J. C. Smith

National Renewable Energy Laboratory, Golden, Colorado, United States

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Publications (20)7.67 Total impact

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    ABSTRACT: This Expert Group Report provides recommendations based on more than 8 years of work within International Energy Agency (IEA) Wind Task 25 Design and Operation of Power Systems with Large Amounts of Wind Power. The report is issued as an IEA Wind Recommended Practices document to provide research institutes, consultants, and system operators with the best available information on how to perform a wind integration study. The recommendations will be updated as further work in IEA Wind Task 25 reveals improved integration study methodologies based on real wind integration experiences. This Expert Group Report describes the methodologies, study assumptions, and inputs needed to conduct a wind integration study. Findings and results from previous wind integration studies are discussed in the two summary reports (Holttinen et al. 2009; and 2013). The Task 25 Expert Group developed a flow chart that outlines the phases of a complete wind integration study. The flow chart could also direct integration studies for other variable renewables, such as photovoltaics.
    Edited by Hannele Holttinen, 10/2013; IEA Wind www.ieawind.org.
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    ABSTRACT: High penetration of PVs in distribution systems can causes a number of issues on the system. Determining whether or not an issue exists for a given distribution circuit with PV is a non-trivial task. Accurate knowledge regarding the conditions under which issues can be positively ruled out would be immensely beneficial for solar projects as this would eliminate the need for a costly and time-consuming system impact study. In this paper, we focus on the challenges associated with evaluating the types of systems for which potential PV related problems turn into actual problems. In this context, we summarize utility experiences with PV on their system as discussed during UVIG meetings and reported in the pertinent literature. Furthermore, we present simulation results of a PV integration study we conducted for CEATI and discuss the implications of simulation challenges and simplifying assumption often associated with these types of studies.
    Power and Energy Society General Meeting (PES), 2013 IEEE; 01/2013
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    ABSTRACT: The paper presents the functions of the Integration of Variable Generation Task Force (IVGTF) created by the planning and operating committees of the North American Electric Reliability Corporation (NERC) in 2008. This is in anticipation of the substantial growth of renewable variable generation such as wind and solar resources.
    IEEE Power and Energy Magazine 11/2011; 9(6):75-85. · 1.58 Impact Factor
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    ABSTRACT: This article examines the design and operation of a cross section of electricity markets in the United States. Experience with the evolution of such markets in the recent past to accommodate limited amounts of variable renewable energy is discussed. Based on this experience, insights into what is necessary for these markets to be able to accommodate significantly higher levels of variable renewable energy generation in the future are provided.
    IEEE Power and Energy Magazine 11/2010; · 1.58 Impact Factor
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    ABSTRACT: This paper reviews the design and operation of a number of large, regional organized markets in the US, as well as the operation of stand-alone single balancing area bilateral markets, from the viewpoint of integrating large amounts of variable output renewable energy sources. Significant differences between the two types of markets are noted. In addition, a series of shortcomings of the first generation market designs are discussed, and some thoughts on the design changes required to enable greater participation of variable output generators in the market are provided.
    Power and Energy Society General Meeting, 2010 IEEE; 08/2010
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    ABSTRACT: This paper reviews six IVGTF tasks related to interconnection and operating requirements, and provides a report on their objectives, milestones and status. The three interconnection tasks are: Interconnection Requirements Enhancement (Task 1.3); Low Voltage Ride-Through (LVRT) Requirements (Task 1.7); and Balancing Authority (BA) Communications (Task 2.2). The three operating tasks are: Incorporating Forecasting in Operations (Task 2.1); Ancillary Services and Balancing Area Solutions (Task 2.3); and Operating Practices, Procedures and Tools (Task 2.4). These tasks are part of a larger series of thirteen tasks identified in Phase 1 of the IVGTF work, and further described in the companion panel session papers.
    01/2010;
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    ABSTRACT: This paper provides an overview of major transmission planning activities related to wind integration studies in the US and Europe. Transmission planning for energy resources is different from planning for capacity resources. Those differences are explained, and illustrated with examples from several regions of the US and Europe. Transmission planning for wind is becoming an iterative process consisting of generation expansion planning, economic-based transmission planning, system reliability analysis, and wind integration studies. A brief look at the policy environment in which this activity is taking place is provided.
