Small Distributed Generation Systems Research Articles

Bus voltage control and optimization strategies for power flow analyses using Petri net approach

Distributed generation (DG) systems—particularly photovoltaic (PV) systems—that can control reactive power can change the behavior of a power system network in spite of their relatively small individual capacities because of bidirectional power flow and reactive power control. Therefore, power flow algorithms should be able to accurately model the response of a power system network that includes DG systems. Various power flow algorithms have modeled DG systems as either a P-Q or P-V bus. However, small DG systems connected to the grid by a short line, but not a long transmission line, or predefined mutually between utilities and DG system owners can participate in the control of reactive power. They can adaptively adjust the reactive power output according to their bus voltage. Thus, the objective of this study is to present a strategy that participates in the control of bus voltage within its limits and reactive power by either injecting or absorbing reactive power. For this purpose, this study presents a Petri net approach that a bus to which a DG system is connected is modeled as a P-Q or P-V bus with equality and inequality constraints. The proposed bus voltage control strategy is verified using the well-known IEEE test feeders.

Improving the efficiency of using small-distributed generation systems through mechanisms of demand management for electricity and gas

Improving the efficiency of using small-distributed generation systems through mechanisms of demand management for electricity and gas

A Management Application for the Small Distributed Generation Systems of Electric Power Based on Renewable Energy

A multitude of factors, from the technological ones to the availability of primary resources and not least the current trend of electricity production at small capacities, led to a significant development of distributed generation. The problems they bring requires a special attention provided by supervisory control and data acquisition (SCADA) solutions. These systems can include or can be extended with new facilities such as the one proposed in this paper.The present paper aims to implement a management solution for isolated or connected to local grid systems of energy production from renewable sources, with small production capacity. The idea at the basis of the proposed solution focuses on using the existing energy management principles for distributed energy production facilities and on the accessible existing communication infrastructure. The proposed system allows the management of multiple energy production systems based on renewable energy including the using of mobile devices.

2615 自動車用ガソリンエンジンを転用した小型バイオマスガスエンジンの開発(G08 動力エネルギーシステム,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

Biomass resources are effective energy sources against global warming. In order to utilize biomass resources effectively, the automotive engine as a small-distributed generation system is one of the effective methods. In this study, a small size engine fueled by biomass gas based on automotive engine has been realized. Operating experiment fueled by low calorie gas simulating biomass gas gave knowledge about combustion characteristics and requirement for stable operation. 26% thermal efficiency was accomplished under appropriate conditions. An engine plant fueled by real biomass gas supplied from gasifying plant generated 19kW at its maximum. Then, auto control program was applied to the system. The control of air-fuel ratio and ignition timings realized stable rotational speed and power generation.

Cycle Analysis of Micro Gas Turbine-Solid Oxide Fuel Cell Hybrid System.

Small distributed generation systems are currently attracting much attention because of their high energy utilization efficiency. Among them, a hybrid system based on micro gas turbine (µGT) and solid oxide fuel cell (SOFC) is expected to achieve a much higher efficiency than traditional µGT. In this paper, we investigate the effects of cycle design parameters on the perfor- mance and feasibility of a µGT-SOFC hybrid system for small apartments and businesses. As a result, a general design strategy is found that less direct fuel input to combustor as well as higher recuperator efficiency lead to higher generation efficiency, while higher steam-carbon ratio mod- erates requirements for the material strength. It is also confirmed that the hybrid system is much superior to the recuperated gas turbine in terms of its power efficiency and aptitude for small distributed generation. The conceptual design of a 30kW µGT-SOFC hybrid system, of which diameter and height are 750mm and 1500mm, respectively, is shown to give a power efficiency over 65% (LHV) in the best possible case.

C201 マイクロガスタービン・燃料電池複合システムのサイクル解析

Small distributed generation systems are currently attracting much attenions because of their high energy utilization efficiency. For them, compact and high performance energy conversion devices such as micro gas turbines (μGT) and small fuel cells (FC) have recently been developed. They offer higher electric power conversion efficiency than traditional devices, but their hybrids, e.g., μGT combined with solid oxide fuel cell (SOFC), are expected to achieve even higher efficiency. In this paper, we investigate the effects of cycle design parameters on the performance and feasibility of a 30kW μGT-SOFC hybrid system for apartments and small businesses. As a result, a general design strategy is found that higher SOFC cell temperature and lower turbine inlet temperature should be preferred under some restrictions. The electric power generation efficiency of μGT-SOFC hybrids can reach 65% and 60% for pressurized and atmospheric cycles, respectively.