106 research outputs found
Operation of distributed generation under stochastic prices
The ongoing deregulation of electricity industries worldwide is providing incentives for microgrids,
entities that use small-scale distributed generation (DG) and combined heat and power (CHP) ap-
plications to meet local energy loads, to evolve independently of the traditional centralised grid in
order to provide greater flexibility and energy efficiency to end-use consumers. We examine the
impact of start-up costs on the option values and operating schedules of on-site DG installed by
a microgrid in the presence of stochastic electricity and fuel prices. We proceed by formulating a
stochastic dynamic programme (SDP) for the microgrid that minimises its expected discounted cost
over a time horizon and solving it using least-squares Monte Carlo (LSMC) simulation. The expected
cost saving that the microgrid realises by having gas-fired DG installed relative to meeting its entire
electric load via off-site purchases is the implied option value of DG. Numerical examples indicate
that although start-up costs do not significantly lower DG value, they, nevertheless, have a profound
impact on the optimal DG operating schedule as the microgrid must incorporate not only current,
but also future, expected start-up costs into its current decision-making process as an opportunity
cost. As a consequence, the microgrid becomes more hesitant to turn DG units on (off), preferring
to wait until the electricity price (natural gas generating cost) exceeds the natural gas generating
cost (electricity price) by a significant margin before taking action. We demonstrate that ignoring
this tradeoff and proceeding myopically as in the case without start-up costs results in drastically
higher expected costs and fewer opportunities to use DG
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A review of microgrid development in the United States – A decade of progress on policies, demonstrations, controls, and software tools
Microgrids have become increasingly popular in the United States. Supported by favorable federal and local policies, microgrid projects can provide greater energy stability and resilience within a project site or community. This paper reviews major federal, state, and utility-level policies driving microgrid development in the United States. Representative U.S. demonstration projects are selected and their technical characteristics and non-technical features are introduced. The paper discusses trends in the technology development of microgrid systems as well as microgrid control methods and interactions within the electricity market. Software tools for microgrid design, planning, and performance analysis are illustrated with each tool's core capability. Finally, the paper summarizes the successes and lessons learned during the recent expansion of the U.S. microgrid industry that may serve as a reference for other countries developing their own microgrid industries
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Provision of secondary frequency regulation by coordinated dispatch of industrial loads and thermal power plants
Demand responsive industrial loads with high thermal inertia have potential to provide ancillary service for frequency regulation in the power market. To capture the benefit, this study proposes a new hierarchical framework to coordinate the demand responsive industrial loads with thermal power plants in an industrial park for secondary frequency control. In the proposed framework, demand responsive loads and generating resources are coordinated for optimal dispatch in two-time scales: (1) the regulation reserve of the industrial park is optimally scheduled in a day-ahead manner. The stochastic regulation signal is replaced by the specific extremely trajectories. Furthermore, the extremely trajectories are achieved by the day-ahead predicted regulation mileage. The resulting benefit is to transform the stochastic reserve scheduling problem into a deterministic optimization; (2) a model predictive control strategy is proposed to dispatch the industry park in real time with an objective to maximize the revenue. The proposed technology is tested using a real-world industrial electrolysis power system based upon Pennsylvania, Jersey, and Maryland (PJM) power market. Various scenarios are simulated to study the performance of the proposed approach to enable industry parks to provide ancillary service into the power market. The simulation results indicate that an industrial park with a capacity of 500 MW can provide up to 40 MW ancillary service for participation in the secondary frequency regulation. The proposed strategy is demonstrated to be capable of maintaining the economic and secure operation of the industrial park while satisfying performance requirements from the real world regulation market
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Spot pricing of electricity and ancillary services in a competitive California market
Typically, in competitive electricity markets, the vertically integrated utilities that were responsible for ensuring system reliability in their own service territories, or groups of territories, cease to exist. The burden falls to an independent system operator (ISO) to ensure that enough ancillary services (AS) are available for safe, stable, and reliable operation of the grid, typically defined, in part, as compliance with officially approved engineering specifications for minimum levels of AS. In order to characterize the behavior of market participants (generators, retailers, and an ISO) in a competitive electricity market with reliability requirements, spot markets for both electricity and AS are modeled. By assuming that each participant seeks to maximize its wealth and that all markets clear, we solve for the optimal quantities of electricity and AS traded in the spot market by all participants, as well as the market clearing prices for each
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Technology and Greenhouse Gas Emissions: An IntegratedScenario Analysis
This report describes an analysis of possible technology-based scenarios for the U.S. energy system that would result in both carbon savings and net economic benefits. We use a modified version of the Energy Information Administration's National Energy Modeling System (LBNL-NEMS) to assess the potential energy, carbon, and bill savings from a portfolio of carbon saving options. This analysis is based on technology resource potentials estimated in previous bottom-up studies, but it uses the integrated LBNL-NEMS framework to assess interactions and synergies among these options. The analysis in this paper builds on previous estimates of possible "technology paths" to investigate four major components of an aggressive greenhouse gas reduction strategy: (1) the large scale implementation of demand-side efficiency, comparable in scale to that presented in two recent policy studies on this topic; (2) a variety of "alternative" electricity supply-side options, including biomass cofiring, extension of the renewable production tax credit for wind, increased industrial cogeneration, and hydropower refurbishment. (3) the economic retirement of older and less efficient existing fossil-find power plants; and (4) a permit charge of /t),l assuming that carbon trading is implemented in the US, and that the carbon permit charge equilibrates at this level. This level of carbon permit charge, as discussed later in the report, is in the likely range for the Clinton Administration's position on this topic
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