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The purported social, economic and environmental benefits are resulting in increased wind penetration in existing power systems. However, due to inherent uncertainty of wind energy, thermal generators are expected to maintain security and reliability of power systems. Further, in view of the huge investments in existing power plant installations, thermal power may not be completely replaced by renewable energy sources such as wind power in near future. Therefore, reduction in capacity factor of the existing thermal generators due to wind integration is a major policy concern. This aspect must be juxtaposed with benefits of wind integration such as cost savings and emission reduction. The current study introduces a Capacity Factor Violation Index (CFVI) to evaluate the impact of wind integration on capacity factor of thermal generators. A distance metric comprising of cost savings, emission reduction, network losses and CFVI is proposed based on Compromise Programming (CP). Sensitivity analysis is performed by varying the wind penetration and turbine ratings and the impact on the distance metric is investigated. The proposed methodology is comprehensively demonstrated in eleven popular test power systems.

An efficient unit commitment planning must consider frequency regulation capacity in the model. Such models are more complicated under a high penetration level of renewable energy because of renewable ramping and uncertainty. This paper addresses these issues in the unit commitment. The proposed model for unit commitment considers uncertainty and ramping of wind power, frequency regulation capacity, spinning reserve, demand response, and pumped-storage hydroelectricity. Two reserve capacities including primary frequency regulation and spinning reserve are designed to handle the intermittency and ramping of renewable energies. In order to optimize the costs, the pumped-storage hydroelectricity and demand response program are also included to deal with ramping and uncertainty. The numerical results specify that the arrangement of frequency regulation capacity, pumped-storage system and demand response can effectively tackle both the ramping and uncertainty. The system includes 10-generator with total power equal to 1070 MW and one wind generator with 300 MW power. The initial wind integration level is about 28%. It is verified that decreasing the frequency regulation capacity by 10% reduces wind integration level by 94%. The demand response and pumped-storage increase wind integration level by 10% and 16%; while both together increase wind integration by 25% compared to the initial level. The wind integration level without large wind ramping can be increased up to 200%. 2010-2012 IEEE. Manuscript received May 9, 2020; revised July 21, 2020; accepted August 13, 2020. Date of publication August 18, 2020; date of current version December 16, 2020. The work of M. Shafie-khah was supported by FLEXIMAR-Project (Novel marketplace for energy flexibility), which has received funding from Business Finland Smart Energy Program, 2017-2021. Also, J.P.S. Catalão acknowledges the support by FEDER funds through COMPETE 2020 and by Portuguese funds through FCT, under POCI-01-0145-FEDER-029803 (02/SAICT/2017). (Corresponding author: Hasan Mehrjerdi.) Reza Hemmati is with the Department of Electrical Engineering, Ker-manshah University of Technology, Kermanshah 67146, Iran (e-mail: r.hemmati@kut.ac.ir). Scopus 2-s2.0-85098279858

Due to environmental concerns and to meet the increasing load growth, the renewables penetration, mainly wind, is increasing rapidly. This leads to changes in system configuration and load flow. Due to this the dynamic interaction due to converters increases, and this amplifies the low frequency oscillations (LFOs) issues in the grid. The study presented analyzed the impact of doubly fed induction generator (DFIG) wind farms location on the small signal stability of the system. The analysis is performed using well established modal analysis technique. The study is carried out on the IEEE benchmark 39-bus test system. The investigations performed can be utilised for the initial phases of grid planning to be integrated with DFIG wind farms.

In this paper, we utilize nodal price data at each thermal-generation facility within the ERCOT footprint between 2014 and 2016 to revisit an empirical question of great interest to various parties: how does wind integration affect the wholesale energy price? We find that for every additional 1000 MW of wind generation in a Real-Time 15-minute Settlement Interval, nodal prices at non-wind resources would be suppressed by $1.45/MWh to $4.45/MWh, with considerable heterogeneity across time and space.

This case study highlights the challenges, innovations and recommendations of wind-diesel integration projects in remote Alaska through the lens of the Chaninik Wind Group. Although energy access and affordability is extremely difficult in remote areas, renewable energy technologies prove valuable in reducing the cost of energy for consumers.

