| 1. |
- Bird, Lori, et al.
(författare)
-
Wind and solar energy curtailment : A review of international experience
- 2016
-
Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 65, s. 577-586
-
Forskningsöversikt (refereegranskat)abstract
- 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.
|
|
| 2. |
- Elkington, Katherine
(författare)
-
The Dynamic Impact of Large Wind Farms on Power System Stability
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As the installed capacity of wind power increases across the world, its impact on power systems is becoming more important. To ensure the reliable operation of a power system which is significantly fed by wind power, the dynamics of the system must be understood. The purpose of this study is to analyse the dynamic impact of large-scale wind farms on the stability of a power grid, and to investigate the possibility of improving the stabilisation and damping of the grid by smart control strategies for wind turbines. When unconventional types of generators are used in a power system, the system behaves differently under abnormal dynamic events. For example, new types of generators such as doubly fed induction generators (DFIGs) cause different modes of oscillation in the system. In order to damp oscillations in the system, it is necessary to understand the equipment causing these oscillations, and the methods of optimally damping the oscillations. Large power oscillations can occur in a power system as a result of disturbances. Ordinarily these oscillations are slow and, in principle, it is possible to damp them with the help of wind power. This suggests the use of a power oscillation damping (POD) controller for a DFIG, similar to a power system stabiliser (PSS) for a synchronous generator. To demonstrate this concept, we design PODs for DFIGs in a wind farm. Voltage stability is another important aspect of the safe operation of a power system. It has been shown that the voltage stability of a power system is affected by induction generators and also DFIGs. The voltage stability must therefore also be analysed in order to guard against a power system collapse. In this study we develop models and control strategies for large wind farms comprising DFIGs, and study the impact of the wind farms on power systems. The design of multiple PODs in a wind farm is performed using linear matrix inequalities (LMIs), and the impact of the wind turbines is investigated through the use of linear and dynamic simulations. It has been demonstrated that DFIGs can be used for damping oscillations, and that they can also improve the critical clearing time of some faults. However, they may have an adverse impact on power systems after large voltage disturbances.
|
|
| 3. |
- Estanqueiro, Ana, et al.
(författare)
-
DLR use for optimization of network design withvery large wind (and VRE) penetration
- 2018
-
Konferensbidrag (refereegranskat)abstract
- Due to the stochastic nature of wind and clouds,the integration of wind and PV generation in the powersystem poses serious challenges to the long-term planning oftransmission systems. Grid reinforcements always involverelevant direct costs while the average load factor of the windand solar PV dedicated transmission lines is usually low.Additionally, in very windy sites, the same high windresource that produces large amounts of wind generation andmay congest the transmission lines transporting it to distantconsumption centres may also have a beneficial effect inincreasing the transmission capacity of those lines. In fact, theoccurrence of wind not only contributes to the loading of theconnecting line, but also increases the line capacity, via theconvective cooling of the cables - one of the main heattransfer mechanisms in conductor heat balance; in otherwords, higher winds speeds contribute to faster cooling ofconductor and therefore higher conductor’s capacitypotential. In this paper the existing methodologies tocharacterize those thermal effects in electrical cables - usuallyreferred as dynamic line rating (DLR) - are applied to severalIEA Task 25 countries case studies to characterize thetechnical value of the dynamic operation of thermallycongested lines, as well as its potential economic benefits.
|
|
| 4. |
- Hannele, Holttinen, et al.
(författare)
-
Impacts of large amounts of wind power on design and operation of power systems, results of IEA collaboration
- 2009
-
Ingår i: 8th International Workshop on LargeScale Integration of Wind Power into Power Systems as well as on Transmission Networks of Offshore Wind Farms.
