FEATURE RENEWABLE ENERGY Linking intelligent power networks
The Energy Department of the AIT Austrian Institute of Technology is working on the future of energy supply by developing automation concepts for intelligent power distribution in smart grids. As these feature varied distributed architectures, IEC 61499 compliant open source control system approaches are considered to be best suited to the task. Powerlink is therefore becoming a real-time data communication standard over Ethernet in smart grid applications
A
s fossil energy sources are dwindling and their combustion has been
producing issues such as global warming, the future of the world’s energy supply depends on our ability to include renewable sources. Some of these, particularly photovoltaic converters and wind farms, are subject to changeable natural forces, thus supplying electricity with less regularity than more traditional forms of generation. Consequently, more and better means of storing energy will be required. Additionally, facilities such as buildings will not only become more energy efficient, some of them will require energy supplies at certain times while supplying electricity at others.
SMART GRIDS A NECESSITY This multi-faceted power generation and consumption model is contrasting with the straightforward traditional approach featuring one big supplier and a multitude of smallish consumers. It therefore requires distribution networks that are different from the existing lines in that they need to be able to allow energy to flow in various directions. This requires smart grids with the ability to react to information acquired from and exchanged with electricity sources, storage facilities and loads. Challenges on a continental scale such
as the development of smart grids cannot be addressed locally, so the European Union has launched the European Electricity Grid Initiative (EEGI) within the Strategic Energy Technology (SET) Plan. The initiative’s activities are coordinated by the energy department of the AIT (Austrian Institute of Technology), which is also supplying smart grid expertise to the International Smart Grid Action Network (ISGAN) and the European Energy Research Alliance (EERA).
14 MAY 2015 | AUTOMATION
Future energy supply will heavily depend on the ability of power grids to accommodate power generated from renewable sources. This will require smart grids
“As IT-based energy distribution control implementations need to interact with existing local systems, proprietary communication protocols are out of the question,” says Dr. Thomas Strasser, senior scientist in charge of the lab automation
Filip Andrén MSc, in charge of Implementation: “Powerlink is the only Industrial Ethernet protocol to fulfil our requirements in terms of topology independence, capability of direct cross communication and the availability in open source”
OPEN STANDARD IS IMPERATIVE “One of the challenges we are facing is the heterogeneous hardware structure of power grids”, says Dr. Thomas Strasser. Since the end of 2010, the scientist with a background in mechanical engineering has been managing a project towards the installation of a universal laboratory- scale test and simulation environment for power distribution algorithms as well as smart grid components and systems. Upon completion later this year, this laboratory will be used to verify and optimise implementations of power distribution strategies through all stages of development from full simulation through hardware in the loop emulation to ported systems. “As IT-based energy distribution control implementations need to interact with existing local systems and require stability as well as adaptability over lengthy periods, proprietary control mechanisms and communication protocols are out of the question. Open solutions such as Powerlink will be the choice for our communication backbone,” says Strasser. The strategies for IT-based energy distribution systems followed by the scientists in Vienna is based on the international IEC 61499 standard. Aiming at the creation of hardware-independent, portable control applications, it defines a universally valid model for distributed control systems, replacing the cyclic execution model of older standards by an event-triggered version using an object- oriented approach with function blocks. As the leading system, they have been implementing the engineering and runtime environments of 4DIAC (Framework for Distributed Industrial Automation & Control), an open source control system for distributed applications.
TOPOLOGY-INDEPENDENT For the communication between control CPUs and remote input and output units in decentralised architectures, a fast and versatile protocol is required.
“We were looking at an Industrial version of Ethernet, because we expect this wide- spread standard to be around for quite some time”, says Filip Andrén MSc, The electrical and automation engineer in charge of implementation. “Major considerations for us were full independence from topologic restrictions, capability of direct cross communication and the availability in open source. Another was the requirement for the real- time protocol to operate on out-of-the shelf Ethernet hardware,” he continues. Surveying the competing protocols used
in industrial applications, the scientists found that only one system fulfilled all of these requirements. “Most of the Industrial Ethernet systems are not available as open source at all,” says Strasser. “Powerlink is the only one of which not only open source implementations have been published, but which is available under a BSD3 (Berkeley Software Distribution) license, which leaves system architects totally unrestricted while protecting their application knowledge.”
SMART GRID STANDARD Powerlink is not only future-proof due to its openness, it is also suitable for communication with remote input and output units in decentralised control architectures such as 4DIAC. By simply introducing object classes for Master and Slave nodes and for the conversions between time and event dependent processes, Andrén and Strasser achieved full integration with the open control system in compliance with IEC 61499. Using Service Interface Function Blocks (SIFBs) for communication over Powerlink, the scientists created a communication environment that is easily adaptable to various hardware without requiring modification of the software itself.
B&R Industrial Automation
www.br-automation.com T: 01733 371320
Enter 205 /AUTOMATION
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