Intelligent Energy Delivery System Research Articles

Next-generation power delivery system with resiliency and environmental affinity

Renewable energy resources play an important role in the realization of the carbon neutrality. The microgrid can efficiently integrate numerous renewable energy systems into power distribution systems to realize power supply resiliency and environmental affinity. This paper reviews the current trend of microgrid and networked microgrid technologies worldwide, particularly in Japan, including the Flexible, Reliable, and Intelligent Energy Delivery System (FRIENDS) and some other examples of the networked microgrid. Some recent digitalized control functions of the microgrid and related systems are also introduced.

A Method for Balancing the Supply and Demand in an Isolated System Consisting of Voltage Control Type Inverters in FRIENDS

The authors have proposed Flexible, Reliable and Intelligent ENergy Delivery System (FRIENDS) as a future power distribution system. In the FRIENDS, new facilities called quality control centers (QCCs), which consist of power electronics devices, distributed generators (DGs), energy storage systems (ESSs), etc., are installed between distribution substations and customers. By controlling and operating those devices in QCCs adequately, various functions can be realized. Particularly, when a power supply from the transmission network is interrupted, isolated local networks which consist of some QCCs are composed in order to realize uninterruptible power supply. In the isolated local network, the DG and ESS in QCCs are employed as backup generators. This paper proposes a novel distributed and autonomous method for balancing the supply and demand during isolated operation. This paper also investigates the effectiveness of the proposed method through some computational simulations using PSCAD/EMTDC.

Evaluation of cost and reliability of power systems with large numbers of distributed generators

AbstractThe authors have proposed the Flexible, Reliable and Intelligent ENergy Delivery System (called “FRIENDS”), which is a new concept for future power distribution systems. Also, a “micro grid” which is a similar concept to FRIENDS has been developed. In a micro grid, an independent distribution system can be constituted by a number of distributed generators. In this paper, FRIENDS, Micro grid, and conventional distribution systems are compared quantitatively in supply reliability and system cost through time sequential Monte Carlo simulations. In addition, for cost evaluation, interruption costs are included to show risk incurred by unsupplied energy. Finally, the authors search for preferable form with install and operation of distributed generators and network composition according to social cost including interruption cost and system cost. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(2): 28–37, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20659

Management of a group of distributed generators aimed at cooperation with the bulk power system

AbstractRecently, the basic framework of electric power systems has been changed significantly by deregulation of electric power industry. Also, distributed generators (DGs) such as renewable energy generations, co‐generations, and energy storage systems have been introduced into the demand sides not only for saving energy and the global environment, but also for compensating voltage drops and supply interruption. In the future power systems, a lot of small‐sized DGs will supply the electricity with existing large‐scale generators under a competitive environment. In this context, it is desirable that DGs contribute to stable, reliable and economic operations by coordinating with existing large‐scale generators. For example, power from large‐scale generators could be leveled if DGs are operated during the peak period. Also, ancillary services such as frequency control, voltage control, and supply of reserve capacity could be executed by controlling DGs directly or indirectly. Under these circumstances, the authors have proposed a new power distribution system: Flexible, Reliable and Intelligent ENergy Delivery System (FRIENDS). This paper investigates some kinds of power supply systems which coordinate DGs with existing large‐scale generators including the concept of FRIENDS and considering how DGs are managed. The effects of DGs which contribute to supply the energy and/or the reserve in every power system are evaluated. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(1): 48–56, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20358

分散電源の導入・運用が経済性および供給信頼度に与える効果に関する研究

The authors have proposed Flexible, Reliable and Intelligent ENergy Delivery System (called “FRIENDS”), which is a new concept for future power distribution systems. Also, “Micro grid” which is the similar concept to FRIENDS has been developed. In Micro grid, on independent distribution system can be constituted by a number of distributed generators. In this paper, FRIENDS, Micro grid and conventional distribution systems are compared quantitatively in supply reliability and system cost through time sequential Monte Carlo simulations. In addition, for cost evaluation, interruption costs are included to show risk incurred by unsupplied energy. Finally, authors search for preferable form with install and operation of distributed generators and network composition according to social cost including interruption cost and system cost.