-
Konferensbidrag (refereegranskat)abstract
- IEA WIND R&D Task 25 on “Design and Operation of Power Systems with Large Amounts of Wind Power” collects and shares information on wind power impacts on power systems, with analyses and guidelines on methodologies. There are dozens of studies made and ongoing related to wind integration, however, the results are not easy to compare. In the stateoftheart report (October, 2007), and the final report of the 3 years period (July, 2009) the most relevant wind power grid integration studies have been analysed especially regarding methodologies and input data. Several issues that impact on the amount of wind power that can be integrated have been identified. Large balancing areas and aggregation benefits of large areas help in reducing the variability and forecast errors of wind power as well as help in pooling more cost effective balancing resources. System operation and functioning electricity markets at less than dayahead time scales help reduce forecast errors of wind power. Transmission is the key to aggregation benefits, electricity markets and larger balancing areas. Best practices in wind integration studies are described. There is also benefit when adding wind power to power systems: it reduces the total operating costs and emissions as wind replaces fossil fuels and this should be highlighted more in future studies.
|
|
| 5. |
- Holttinen, Hannele, et al.
(författare)
-
Impacts of large amounts of wind power on design and operation of power systems, results of IEA collaboration
- 2011
-
Ingår i: Wind Energy. - : Wiley. - 1095-4244 .- 1099-1824. ; 14:2, s. 179-192
-
Tidskriftsartikel (refereegranskat)abstract
- There are dozens of studies made and ongoing related to wind integration. However, the results are not easy to compare. IEA WIND R&D Task 25 on 'Design and Operation of Power Systems with Large Amounts of Wind Power' collects and shares information on wind generation impacts on power systems, with analyses and guidelines on methodologies. In the state-of-the-art report (October, 2007), and the final report of the 3 years period (July, 2009) the most relevant wind power grid integration studies have been analysed especially regarding methodologies and input data. Several issues that impact on the amount of wind power that can be integrated have been identified. Large balancing areas and aggregation benefits of wide areas help in reducing the variability and forecast errors of wind power as well as help in pooling more cost effective balancing resources. System operation and functioning electricity markets at less than day-ahead time scales help reduce forecast errors of wind power. Transmission is the key to aggregation benefits, electricity markets and larger balancing areas. Best practices in wind integration studies are described. There is also benefit when adding wind power to power systems: it reduces the total operating costs and emissions as wind replaces fossil fuels and this should be highlighted more in future studies.
|
|
| 6. |
- Huang, Yalin, 1987-
(författare)
-
Economic Regulation Impact on Electricity Distribution Network Investment Considering Distributed Generation
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of EU’s actions against climate change is to meet 20% of energy consumption from renewable resources by the year 2020 when the project was started. Now this target has increased to at least 27% by the year 2030. In addition, given that the renewable resources are becoming more economical to generate electricity from and that these resources are distributed geographically, more and more distributed generation (DG) is connected to power distribution. The increasing share of DG in the electricity networks implies re-distribution of costs and benefits among distribution system operators (DSOs), customers and DG owners. How the costs and benefits will be allocated among them depends on the established economic regulation.The established economic regulation regulates the DSOs’ revenue and performances. The time when the DSOs are remunerated based on their actual costs has passed. Nowadays the economic regulation is in place to steer efficient investments. Network investments are no longer just to satisfy the load growth, or to higher the investments does not bring higher revenue. Network investments are incentivised by the regulation to be more efficient. Furthermore, the potential of DG to defer network investment is widely recognized. Ignoring this potential of DG may decrease DSOs’ efficiency. Last but not the least; network unbundling is a common practice in Europe. Ignoring the fact that DSOs and DG owners are different decision makers in studies can lead to inaccurate analysis.Driven by the target of a higher DG integration and more efficient investments in the unbundled distribution networks, proper economic regulations are needed to facilitate this change. The objective of this thesis is to evaluate the impact from regulations on distribution network investment considering DG integration. In other words, this thesis aims to develop methods assist regulators to design desirable regulations to encourage the DSOs to make the “smart” decisions. In order to achieve that, we propose a modelling approach to quantify the economic regulation impacts and the benefit of innovative investments. Regulations are encoded into the network investment model. The developed models, in other words, assist DSOs to make the “right” investment in the “right” place at the “right” time under the given regulation.
|
|
| 7. |
- Huertas-Hernando, Daniel, et al.