With competitive electricity market operation, open access to the transmission and distribution network is essential for transparent and efficient market operation. Like transmission pricing, distribution network pricing must also be transparent and must include tile variations based on the change in the operating state of the system, integration of renewable sources and must be real time. In this paper, a distribution system nodal pricing scheme is proposed for radial distribution system with integration of wind power in the system. The main objective of the paper is: (i) an optimal power flow based approach for determination of nodal prices for distribution system, (ii) impact of wind generation on nodal prices. The results have been obtained for IEEE 33 bus test system.Keywords: Distribution system, electricity market; nodal prices, wind power integration

The penetration of renewable energy sources, particularly wind energy, into power systems has been rapidly increasing in recent years. However, the integration of wind power has posed many challenges for power system operation. For instance, this type of energy source is relatively variable and unpredictable. The installation of this renewable source might require the grid to transmit power at full capacity and some transmission lines could become congested. As a result, in some operating conditions, wind power could be curtailed, which will drive up costs for system operators. One of the actions that can be taken to support the integration of the wind is using energy storage systems. In this paper, a multiperiod ac optimal power flow problem with battery energy storages (BESs) is formulated and sets of candidate buses for BES installation are identified based on an economic criterion. Tests are carried out on IEEE 14-bus and IEEE 118-bus systems to assess the robustness of storage location on system operation.

The share of wind generation in the Irish and British electricity markets is set to increase by 2020 due to renewable energy (RE) targets. The United Kingdom (UK) and Ireland have set ambitious targets which require 30% and 40% of electricity demand to come from RE, mainly wind, by 2020, respectively. Ireland has sufficient indigenous onshore wind energy resources to exceed the RE target, while the UK faces uncertainty in achieving its target. A possible solution for the UK is to import RE directly from large scale onshore and offshore wind energy projects in Ireland; this possibility has recently been explored by both governments but is currently on hold. Thus, the aim of this paper is to estimate the effects of large scale wind energy in the Irish and British electricity markets in terms of wholesale system marginal prices, total generation costs and CO2 emissions. The results indicate when the large scale Irish-based wind energy projects are connected directly to the UK there is a decrease of 0.6% and 2% in the Irish and British wholesale system marginal prices under the UK National Grid slow progression scenario, respectively.

The authors employed a novel optimization framework coupled with an econometric model of wind to study market performance. One conclusion: in circumstances with high uncertainty in the market – as with high penetration of renewables – relying more on a real-time market, similar to the National Electricity Market in Australia, may be a better way to deal with this uncertainty because it uses updated and more accurate information about the wind variability.

Growing development of renewable energy sources, particularly wind power, has caused great challenges in power system operations need to be carefully investigated. Variability in wind power generation is the main concern regarding wind integration which should be adjusted with a reasonable cost in order to maintain system balance between supply and demand. The continuous augment of Plug-in Electric Vehicles (PEVs) has made them as one promising solution due to their flexibility and low-emission. This paper evaluates the interaction of PEV Parking Lots (PLs) in both energy and reserve markets considering the impact of dispersed and gathered wind generation. To this end, a two-stage stochastic framework is adopted with the aim of modeling the day-ahead network-constrained market clearing. The proposed method considers the uncertainty of wind generation as well as the PEV owner's behavior takes into account the arrival/departure time of PEVs to/from the PL, the initial state of charge (SOC) of PEVs, and their battery capacity using a set of scenarios. Several numerical analyzes are carried out to assess the reserve requirement as a result of dispersed or gathered wind generation. Also, the effectiveness of PEV PLs participation in energy and reserve market on wind integration is examined.

This chapter discusses the challenges and solutions associated with integration of large-scale wind generation in the Electric Reliability Council of Texas (ERCOT) system. It begins with a brief introduction to the ERCOT system and the factors that have contributed to the success of large-scale wind generation build out such as wind resource, support schemes, and transmission access. This is followed by a short description of the ERCOT’s energy market and ancillary services. Next, the chapter focuses on the impacts that the changing generation mix has on synchronous inertia of the system, ancillary service needs and system frequency performance. The solutions already implemented in ERCOT and changes still under discussion to further address those impacts are presented. Finally, due to the variability and uncertainty of power production from renewable energy resources, there is a need for additional monitoring and prediction tools to assess the impact of renewables on the system frequency response. Some features of these tools, which were recently developed in ERCOT, are introduced in the chapter.

