Networks for IEC61499 compliant smart grids
Intelligent power distribution. smart grids are being developed featuring heterogeneous, distributed architectures, for which IEC 61499 compliant open source control systems are ideal.
MODERN MULTI-FACETED power generation and consumption models demand energy flows in various directions. This requires smart grids, so the EU has launched the European Electricity Grid Initiative (EEGI) within the Strategic Energy Technology (SET) Plan. Activities are being co-ordinated by the energy department of the AIT (Austrian Institute of Technology).
Open is imperative
ˇ°One challenge is the heterogeneous hardware structure of power gridsˇ±, says Dr. Thomas Strasser, senior scientist in charge of lab automation. ˇ°As IT-based energy distribution control implementations must interact with existing local systems and need stability as well as adaptability over lengthy periods, so open solutions must be used for the communication backbone.
Implementation strategies for IT-based energy distribution systems are based on IEC 61499, which defines a universally valid model for DCS, replacing the cyclic execution model of older standards by an event-triggered version using an object-oriented approach with function blocks. The scientists have been implementing the engineering and runtime environments of 4DIAC (Framework for Distributed Industrial Automation & Control), an open source control system for distributed applications as an IEC 61499 representation.
For communication between control CPUs and remote I/O units in decentralised architectures, a fast, versatile protocol is required. Says Filip Andr¨¦n MSc, the engineer in charge of implementation: ˇ°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.ˇ±
Surveying the competing industrial protocols, the scientists found that one system fulfilled all requirements. Says Strasser, ˇ°Powerlink is the only one for which not only have open source implementations been published, but it is also available under a BSD3 license, which leaves system architects unrestricted while protecting their application knowledge. ˇ°It is also an important asset that the EPSG possesses all relevant patentsˇ±, adds Filip Andr¨¦n. ˇ°So users are safe from legal threats.ˇ±
This protocol was also considered ideal for communication with remote I/Os in decentralised control architectures such as 4DIAC. By introducing object classes for master and slave nodes, and for the conversions between time and event dependent processes, full integration with the open control system in compliance with IEC 61499 was achieved.
Using Service Interface Function Blocks (SIFBs) for communication over Powerlink, a communication environment was created that is easily and quickly adaptable to a variety of hardware without software modification.
These SIFBs are soon to be published as open source implementations and will be incorporated in 4DIAC - the foundation for the MAS (Multi Agent System) Grid Project.
Article supplied by EPSG.