Power Connections
The most important benefits and challenges of interconnected electricity networks. By Dr. Alessandro Clerici & Elena Virkkala Nekhaev
social development, health, education and other aspects of contemporary society. Electricity can be transported from the generating plant to the final consumer over long distances using transmission lines, grid interconnections and distribution systems which provide ‘economies of scale’ for centralised electricity production. In the case of distributed generation, the consumer is usually close to the generating unit, be it solar panels or other technologies using mainly renewables. It has taken several centuries to develop electricity into its
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modern form and this development continues, as demand for electricity soares all over the world and new requirements, mainly related to efficiency or environment, are being introduced. Today, approximately 1.6 billion people – roughly one quarter of the world’s population– do not have access to electricity. Most of them live in rural areas of developing countries which are not connected to transmission networks. In the vast majority of countries,
ur modern society could not exist without a reliable, clean and affordable supply of electricity. Electricity is a basic requirement for economic and
planning; basic technical, economic, social environmental drivers and issues, in the European Union, CIS, South- North Mediterranean, Black Sea and the Caspian, Turkey, Middle East & the Gulf, Australia, North, Central and South America, East and South-East Asia, and Sub-Saharan Africa.
■ Markets, political, regulatory and legal aspects, business governance and models, economics, risks and finance, including security of supply and limits to the extension of interconnected systems and issues associated with interconnections of small countries into large grids, human resources, technical expertise and skills, roles and responsibilities of different stakeholders.
What is Interconnectivity, Why is it Important? The standard definition of an interconnection used to be
the electricity sector used to be owned and run by the state, and this is still the most common arrangement. The recent reshaping of the electricity sector started in the late 1980s with privatisation and the introduction of market mechanisms in a number of major countries and regions. In many cases this involved the unbundling of generation from transmission and distribution networks, and has, nearly everywhere, exposed transmission ‘bottlenecks’ limiting the development of well-functioning markets. In terms of the electricity value chain, transmission on average accounts for less than 10-15% of the final cost paid by the end- user for each kWh. Today, however, transmission is becoming a key issue for the effective operation of liberalised markets and their further development. An integrated and adequate transmission infrastructure is of utmost importance for ensuring the delivery of the most competitively priced electricity to customers, both near and far from power generating facilities. In 2008 the World Energy Council launched a study on
interconnectivity to indentify and assess the most important benefits and challenges of interconnections. The study covered the majority of the related topics:1 ■ Main types of interconnections, including integrated grids, feeding of isolated low load areas, integration of renewables, CO2 impacts on competitiveness of various options.
■ The role of various technologies, including “smart transmission grids” and the interaction between different technologies.
■ Current status and trends around the world, including existing interconnections and those under construction or
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... transmission on average accounts for less than 10-15% of the final cost paid by the end-user for each kWh
“a line that connects two electrically separated transmission grids”. This term goes back to the last century when the first large grids were developed and then interconnected in order to create larger structures. Today, interconnection can also mean a line connecting two points on an interconnected grid. At present nearly all countries have an electricity grid and in many
cases, the national grids are connected to each other at some points, even if they are not synchronously operated. These interconnecting transmission lines are often used to share spinning reserve, support neighbouring grids in case of emergency, but sometimes also for electricity exchange. However, the main question is for what purpose has an
interconnection been established. Was it for: ■ Mutual operational help? ■ Electricity trading? ■ Load transmission?
Role of Technologies for Interconnections Interconnections perform a large variety of different
operations, such as bulk transmission over long distances, enhancement of transport capacity within strongly meshed networks, feeding of small loads in remote areas, connecting ‘smart transmission grids’, to name just a few. Therefore, all the present and future technologies (not only hardware) should be evaluated when designing new interconnections. In particular, considering various operational factors and the constantly growing constraints posed by environmental requirements, both AC and DC solutions are to be taken into account together with the technological developments/applications of key components/subsystems such as: ■ OHTL’s (overhead transmission lines). ■ Underground and undersea cables. ■ AC substations.
worldPower 2010
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