Recently, the scarcity of natural resources and rapid increases in energy demands have been raised as worldwide problems; thus, it has become necessary to promote renewable energy generation as a means of energy conservation. As a result, power plants of renewable energies draw attentions such as solar power, wind power, geothermal power, and so on. They are expected not only from the viewpoint of energy demands but also environmental consciousness. However, controlling output power for renewable energy generation is difficult because energy output is subject to violent fluctuations, different from the traditional power source like thermal power, hydroelectric power, and atomic power. To address this issue, attention has been focused on the potential for Smart Grid to work efficiently in energy networks.
While there are various definitions for Smart Grid depending on literatures, a typical idea is to control the power grids by the information and communication technology (ICT) to improve the efficiency of the power grids. It also includes power plants of renewable energies to supplement the traditional power plants in many cases . Although it is preferable to include renewable energies from the viewpoint of energy demands problem, they cannot provide a stable energy as mentioned above. Therefore, information gathered and analyzed based on ICT is used to supply a stable energy in Smart Grid.
As another viewpoint of the energy demands and environmental consciousness, the electric vehicle (EV) is also drawing attention recently. EV is closely related to the Smart Grid. Each EV has a high-capacity battery, which is not only used as a vehicle but is also treated as a power resource that can charge and discharge energy as needed. This energy exchange is referred to as ‘Vehicle-to-Grid’ (V2G), which is expected to be used as a method of stable energy supply in the Smart Grid.
However, V2G power grids are different from traditional power grids that deliver electricity from power plants to users in a single direction. Power resources in V2G power grids are widely distributed within a given area, and electric transmission is bidirectional. In this case, meticulous control regulation to stabilize power flow is necessary, i.e., it is necessary to monitor the electric potential of each point on the grid, to exchange information through the network and to control the distribution of power sources. In such a case, the Smart Grid is the best platform for gathering and analyzing the information.
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(Author: Keiko Karaishi, Masato Oguchi