    01/2010;
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    ABSTRACT: The rapid growth of wind generation is introducing additional variability and uncertainty into power system operations and planning. While wind power forecasts are increasingly important, forecasts are not sufficient: we must also identify how forecasts are to be used and the tools necessary to support operators and planners. We present a broad view of these challenges and focus on some of the more immediate opportunities to use forecasts. In particular, we focus on opportunities to use visualization, warning systems, and automation to support control-room operations.
    Power & Energy Society General Meeting, 2009. PES '09. IEEE; 08/2009
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    J. C. Smith, B. Parsons
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    ABSTRACT: I it is a great pleasure for Brian Parsons of the National Renewable Energy Laboratory (NREL) and myself to once again serve as guest editors of IEEE Power & Energy Magazine. This special issue is dedicated to the integration of wind power plants into power system planning and operations. It has been truly phenomenal to watch the explosion of interest and information about this topic in the past fi ve years. We have gone from a situation in which wind energy was a boutique business that was not taken very seriously to one in which wind now accounts for the second-largest share of new generating capacity installed in the past year (just behind natural gas).
    IEEE Power and Energy Magazine 01/2009; 7(6):14-24. · 1.58 Impact Factor
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    ABSTRACT: http://www.vtt.fi/inf/pdf/tiedotteet/2009/T2493.pdf see also more recent update http://www.vtt.fi/inf/pdf/technology/2012/T75.pdf
    01/2009: pages 1-232; Julkaisija-Utgivare., ISBN: 9789513873080
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    N. Samaan, R. Zavadil, J.C. Smith, J. Conto
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    ABSTRACT: This paper presents guidelines for estimating short- circuit contribution from wind power plants to the transmission network. Only squirrel-cage induction generator based turbines have been considered. A commercial software package has been used to model the plant in detail. Transient analysis is performed to explore the nature of the plant short-circuit current. AC symmetrical short-circuit currents are calculated and used through a network reduction technique to obtain the equivalent positive and zero sequence impedances for the wind power plant. Case studies have been performed on a sample 50 MW wind power plant. The plant contribution during the initial cycle of the fault (asymmetrical current) can be as high as 6 or more times the rated turbine current. As the fault persists, the contribution decreases in magnitude. Comparison shows that the equivalent circuit gives identical results to the detailed model. The equivalent circuit can be used to represent the wind power plant in short-circuit analysis at the transmission level.
    Transmission and Distribution Conference and Exposition, 2008. T&D. IEEE/PES; 05/2008
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    ABSTRACT: In only six years, from 2000 to 2006, wind energy has become a significant resource on many electric utility systems, with nearly 74 000 MW of nameplate capacity installed worldwide at the end of 2006. Wind energy is now "utility scale" and can affect utility system planning and operations for both generation and transmission. The utility industry in general, and transmission system operators in particular, are beginning to take note. At the end of 2005, the Power Engineering Society (PES) published a special issue of its Power & Energy Magazine that focused on integrating wind into the power system. This paper provides a summary and update on many of the salient points from that special issue about the current state of knowledge regarding utility wind integration issues.
    IEEE Transactions on Power Systems 09/2007; · 2.92 Impact Factor
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    ABSTRACT: As the size and number of wind power plants (also called wind farms) increases, power system planners will need to study their impact on the power system in more detail. As the level of wind power penetration into the grid increases, the transmission system integration requirements becomes more critical. A very large wind power plant may contain hundreds of megawatt-size wind turbines. These turbines are interconnected by an intricate collector system. While the impact of individual turbines on the larger power system network is minimal, collectively, wind turbines can have a significant impact on the power systems during a severe disturbance such as a nearby fault. Since it is not practical to represent all individual wind turbines to conduct simulations, a simplified equivalent representation is required. This paper focuses on our effort to develop an equivalent representation of a wind power plant collector system for power system planning studies. The layout of the wind power plant, the size and type of conductors used, and the method of delivery (overhead or buried cables) all influence the performance of the collector system inside the wind power plant. Our effort to develop an equivalent representation of the collector system for wind power plants is an attempt to simplify power system modeling for future developments or planned expansions of wind power plants. Although we use a specific large wind power plant as a case study, the concept is applicable for any type of wind power plant
    Power Engineering Society General Meeting, 2006. IEEE; 01/2006
  • R.M. Zavadil, J.C. Smith
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    ABSTRACT: As the number and size of wind power plants continue to grow, utility system operators and transmission network operators around the globe have begun to take note of the possible impact of the plants on power system performance during both normal and abnormal system conditions. Until recently, the number and size of wind power plants was such that it was not uncommon for interconnection practices to require that the plant be disconnected from the grid during a system disturbance, and reconnected when the system had returned to a normal state. This is no longer commonly accepted practice, as the size of recent wind power plants is as large as a typical fossil unit, and their behavior is an important component of overall system behavior both during normal and abnormal conditions.