The integration process of renewable energy sources (RES) and distributed energy resources (DER) into the power system, is characterized by concerns that originate from their stochastic and uncontrollable nature. This means that system operators require reliable forecasting tools, in order to ensure efficient and reliable operation. Accordingly, this paper proposes the use of demand flexibility, to counteract the RES forecasting errors. For this purpose, distributed and decentralized intelligence is used, via the SG-BEMS framework, to invoke demand flexibility in a timely and effective fashion, while taking into account the negative effects on the building occupants comfort. Lastly, numerical results from a simulated case of study are presented, which confirm that demand flexibility can be used to mitigate the magnitude of forecast errors.

In the recent years, the debate on the necessity of pumped storage systems in the Greek power supply system has started. In the current decade, the Greek power system will gradually try higher RES penetration, mainly due to wind energy and photovoltaics integration. Variability of wind and PV generation and the current structure of the Greek power system introduce technical constraints, which should be taken into consideration in the forthcoming large scale RES integration. This paper examines the ability of the Greek power system to absorb renewable power and the necessity of pumped storage systems. The feasibility of pumped storage systems is discussed in three different scenarios of wind–photovoltaics integration. Results show that for the gradual increase of variable output RES, pumped storage systems are required, but the feasibility of pumped storage systems is not proved in the intermediate scenarios of RES integration.

Many jurisdictions worldwide are greatly increasing the amount of wind production, with the expectation that increasing renewables will cost-effectively reduce greenhouse emissions. This paper discusses the interaction of increasing wind, transmission constraints, renewable credits, wind and demand correlation, intermittency, carbon prices, and electricity market prices using the particular example of the Electric Reliability Council of Texas market. An estimate is made of the cost of using wind to mitigate greenhouse gas emissions.

As wind plants become a more substantial portion of the generation resource, the ability of and manner in which this new fleet of generation supports meeting the power system load in a given area must be quantified in order to ensure security of supply. This paper describes the manner in which a reanalysis dataset—the National Aeronautics and Space Administration (NASA) Modern Era Retrospective-Analysis for Research and Applications (MERRA) dataset—was utilized in conjunction with the National Renewable Energy Laboratory (NREL) Eastern Wind Integration Dataset in order to perform an estimation of the interannual variability in wind power production as related to the capacity value of the investigated potential wind plants. Also described in the paper is a comparison of the MERRA data with publicly available wind data collected by the University of Massachusetts Wind Energy Center (UMass WEC).

The Public Utility District No. 2 of Grant County, Washington, USA, in collaboration with the National Renewable Energy Laboratory and Northern Arizona University, conducted an analysis of the impact wind integration on their hydropower dominant generation system. Wind power penetration levels of 12 MW (2.0%), 63.7 MW (10.4%) and 150 MW (24.6%) were considered. For the 2006 study year, a statistical summary of the changes in the regulation and load following requirements expected due to wind variability was conducted. The results demonstrated that the impact of wind power upon minute-to-minute regulation requirements is small, and small to modest on the load following requirements. However, changes in the distribution of load following hourly changes could result in infringement upon system constraints. A chronological simulation of preschedule (i.e. day ahead) planning was therefore conducted indicating an increased incidence of constraint “exceedences.” The nature of the increase in exceedences is presented and discussed.

Large penetration of Renewable Energy Sources (RES) impacts Energy Supply Industry (ESI) in many aspects leading to a fundamental change in electric power systems. It raises a number of technical challenges to the Transmission System Operators (TSOs), Distribution System Operators (DSOs) and Wind Turbine Generators (WTG) constructors. This paper aims to present in a thorough and coherent way the redrawn picture for Energy Systems under these conditions. Topics related to emergent technical challenges, technical solutions required and finally the impact on ESI due to large wind power penetration, are analyzed. Finally, general conclusions are extracted about the ESI current and future state and general directions are recommended.

