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Dr. Dai Orihara
National Institute of Advanced Industrial Science and Technology (AIST)

Basic Info

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Research Keywords & Expertise

0 Power Electronics
0 Power System Stability
0 Power System Control
0 power system
0 Electrical Engineering

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Short Biography

Dai Orihara received the Ph.D. degree in electrical engineering from Tohoku University, Sendai, Japan in 2017. He was an Assistant Professor with school of engineering, department of electrical engineering, Tohoku University from 2017-2018. He is currently a Researcher with the Fukushima Renewable Energy Institute, AIST (FREA). His research interest includes power system stability and power system control under high renewable penetration.

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Journal article
Published: 30 August 2021 in Energies
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The high penetration of the distributed energy resources (DERs) encourages themselves to implement grid-supporting functions, such as volt-var control. The quasi-static time-series (QSTS) simulation is an essential technique to evaluate the impact of active DERs on the grid. Meanwhile, the increase of complexity on the circuit model causes a heavy computational burden of QSTS simulation. Although circuit reduction methods have been proposed, there have been few methods that can appropriately handle the distribution system (DS) with multiple voltage control devices, such as DERs implementing volt-var control. To address the remaining issues, this paper proposes an offline bus aggregation method for DS with volt-var control. The method determines the volt-var curve for the aggregated bus on the basis of historical data to reduce error in the aggregated model, and its offline process solves the computational convergence issue concerned in the online one. The effectiveness of the proposed method is validated in the simulation using a Japanese low-voltage DS model. The simulation results show that the proposed method can reduce the voltage error and computational time. Furthermore, the versatility of the proposed method is verified to show the performance does not heavily depend on how to select historical data for model-building.

ACS Style

Hiroshi Kikusato; Taha Selim Ustun; Dai Orihara; Jun Hashimoto; Kenji Otani. Aggregation of Radial Distribution System Bus with Volt-Var Control. Energies 2021, 14, 5390 .

AMA Style

Hiroshi Kikusato, Taha Selim Ustun, Dai Orihara, Jun Hashimoto, Kenji Otani. Aggregation of Radial Distribution System Bus with Volt-Var Control. Energies. 2021; 14 (17):5390.

Chicago/Turabian Style

Hiroshi Kikusato; Taha Selim Ustun; Dai Orihara; Jun Hashimoto; Kenji Otani. 2021. "Aggregation of Radial Distribution System Bus with Volt-Var Control." Energies 14, no. 17: 5390.

Journal article
Published: 11 January 2021 in Energies
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As distributed power sources via grid-connected inverters equipped with functions to support system stabilization are being rapidly introduced, individual systems are becoming more complex, making the quantification and evaluation of the stabilizing functions difficult. Therefore, to introduce distributed power sources and achieve stable system operation, a system should be reduced to a necessary but sufficient size in order to enable the quantification of its behavior supported by transient theory. In this study, a system in which multiple distributed power supplies equipped with virtual synchronous generator control are connected is contracted to a two-machine system: a main power supply and all other power supplies. The mechanical torque of each power supply is mathematically decomposed into inertia, damping, synchronization torques, and the governor effect. The system frequency deviations determined by these elements are quantitatively indexed using MATLAB/Simulink. The quantification index displayed in three-dimensioned graphs illustrates the relationships between the various equipment constants of the main power supply, the control variables of the grid-connected inverter control, and the transient time series. Moreover, a stability analysis is performed in both the time and frequency domains.

ACS Style

Yuko Hirase; Kazusa Uezaki; Dai Orihara; Hiroshi Kikusato; Jun Hashimoto. Characteristic Analysis and Indexing of Multimachine Transient Stabilization Using Virtual Synchronous Generator Control. Energies 2021, 14, 366 .

AMA Style

Yuko Hirase, Kazusa Uezaki, Dai Orihara, Hiroshi Kikusato, Jun Hashimoto. Characteristic Analysis and Indexing of Multimachine Transient Stabilization Using Virtual Synchronous Generator Control. Energies. 2021; 14 (2):366.

Chicago/Turabian Style

Yuko Hirase; Kazusa Uezaki; Dai Orihara; Hiroshi Kikusato; Jun Hashimoto. 2021. "Characteristic Analysis and Indexing of Multimachine Transient Stabilization Using Virtual Synchronous Generator Control." Energies 14, no. 2: 366.

Conference paper
Published: 01 December 2017 in 2017 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia)
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The Battery Energy Storage (BES) is expected to be a device supplying frequency control reserves in a power system penetrating large amount of Intermittent Renewable Energy Sources (IRES). The authors presented the Battery-Assisted Load Frequency Control (BALFC) as a novel BES utilization method contributing to enhance the LFC performance in previous works. In the BALFC, the BES compensates the slow responsivities of the LFC units by absorbing components of the LFC signal exceeding the maximum ramp rate of each unit. This paper proposes the Improved-BALFC in which the BES control signal is processed from the output signal of power plants including the control signal of Economic Load Dispatching (ELD) in addition to the LFC signal. A simulation study shows that the Improved-BALFC can suppress the frequency fluctuation larger than the BALFC when the load demand has long-period change.

