Sustainable Energy and Smart Grids: Breakthrough in Thinking, Modelling, and Technology

In the last few years the steady growth of distributed generation and the expected higher penetration of renewable energy sources, together with policies on electricity distribution supporting the need for a "smarter grid", have begun to change the structure of the sector. It is within this context that the concept of smart grids has surfaced and certain significant technological developments are taking place.

In the near future, electric energy supply systems will change further. It is likely that large-scale power plants will be complemented by a large number of small-scale energy generation units. Among other suppliers, individual households will generate solar or wind energy. Intelligent systems will be used to communicate, control, protect and balance the supply and demand of energy more comprehensively. The whole system of central and local energy generation, transmission and distribution, enabling intelligent control and information systems, is called a smart grid. Smart grids will integrate micro grids (local systems) and super grids (high-voltage transmission and bulk generation systems).

Figure 7 illustrates the new concept of smart grids and the functional relationship among the different subsystems and technologies. The bulk generation, transmission and distribution to customers are directly and electrically connected and are themselves linked via communication systems with the Markets, Operations and Service Providers.

Figure 7. Concept of smart grids that involve integral sustainable energy sources (CHPis combined heat and power generation)

The ultimate goal is to create not just a smart grid but a smarter one. By applying technologies, tools and techniques currently available, as well as those under development, the goal is to make the grid work more efficiently by ensuring its reliability to degrees not possible before, while maintaining its affordability. It would reinforce global competitiveness, while accommodating renewable and traditional energy sources and potentially reducing our carbon footprint. But it requires introducing advancements and efficiencies that are yet to be envisioned.

The grid of the future, according to the US Department of Energy (LSC, 2010), needs to satisfy the requirements of being more reliable, more secure,more economical, more efficient, friendlier to the environment and safer. To realize this from an architectural perspective, the grid needs to have the following attributes: an evolved energy supply mix, enhancements of the trans- mission grid, the co-existence of many grid configurations and the activation of the end-user as producer. These can be realized by further advancements in enabling technologies and control methods.

In addition, the following aspects on the supply side, demand and systems design should be considered. On the supply side, there needs to be a higher penetration of renewable resources, improvements in energy storage and balancing and the integration of isolated 'islands' with renewable energy grids. On the demand side, utility control systems need to respond to local demand with aggregated local energy storage and the use of privately-owned energy storage, and to transport this energy efficiently. Managing supply and demand in these ways requires an architecture of complex autonomous adaptive systems with effective cyber security.

The architectural concepts depend on a number of new functionalities that will be supported by future technologies that include power electronics, communications and computer science disciplines. In their fields of research new and detailed definitions need to be developed for cyber security and systems engineering, as well as for enabling functions, such as communications networks, visualization and data management, and markets and economics. Performance will be monitored by new operations and control systems, as well as by planning, analysis and simulations.

Besides the physical components, the technological and computational concepts will involve a new distributed systems architecture, which connects the world of people, devices and systems. This requires new approaches in self-integrating systems, multi-agent systems, virtual computing architectures, and the messaging-oriented middle (software or hardware infrastructure for distributed systems).

The computational aspects will also involve the development of new computer applications to address smart grid areas. This includes control systems that respond to the market, tools that monitor and control as well as model and simulate. Such systems will carry out signal processing, protection, performance monitoring, state estimation, contingency analysis, stochastic analysis, and prognostics and asset management. Advancements in many areas of computer science are still needed to make smart grids a reality, including the information science for visualization, artificial intelligence, data analytics, high-performance computing, internet for real-time systems. Finally, these systems require high levels of cyber security technology to reduce damage from potential attacks, and to protect the integrity and privacy of information.