(författare)
-
Hydropower Flexibility for Power Systems with Variable Renewable Energy Sources: An IEA Task 25 Collaboration
- 2019
-
Ingår i: Advances in Energy Systems. - : Wiley. ; , s. 385-405
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In order to effectively utilize hydro production flexibility, a sufficient amount of transmission capacity has to be available between the hydro-dominated part of the system and the part that requires operational flexibility. This chapter starts with a rough categorization of “base” hydropower flexibility, investigating the types of hydropower plants installed in power systems today. The “effective” hydropower flexibility available to support the integration of variable generation is a far more complex and case-specific aspect. It is discussed through national experiences. The chapter presents potential developments that would increase the participation of hydropower and discuss the ensuing challenges. Modeling a flow-based hydro system is a complex exercise, as is modeling the power system. Especially important is the correct assessment of hydropower flexibility to support power systems with a large share of variable generation (VG) and its value for storage. With increasing uncertainty and variability, a stochastic scheduling approach should yield lower costs.
|
|
| 8. |
- Kiviluoma, Juha, et al.
(författare)
-
Variability in Large-Scale Wind Power Generation
- 2016
-
Ingår i: Wind Energy. - : John Wiley & Sons. - 1095-4244 .- 1099-1824. ; 19:9, s. 1649-1665
-
Tidskriftsartikel (refereegranskat)abstract
- The article demonstrates the characteristics of wind power variability and net load variability in multiple power systems based on real data from multiple years. Demonstrated characteristics include probability distribution for different ramp durations, seasonal and diurnal variability, and low net load events. In some characteristics the power systems are different, but in others they are significantly similar. Somewhat surprisingly there seems to be no straightforward correlation between wind power penetration level and variability. As long as there are several wind power plants with enough geographical spread, most of the smoothing impact is captured. Wind power variability is mainly explained by the extent of geographical spread, but also higher capacity factor causes higher variability. It was also shown how wind power ramps are auto correlated and dependent on the operating output level. In most cases wind power did not have strong diurnal or seasonal variations in the variability. However, there can be exceptions depending on the latitude and on the local characteristics of the wind resource.
|
|
| 9. |
- Nordström, Henrik, et al.
(författare)
-
Strategies for Continuous Balancing in Future Power Systems with High Wind and Solar Shares
- 2023
-
Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 16:14
-
Forskningsöversikt (refereegranskat)abstract
- The use of wind power has grown strongly in recent years and is expected to continue to increase in the coming decades. Solar power is also expected to increase significantly. In a power system, a continuous balance is maintained between total production and demand. This balancing is currently mainly managed with conventional power plants, but with larger amounts of wind and solar power, other sources will also be needed. Interesting possibilities include continuous control of wind and solar power, battery storage, electric vehicles, hydrogen production, and other demand resources with flexibility potential. The aim of this article is to describe and compare the different challenges and future possibilities in six systems concerning how to keep a continuous balance in the future with significantly larger amounts of variable renewable power production. A realistic understanding of how these systems plan to handle continuous balancing is central to effectively develop a carbon-dioxide-free electricity system of the future. The systems included in the overview are the Nordic synchronous area, the island of Ireland, the Iberian Peninsula, Texas (ERCOT), the central European system, and Great Britain.
|
|
| 10. |
- Söder, Lennart, 1956-, et al.
(författare)
-
Wind Generation in Adequacy Calculations and Capacity Markets in Different Power System Control Zones
- 2018
-
Ingår i: 17th International Wind Integration Workshop, Stockholm, 17-19 October 2018.
-
Konferensbidrag (refereegranskat)abstract
- Generation capacity adequacy is a major issue in most power systems, but there are many approaches which canbe assessed. Power system planners often define target values for the capacity adequacy, which may be achieved through capacity markets/auctions, capacity reserves, or capacity purchases. Wind power contributes to the generation capacity adequacy of the power system since there is a possibility that wind power will generate in high load situations and thereby decreases the risk of generation capacity deficit compared tothe system without this source. The contribution is probabilistic– as it is with any other source, since nothing is 100% reliable - but the capacity value of wind power is significantly smaller compared to the capacity value of conventional fossil-fueled plants.In this article, an overview of the fundamental challenges inthe regulation of capacity adequacy as well as how wind poweris treated in some selected existing jurisdictions is presented.The jurisdictions that are included are Sweden, Great Britain,France, Ireland, United States (PJM), Finland, Portugal, SpainNorway and Denmark.
|
|
