Search

The introduction of a large number of photovoltaic systems to distribution systems has increased the complexity of the voltage profile. It is thus necessary to manage voltage at a higher system level. For this purpose, the voltage profile of the distribution system can be calculated using state estimation and the voltage can be controlled based on the estimated values. Many methods for estimating voltage profiles using state estimation have been developed. However, the estimation accuracy of voltage profiles required for proper voltage control has not been discussed. If the assumed required estimation accuracy is too high, then more meters than necessary will be installed, unnecessarily increasing costs. Conversely, if the assumed required estimation accuracy is too low, voltage control equipment will not operate properly, and voltage violations may occur. Thus, it is important to determine the required estimation accuracy of voltage profiles for proper voltage control. In this paper, the estimation error of the voltage profile is expressed using a probability density function, and the estimation accuracy of voltage profiles required for proper voltage control is examined. A numerical case study was performed on a distribution network model with 2160 consumers, and revealed the following. To prevent voltage violations, an estimation accuracy of voltage profile that is approximately 10 times lower than that of the estimation accuracy based on current measurement equipment data is sufficient. To minimize the number of tap operations, an estimation accuracy needs to be improved by 70% compared with the estimation accuracy based on current measurement equipment data. [ABSTRACT FROM AUTHOR]

The enforcement of a feed‐in tariff (FIT) program in Japan has increased the number of installations of photovoltaic generation systems in its residential sector. After the end of an FIT program, the surplus electricity of an individual prosumer is purchased by the utility company at a reduced price, which may have an economic impact on the prosumer. To avoid this adverse effect, peer‐to‐peer (P2P) electricity transactions among prosumers based on blockchain and smart contract technologies as well as introduction of residence‐use stationary storage batteries are generating significant interest. In this study, the potential economic merit of P2P transactions and residential storage battery introduction are evaluated using a total optimization approach. For realizing a more practical perspective, this study also investigates the economic merit based on a partial optimization approach, in which an individual prosumer pursues its own profit. Furthermore, in this study, the grid‐side merit of P2P electricity transactions among prosumers is examined. Comparison of the merits determined by the total and partial optimization approaches shows that the realization of P2P transactions could provide a notable economic merit to the participants and reduce both the required facility capacity and power flow variation. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

SUMMARY To reduce the environment load, electric vehicles (EV) have been attracting attention and expectations. since they can run with at good fuel efficiency and without exhaust gases. It is expected that EV will become more and more popular. Generally, EVs would be used for driving during daytime and be charged during the nighttime, considering lifestyle and time-of-use patterns. If most EV owners adopt this use pattern, feeder voltage profiles could be greatly affected, causing severe voltage drops. The battery charger for EVs described in this papers consists of a self-commutated inverter, which in principle can control not only active power but also reactive power. We propose a basic feeder voltage regulation algorithm, 'PQ control', using EVs which involves adjustment of the EV charging schedule and reactive power injection. In addition, we propose 'prediction control', which is based on 'PQ control' and is takes account of prediction of the receiving voltage. Advanced 'communication control' regulation algorithms, utilizing communication among EVs and the distribution system operator, are also proposed. The purpose of this paper is to confirm the effectiveness of the three proposed algorithms by simulations. [ABSTRACT FROM AUTHOR]

The 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 [ABSTRACT FROM AUTHOR]

The authors have proposed the Flexible Reliable and Intelligent Electric eNergy Delivery System (FRIENDS) as a future electric power distribution system. In order to realize FRIENDS it is indispensable to design the concrete interior structure of the key facility, the Quality Control Center. This paper proposes an interior structure and control schemes for the Quality Control Center from the viewpoint of customized power quality service, which is one of the most important objectives of FRIENDS. The validity of the proposed structure and control schemes is confirmed through transient analysis using PSCAD/EMTDC. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 139(3): 45–52, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.1159 [ABSTRACT FROM AUTHOR]