C-DAX is based on the Information-Centric Networking (ICN) concept where communication is centric to information (i.e., what) rather than the host locations (i.e., where). It uses a topic-based publish-subscribe engine that decouples the time and space of data producers and consumers. Decoupling of the communicating end hosts simplifies the configuration needs of multipoint-to-multipoint communications in a decentralized manner and provides inherent security protection by obscuring target hosts. Full mesh point-to-point communication is eliminated improving scalability and reducing needed bandwidth. C-DAX simplifies automatic reconfigurations and continuous data delivery in case of grid topology changes, e.g. due to faults or maintenance operations.
The figure on the right shows the basic publish subscribe concept:
- Publisher client: produces data, e.g. PMU data
- Subscriber client: consumes data, e.g. backend application of the DSO to perform real-time state estimation of the grid
- Broker: stores and forwards data
- Broker discovery service: tells publishers and subscribers what broker to use
The C-DAX architecture was developed based on this topic-based publish-subscribe concept and is shown above.
- Clients produce or consume topic data and provide access for smart grid applications to the C-DAX cloud (through an API).
- A Designated Node (DN) provides the first point of contact for the clients to the C-DAX cloud. There are DNs for publishers (PubDNs) and for subscribers (SubDNs).
- Data brokers (DBs) receive topic data from PubDNs and forward them to SubDNs. They can also cache topic data.
- The Resolver (RS) resolves topic names to DBs.
- The Security Server provides security-related functionalities to the C-DAX cloud, including authentication, authorization, and key distribution.
- Finally, the Monitoring & Management system is responsible for gathering, aggregating and forwarding monitored information in the C-DAX cloud, and managing the C-DAX network resources.
C-DAX is implemented as a software prototype guided by three realistic use cases, that is extensively tested and optimized. The C-DAX software is validated in multiple phases:
- Through modelling, simulation and mathematical analysis.
- Functional tests in a laboratory IT environment.
- Integrated in field equipment, deployed into real-time hardware in the loop emulation test bed.
- In the Alliander’s MS LiveLab.
This last validation will represent the main proof of the C-DAX applicability in a live electricity network with real world monitoring and control requirements.