Optimal network configuration of FRIENDS taking power supply reliability into account

AbstractFRIENDS (Flexible, Reliable and Intelligent ENergy Delivery System) is a new concept for a future power delivery system in which so‐called QCC (Quality Control Center) plays an important role to realize the customized power quality services and to connect a large number of distributed generators to distribution systems. In FRIENDS, QCCs are connected as a network through distribution cables to realize a reliable power supply. In this paper, a method to find the optimal network configuration of FRIENDS is proposed. The method can minimize the sum of facility installation cost and operational cost (distribution loss) under the constraint that the expected power interruption cost is less than a predetermined endurable value. The solution algorithm is based on tabu search, and employs a sensitivity analysis to select efficient facilities to be installed or to eliminate constraint violations. In the algorithm, single and double faults of power distribution system are taken into account to calculate the power supply reliability or expected power interruption cost. Several numerical real‐world examples are shown to demonstrate the validity of the algorithm. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(3): 32–40, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20264

Reliability evaluation considering customized power quality supply in FRIENDS

AbstractThe authors have proposed a Flexible, Reliable and Intelligent ENergy Delivery System (called “FRIENDS”), which is a new concept for a future power distribution system. One of the most important feature of FRIENDS is to be able to manage the reliability of power supply. In this paper, FRIENDS and a conventional distribution system are compared quantitatively as to supply reliability and cost through time sequential Monte Carlo simulation. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(4): 25–35, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20053

Optimal Network Configuration of FRIENDS Taking Power Supply Reliability into Account

FRIENDS (Flexible, Reliable and Intelligent ENergy Delivery System) is a new concept for future power delivery system in which so-called QCC (Quality Control Center) plays an important role to realize the customized power quality services and to connect a large number of distributed generators to distribution systems. In FRIENDS, QCCs are connected as a network through distribution cables to realize a reliable power supply. In this paper, a method to find the optimal network configuration of FRIENDS is proposed. The method can minimize the sum of facility installation cost and operational cost (distribution loss) under the constraint that the expected power interruption cost is less than a predetermined endurable value. The solution algorithm is based on tabu search, and employs a sensitivity analysis to select efficient facilities to be installed or to eliminate constraint violations. In the algorithm, single and double faults of power distribution system are taking into account to calculate the power supply reliability or expected power interruption cost. Several numerical examples in real world are shown to demonstrate the validity of the algorithm.

A study of transfer switching for the purpose of fault detection in FRIENDS

AbstractThe authors have proposed a new concept of a distribution system “Flexible, Reliable and Intelligent ENergy Delivery System (FRIENDS)” with intent to solve imminent operating problems faced by utilities in providing their customers with reliable supply of power at several levels of quality. The main idea of FRIENDS is to introduce new facilities, so‐called Quality Control Centers (QCCs), which are installed very close to the customers for the purpose of implementing multiple functions, such as Customized Power Quality Service. In addition, these QCCs form a network for energy and information transmission at a level below distribution substations. QCCs make it possible to frequently change configuration of the network depending on the system and load conditions. These frequent reconfigurations of the network require fast and reliable Transfer Switching in the QCCs to ease an effect on customers. The reconfiguration for the purpose of fault area isolation also requires a fast Fault Detection feature.This paper presents a new method for controlling Transfer Switching and a method of Fault Detection in order to realize a fast and reliable reconfiguration of QCC network in a normal state, as well as under fault conditions. This paper also analyzes the methods in terms of instantaneous values calculated by PSCAD/EMTDC. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 25–35, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10298

Reliability Evaluation Considering Customized Power Quality Supply in FRIENDS

The authors have proposed Flexible, Reliable and Intelligent ENergy Delivery System (called “FRIENDS”), which is a new concept for a future power distribution system. One of the most important feature of FRIENDS is to be able to manage the reliability of power supply. In this paper, FRIENDS and a conventional distribution system are compared quantitatively in supply reliability and cost through time sequential Monte Carlo simulation.

