Tom Hammons

Integrating Renewable Energy Sources into European Grids

This paper examines the integration of new sources of renewable energy into the power systems in Europe-challenges and possible solutions, application of wind power prediction tools for power system operation, new tasks that create new solutions for communication in distribution systems, wind power in Greece, integration of dispersed generation in Denmark, EdF and distributed energy resources in France, and new renewable sources in Italy, The paper also examines the European Commission Technology Platforms vision paper on Electricity Networks of the Future that was published in January 2006. In this respect, drivers towards smart grids, grids today, and key challenges for smart grids of the future are critically assessed

African electricity infrastructure interconnections and electricity exchanges

This paper discusses African electrical energy resources: feasibility studies, interconnection of power systems, the present state of the electric power sector, future expansion of African power systems, and implementation of an African power grid network. It examines involvement of the World Bank with African electricity infrastructure, Grand Inga interconnection projects, the Great Lakes project, and prospects for evaluation of a unified power system in Africa. First, the poorness of African countries and their limited electricity infrastructure is discussed. Objectives for electricity infrastructure development in response to perceived needs is examined and the development challenge for the future, with ways of meeting that challenge defined. Grand Inga interconnections projects are then reviewed. The Democratic Republic of Congos potential is equivalent to 88400 MW of continuous energy; 42000 MW is located in the Inga region. Development of the Great Lakes interconnected network which links Burundi, Rwanda and Democratic Republic of Congo is also reviewed. The paper discusses existing power systems in Africa and presents the idea of dividing the continent into five main regions of about the same surface area for electricity trade. Feasibility studies of an HVDC line from Democratic Republic of Congo to Egypt and other studies to South Africa and Europe are discussed. A scenario for energy balance for the 2050 is presented, and export of electricity to neighboring continents, mainly Europe, in excess of 200 TWh/year by 2050 is outlined. Implementation of an integrated African grid network is discussed.

Geothermal power generation worldwide

This paper discusses the state of art in harnessing geothermal power for medium- and large-scale generation of electricity (and for space heating) worldwide. It reviews current, probable, possible and potential developments both in developed and developing countries in near future and long term. First, world energy consumption is reviewed. Then relative contribution of energy sources in the world in OECD countries with respect to renewables is discussed. The paper examines the salient technological aspects of geothermal power generation with geothermal energy in the United States and highlights heat flow, tectonic controls, types of geothermal systems, U.S. geothermal potential, geothermal energy in the United States, operation conditions for electricity generation, and environmental constraints. The central part of the paper goes on to review field experience with innovative geothermal plants considering geothermal power plant analysis and design (optimization in design of geothermal power plants, optimization of prime movers, heat cycle considerations, resource considerations), a review of experimental plants (proposed systems and tested systems), and innovative power plants in commercial operation (low enthalpy, moderate enthalpy, and high enthalpy resources) is discussed. The paper then examines R&D programs that are underway to significantly enhance the use of geothermal. Highlighted is typical research and development projects such as enhanced heat transfer in air-cooled condensers, materials research, instruments for real time monitoring of geothermal processes, plant optimization, removal of non-condensable gases from binary power plants, silica and metals extraction, and small-scale power plant field verification projects. Geothermal drilling R&D is also reviewed. The final part of the paper considers goals and objectives of improving geothermal power plants where potential impact of geothermal R & D is reviewed. Integration and connection of dispersed geothermal generation to the grid network is also discussed.

Notice of Violation of IEEE Publication Principles Dispersed generation and its impact in Europe on power system structure and secure power system operation

The paper discusses modern power system as a critical infrastructure. The expected insertion of distributed generation (DG) in the distribution networks entailed by environmental, regulation and economical aspects will modify the way the entire system is planned and operated. Due to its dispersed nature, DG will require a more flexible operated system. This situation will emerge through various applications and developments of distribution automation. In addition, DG has already showed some impacts on system security. Active user participation in energy markets through activation of distributed energy resources is considered, as is distributed generation towards an effective contribution to power system security and communication requirements and solutions for secure power system operation. Increase of the contribution of dispersed and renewable energy resources (D&RES) in the peak power balance up to 60% in accordance with goals of the European Communities for the year 2010 requires innovative approaches to keep security of the power supply at the current high level.

African regional power pools: status, plans of action, further development and recommendations

Historically electricity trading in Southern Africa started in the early 1960 as bilateral trade after the commissioning of the Kariba Hydro Power Station situated on the border between Zambia and Zimbabwe. The great hydro potential of the Zambezi River gave rise to the commissioning of more plants. This saw the extension and more bilateral electricity trading arrangements being put in place. The Southern African Power Pool (SAPP) was created in April 1995 through the SADC treaty to optimize the use of available energy resources in the region and support one another during emergencies. At the time of creation, the SADC governments agreed to allow their national power utilities to enter into the necessary agreements that regulate the establishment and operation of the SAPP. The past, the present and the future of SAPP would be addressed in this paper. SAPP is transforming from a cooperative into a competitive pool.

