50,201 research outputs found
Impact of Forecast Errors on Expansion Planning of Power Systems with a Renewables Target
This paper analyzes the impact of production forecast errors on the expansion
planning of a power system and investigates the influence of market design to
facilitate the integration of renewable generation. For this purpose, we
propose a stochastic programming modeling framework to determine the expansion
plan that minimizes system-wide investment and operating costs, while ensuring
a given share of renewable generation in the electricity supply. Unlike
existing ones, this framework includes both a day-ahead and a balancing market
so as to capture the impact of both production forecasts and the associated
prediction errors. Within this framework, we consider two paradigmatic market
designs that essentially differ in whether the day-ahead generation schedule
and the subsequent balancing re-dispatch are co-optimized or not. The main
features and results of the model set-ups are discussed using an illustrative
four-node example and a more realistic 24-node case study
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Determining Utility System Value of Demand Flexibility From Grid-interactive Efficient Buildings
This report focuses on ways current methods and practices that establish the value to electric utility systems of distributed energy resource (DER) investments can be enhanced to determine the value of demand flexibility in grid-interactive efficient buildings that can provide grid services. The report introduces key valuation concepts that are applicable to demand flexibility that these buildings can provide and links to other documents that describe these concepts and their implementation in more detail.The scope of this report is limited to the valuation of economic benefits to the utility system. These are the foundational values on which other benefits (and costs) can be built. Establishing the economic value to the grid of demand flexibility provides the information needed to design programs, market rules, and rates that align the economic interest of utility customers with building owners and occupants. By nature, DERs directly impact customers and provide societal benefits external to the utility system. Jurisdictions can use utility system benefits and costs as the foundation of their economic analysis but align their primary cost-effectiveness metric with all applicable policy objectives, which may include customer and societal (non-utility system) impacts.This report suggests enhancements to current methods and practices that state and local policymakers, public utility commissions, state energy offices, utilities, state utility consumer representatives, and other stakeholders might support. These enhancements can improve the consistency and robustness of economic valuation of demand flexibility for grid services. The report concludes with a discussion of considerations for prioritizing implementation of these improvements
On the Behavioral Modeling of Integrated Circuit Output Buffers
The properties of common behavioral macromodels for single ended CMOS integrated circuits output buffers are discussed with the aim of providing criteria for an effective use of possible modeling options
Impact of Equipment Failures and Wind Correlation on Generation Expansion Planning
Generation expansion planning has become a complex problem within a
deregulated electricity market environment due to all the uncertainties
affecting the profitability of a given investment. Current expansion models
usually overlook some of these uncertainties in order to reduce the
computational burden. In this paper, we raise a flag on the importance of both
equipment failures (units and lines) and wind power correlation on generation
expansion decisions. For this purpose, we use a bilevel stochastic optimization
problem, which models the sequential and noncooperative game between the
generating company (GENCO) and the system operator. The upper-level problem
maximizes the GENCO's expected profit, while the lower-level problem simulates
an hourly market-clearing procedure, through which LMPs are determined. The
uncertainty pertaining to failures and wind power correlation are characterized
by a scenario set, and their impact on generation expansion decisions are
quantified and discussed for a 24-bus power system
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Network-constrained models of liberalized electricity markets: the devil is in the details
Numerical models for electricity markets are frequently used to inform and support decisions. How robust are the results? Three research groups used the same, realistic data set for generators, demand and transmission network as input for their numerical models. The results coincide when predicting competitive market results. In the strategic case in which large generators can exercise market power, the predicted prices differed significantly. The results are highly sensitive to assumptions about market design, timing of the market and assumptions about constraints on the rationality of generators. Given the same assumptions the results coincide. We provide a checklist for users to understand the implications of different modelling assumptions
A Link-based Mixed Integer LP Approach for Adaptive Traffic Signal Control
This paper is concerned with adaptive signal control problems on a road
network, using a link-based kinematic wave model (Han et al., 2012). Such a
model employs the Lighthill-Whitham-Richards model with a triangular
fundamental diagram. A variational type argument (Lax, 1957; Newell, 1993) is
applied so that the system dynamics can be determined without knowledge of the
traffic state in the interior of each link. A Riemann problem for the
signalized junction is explicitly solved; and an optimization problem is
formulated in continuous-time with the aid of binary variables. A
time-discretization turns the optimization problem into a mixed integer linear
program (MILP). Unlike the cell-based approaches (Daganzo, 1995; Lin and Wang,
2004; Lo, 1999b), the proposed framework does not require modeling or
computation within a link, thus reducing the number of (binary) variables and
computational effort.
The proposed model is free of vehicle-holding problems, and captures
important features of signalized networks such as physical queue, spill back,
vehicle turning, time-varying flow patterns and dynamic signal timing plans.
The MILP can be efficiently solved with standard optimization software.Comment: 15 pages, 7 figures, current version is accepted for presentation at
the 92nd Annual Meeting of Transportation Research Boar
Network-aware design-space exploration of a power-efficient embedded application
The paper presents the design and multi-parameter optimization of a networked embedded application for the health-care domain. Several hardware, software, and application parameters, such as clock frequency, sensor sampling rate, data packet rate, are tuned at design- and run-time according to application specifications and operating conditions to optimize hardware requirements, packet loss, power consumption. Experimental results show that further power efficiency can be achieved by considering also communication aspects during design space exploratio
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