Dr Andrew Dodds, the director of group development at electric test equipment provider Megger, writes on having a déjà vu when discussing about industrial automation
To its proponents, IEC61850 spells out a unique and perfect path to the future of substation automation. Others, however, are not so sure that this heavily promoted standard will deliver on its promises.
When I’m involved in discussions surrounding IEC61850, I have a strong sense of déjà vu. I’ve seen before something like the story that’s now being played out around IEC61850 – with similar participants. In a previous career, I was involved with industrial automation and, in particular, with fieldbus systems.
FIELDBUS SYSTEMS
Common Fieldbus
Created for industrial applications, fieldbus systems are widely used to link together devices like sensors, actuators and programmable controllers of an automation system, replacing the parallel-wired control systems of the past. In other words, they do a job that in many ways is similar to that which networks based on IEC61850 are intended to do in substations.
In the early days, different manufacturers of industrial automation products produced their own proprietary fieldbus systems, but these were not readily interoperable. This is a situation that has been paralleled in the world of substations, as is the subsequent desire for standardisation. After all, standardisation allows products from different vendors to be freely mixed, providing interoperability of devices and increased choice which should drive down market prices.
Eventually in the world of industrial automation a new fieldbus standard – EN50170 – was developed. But has it delivered on its promises? That is debateable, as take up for the new technology proved to be very slow. The new standard was adopted by many industrial automation vendors; after all, no one wants to be left out of the club – or off the approved vendor list, once it was apparent that the collection of fieldbus solutions represented within EN50170 was becoming accepted by early end users, especially in Europe.
INTERNATIONAL STANDARD
So far so good, as the physical connectivity and the basic communication parameters of the networks had been taken care of. But what about the interoperability and openness of the control system and associated software that would make it possible to use EN50170 with real world devices? This was addressed through IEC1131 (later renumbered as IEC61131), which defined the international standard for programmable controllerprogramming languages that invariably formed the hub of fieldbus systems.
In practice almost every implementation of IEC1131, although based on the standard, has its own vendorspecific refinements and tweaks that provided value over and above the defined programming language. These are often explained away as being necessary to provide additional functionality, or to make the systems easier to use. Only a cynic would suggest that the primary purpose of some or even all of them is to preserve a proprietary stranglehold over users while paying lip service to the adoption of the standard.
Be that as it may, the end result is that many IEC113- compliant programmes are not equipped with the same software network which they are supposed to have. This means that they are certainly not interchangeable or portable to another control system – at least not without a lot of rewriting of the original code.
MAJOR HURDLES
The next major hurdles to be faced involve interoperability, guarantees, warranties and responsibility. If the system faced commissioning difficulties or failed later, where would the support come from? Who would be blamed and which of the two or more vendors involved would take responsibility? And what would be the position in relation to warranties?
Arguably, these issues slowed the implementation of open fieldbus solutions. Many plant owners who considered the risks in comparison to the cost-saving decided to remain with conventional parallel wired control systems, while others who could see the advantages of fieldbus solution moved to a single-vendor approach with guaranteed interoperability and defined responsibilities.
Anyone taking an interest in IEC61850 will be all too conscious of the many parallels with industrial automation fieldbuses. At present, for example, the networking elements of IEC61850 are well defined, as they were with EN50170. But the situation in relation to programming languages and software is far less satisfactory. Suppliers of substation IEDs appear to be enthusiastically adding vendor-specific parameters and functionality not covered by IEC61850 to their products, just as the vendors of the supposed IEC1131-compliant products had done.
Could this, along with warranty and guarantee issues, lead to a move toward singlevendor substation solutions, rather than toward the open multi-vendor scenario that is promoted as a key benefit of IEC61850? Unless these issues are addressed, implementation of IEC61850 will fall short of its original objectives. Let us suppose, however, that it does prove possible to implement multi-vendor protection schemes based on IEC61850. Who will then be responsible for issues relating to risk, compliance and the provision of warranties? And who is culpable when things go wrong?
There’s little doubt that those working on the IEC61850 standard are doing a sterling job on the technical front, and that they are devising innovative solutions to many of the problems involved in substation automation. Maybe, however, in an attempt to maximise future-proofing and flexibility, they are leaving just a few too many options open, creating opportunities for divisive vendor-specific functionality, as already discussed.
The proponents of IEC61850 are also vigorous – even strident – in its promotion. It has great potential, for sure, but it’s not ready yet for other than the most limited deployment. So, is the unremitting pressure for its adoption truly justified at the present time?
DIFFICULT ISSUES
Finally, returning to my earlier theme, it certainly seems that little if any work is being done on the ‘soft’ non-technical issues like warranties, divided responsibility and culpability in multi-vendor installations. These will most certainly be difficult issues to address, but addressed they must be if IEC61850 is ever to come anywhere close to delivering on its promises.
So is IEC61850 a panacea or a chimera? In truth, it’s still too early to offer a final answer. However, given that discussion of IEC61850 implementation often goes hand-in-hand with SMART grid considerations, we are guaranteed to hear about this subject area for many years, as long as the substation plant life expectancy, together with current low-investment levels, suggests we are tens of years away from the SMART integrated control of power systems.
If lessons are learnt from the problems that have afflicted the development and implementation of the industrial fieldbus standard, and if the ‘soft’ issues are fully addressed, then IEC61850 could smooth the path forward. If, however, these problems and issues continue to be overshadowed by the search for technical perfection, the value and future of IEC61850 are far less certain.