ACS Style

Dai Orihara; Hiroumi Saitoh. Battery-assisted load frequency control coordinated with economic load dispatching. 2017 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia) 2017, 1 -5.

AMA Style

Dai Orihara, Hiroumi Saitoh. Battery-assisted load frequency control coordinated with economic load dispatching. 2017 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia). 2017; ():1-5.

Chicago/Turabian Style

Dai Orihara; Hiroumi Saitoh. 2017. "Battery-assisted load frequency control coordinated with economic load dispatching." 2017 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia) , no. : 1-5.

Conference paper
Published: 01 December 2017 in 2017 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia)
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A hybrid real-time simulator is proposed in order to evaluate the applicability of various customers' equipment to direct load control (DLC). The real-time simulator (H- DLCSim) is composed of a PC, actual equipment and interfaces between the PC and the equipment. In the PC, a power system model and load controllers are installed as software. The actual equipment is the candidate of controllable load to be studied for DLC. In our study, two types of geothermal heat pump air conditioners (GeoHPs) were chosen as the candidates. An H-DLCSim for DLC assisting load frequency control (LFC) was developed and a case study showed its usefulness.

ACS Style

Hiroumi Saitoh; Yasuhiko Koshi; Takahiro Sato; Masahiro Abe; Dai Orihara; Daisuke Iioka; Atsushi Okamoto; Yukihide Shiba; Koji Tanifuji. Hybrid real-time simulator for evaluation of direct load control to assist power system control. 2017 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia) 2017, 1 -5.

AMA Style

Hiroumi Saitoh, Yasuhiko Koshi, Takahiro Sato, Masahiro Abe, Dai Orihara, Daisuke Iioka, Atsushi Okamoto, Yukihide Shiba, Koji Tanifuji. Hybrid real-time simulator for evaluation of direct load control to assist power system control. 2017 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia). 2017; ():1-5.

Chicago/Turabian Style

Hiroumi Saitoh; Yasuhiko Koshi; Takahiro Sato; Masahiro Abe; Dai Orihara; Daisuke Iioka; Atsushi Okamoto; Yukihide Shiba; Koji Tanifuji. 2017. "Hybrid real-time simulator for evaluation of direct load control to assist power system control." 2017 IEEE Innovative Smart Grid Technologies - Asia (ISGT-Asia) , no. : 1-5.

Conference paper
Published: 24 November 2016 in 2016 IEEE International Conference on Power System Technology (POWERCON)
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The growth of Renewable Energy Sources (RES) requires more reserve for generation-demand balancing. Recently, energy storage system such as battery is expected as additional reserve power source. The authors have proposed Battery-Assisted Load Frequency Control (BALFC). The method makes it possible to compensate reserve deficiency by providing excess components of LFC signal over ramp rate limits and upper/lower limits of LFC units such as thermal power plants. This paper illustrates that the BALFC can save required battery power capacity by effective use of battery's high responsiveness compared with a conventional method. Moreover, it is clarified that frequency control reserves can be saved by using battery with the BALFC instead of increasing LFC units.

ACS Style

Dai Orihara; Hiroumi Saitoh. Saving of secondary reserves by battery-assisted load frequency control. 2016 IEEE International Conference on Power System Technology (POWERCON) 2016, 1 -6.

AMA Style

Dai Orihara, Hiroumi Saitoh. Saving of secondary reserves by battery-assisted load frequency control. 2016 IEEE International Conference on Power System Technology (POWERCON). 2016; ():1-6.

Chicago/Turabian Style

Dai Orihara; Hiroumi Saitoh. 2016. "Saving of secondary reserves by battery-assisted load frequency control." 2016 IEEE International Conference on Power System Technology (POWERCON) , no. : 1-6.

Journal article
Published: 01 May 2014 in Journal of Electrical Engineering & Technology
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ACS Style

Dai Orihara; Hiroumi Saitoh; Yuji Higuchi; Tadatoshi Babasaki. Load Dispatching Control of Multiple-Parallel-Converters Rectifier to Maximize Conversion Efficiency. Journal of Electrical Engineering & Technology 2014, 9, 1132 -1136.

AMA Style

Dai Orihara, Hiroumi Saitoh, Yuji Higuchi, Tadatoshi Babasaki. Load Dispatching Control of Multiple-Parallel-Converters Rectifier to Maximize Conversion Efficiency. Journal of Electrical Engineering & Technology. 2014; 9 (3):1132-1136.

Chicago/Turabian Style

Dai Orihara; Hiroumi Saitoh; Yuji Higuchi; Tadatoshi Babasaki. 2014. "Load Dispatching Control of Multiple-Parallel-Converters Rectifier to Maximize Conversion Efficiency." Journal of Electrical Engineering & Technology 9, no. 3: 1132-1136.