This deliverable summarizes the content of the FP7 project UMBRELLA. It describes the objectives and the results achieved by the end of the four project years. UMBRELLA is also cooperating with the related FP7 project iTesla, i.e. some public workshops are performed commonly, test environments are harmonized and a common proposal on potential development of future TSO rules is proposed.

In this paper a new concept for control and performance assessment of compressed air energy storage (CAES) systems in a hybrid energy system is introduced. The proposed criterion, based on the concept of energy harvest index (HEI), measures the capability of a storage system to capture renewable energy. The overall efficiency of the CAES system and optimum control and design from the technical and economic point of view is presented. A possible application of this idea is an isolated community with significant wind energy resource. A case study reveals the usefulness of the proposed criterion in design, control and implementation of a small CAES system in a hybrid power system (HPM) for an isolated community. Energy harvested index and its effectiveness in increasing the wind penetration rate in the total energy production is discussed.

This deliverable is a halfway summary of the FP7 project UMBRELLA. It describes the objectives and the results achieved by the end of the second of four project years. UMBRELLA is also cooperating with the related FP7 project iTesla, i.e. some public workshops are performed commonly, test environments are harmonized and a common proposal on potential development of future TSO rules will be proposed at the end of both projects in 2015.

The uncertain and variable nature of renewable energy sources in modern power systems raises significant challenges in achieving the dual objective of reliable and economically efficient system operation. To address these challenges, advanced scheduling strategies have evolved during the past years, including the co-optimization of energy and reserves under deterministic or stochastic Unit Commitment (UC) modeling frameworks. This paper presents different deterministic and stochastic day-ahead UC formulations, with focus on the determination, allocation and deployment of reserves. An explicit distinction is proposed between the uncertainty and the variability reserve, capturing the twofold nature of renewable generation. The concept of multi-timing scheduling is proposed and applied in all UC policies, which allows for the optimal procurement of such reserves based on intra-hourly (real-time) intervals, when concurrently optimizing energy and commitments over hourly intervals. The day-ahead scheduling results are tested against different real-time dispatch regimes, with none or limited look-ahead capability, or with the use of the variability reserve, utilizing a modified version of the Greek power system. The results demonstrate the enhanced reliability achieved by applying the multi-timing scheduling concept and explicitly considering the variability reserve, and certain features regarding the allocation and deployment of reserves are discussed.

This paper summarizes the California ISO's renewable integration studies performed to evaluate the need for flexible resources in the year 2020 as the fleet of resources transitions from flexible conventional resources to intermittent and variable resources under higher renewable penetration levels. California's Renewable Portfolio Standard (RPS) requires that 33% of all energy consumed be met by renewable resources. In the same time period environmental policy will result in coastal once-through-cooled steam resources being retired or repowered. The result of these two environmental policies is a significant change in the operating characteristics and capability of the fleet. There will be an increase of supply variability and a decrease in the amount of flexibility to balance the system. The California ISO performed studies to quantify the flexibility requirements and fleet needs in order to maintain load and supply in balance. The presentation will: 1) describe the planning assumption, 2) explain the study methodology, 3) summarize results and conclusions and lastly suggest some areas of further study.

Transmission operating and planning procedures in Europe and elsewhere are changing in response to the new challenges posed by wind integration. Evolving procedures for managing transmission congestion and augmenting transmission capacity in Europe and Alberta are summarized and contrasted.

This deliverable contains a questionnaire for TSOs in order to determine thedetails for information exchange required for both projects.

The uncertainty of generation required to maintain system balancing has been growing significantly due to the increasing penetration of wind generation. To deal with such uncertainty, Transmission System Operators require more look-ahead and forecasting capabilities beyond real-time. This paper presents the design of an enhanced dispatch system to address the challenges posed by wind energy integration. With advanced wind power forecast, robust dispatch algorithm and strong wind event monitoring capability, the proposed system will provide adequate system ramping capability to cope with uncertain intermittent resources while maintaining system reliability in large grid operations.

