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Ndreko M.,Technical University of Delft | Popov M.,Technical University of Delft | van der Meijden M.A.M.M.,Technical University of Delft | van der Meijden M.A.M.M.,TenneT TSO bv
International Journal of Electrical Power and Energy Systems | Year: 2017

In this paper three new control modules are introduced for offshore wind power plants with VSC-HVDC transmission. The goal is to enhance the Fault Ride Thought (FRT) capability of the HVDC system and the connected offshore wind power plant during balanced and unbalanced AC faults. Firstly, a positive-sequence-voltage-dependent (PSVD) active current reduction control loop is introduced to the offshore wind turbines. The method enhances the performance of the offshore AC voltage drop FRT compliance strategy. Secondly, an adaptive current limiting control strategy which operates simultaneously on the positive and the negative sequence current is discussed. It enables negative sequence current injection, while at the same time respecting the maximum fault current capacity of the HVDC converter station. Finally, a state machine is proposed for the VSC-HVDC system and for the offshore wind turbines respectively. It coordinates the fault and the post-fault response during balanced as well as unbalanced faults, ensuring a smooth shift from the normal operating point towards the fault and the post-fault period. The test system consists of a two level VSC-HVDC link, rated at ±250 kV, connecting an offshore wind power plant with 700 MW generation capacity. Simulation results with a detailed EMT type model in PSCAD/EMTDC environment are presented. © 2016 Elsevier Ltd

Steiner A.,German Weather Service | Kohler C.,German Weather Service | Metzinger I.,German Weather Service | Braun A.,Fraunhofer Institute For Windenergie Und Energiesystemtechnik | And 4 more authors.
Renewable Energy | Year: 2017

A constantly increasing share of weather dependent renewable energies in Germany's power mix poses new challenges concerning grid management and security of energy supply. An evaluation of the three year period from 2012 to 2014 reveals, that 60% of days with largest errors in the day-ahead wind power forecasts for Germany are linked to cyclones and troughs traversing the North Sea, the Baltic Sea or Germany. A cyclone detection algorithm has been developed to automatically indicate these critical weather situations. The algorithm is based on Numerical Weather Prediction model forecasts of mean sea level pressure. The cyclone detection is used to design an automated weather information tool for end-users such as Transmission System Operators (TSOs). For 2014, it identified a critical weather development in 38% of all days. The root mean square error of day-ahead wind power forecasts increased by 1% of installed capacity during these periods. A real time application of the tool is being implemented in order to support a sustainable and save integration of the increasing wind power production. It will then be provided to, and will be tested by, three German TSOs with the purpose of an operative usage to guarantee the security of supply. © 2016 The Authors

Agency: European Commission | Branch: H2020 | Program: RIA | Phase: LCE-06-2015 | Award Amount: 17.86M | Year: 2016

By 2020, several areas of the HVAC pan-European transmission system will be operated with extremely high penetrations of Power Electronics(PE)-interfaced generators, thus becoming the only generating units for some periods of the day or of the year due to renewable (wind, solar) electricity. This will result in i) growing dynamic stability issues for the power system (possibly a new major barrier against future renewable penetration), ii) the necessity to upgrade existing protection schemes and iii) measures to mitigate the resulting degradation of power quality due to harmonics propagation. European TSOs from Estonia, Finland, France, Germany, Iceland, Ireland, Italy, Netherlands, Slovenia, Spain and UK have joined to address such challenges with manufacturers (Alstom, Enercon, Schneider Electric) and universities/research centres. They propose innovative solutions to progressively adjust the HVAC system operations. Firstly, a replicable methodology is developed for appraising the distance of any EU 28 control zone to instability due to PE proliferation and for monitoring it in real time, along with a portfolio of incremental improvements of existing technologies (the tuning of controllers, a pilot test of wide-area control techniques and the upgrading of protection devices with impacts on the present grid codes). Next, innovative power system control laws are designed to cope with the lack of synchronous machines. Numerical simulations and laboratory tests deliver promising control solutions together with recommendations for new PE grid connection rules and the development of a novel protection technology and mitigation of the foreseen power quality disturbances. Technology and economic impacts of such innovations are quantified together with barriers to be overcome in order to recommend future deployment scenarios. Dissemination activities support the deployment schemes of the project outputs based on knowledge sharing among targeted stakeholders at EC level.

