relationship between series and shunt converters. Based on this accurate model, the nonlinear models of the DPFC converters both in the shunt and series side are constructed, and their feedback linearization equations are deduced, consequently, the decoupling control strategy of the DPFC is proposed. The DPFC based on the proposed control method can well respond to the systems control requirements whether the systems are in normal operation or in fault. The achievements of this study will provide the theoretical basis for further research and engineering applications of DPFC with powerful functions, low investment cost and small operation and maintenance cost, and small footprint. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

This paper addresses the issue of power system transient stability assessment and control (TSA&C) based on phase plane representation of the power angle and rotor speed. First, the relationship between transient stability–instability and concavity–convexity of the phase‐plane trajectory is found and proved based on the single machine infinite bus (SMIB) system, and a transient instability criterion is derived for real‐time instability detection. Second, with the aim that the phase‐plane trajectory swings back before the unstable equilibrium point (UEP) once instability is detected, near‐optimal control size of generator tripping to stabilize the system is determined based on the relationship between unbalanced power and the slope of the phase‐plane trajectory. Finally, the instability detection and control technique is extended to a multimachine power system based on SMIB equivalent transform. The proposed method is independent of the network structure and operation mode, which can be applied for real‐time emergency control based on wide area measurement system (WAMS). The simulations in the Institute of Electrical and Electronics Engineers (IEEE) 39‐bus system and the Sanhua Power Grid (in China) validate the accuracy and efficiency of the proposed method. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

In this paper, the transient stability enhancement and voltage regulation of a multimachine power system are investigated taking into account the generator parameter uncertainties. An interval type‐2 Takagi–Sugeno (IT2 T‐S) fuzzy model is proposed to represent the nonlinear plant subject to parameter uncertainties. New basic concepts of the IT2 T‐S fuzzy model are proposed to reduce considerably the number of models adopted. A Lyapunov‐based approach is employed to analyze the stability and the pole placement of the IT2 fuzzy closed‐loop system formed by the IT‐2 T‐S fuzzy model and the IT‐2 fuzzy controller. This approach presents a simple closed mathematical form that provides the possibility to regulate the system under uncertain model parameters with closed‐loop design specifications as linear matrix inequality (LMI)‐based optimization problems without any assumptions about the membership functions. A simulation example is given to illustrate the effectiveness of the proposed IT‐2 fuzzy model‐based control approach. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

A modular cascade machine (MCM) system is employed as the driving system in electric vehicles (EVs). It is comprised of unit motors like series batteries, which can expand the high‐efficiency region effectively and can be regarded as a redundant system with excellent fault‐tolerance ability. In this paper, an improved rule‐based torque distribution strategy for the MCM system is developed. First, the simulation model of EVs using the MCM system is built with the ideology of reverse simulation, providing a platform for the study of the torque distribution strategy. Then, according to the power requirement of the EV, a rule‐based strategy of output torque distribution is proposed, which can improve vehicle economy and the motor's working conditions. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Japan's 'miracle' is an ongoing, evolving one. A long with the explosive rise of Japan's economic fortunes the number of theories about the business strategy of Japan's most successful firms, her Kaisha, is also exploding. The focus here is not on individual building- block strategic patterns but on: (1) linkages between the patterns, and (2) how (and why) some patterns may be combined to create even greater advantage. At the level of the firm a few basic themes are discussed and roughly modeled as a sequence, a 'pattern of patterns'. It is argued that (in retrospect) several patterns of Japanese strategy have been (to differing degrees in different firms) parts of a larger, synergistic, internally logical, and powerful synthesis. The point is that additional strategic advantages can emerge for firms which think about how to link together strategic patterns. Evidence is offered illustrating these arguments and demonstrating one way Japanese patterns combine to form an integrated strategy. [ABSTRACT FROM AUTHOR]

