Now showing 1 - 10 of 10
  • Publication
    Current methods to calculate capacity credit of wind power, IEA collaboration
    Power systems must have enough generation to meet demand at each moment of the day. In addition, they must also have enough reserve to deal with unexpected contingencies. The increase in the penetration of wind generation in recent years has led to a number of challenges in the calculations required to facilitate wind generation while maintaining the existing level of security of supply. A key calculation in this process is the capacity credit or value of wind generation. Capacity credit/value of wind generation can be broadly defined as the amount of firm conventional generation capacity that can be replaced with wind generation capacity, while maintaining the existing levels of security of supply. This topic has been the subject of much study and debate in recent times. The aim of this paper is to give an overview of the state of the art in this area, in particular with regard to the work of IEA WIND Task 25 and the work detailed in its state of the art report on the design and operation of power systems with large amounts of wind power.
      2212Scopus© Citations 58
  • Publication
    Wind and solar curtailment: a review of international experience
    Greater penetrations of variable renewable generation on some electric grids have resulted in increased levels of curtailment in recent years. Studies of renewable energy grid integration have found that curtailment levels may grow as the penetration of wind and solar energy generation increases. This paper reviews international experience with curtailment of wind and solar energy on bulk power systems in recent years, with a focus on eleven countries in Europe, North America, and Asia. It examines levels of curtailment, the causes of curtailment, curtailment methods and use of market-based dispatch, as well as operational, institutional, and other changes that are being made to reduce renewable energy curtailment.
      3337Scopus© Citations 390
  • Publication
    Capacity value of wind power
    Power systems are planned such that they have adequate generation capacity to meet the load, according to a defined reliability target. The increase in the penetration of wind generation in recent years has led to a number of challenges for the planning and operation of power systems. A key metric for generation system adequacy is the capacity value of generation. The capacity value of a generator is the contribution that a given generator makes to generation system adequacy. The variable and stochastic nature of wind sets it apart from conventional energy sources. As a result, the modeling of wind generation in the same manner as conventional generation for capacity value calculations is inappropriate. In this paper a preferred method for calculation of the capacity value of wind is described and a discussion of the pertinent issues surrounding it is given. Approximate methods for the calculation are also described with their limitations highlighted. The outcome of recent wind capacity value analyses in Europe and North America, along with some new analysis are highlighted with a discussion of relevant issues also given.
      2132Scopus© Citations 289
  • Publication
    A flexible power system operations simulation model for assessing wind integration
    With the advent of wind power generation on worldwide power systems, many operators and researchers are analyzing the impacts that higher future amounts may have on system operations. Many of the tools are analyzing longer term impacts on the steady-state operations of power systems and are primarily using cost as a metric. They are also using tools that are often inflexible to accommodating different market designs or operational structures. In this paper a model was developed to mimic operator behavior using a combination of security-constrained unit commitment, security-constrained economic dispatch, and automatic generation control programs. New metrics are used to compare reliability in terms of energy imbalance for different systems or different market and operational structures at very high time resolution. Finally an example application of the tool and results for a test system are shown.
      569Scopus© Citations 28
  • Publication
    Evolution of operating reserve determination in wind power integration studies
    The growth of wind power as an electrical power generation resource has produced great benefits with reductions in emissions and the supply of zero cost fuel. It also has created challenges for the operation of power systems arising from the increased variability and uncertainty it has introduced. A number of studies have been performed over the past decade to analyze the operational impacts that can occur at high penetrations of wind. One of the most crucial impacts is the amount of incremental operating reserves required due to the variability and uncertainty of wind generation. This paper describes different assumptions and methods utilized to calculate the amount of different types of reserves carried, and how these methods have evolved as more studies have been performed.
      1327Scopus© Citations 117
  • Publication
    Integration of variable generation : capacity value and evaluation of flexibility
    As integration of variable generation continues to grow rapidly in power systems globally, system planners are seeking new tools to understand the role of variable output generators and the challenges experienced with their integration. The North American Electric Reliability Corporation (NERC) has established a task force to examine the integration of variable generation. This paper details the achievements to date and outlines ongoing efforts from Task 1.2 on the capacity value of variable generation and from Task 1.4 on the concept of flexibility in power systems and options for its definition. Arising from international collaboration with the International Energy Agency, a discussion on the definition of flexible resources is presented. A potential metric for flexibility offered by conventional plant is developed and applied to a test system.
      1279Scopus© Citations 45
  • Publication
    Unit Commitment With Dynamic Cycling Costs
    (Institute of Electrical and Electronics Engineers, 2012-11) ; ; ;
    Increased competition in the electricity sector and the integration of variable renewable energy sources is resulting in more frequent cycling of thermal plant. Thus, the wear-and-tear to generator components and the related costs are a growing concern for plant owners and system operators alike. This paper presents a formulation that can be implemented in a MIP dispatch model to dynamically model cycling costs based on unit operation. When implemented for a test system, the results show that dynamically modeling cycling costs reduces cycling operation and tends to change the merit order over time. This leads to the burden of cycling operation being more evenly distributed over the plant portfolio and reduces the total system costs relative to the case when cycling costs are not modeled.
      722Scopus© Citations 53
  • Publication
    Impact of wind power on the unit commitment, operating reserves, and market design
    This article highlights and demonstrates the new requirements variable and partly unpredictable wind power will bring to unit commitment and power system operations. Current practice is described and contrasted against the new requirements. Literature specifically addressing questions about wind power and unit commitment related power system operations is surveyed. The scope includes forecast errors, operating reserves, intra-day markets, and sharing reserves across interconnections. The discussion covers the critical issues arising from the research.
      965Scopus© Citations 39
  • Publication
    Variability of load and net load in case of large scale distributed wind power
    Large scale wind power production and its variability is one of the major inputs to wind integration studies. This paper analyses measured data from large scale wind power production. Comparisons of variability are made across several variables: time scale (10-60 minute ramp rates), number of wind farms, and simulated vs. modeled data. Ramp rates for Wind power production, Load (total system load) and Net load (load minus wind power production) demonstrate how wind power increases the net load variability. Wind power will also change the timing of daily ramps.
  • Publication
    Capacity value of wind power: summary
    The capacity value of a generator is the contribution that a given generator makes to generation system adequacy. Due to the variable and stochastic nature of wind, the modeling of wind generation in the same manner as conventional generation for capacity value calculation is inappropriate. In this paper a short summary of the issue is given. This summary is largely based on IEA task 25 activities and the output of an IEEE task force. A preferred method for calculating capacity value along with approximate methods for the calculation are also described with their limitations outlined.