Agency: European Commission | Branch: H2020 | Program: IA | Phase: LCE-05-2015 | Award Amount: 51.69M | Year: 2016

In order to unlock the full potential of Europes offshore resources, network infrastructure is urgently required, linking off-shore wind parks and on-shore grids in different countries. HVDC technology is envisaged but the deployment of meshed HVDC offshore grids is currently hindered by the high cost of converter technology, lack of experience with protection systems and fault clearance components and immature international regulations and financial instruments. PROMOTioN will overcome these barriers by development and demonstration of three key technologies, a regulatory and financial framework and an offshore grid deployment plan for 2020 and beyond. A first key technology is presented by Diode Rectifier offshore converter. This concept is ground breaking as it challenges the need for complex, bulky and expensive converters, reducing significantly investment and maintenance cost and increasing availability. A fully rated compact diode rectifier converter will be connected to an existing wind farm. The second key technology is an HVDC grid protection system which will be developed and demonstrated utilising multi-vendor methods within the full scale Multi-Terminal Test Environment. The multi-vendor approach will allow DC grid protection to become a plug-and-play solution. The third technology pathway will first time demonstrate performance of existing HVDC circuit breaker prototypes to provide confidence and demonstrate technology readiness of this crucial network component. The additional pathway will develop the international regulatory and financial framework, essential for funding, deployment and operation of meshed offshore HVDC grids. With 35 partners PROMOTioN is ambitious in its scope and advances crucial HVDC grid technologies from medium to high TRL. Consortium includes all major HVDC and wind turbine manufacturers, TSOs linked to the North Sea, offshore wind developers, leading academia and consulting companies.

The European electricity system is facing major challenges to implement a strategy for a reliable, competitive and sustainable electricity supply. The development and the renewal of the transmission infrastructure are central and recognised issues in this strategy. Indeed the transmission system is a complex and strongly interconnected infrastructure that offers a wide range of benefits like reliability improvement, promotion of competitive electricity markets and of economic growth, support for development of new generation and for exploitation of renewable resources. Within this context, the objective of REALISEGRID is to develop a set of criteria, metrics, methods and tools (hereinafter called framework) to assess how the transmission infrastructure should be optimally developed to support the achievement of a reliable, competitive and sustainable electricity supply in the European Union (EU). The project encompasses three main activity-packages: 1) identification of performances and costs of novel technologies aimed at increasing capacity, reliability and flexibility of the transmission infrastructure; 2) definition of long term scenarios for the EU power sector, characterized by different evolutions of demand and supply; 3) implementation of a framework to facilitate harmonisation of pan-European approaches to electricity infrastructure evolution and to evaluate the overall benefits of transmission expansion investments. The expected output of the project is fourfold: - Implementation of the framework to assess the benefits provided by transmission infrastructure development to the pan-European power system. - Preparation of a roadmap for the incorporation of new transmission technologies in the electricity networks. - Analysis of impacts of different scenarios on future electricity exchanges among European countries. - Testing and application of the framework for the cost-benefit analysis of specific transmission projects.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2009.7.1.1 | Award Amount: 56.70M | Year: 2010

A group of 6 Transmission System Operators (Belgium, Denmark, France, Germany The Netherlands and Spain) with 2 generator companies, 5 manufacturers and research organisations, propose 6 demonstration projects to remove, in 3 years, several barriers which prevent the electric system from welcoming more wind electricity, and wind electricity from contributing more to the electric system. The full scale demonstrations aim at proving the benefits of novel technologies (most of them available from manufacturers) coupled with innovative system management approaches. The contribution of wind energy to the system will show how aggregated wind farms can provide system services (voltage and frequency control) in Spain. The aggregation of wind farms with flexible generation and loads will be demonstrated in Denmark using a scalable IT platform developed by a generator. Increasing the flexibility of transmission networks will be tested in Belgium (existing sensors and coordinated power flow control devices avoiding possible large scale instabilities induced by wind farms in the CWE region) and in Spain (dynamic wind power evacuation capacity using real-time computations based on short-term generation forecasts and use of a mobile Overload Line Controller). Off-shore wind farms are addressed from a security viewpoint. Secure HVDC meshed networks will be validated in France using simulations and full scale experiments of two different HVDC circuit breaker technologies. Off-shore wind farm shut downs under stormy conditions will be demonstrated in Denmark using the world largest off-shore wind farm with balancing power provided by the Norwegian hydro capacities through a HVDC link. The experimental results will be integrated into European impact analyses to show the scalability of the solutions: routes for replication will be provided with benefits for the pan European transmission network and the European electricity market as soon as 2014, in line with the SET plan objectives.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2011.7.2-1 | Award Amount: 5.25M | Year: 2012