SUMMARY Because of significant change in environmental policies and electric power deregulation in the last decades, a lot of photovoltaic (PV) generations have so far been installed to the power system in Japan. When a huge amount of PVs generation is installed into the power system, we are very much concerned that the disconnection of the PVs due to a system fault has a big impact on the power system stability and transient voltage stability. So it is important to equip the PV with Fault Ride Through (FRT) function in order to maintain power supply-demand balance. In addition, Dynamic Voltage Support (DVS) function of the PV is effective to recover the voltage after the system fault. However, it is unclear how the PVs which are equipped with the FRT and DVS functions affect transient stability and voltage stability. In this paper, how the power factor of the PV power output affects the power system after a system fault is analyzed using P- δ curve. Then, a new PV power factor control method for improving the transient stability is proposed and its effectiveness is shown by digital simulations on a simple power system model. [ABSTRACT FROM AUTHOR]

A new application of SMES (Superconducting Energy Storage) for on-line grasping of power system stability is proposed. Experiment was carried out on a power system simulator with actual rotating generator models, which is a property of Central Research Institute of Electric Power Industry (CRIEPI), Japan. SMIES system was designed and developed. Small power deviation of known pattern was generated by SMES and, by means of system identification, eigen-value of the power system was analysed from system response due to the power modulation. It was successful in evaluating the stability by eigen-values measured with the proposed method. [ABSTRACT FROM AUTHOR]

We have recently proposed a new controller based on equilibrium point analysis for power system models. In this paper, first the Japanese standard one-machine infinite-bus system model is formulated, and the equilibrium points are analyzed. Next, complementary control inputs for AVR and GOV with limiters of the system model are determined on the basis of the analysis. Finally, it is shown that the unstable equilibrium point is eliminated by adding the proposed inputs, and then the critical clearing time can be improved in comparison with PSS of the standard model. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(3): 16–23, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20359 [ABSTRACT FROM AUTHOR]

Research on decentralized control of an electric power system is important for stabilizing control problems. In particular, since an electric power system is a large-scale nonlinear control system, decentralized (not divided) systems with cooperation should be constructed. This paper presents ways to construct decentralized systems for an electric power system. In section 2, swing data of a three-machine model infinite-bus system with AVR and GOV are estimated by the least square method. In section 4, the equivalence calculated using estimated values is discussed, and the effect of conditions on the fault is considered. Finally, section 5 is devoted to summarizing results of decentralized system identification. [ABSTRACT FROM AUTHOR]

Japan's manufacturing practices are an abiding obsession of the West. Study tours arrive almost weekly at Tokyo Narita airport, and it was one such tour that the author joined in June 1987. Nine companies were visited, ranging from conventional batch manufacture to the kind of JIT/kanban operation in automotive companies that we have all read about, and which many American and European companies are currently aspiring to imitate. Imitation was the goal for most of our party: manufacturing executives from six European countries whose companies were implementing or considering adopting JIT practices. Their professional curiosity and background knowledge of equivalent western operations gave both the plant tours and subsequent question-and-answer sessions focus, and our Japanese hosts were generous with information and English language written materials describing their systems, some of which have been adapted for the figures below. This article seeks to provide a contribution in three areas. First, to describe in detail two aspects of Japanese manufacturers not widely covered in the literature, namely their planning systems and personnel development as part of a wider company improvement initiative. Second, to relate more general impressions of both JIT and non-JIT companies, some of which reinforce and some of which contradict our received ideas about Japanese manufacture. Third, to question whether just-in-time as a concept and as a term is of continuing value, and to suggest areas which future work on Far Eastern manufacturers might investigate. Detailed comments are made on four companies, called, for reasons of confidentiality, A, B, C and D. [ABSTRACT FROM AUTHOR]

JT-60SA, the largest tokamak that will operate before ITER, has been designed and built jointly by Japan and Europe, and is due to start operation in 2020. Its main missions are to support ITER exploitation and to contribute to the demonstration fusion reactor machine and scenario design. Peculiar properties of JT-60SA are its capability to produce long-pulse, high-β, and highly shaped plasmas. The preparation of the JT-60SA Research Plan, plasma scenarios, and exploitation are producing physics results that are not only relevant to future JT-60SA experiments, but often constitute original contributions to plasma physics and fusion research. Results of this kind are presented in this paper, in particular in the areas of fast ion physics, high-beta plasma properties and control, and non-linear edge localised mode stability studies. [ABSTRACT FROM AUTHOR]