Smart by necessity
Grids need to smarten up to meet the challenges of growing demand.
Electrical grids need to be upgraded into smart grids to meet the challenges of growing demand and the integration of renewable power. This will not be an easy task, says power and automation technologies company ABB.
Electrical power grids are critical infrastructures in all modern societies. However, many are aging and are stressed by operational scenarios and challenges never envisioned when the majority of the grids were developed many decades ago.
These grids now need to be transformed into smart grids in order to meet the challenges facing developed and developing countries alike, such as the growing demand for electric power, the need to increase efficiency in energy conversion, delivery, consumption, the provision of high quality power, and the integration of renewable resources for sustainable development.
The term smart grid has been frequently used in the last few years in the electric power industry to describe a digitised version of the present day power grid. Smart grids can be achieved through the application of existing and emerging technologies.
However, it will take time and many technical and non technical challenges, such as regulation, security, privacy and consumer rights need to be overcome.
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 (IEA) 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 digitalised 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 percent of all greenhouse gas effects and electric power generation is the largest single source of CO2 emissions.
Shockingly, more than 40 percent 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 (DR), 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 US 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, ie, 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, from the entire energy production cycle right through to delivery and utilisation, smart.
The most urgent technical challenges include:
- The economic buildup of grid capacity while minimising, as much as possible, its environmental impact.
- Increasing grid asset utilisation 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 optimising 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 utilisation.
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 (IED), 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.
These control directives, when executed by actuators, effect changes in the physical layer to modify the output from power plants and the flows on the grid.
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. The more the output of power plants, the power flow on transmission lines and the power- consumption level of consumers are controlled, the more efficient and reliable grid operation can be.
If, for example, the power flow control capability offered by flexible AC transmission system (FACTS) technology wasn’t available, an independent system operator (ISO) would not be able to relieve transmission congestions without resorting to less economical dispatch plans.
Or without the ability to control devices such as transformer tap changers or automatic switched capacitor banks, the industry will not even contemplate the development of voltage and var optimization control to reduce power loss.
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.
This article was written by Enrique Santacana, ABB president and CEO, Bazmi Husain and Friedrich Pinnekamp, from ABB Smart Grids, Per Halvarsson, from ABB Power Systems, Gary Rackliffe, ABB Power Products, as well as Le Tang and Xiaoming Feng from ABB Corporate Research.