The growing share of electricity generation from intermittent renewable energy sources as well as increasing market-based cross border flows and related physical flows are leading to rising uncertainties in transmission network operation. In the mainland central Europe synchronous area due to large installations of renewable energy generation such as wind and photovoltaic, the difference between actual physical flows and the market exchanges can be very substantial. Remedial actions were identified by previous smart grid studies within the 6th European framework program in operational risk assessment, flow control and operational flexibility measures for this area. At the same time an efficient and sustainable electricity system requires an efficient usage of existing and future transmission capacities to provide a maximum of transportation possibilities. New interconnections and devices for load flow control will be integrated in future transmission networks and will offer new operational options. Further developments of coordinated grid security tools are one of the major challenges TSOs will face in future. The methods to be applied have to take into account all technological measures to enhance flexibility of power system operations. The zonal structure of the European energy market along with the legal responsibilities of TSOs for different system areas will continue to pose increasingly complex requirements to the system operators concerning the quality and accuracy of cooperation. The proposed UMBRELLA research and demonstration project is designed for coping with these challenging issues and boundary conditions. The toolbox to be developed will enable TSOs to ensure secure grid operation also in future electricity networks with high penetration of intermittent renewables. It enables TSOs to act in a coordinated European target system where regional strategies converge to ensure the best possible use of the European electricity infrastructure.

Fadriansyah T.,TenneT TSO bv | Strous T.D.,Huisman | Polinder H.,Technical University of Delft
Proceedings - 2012 20th International Conference on Electrical Machines, ICEM 2012 | Year: 2012

A prototype generator for application in hybrid electric vehicles has been developed. This generator has a fractional-slot concentrated winding and a surface mounted permanent magnet (SMPM) rotor. The magnets are laminated in the axial direction to reduce the eddy current losses and to prevent excessive heating of the magnets. However, lamination of the magnets increases the production cost of the generator. To reduce production cost the relation between magnet lamination thickness (and consequently the number of magnet laminations) and rotor losses is investigated. To optimize a generator design for cost, the number of laminations should be low, while losses in the magnets should not overheat the magnets. Investigating the effect of axial lamination of the magnets on the eddy current losses requires a 3D FEM simulation, which is time consuming. To overcome this problem, a 2D FEM model is used where a correction factor is implemented. The correction factor is used to include the end effects in the magnets, which are neglected in a 2D model. These end effects can not be neglected because of the low ratio of magnet length to magnet width. With this method, the magnet losses are calculated for a number of magnet laminations, with different lamination widths in the axial direction. The calculation results are validated by using a 3D FEM time harmonics simulation. © 2012 IEEE.

Ciupuliga A.R.,Technical University of Delft | Gibescu M.,Technical University of Delft | Pelgrum E.,TenneT TSO bv | Jacobs P.G.H.,TenneT TSO bv | And 2 more authors.
IEEE Transactions on Sustainable Energy | Year: 2012

The ongoing liberalization process together with the growing penetration of renewable energy sources (RES), e.g., wind power, require an internationally oriented transmission planning approach that considers the increased uncertainties in terms of trade, location of generation, and output of intermittent generation. This paper identifies and ranks bottlenecks, which is the first step of the transmission planning process for interconnected high-voltage grids. A round-the-year approach is proposed by combining market simulations with static security analysis. Many combinations of load and generation (including RES) are created and analyzed, using unit dispatch based on cost optimization. For each combination, the branch loadings are determined for normal and contingency situations. A statistical risk-based approach for ranking the most severe bottlenecks is developed. The method is illustrated on a modified New England test system where wind power was added at several buses. The risk of overload versus amount of installed wind power is also assessed. © 2010 IEEE.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ICT-2009.6.3 | Award Amount: 3.39M | Year: 2010

The EU electric power system experiences a fundamental change in the quasi-monopolistic, top-down oriented, stable, and reasonable predictable arrangements of the past. It now spans continents, has hundreds of millions consumers and hundreds of thousands of producers, from nuclear power plants to privately-owned and operated badly predictable renewables such as solar cells, wind and microturbines and operates in an increasingly liberalized market. These developments pose huge challenges for its reliable and economic operation. This proposal focuses on the real-time power imbalance in the power net, which arises as a consequence of errors in the prediction of both production and demand. As this power imbalance will increase both in size and in frequency, presents arrangements to cope with this imbalance are no longer valid. They are neither reliable nor economic anymore. This project proposes an advanced ICT and control framework for ancillary services (reserve capacity) which allows a more intelligent solution by giving consumers and producers clear, real-time financial incentives to adapt their consumption/production according to the actual needs of the power system. This design is based on a distributed control structure, enabled by a fast ICT infrastructure and advanced control theory to reliably and economically deal with the necessary ancillary services. Decisions by consumers, producers, power exchanges and TSOs can be taken locally, based on local or national preferences and regulation. Still, the embedded incentives of the proposed framework can guarantee that all these local decisions together contribute to the global objectives of the EE power net: a reliable electric energy supply at the lowest costs.\nInstead of investing in additional expensive and environment-unfriendly reserve production or storage facilities with a low utilization rate, the reliability and economy are enforced by intelligent ICT and control.

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