This report summarizes an analysis, conducted by the National Renewable Energy Laboratory (NREL) in May 2010, of the economic characteristics of a particular utility-scale wind configuration project that has been referred to as the 'Big Wind' project.

Serbia has wind with good capacity factor, which respectable potential has been not used so far. There are a number of proposal projects with envisaged capacity of up to 2500 MW and proposed project documentation for 1300 MW in wind power units. Within the existing feed in tariff scheme only 450 MW are eligible. This limitation is set in a conservative manner having in view technical problems due to intermittency of wind power generation. Within existing structure of power generation in Serbian power system, with the significant of hydro generation and available pumped storage hydro capacity and good exporting capacities there are lots of possibilities to provide ancillary services needed for reliable grid technical performance and for balancing the wind production. In this article the critical excess electricity production under different scenarios of wind power penetration into Serbian power system will be analyzed. Several options of technical constraints and the impact of the objective function will be qualified. Possible new technical control strategies for providing ancillary services for improved usage of available wind power production will be also discussed. This paper presents methodology for simulating wind penetrations using EnergyPLAN model.

EU Member States increase deployment of intermittent renewable energy sources to deliver the 20% renewable target formulated in the European Renewables Directive of 2008. To incorporate these intermittent sources, a power market needs to be flexible enough to accommodate short-term forecasts and quick turn transactions. This flexibility is particularly valuable with respect to wind energy, where wind forecast uncertainty decreases significantly in the final 24 hours before actual generation. Therefore, current designs of intraday and balancing markets need to be altered to make full use of the flexibility of the transmission system and the different generation technologies to effectively respond to increased uncertainty. This paper explores the current power market designs in European countries and North America and assesses these designs against criteria that evaluate whether they are able to adequately handle wind intermittency.

In March 2009, AWS Truepower was engaged by the National Renewable Energy Laboratory (NREL) to develop a set of wind resource and plant output data for the Hawaiian Islands. The objective of this project was to expand the methods and techniques employed in the Eastern Wind Integration and Transmission Study (EWITS) to include the state of Hawaii.

The Puerto Rico Electric Power Authority (PREPA) supports an orderly development of the renewable energy potential on the islands. To attain this goal, PREPA is conducting science-based analytical studies and research to increase knowledge on these technologies. As part of this effort, PREPA commissioned the Electric Power Research Institute (EPRI) to assess the potential impacts that different penetration levels of waste-to-energy (WTE) and wind generation on PREPA power system operations. The study covered different technical and economic aspects of wind integration. This paper summarizes the impact of hourly wind power variability and wind generation forecast uncertainty on system operation cost The analytical approach and evaluation results are described.

The 2001/77/CE Renewable Energies European Directive together with Kyoto Protocol ratification by many countries, supported by some Governments vision and strong objectives on the reduction of external oil dependence, put Europe and other developed economies in the front line to achieve a remarkable wind energy penetration within ten years time. These goals will not be achieved without technical costs and risks, but mainly, without a careful planning and assessment of the power system behaviour with large amounts of wind generation (SRA, 2008; IEAWind, 2008). These days, one of the most relevant difficulties the wind sector faces was caused by this technology own extreme success. The high capacity installed in the last decade introduced a brand new set of power system technological concerns that recently became one of the more referenced subjects among developers, network planners and system operators. These concerns are not anymore a negligible distribution grid integration issue that some years ago the experts tended not to give too much relevance since they were easily solved and even more easily avoided through good design and planning, but this is a real power system operation and planning challenge (Holttinen et al, 2009): will the power systems be capable to cope with the specificities of the wind power production in large quantities (aka “high penetration”) without requiring new wind park models, system operation tools, increased performance of the wind turbines or even a change in the Transmission System Operators (TSOs) conventional mode of operation? The recent concern of the TSOs is very legitimate, since it is their responsibility to design and manage the power system global production and its adjustment to the consumer loads as well as to assure the technical quality of the overall service, both in steady-state and under transient occurrences. The wind power capacity reached such a dimension in some European power systems that obliged the TSOs not to neglect the typical behaviour of these spatially distributed renewable power plants, that being a situation that must be addressed by the wind park developers, the wind manufacturers, the TSO planners and regulators together with the experts in this technology grid integration behaviour.