Interior structure of UPQC‐type QCC at the low‐voltage side in the FRIENDS

AbstractRecently, the worldwide deregulation of the electric power industry is progressing. Further, it is expected that a many distributed generation facilities and energy storage systems will be installed at the end point of the power systems. Therefore, the future power system must be able to cope with these various qualities of power in the deregulated situation. The authors have proposed the FRIENDS (Flexible, Reliable, and Intelligent ENergy Delivery System) concept as a new distribution system that copes with a new framework of the electric power business in the near future. The most typical aspect of FRIENDS is the introduction of new equipment; Quality Control Centers (QCC) between distribution substations and customers. In this paper, the authors propose a concrete interior structure and investigate some control methods for realizing unbundling power quality supply and power conditioning using the proposed UPQC‐type QCC. The effectiveness of the proposed method is confirmed through the instantaneous value analysis using PSCAD/EMTDC. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(3): 26–38, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10243

State of the Arts of Friends on 2003

FRIENDS(Flexible, Reliable and Intelligent Energy Delivery System)is a new power delivery concept which enablesto connect distributed power resources to power delivery system and to realize customized power quality servicesby controlling them. This paper introduces following 4 items of recent technological developments in FRIENDS: (1) an optimal network configuration method of FRIENDS in urban area from a viewpoints of supply reliability, (2) a fault state autonomous restoration method of FRIENDS through multi-agent system, (3) DC loop type QCC(Quality Control Center) to realize the customized power quality services for the area where DC power supply is dominating, (4) economical aspect of the customized power quality services.

A study on the improvement of area economic efficiency by multiple menu service using a distributed energy storage system

AbstractFRIENDS (Flexible, Reliable and Intelligent ENergy Delivery System) is a new concept for a future energy delivery system. FRIENDS is characterized by the Quality Control Center (QCC) with dispersed generator and/or storage system intended to improve the system reliability.In this paper, the social cost is assumed as the sum of the rate of electricity, interruption cost, and QCC cost. The effect of the QCC on the improvement of the area economic efficiency is evaluated by means of the Monte Carlo simulation. It is demonstrated that, depending on the desired reliability level, the area social cost may be improved by the QCC. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(4): 9–21, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10162

A Study on Transfer Switching in Consideration of Fault Detection in FRIENDS.

The authors have proposed a new concept of a distribution system ‘Flexible, Reliable and Intelligent ENergy Delivery System (FRIENDS)’ with a view of solving problems in near future and providing several services for electric companies and customers. The main idea of FRIENDS is to install new facilities named Quality Control Center (QCC) in the neighborhood of customers to realize various functions, e.g. Customized Power Quality Service. In addition, these QCCs make a network of electricity and information below distribution substations. The configuration of the network can be changed frequently depending on the system and load conditions. This frequent reconfiguration of the network requires fast and reliable Transfer Switching in QCC to ease an effect on customers. The reconfiguration with the aim of removing a fault wire also requires fast Fault Detection. This paper presents a new method for controlling Transfer Switching and a method of Fault Detection in order to realize a fast and reliable reconfiguration of QCC network in an ordinary state, and even in a fault. Besides, this paper analyzes the methods in terms of instantaneous values calculated by PSCAD/EMTDC.

FRIENDSにおけるUPQC型QCC低圧側内部構成

Recently, the worldwide deregulation of the electric power industry is progressing. Further, it is expected that a many distributed generation facilities and energy storage systems will be installed at the end point of the power systems. Therefore, the future power system must be able to cope with these various qualities of power in the deregulated situation. The authors have proposed the FRIENDS (Flexible, Reliable, and Intelligent ENergy Delivery System) concept as a new distribution system that copes with a new framework of the electric power business in the near future. The most typical aspect of FRIENDS is the introduction of new equipment; Quality Control Centers (QCC) between distribution substations and customers. In this paper, the authors propose a concrete interior structure and investigate some control methods for realizing unbundling power quality supply and power conditioning using the proposed UPQC-type QCC. The effectiveness of the proposed method is confirmed through the instantaneous value analysis using PSCAD/EMTDC. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(3): 26–38, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10243