77,536 research outputs found
A multi-state model for the reliability assessment of a distributed generation system via universal generating function
International audienceThe current and future developments of electric power systems are pushing the boundaries of reliability assessment to consider distribution networks with renewable generators. Given the stochastic features of these elements, most modeling approaches rely on Monte Carlo simulation. The computational costs associated to the simulation approach force to treating mostly small-sized systems, i.e. with a limited number of lumped components of a given renewable technology (e.g. wind or solar, etc.) whose behavior is described by a binary state, working or failed. In this paper, we propose an analytical multi-state modeling approach for the reliability assessment of distributed generation (DG). The approach allows looking to a number of diverse energy generation technologies distributed on the system. Multiple states are used to describe the randomness in the generation units, due to the stochastic nature of the generation sources and of the mechanical degradation/failure behavior of the generation systems. The universal generating function (UGF) technique is used for the individual component multi-state modeling. A multiplication-type composition operator is introduced to combine the UGFs for the mechanical degradation and renewable generation source states into the UGF of the renewable generator power output. The overall multi-state DG system UGF is then constructed and classical reliability indices (e.g. loss of load expectation (LOLE), expected energy not supplied (EENS)) are computed from the DG system generation and load UGFs. An application of the model is shown on a DG system adapted from the IEEE 34 nodes distribution test feeder
Uncertainty Analysis of the Adequacy Assessment Model of a Distributed Generation System
Due to the inherent aleatory uncertainties in renewable generators, the
reliability/adequacy assessments of distributed generation (DG) systems have
been particularly focused on the probabilistic modeling of random behaviors,
given sufficient informative data. However, another type of uncertainty
(epistemic uncertainty) must be accounted for in the modeling, due to
incomplete knowledge of the phenomena and imprecise evaluation of the related
characteristic parameters. In circumstances of few informative data, this type
of uncertainty calls for alternative methods of representation, propagation,
analysis and interpretation. In this study, we make a first attempt to
identify, model, and jointly propagate aleatory and epistemic uncertainties in
the context of DG systems modeling for adequacy assessment. Probability and
possibility distributions are used to model the aleatory and epistemic
uncertainties, respectively. Evidence theory is used to incorporate the two
uncertainties under a single framework. Based on the plausibility and belief
functions of evidence theory, the hybrid propagation approach is introduced. A
demonstration is given on a DG system adapted from the IEEE 34 nodes
distribution test feeder. Compared to the pure probabilistic approach, it is
shown that the hybrid propagation is capable of explicitly expressing the
imprecision in the knowledge on the DG parameters into the final adequacy
values assessed. It also effectively captures the growth of uncertainties with
higher DG penetration levels
A Multi-State Power Model for Adequacy Assessment of Distributed Generation via Universal Generating Function
The current and future developments of electric power systems are pushing the
boundaries of reliability assessment to consider distribution networks with
renewable generators. Given the stochastic features of these elements, most
modeling approaches rely on Monte Carlo simulation. The computational costs
associated to the simulation approach force to treating mostly small-sized
systems, i.e. with a limited number of lumped components of a given renewable
technology (e.g. wind or solar, etc.) whose behavior is described by a binary
state, working or failed. In this paper, we propose an analytical multi-state
modeling approach for the reliability assessment of distributed generation
(DG). The approach allows looking to a number of diverse energy generation
technologies distributed on the system. Multiple states are used to describe
the randomness in the generation units, due to the stochastic nature of the
generation sources and of the mechanical degradation/failure behavior of the
generation systems. The universal generating function (UGF) technique is used
for the individual component multi-state modeling. A multiplication-type
composition operator is introduced to combine the UGFs for the mechanical
degradation and renewable generation source states into the UGF of the
renewable generator power output. The overall multi-state DG system UGF is then
constructed and classical reliability indices (e.g. loss of load expectation
(LOLE), expected energy not supplied (EENS)) are computed from the DG system
generation and load UGFs. An application of the model is shown on a DG system
adapted from the IEEE 34 nodes distribution test feeder.Comment: Reliability Engineering & System Safety (2012) 1-2
Developing a distributed electronic health-record store for India
The DIGHT project is addressing the problem of building a scalable and highly available information store for the Electronic Health Records (EHRs) of the over one billion citizens of India
Bringing power and progress to Africa in a financially and environmentally sustainable manner
EXECUTIVE SUMMARY:
The future of electricity supply and delivery on the continent of Africa represents one of the thorniest
challenges facing professionals in the global energy, economics, finance, environmental, and
philanthropic communities.
Roughly 600 million people in Africa lack any access to electricity. If this deficiency is not solved,
extreme poverty for many Africans is virtually assured for the foreseeable future, as it is widely
recognized that economic advancement cannot be achieved in the 21st Century without good electricity
supply. Yet, if Africa were to electrify in the same manner pursued in developed economies around the
world during the 20th Century, the planet’s global carbon budget would be vastly exceeded, greatly
exacerbating the worldwide damages from climate change.
Moreover, due to low purchasing power in most African economies and fiscal insolvency of most African
utilities, it is unclear exactly how the necessary infrastructure investments can be deployed to bring
ample quantities of power – especially zero-carbon power – to all Africans, both those who currently are
unconnected to any grid as well as those who are now served by expensive, high-emitting, limited and
unreliable electricity supply.
With the current population of 1.3 billion people expected to double by 2050, the above-noted
challenges associated with the African electricity sector may well get substantially worse than they
already are – unless new approaches to infrastructure planning, development, finance and operation
can be mobilized and propagated across the continent.
This paper presents a summary of the present state and possible futures for the African electricity
sector. A synthesis of an ever-growing body of research on electricity in Africa, this paper aims to
provide the reader a thorough and balanced context as well as general conclusions and
recommendations to better inform and guide decision-making and action. [TRUNCATED]This paper was developed as part of a broader initiative
undertaken by the Institute for Sustainable Energy (ISE) at
Boston University to explore the future of the global
electricity industry.
This ISE initiative – a collaboration with the Global Energy
Interconnection and Development Cooperation Organization
(GEIDCO) of China and the Center for Global Energy Policy
within the School of International and Public Affairs at
Columbia University – was generously enabled by a grant
from Bloomberg Philanthropies.
The authors gratefully acknowledge the support and
contributions of the above funders and partners in this
research
Internet of Things-aided Smart Grid: Technologies, Architectures, Applications, Prototypes, and Future Research Directions
Traditional power grids are being transformed into Smart Grids (SGs) to
address the issues in existing power system due to uni-directional information
flow, energy wastage, growing energy demand, reliability and security. SGs
offer bi-directional energy flow between service providers and consumers,
involving power generation, transmission, distribution and utilization systems.
SGs employ various devices for the monitoring, analysis and control of the
grid, deployed at power plants, distribution centers and in consumers' premises
in a very large number. Hence, an SG requires connectivity, automation and the
tracking of such devices. This is achieved with the help of Internet of Things
(IoT). IoT helps SG systems to support various network functions throughout the
generation, transmission, distribution and consumption of energy by
incorporating IoT devices (such as sensors, actuators and smart meters), as
well as by providing the connectivity, automation and tracking for such
devices. In this paper, we provide a comprehensive survey on IoT-aided SG
systems, which includes the existing architectures, applications and prototypes
of IoT-aided SG systems. This survey also highlights the open issues,
challenges and future research directions for IoT-aided SG systems
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