    Power Engineering Society General Meeting, 2005. IEEE; 07/2005
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    ABSTRACT: Electric utility system planners and operators are concerned that variations in wind plant output may increase the operating costs of the system. This concern arises because the system must maintain an instantaneous balance between the aggregate demand for electric power and the total power generated by all power plants feeding the system. This is a highly sophisticated task that utility operators and automatic controls perform routinely, based on well-known operating characteristics for conventional power plants and a great deal of experience accumulated over many years. System operators are concerned that variations in wind plant output will force the conventional power plants to provide compensating variations to maintain system balance, thus causing the conventional power plants to deviate from operating points chosen to minimize the total cost of operating the system. The operators' concerns are compounded by the fact that conventional power plants are generally under their control and thus are dispatchable, whereas wind plants are controlled instead by nature. Although these are valid concerns, the key issue is not whether a system with a significant amount of wind capacity can be operated reliably, but rather to what extent the system operating costs are increased by the variability of the wind.
    02/2004
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    ABSTRACT: Because of wind power's unique characteristics, many concerns are based on the increased variability that wind contributes to the grid, and most U.S. studies have focused on this aspect of wind generation. Grid operators are also concerned about the ability to predict wind generation over several time scales. In this report, we quantify the physical impacts and costs of wind generation on grid operations and the associated costs.
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    ABSTRACT: In this paper, we describe methods to derive and validate equivalent models for a large wind farm. FPL Energy's 204-MW New Mexico Wind Energy Center, which is interconnected to the Public Service Company of New Mexico (PNM) transmission system, was used as a case study. The methods described are applicable to any large wind power plant.
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    ABSTRACT: Wind energy continues to be one of the fastest growing technology sectors. This trend is expected to continue globally as we attempt to fulfill a growing electrical energy demand in an environmentally responsible manner. As the number of wind power plants continues to grow and the level of penetration reaches high levels in some areas, there is an increased interest on the part of power system planners in methodologies and techniques that can be used to adequately represent wind power plants in the interconnected power systems. Wind power plants can be very large in terms of installed capacity. The number of turbines within a single wind power plant can be as high 200 turbines or more, and the collector system within the wind power plant can have several hundred miles of overhead and underground lines. It is not practical to model in detail all individual turbines and the collector system for simulations typically conducted by power system planners. To simplify, it is a common practice to represent the entire wind power plant with a small group of equivalent turbine generators or a single turbine generator. The question is how much can a model be simplified and still preserve its faithfulness? In this presentation, we will describe methods to derive and validate equivalent models for a large wind farm. FPL Energy's 204-MW New Mexico Wind Energy Center, which is interconnected to the Public Service Company of New Mexico (PNM) transmission system, was used as a case study. The methods described are applicable to any large wind power plant. We will illustrate how to derive a simplified single-machine equivalent model of a large wind power plant (which includes an equivalent collector system model), preserving the net steady state and dynamic behavior of the actual installation. We use steady state as well as the dynamic analysis to derive the equivalent model. To verify the derivations, we compare the steady state and dynamic performance of the equivalent model against a detailed model of the wind power plant, which contains all the wind turbine generators and associated collector system.
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    ABSTRACT: In only 6 years, from 2000 to 2006, wind energy has become a significant resource on many electric utility systems, with nearly 74,000 MW of nameplate capacity installed worldwide at the end of 2006. Wind energy is now "utility scale" and can affect utility system planning and operations for both generation and transmission. The utility industry in general, and transmission system operators in particular, are beginning to take note. As a result, numerous utility wind integration studies are being conducted in the US under a variety of industry structures. This paper will summarize results from a number of case studies conducted recently in the US, and outline a number of mitigation measures based on insights from the recent studies.
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    ABSTRACT: This paper focuses on our effort to develop an equivalent representation of a wind power plant collector system for power system planning studies.