Let us begin with my understanding of what interoperability is.
Interoperability is defined in various fora but essentially describes the ease and ability with which different components of a networked system can communicate effectively with each other. A highly interoperable system is one where
- The different blocks or nodes of the system speak the same language between each pair and do not require translator devices to intermediate
- Common modeling and naming of the fundamental information that is to be exchanged across the system end-to-end is available. This may not be the same as the model and naming utilized by each communication link or protocol since different standards may be used at different levels. A system wide definition of model and naming can be significantly useful for interoperability to maintain a common anchor for each piece of information
- The blocks or nodes representing equipment can be easily sourced from multiple vendors without requiring significant rework of the system configuration
Incidentally, Â Â Interchangeability is a related concept which is even more difficult a goal to attain than Interoperability. A system that provides for interchangeability would ensure seamless integration of equipment from multiple vendors, effectively allowing drop-in replacement of different vendor equipment for any specified block in the system without requiring ANY rework of configuration. This is almost an impossible ideal at the current state of technology but specific initiatives are moving towards this goal so that a certain â€œdegree” of interchangeability can be achieved.
Next let us look into the various challenges the industry needs to surmount to achieve interoperability:
Technology Challenge – There are a plethora of technologies that promise various levels of performance, reliability, security, cost and ease of development. Broadly, these can be divided into the following segments of technology: RF / Wireless and PLC / Wired. Within these broad segments, there are multiple technologies complying with SDO standards, Industry User Group standards and Proprietary standards.
Standards Challenge – The multiple technologies and standards generally do not co-exist. The efforts by IEC and NIST/SGIP is towards trying to define or adopt interoperable standards or define interoperability to existing standards, so that they can co-exist
Regulatory and Policy Challenge – Smart Grid deployments are regulated primarily by two sets of agencies- the Electricity regulators and the telecommunication regulators. The fast pace of technology development, the multitude of technologies and options and the slow pace of regulation and policy in most countries always present a chicken and egg story for technology development and standards. Should standardization be born out of regulation or should standards be there to enable policy makers to regulate? Should technology development follow regulation and standards or standards follow technology and regulation? There is no right or wrong answer – but since technology evolves faster and regulation and standards are slow processes, this is a challenge each country and each utility will have to overcome.
Interoperable Last Mile Standards
To address the interoperability problem there are multiple on-going initiatives under various SDO’s and other Industry user groups. One of the key aspects of the initiative is the work of integrating multiple standards from different SDO’s and Industry user groups: IETF’s work on IPV6 for Low Power Personal Area networks, the adaptation layer for IPV6 between RF and PLC networks. Further, the work by IEEE on the 802.15.4 standard to make it interoperable at the PHY and MAC layer and expand adaptation to various country regulations on the spectrum availability has helped this effort greatly.
The above architecture defines an interoperable last mile standardization stack that integrates both the RF and the PLC technologies at the last mile and maps them through an IPV6 based standardization interface. Further mapping to the application standards from IEC for the Smart Grid enables this framework to be universally adopted for Smart Grid Last Mile and achieve Interoperability.
Last mile technology deployment is the most expensive investment in communication infrastructure for smart grid. It is hence important that the utilities and regulators promote an interoperable technology adoption at the last mile based on IPV6 and promoted by IETF / IEC and IEEE.