Electric grids in most developed countries are engineered around centralized production from large hydropower installations, nuclear generators or combined heat-electric plants. These systems are designed for efficient production and distribution of electricity. Power generation is determined by projected demand, and when shortfalls occur reserve generators are brought online.
But the electricity we use in the future will need to come from a wide variety of sources. In many countries, private-sector companies and government agencies are making major investments in wind, solar and other renewable energy. This is positive for the environment, but may be setting the stage for future problems with electric grids. The old rules of energy production are not always valid, and new production resources are not as simple to monitor and project. Variations in wind speed and incoming solar radiation can dramatically affect production quality, and new technologies will be required to handle the new demands.
For example, electricity production may need to be shifted from a meteorologically calm region to one where strong winds are blowing—without overloading the network. Distributed production units can lead to electricity flowing in the “wrong direction.” And we can expect a future in which large numbers of electric cars will be charging from the grid. All this underlines the need for a smart, flexible electric grid.
”Smart grids” encompass a vision of how future electrical networks can be shaped in societies with many different energy sources. “A smart grid can receive electricity from different points in the network, directing both production and consumption,” says Karl Elfstadius, manager for ABB’s Smart Grid program. “It must be much more flexible than today’s networks.” In the European Union, “smart grid” is defined as “the new network, which can handle all types of users’ needs and simultaneously enable sustainable and secure electricity production.”
An important consideration in smart grids is that consumers must be able to cooperate with producers to adapt their consumption to actual production. One outcome of this is likely to be that industry and households will have to accept the need to reduce electrical consumption during peak load periods. That calls for smart controllers and electric meters.
It has become fairly common for homeowners to install solar panels or perhaps a small wind generator, and industry is showing an interest in self-generated electricity. The Swedish automaker Volvo, for instance, now has windmills in the parking lots of its assembly plant in Gent, Belgium. For some times of day or parts of the year, there may be excess electricity generated, which could be directed back into the network. The problem is establishing technical solutions that will allow electricity to flow upstream in the network while setting up charging systems so small generators are credited for their contributions. The smart distribution network allows electricity to flow in both directions, and the smart meter measures both incoming and outgoing current.
The Swedish-Swiss electrical engineering giant ABB has developed several key technologies within the framework of its Smart Grid program, and the company plans to be a major player in the emerging new field.
A smart grid might be based on a wind power park in which electricity is transferred via underground high-voltage DC lines to the fixed network. Technologies built into the network provide stability and reliability, while banks of batteries can provide extra power when required. The network is monitored by an advanced control system able to manage geographically distributed sources as well as variations in electrical production and consumption.
It must be possible to rapidly re-direct large amounts of energy and sometimes even change direction. For the system to perform properly, operations and consumption must be closely monitored in real time. The traditional once-a-month reading of the electric meter is inadequate; instead, two-way communication must be possible via the mobile phone network or the Internet. “Production and consumption must be in balance,” Elfstadius says.
Article published in August 2009