ERCOT has been experiencing an increase in installed wind capacity over the past several years. At present, there is approximately 7500MW of installed wind capacity in the ERCOT Interconnect and there are observed instances of significant wind generation variation (approximately 27% of installed wind capacity over two hour periods). Additionally, the rapid rate of wind generation installation has easily outpaced the up-gradation of transmission facilities in the region. These things, along with the high variability in wind generation, have imposed several challenges to ERCOT Operations. Voltage regulation utilizing inductive generators is a new experience for ERCOT, and new requirements have been placed on frequency control and ancillary service in the ERCOT system. This paper will address current operational challenges observed by ERCOT during high wind output and extreme wind variation conditions and will share some of the experience gained by ERCOT Operations during such scenarios.

This paper presents the overview of the wind evaluation which over the past two years, a major effort was undertaken in the U.S. to examine the feasibility of providing substantial amounts of electricity to the Nation's electric power system from wind power. A group of nearly100 individuals became engaged in a variety of capacities to consider a prospective picture of 20% electricity from wind by 2030. The U.S. 20% wind evaluation arose through a convergence of strategic thinking among the American Wind Energy Association (AWEA), the U.S. Department of Energy (DOE), and the National Renewable Energy Laboratory (NREL) and other Federal energy laboratories. In parallel across the Atlantic, significant activities have been underway for several years to address issues associated with high penetrations of wind power. This panel includes reports from two of these efforts: the European Wind Integration Study, and a study of ultra-high wind energy penetration in the isolated island power system of Ireland.

In recent years, the share of renewable energy sources (RES) in the electricity generation mix has been expanding rapidly. However, limited predictability of the RES poses challenges for traditional scheduling and dispatching mechanisms based on unit commitment (UC) and economic dispatch (ED). This paper presents an advanced UC-ED model to incorporate wind generators as RES-based units alongside conventional centralized generators. In the proposed UC-ED model, an imbalance cost is introduced reflecting the wind generation uncertainty along with the marginal generation cost. The proposed UC-ED model aims to utilize the flexibility of fleets of plug-in electric vehicles (PEVs) to optimally compensate for the wind generation uncertainty. A case study with 15 conventional units and 3 wind farms along with a fixed-sized PEV fleet demonstrates that shifting of PEV fleets charging at times of high wind availability realizes generation cost savings. Nevertheless, the operational cost saving incurred by controlled charging appears to diminish when dispatched wind energy becomes considerably larger than the charging energy of PEV fleets. Further analysis of the results reveals that the effectiveness of PEV control strategy in terms of CO2 emission reduction is strongly coupled with generation mix and the proposed control strategy is favored in cases where less pollutant-based plants like nuclear and hydro power are profoundly dominant.

The growing share of electricity production from variable renewable energy sources increases the stochastic nature of the power system. This has repercussions on the markets for electricity. Deviations from forecasted production schedules require balancing of a generator’s position within a day. Short term products that are traded on power and/or reserve markets have been developed for this purpose, providing opportunities to actors who can offer flexibility in the short term. The value of flexibility is typically modelled using stochastic scenario extensions of dispatch models which requires, as a first step, understanding the nature of forecast uncertainties. This study provides a new approach for determining the forecast errors of wind power generation in the time period between the closure of the day ahead and the opening of the first intraday session using Spain as an example. The methodology has been developed using time series analysis for the years 2010–2013 to find the explanatory variables of the wind error variability by applying clustering techniques to reduce the range of uncertainty, and regressive techniques to forecast the probability density functions of the intra-day price. This methodology has been tested considering different system actions showing its suitability for developing intra-day bidding strategies and also for the generation of electricity generated from Renewable Energy Sources scenarios. This methodology could help a wind power producer to optimally bid into the intraday market based on more accurate scenarios, increasing their revenues and the system value of wind.