8,407 research outputs found

    Building Blocks: Investment in Renewable and Non-Renewable Technologies

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    Over the last several years, there has been a nation-wide intensification of policies directed at increasing the level of renewable sources of electricity.  These environmental policy changes have occurred against a backdrop of shifting economic regulation in power markets that has fundamentally redefined the mechanisms through which investors in power plants earn revenues. Rather than base payments upon costs, revenues in many regions are now based upon fluctuating energy prices and, in some cases, supplemental payments for installed capacity. This paper studies the interaction between these two major forces that are currently dominating the economic landscape of the electricity industry.  Using data from the western U.S., we examine how the large-scale expansion of intermittent resources of generation could influence long-run equilibrium prices and investment decisions under differing wholesale power market designs.  We find that as the level of wind penetration increases, the equilibrium investment mix of other resources shifts towards less baseload and more peaking capacity.  As wind penetration increases, an “average” wind producer earns increasingly more revenue under markets with capacity payments than those that base compensation on energy revenues.   Investment; Renewable Energy; Capacity Markets

    Network-constrained models of liberalized electricity markets: the devil is in the details

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    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.Market power, Electricity, Networks, Numeric models, Model comparison

    Comparison between unipolar and bipolar single phase grid-connected inverters for PV applications

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    An inverter is essential for the interfacing of photovoltaic panels with the AC network. There are many possible inverter topologies and inverter switching schemes and each one will have its own relative advantages and disadvantages. Efficiency and output current distortion are two important factors governing the choice of inverter system. In this paper, it is argued that current controlled inverters offer significant advantages from the point of view of minimisation of current distortion. Two inverter switching strategies are explored in detail. These are the unipolar current controlled inverter and the bipolar current controlled inverter. With respect to low frequency distortion, previously published works provide theoretical arguments in favour of bipolar switching. On the other hand it has also been argued that the unipolar switched inverter offers reduced switching losses and generates less EMI. On efficiency grounds, it appears that the unipolar switched inverter has an advantage. However, experimental results presented in this paper show that the level of low frequency current distortion in the unipolar switched inverter is such that it can only comply with Australian Standard 4777.2 above a minimum output current. On the other hand it is shown that at the same current levels bipolar switching results in reduced low frequency harmonics

    Comparison between unipolar and bipolar single phase grid-connected inverters for PV applications

    Get PDF
    An inverter is essential for the interfacing of photovoltaic panels with the AC network. There are many possible inverter topologies and inverter switching schemes and each one will have its own relative advantages and disadvantages. Efficiency and output current distortion are two important factors governing the choice of inverter system. In this paper, it is argued that current controlled inverters offer significant advantages from the point of view of minimisation of current distortion. Two inverter switching strategies are explored in detail. These are the unipolar current controlled inverter and the bipolar current controlled inverter. With respect to low frequency distortion, previously published works provide theoretical arguments in favour of bipolar switching. On the other hand it has also been argued that the unipolar switched inverter offers reduced switching losses and generates less EMI. On efficiency grounds, it appears that the unipolar switched inverter has an advantage. However, experimental results presented in this paper show that the level of low frequency current distortion in the unipolar switched inverter is such that it can only comply with Australian Standard 4777.2 above a minimum output current. On the other hand it is shown that at the same current levels bipolar switching results in reduced low frequency harmonics

    Electricity System Expansion Studies to Consider Uncertainties and Interactions in Restructured Markets

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    This dissertation concerns power system expansion planning under different market mechanisms. The thesis follows a three paper format, in which each paper emphasizes a different perspective. The first paper investigates the impact of market uncertainties on a long term centralized generation expansion planning problem. The problem is modeled as a two-stage stochastic program with uncertain fuel prices and demands, which are represented as probabilistic scenario paths in a multi-period tree. Two measurements, expected cost (EC) and Conditional Value-at-Risk (CVaR), are used to minimize, respectively, the total expected cost among scenarios and the risk of incurring high costs in unfavorable scenarios. We sample paths from the scenario tree to reduce the problem scale and determine the sufficient number of scenarios by computing confidence intervals on the objective values. The second paper studies an integrated electricity supply system including generation, transmission and fuel transportation with a restructured wholesale electricity market. This integrated system expansion problem is modeled as a bi-level program in which a centralized system expansion decision is made in the upper level and the operational decisions of multiple market participants are made in the lower level. The difficulty of solving a bi-level programming problem to global optimality is discussed and three problem relaxations obtained by reformulation are explored. The third paper solves a more realistic market-based generation and transmission expansion problem. It focuses on interactions among a centralized transmission expansion decision and decentralized generation expansion decisions. It allows each generator to make its own strategic investment and operational decisions both in response to a transmission expansion decision and in anticipation of a market price settled by an Independent System Operator (ISO) market clearing problem. The model poses a complicated tri-level structure including an equilibrium problem with equilibrium constraints (EPEC) sub-problem. A hybrid iterative algorithm is proposed to solve the problem efficiently and reliably

    A Tri-level Model of Centralized Transmission and Decentralized Generation Expansion Planning for an Electricity Market: Part I

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    We develop a tri-level model of transmission and generation expansion planning in a deregulated power market environment. Due to long planning/construction lead times and concerns for network reliability, transmission expansion is considered in the top level as a centralized decision. In the second level, multiple decentralized GENCOs make their own capacity expansion decisions while anticipating a wholesale electricity market equilibrium in the third level. The collection of bi-level games in the lower two levels forms an equilibrium problem with equilibrium constraints (EPEC) that can be approached by either the diagonalization method (DM) or a complementarity problem (CP) reformulation. We propose a hybrid iterative solution algorithm that combines a CP reformulation of the tri-level problem and DM solutions of the EPEC sub-problem

    Flexibility value in electric transmission expansion planning

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    Electric Transmission Expansion Planning (TEP) is a complex task exposed to multiple sources of uncertainties when the electricity market has been restructured. Approaches like those based on scenarios and robustness have been proposed and used by planners to deal with uncertainties. Alternatives of solution for expansion are identified and economically evaluated through methodologies based on Discounted Cash Flow (DCF). In general, these approaches have the risk to produce undersized or oversized designs of transmission lines because of uncertainties in demand growth rates and economies of scale. In addition, DCF helps to make a decision only with the information available today and it does not consider managerial flexibility. In consequence, transmission expansion projects are auctioned and the winner investor is forced to execute the project under bidding terms without the possibility to adapt the project to unpredictable events. This research introduces flexibility in TEP process and estimates its value as an approach to cope with uncertainties. A methodology based on Real Options is used and the value of flexibility is estimated in terms of social welfare. In particular, an option to defer a transmission expansion is applied and its value is estimated by using a binomial tree technique. Two case studies are analyzed: A two-node case and a reduced version of the Colombian transmission network. Conclusions suggest flexibility is a valid approach to be introduced in TEP in order to handle uncertainties.DoctoradoDoctor en IngenierĂ­a Industria
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