Turbine, generator, system modeling and impact of variable-frequency ripple currents on torsional stressing of generators in Poland and Sweden: Lithuania/Poland and Sweden/Poland HVDC links

This paper analyzes rectifier ripple current superimposed on the direct current of a 600 MW asynchronous bipolar link between Lithuania and Poland and a 600 MW asynchronous monopolar link between Poland and Sweden in evaluating possible torsional vibrations in steam turbine-generator-exciter shafts. The studies are performed for machines in Northeastern Poland and in Southern Sweden close to the inverter station which are most at risk. Analyses are performed for the generators in Poland for the Lithuania/Poland link and for the generators in Sweden for the Poland/Sweden link. The paper examines system scaling factors for the Lithuania/Poland Link. It then examines AC system scaling factors and generator scaling factors for modulation product harmonic currents impressed on generators connected to the Swedish Grid Network by the inverter. Amplitude of shaft torsional torque due to resonant excitation imposed by the link on the generators in Sweden is evaluated for different scenarios of system and generator load. First, theory which relates magnitude of harmonic AC current injected into the AC system by the inverter is summarized. Dispersion of the injected harmonic AC current to proportion the current to individual generators is then reviewed, considering impedance of the generators, loads, and other system elements. Significance of simple and detailed shaft train models of machine shafts as well as approximate (Id, Iq) and detailed (2d, 3q) generator damper models on resonant torques is reviewed. Then, effects of both power factor and generator load on generator scaling factors is illustrated.

Tidal Power in the United Kingdom

This paper discusses the role of tidal power in the UK in fulfilling the UKpsilas requirements for reducing greenhouse gas emissions. Generating electricity from tidal range of the Severn Estuary has the potential to generate some 5% of UK electricity from a renewable indigenous resource. A study is underway to: (1) assess in broad terms the costs, benefits and impact of a project to generate power from the tidal range of the Severn Estuary, including environmental, social, regional, economic, and energy market impacts; (2) identify a single preferred tidal range project (which may be a single technology/location or a combination of these) from the number of options that have been proposed; (3) consider what measures the government could put in place to bring forward a project that fulfils regulatory requirements, and the steps that are necessary to achieve this; and (4) decide, in the context of the governmentpsilas energy and climate change goals and the alternative options for achieving these, and after public consultation, whether the government could support a tidal power project in the Severn Estuary and on what terms. The study is expected to last roughly two years (until January 2010). Under consideration is tidal range, including barrages, lagoons and other technologies, and includes a strategic environmental assessment of plans for generating electricity from the Severn Estuary tidal range to ensure a detailed understanding of its environmental resource recognising the nature conservation significance of the Estuary. The scheme would use proven technology of a hydroelectric dam but filled by the incoming tide rather than by water flowing downstream. The Severn Estuary has some of the best tidal potential in the world and could more than double the current UK supply of renewable electricity and contribute significantly to targets for renewable energy and CO2 emissions reduction. The scheme would have a capacity of 8640 MW and produce roughly 17 TWhrs/year with a load factor of 0.22.

Panel session: Part A Europe: Status of integrating renewable electricity production into the grids (Panel Session Paper 291-0)

1. Bernd Michael Buchholz, Vice President, Siemens AG, Erlangen, Germany and Yvonne Saßnick, Vattenfall Europe Transmission GmbH, Berlin, Germany. The German Experience of the grid integration of renewable energy sources 2. Nikos Hatziargyriou, National Technical University of Athens, Athens, Greece; I Skotinos, National Technical University of Athens, Athens, Greece; and A. Tsikalakis, National Technical University of Athens, Athens, Greece. Status of Integrating Renewable Electricity Production in Greece: Prospects and Problems. 3. John Olav Tande, SINTEF Energy Research, Trondheim, Norway. Options for Large Scale Integration of Wind Power 4. Joao A. Peças Lopes, INESC Porto and Faculty of Engineering, Porto University, Portugal. Technical and Commercial Impacts of the Integration of Wind Power in the Portuguese System having in mind the Iberian Electricity Market. 5. Juan Manuel Rodríguez García, Fernando Soto Martos, David Alvira Baeza; Red Eléctrica de España., Madrid, Spain; and Susana Bañares, Red Eléctrica Internacional., Madrid, Spain.. The Spanish Experience of the grid integration of wind energy sources 6. D. Barry, ESB National Grid, Dublin, Ireland; and P. Smith, ESB National Grid, Dublin, Ireland.. Analysis of the Integration of Wind Generation into the Irish System

International practices in distributed generation

Distributed generation (DG) is related with the use of small generating units installed at strategic points of the electric power system or locations close to load centers. DG can be used in an isolated way, supplying the consumers local demand, or integrated into the grid supplying energy to the electrical power system. Distributed generation can run on renewable energy resources, fossil fuels or waste heat. Equipment ranges in size from less than a kilowatt (kW) to tens of megawatts (MW). Distributed generation can meet all or part of a customers power needs. If connected to a distribution or transmission system, power can be sold to the utility or a third party. DG and renewable energy sources (RES) have attracted a lot of attention worldwide. Both are considered to be important in improving the security of energy supplies by decreasing the dependency on imported fossil fuels and in reducing the emissions of greenhouse gases (GHGs). The viability of DG and RES depends largely on regulations and stimulation measures that are a matter of political decisions.

Europe: Impact of Dispersed Generation on Power System Structure and Secure Power System Operation

The power system is a critical infrastructure for which its secure operation has a decisive influence on the development of industrial nations. Changes in structure of primary energy resources will also modify the structure and operation of the power system in order to fulfill the high requirements of the infrastructure. In this context, a vision sees the power system of the future consisting of a number of self-balancing distribution network areas. In each of these areas a significant share of power demand will be covered by renewable and CHP generation. However, the power balance of these areas should be plan-able and dispatch-able in such a way that import or export of power from or into the higher-level network has to follow a schedule that can be predicted in advance with a high level of accuracy.