The potential — and potential pitfalls — of the Smart Grid
The National Governors Association Convention in the United States in February 2009, the CEO of a major utility started his speech with the confession that he didn’t really know what the term Smart Grid meant. Shocking as it may seem, such a confession may have absolved many in the engineering community who secretly felt the same way.
The definition of a Smart Grid may vary depending on where you are in the world. In the United States, for example, the following attributes are commonly cited as being necessary to define a Smart Grid:
· It should be self-healing after power disturbance events
· It should enable active participation by consumers in demand response
· It should operate resiliently against physical and cyber attacks
· It should provide quality power to meet 21st century needs
· It should accommodate all generation and storage options
· It should enable new products, services and markets
· It should optimize asset utilization and operating efficiency
According to a European Commission report, a Smart Grid in Europe is described as one that is:
· Flexible: It should fulfill customers’ needs while responding to the changes and challenges ahead
· Accessible: Connection access to all network users should be possible. In particular the Smart Grid should be accessible to renewable power sources and high efficiency local generation with zero or low carbon emissions
· Reliable: This means the grid is secure and the quality of the supply is assured. It should be consistent with the demands of the digital age and resilient to hazards and uncertainties
· Economical: The best possible value is provided through innovation, efficient energy management and a level playing field in terms of competition and regulation.
China, one of the biggest power-hungry economies on the planet, is also developing the Smart Grid concept. According to a memo issued by the joint US-China cooperation on clean energy (JUCCCE) in December 2007, “the term Smart Grid refers to an electricity transmission and distribution system that incorporates elements of traditional and cutting-edge power engineering, sophisticated sensing and monitoring technology, information technology and communications to provide better grid performance and to support a wide range of additional services to consumers. A Smart Grid is not defined by what technologies it incorporates, but rather by what it can do.”
The need for Smart Grids
Electricity is the most versatile and widely used form of energy in the world. More than five billion people worldwide have access to electrical energy and this figure is set to increase. The level of electrical power consumption, reliability, and quality has been closely linked to the level of economic development of a country or region. According to an International Energy Agency forecast, the worldwide demand for electrical energy is growing twice as fast as the demand for primary energy, and the growth rate is highest in Asia. Meeting this rise in demand will mean adding a 1 GW power plant and all related infrastructure every week for the next 20 years.
At the same time, an increasingly digitalized society demands high power quality and reliability. Simply put, poor reliability can cause huge economic losses.
To illustrate this point, a Berkley National Laboratory report in 2005 stated that in the United States the annual cost of system disturbances is an estimated $80 billion, the bulk of which ($52 billion) is due to short momentary interruptions. In addition, the threat of terrorist attacks on either the physical or cyber assets of the grids also heightens the need for power grids that are more resilient and capable of self-healing.
The impact on the environment is another major concern. CO2 is responsible for 80% of all greenhouse gas effects and electric power generation is the largest single source of CO2 emissions. Shockingly, more than 40% of the CO2 emissions from power plants are produced by traditional power plants. To reduce this carbon footprint while satisfying the global need for increased electrical energy, renewable energy, demand response, efficiency and conservation will be needed.
However, the increasing penetration of renewable energy brings with it its own challenges; for example, not only is the uncertainty in the supply increased but the remote geographical locations of wind farms and solar energy sources stress existing infrastructures even more.
These new requirements can only be met by transforming existing grids, which, for the most part, were developed many decades ago and have been showing signs of aging under increased stress. The growing consensus and recognition among the industry and many national governments is that Smart Grid technology is the answer to these challenges.
This trend is evidenced by the appropriation – toward the end of 2009 – of more than $4 billion by the U.S. government in grants to fund research and development, demonstration, and the deployment of Smart Grid technology and the associated standards. The European union (EU) and China also announced major initiatives for Smart Grid technology research, demonstration and deployment in 2009.
Smart Grid challenges
The main challenges facing Smart Grids – doing more with less and improving efficiency, reliability, security and environmental sustainability, will depend on a combination of sensor, communication, information and control technologies to make the whole grid smart – from the entire energy production cycle right through to delivery and utilization, smart.
The most urgent technical challenges include:
· The economic buildup of grid capacity while minimizing, as much as possible, its environmental impact
· Increasing grid asset utilization with power flow control and management
· Managing and controlling power flow to reduce power loss and peak demand on both the transmission and distribution systems
· Connecting renewable energy resources from local and remote locations to the grid and managing intermittent generations
· Integrating and optimizing energy storage to reduce capacity demand on grids
· Integrating mobile loads, (for example, plug-in electrical vehicles) to reduce stress on the grid and to use them as resources
· Reducing the risk of blackouts; and when one has occurred, detecting and isolating any system disturbances and the quick restoration of service
· Managing consumer response to reduce stress on the grid and optimize asset utilization.
Smart Grid technology components
A Smart Grid consists of technologies, divided into four categories, that work together to provide Smart Grid functionalities. The bottom or physical layer is analogous to the muscles in a human body and it is where energy is converted, transmitted, stored, and consumed; the sensor and actuator layer corresponds to the sensory and motor nerves that perceive the environment and control the muscles; the communication layer corresponds to the nerves that transmit the perception and motor signals; and the decision-intelligence layer corresponds to the human brain.
The decision intelligence layer is made up of all the computer programs that run in a relay, an intelligent electronic device, a substation automation system, a control center or enterprise back office.
These programs process the information from the sensors or the communication and IT systems, and produce either the control directives or information to support business process decisions.
The importance of decision intelligence and the actuator system in Smart Grids cannot be overstated; without controllable grid components to change the state of the power grid to a more efficient and reliable one, all data collected and communicated will be of very limited value.
For the decision intelligence layer to work, data from the devices connected to the grid need to be transmitted to the controllers – most likely located in the utility control center – where it is processed before being communicated back to the devices in the form of control directives.
All of this is accomplished by the communication and IT layer, which reliably and securely transmits information to where it is needed on the grid. However, device-to-device (for example, controller-to-controller or IED-to-IED) communication is also common as some real-time functionality can only be achieved through inter-device communications.
Interoperability and security is essential to assure ubiquitous communication between systems of different media and topologies and to support plug-and-play for devices that can be automatically configured when they are connected to the grid.
Excerpted from an article in the The ABB Review.