1. Introduction
Without standards it is almost impossible
for utilities to choose several suppliers within one IT infrastructure. When
using a proprietary protocol, a lot of custom-made, time-consuming and
expensive solutions, e.g. gateways, are usually necessary to build up a
multivendor communication environment. Therefore, the major reasons for setting
up protocol communication standards seem obvious: a) optimisation of cost per
unit; b) risk management; c) strategic reorientation of the utilities (a.o.
flexibility) and d) optimisation of costs of assets. The users are the ones who
benefit most from standardisation, but suppliers also see that standardisation
is beneficial to them.
The working groups in TC57 have worked
out several protocols in response to this need of utilities worldwide. An
overview is given in Figure 1.
2. 60870-5 series
The 60870-5 protocol series is based on
technology with limited performance and capacity. The costs of the
infrastructure and hardware, e.g. processors and memory, have decreased
tremendously and pose no restriction at the moment in the consideration to add
intelligent features and functionality. The cost reduction has given the
equipment more functionality and the opportunity to distribute the intelligence
of the telemetry system. Substation automation systems using IEC 60870-5 series
with built-in intelligence are the result. Therefore, these devices provide for
a lot of utilities a reasonable and sufficient solution with proven technology
and optimised price/quality ratio. Working Groups 10, 11 and 12 use the lessons
learned in the new IEC 61850, which is new future technology but not proven
technology yet. IEC 61850 seems another new protocol. However, it is not. It is
definitely a new way of Substation Automation that affects engineering,
maintenance, procedures and the utilities’ organisation and focuses on the
substation environment.
3. Will 61850 be used for telemetry?
IEC 61850 will not replace all other
protocols in use now. As figure 1 shows, it has a different application where
it is also dotted between control centre and substation level. It is developed
to create an open communication environment in substations on station and
process level, not for telecontrol and -monitoring. At the moment we expect it
will not be used for telecontrol and –monitoring, because the applications and
installed hardware (scada/EMS) do not support this.
A lot of utilities have started already
or will start to migrate from proprietary protocols to the serial TCS101/PCS103
or the TCS104. This is already a major operation in today’s hectic utility
environment. No unambiguous answer can be given to the question what protocol
is the best choice for you. It highly depends on your present situation, e.g.
what equipment is installed, is it obsolete or not yet? Do you have the time,
money and personnel available for replacement and new projects? What is
important is that your automation system is an open system in which devices are
interoperable or even interchangeable, independent of the supplier. Whatever
the open protocol you’ve chosen, TC57 will take care of the object mapping from
the 60870-5 series to IEC 61850. It is the next work to do on the agenda of
TC57. Don’t neglect the current IEC 870-5 series-based system but stick to an
open system because migrating from an open IEC 60870-5 series system is much
easier and more cost-effective. Meanwhile, it is important to think about and
possibly set up a migration strategy.
4. Who benefits from a standard?
Why use standards and who benefits from
them? It seems this question can easily be answered just by looking at a
parallel, a GSM mobile phone. What would a GSM phone cost if every country
within one continent used its own GSM standard? A supplier should be able to
manufacture a lot of GSM phones when exporting. And what about the user? He
will be very unhappy and frequently annoyed because for every country he needs
another phone or configuration. Who will bear the costs of all these extra
efforts? The user will, as always. The same situation, just as every
standardisation issue, applies to communication protocols. So, I dare to
conclude that the use of standard communication protocols is a very important
factor (and may be most important one) that leads to structural cost reduction,
maximised flexibility and risk management within the utility sector (see
paragraph 1). The following benefits for utilities and suppliers are derived
from this.
Utilities’ benefits are: a) open system
connectivity; b) supplier independence; c) more reliable products at optimised
costs; d) risk management and d) freely available knowledge and specifications.
Benefits for suppliers include: A) bigger
market/able to compete on price performance instead of technical details only;
B) lower costs of installation and maintenance; C) more cost-effective project
implementation because of learning curve; D) fewer proprietary protocols to
maintain and E) freely available knowledge and specifications.
The answer is no. Why not? There are four
major reasons: 1) the standard defines 90%, 10% is optional; there are some
options freely to choose because of the widespread use of the standards (e.g.
address length, M_EI, command parameters, Quality descriptors); 2) partial
implementation is possible; not all the functions and asdu’s are implemented by
all suppliers; 3) user specifications are not defined (e.g. redundancy,
performance, configuration, addressing, et cetera); 4) the implemented protocol
may not be in conformance with the Standard or Protocol Implementation Document
(PID); because of the human interaction (e.g. programming bugs, interpretation
differences, et-cetera) verification for compliance is Highly recommended or
regarding our re-test statistics in fact unavoidable.
Using standard protocols has benefits,
but it has transferred responsibility for the interoperability of the
communication environment from supplier to utility. The standard gives the
utility the opportunity to define its own requirements based on standards,
instead of leaving this up to the different suppliers, as was the case when
proprietary protocols were used.
6. The structured project approach in 10 steps!
After analysing several ‘bad’ experiences
of utilities, our involvement in (research) projects and (type conformance)
testing, we are convinced that following the structured project approach is the
procedure to optimise utilities’ benefits from using standardised protocols:
1) Ask yourself as a utility: what information do I want to exchange
between locations A and B within about 2-5 or 2-10 years?
2) Translate system functionality into protocol functionality.
3) Which standard(s) best fit(s) my situation?
4) Define a Protocol Implementation Document (PID). Take as the basis
the PICS (Interoperability sheet) and add additional requirements. The PID is
used to close all open ends in the standard and specifies the use of the
standard for one network. The network can be a utility, a group of utilities, a
country or a continent.
5) This document is part of the contract between vendor and user.
The above 5 steps have to be taken before
the delivery contract between supplier and utility is signed. The next few
steps after signing the contract are:
6) Only accept a third party verified protocol implementation
(conformance tested and approved) in the delivered product before installing
the equipment on-site, resulting in an Attestation of Conformity of e.g. KEMA.
This may be done before or as part of the FAT.
7) Interoperability testing on-site for detecting and solving
configuration mismatches and telecom problems. This depends on the strategy and
approach on how to put new systems into operation, which can differ per
utility.
These are the steps before putting the
system into operation. After the system has been put into operation the
following steps apply:
8) Update the PID with the experiences of the last project.
9) Require a verified implementation of the updated software before
installing it on site, proved by an Attestation of Conformity
The last step for the next tender is:
10) The updated PID is part of the next tender containing the
experiences of the past projects
Go to step 1 and so on. It is an
iterative process, which costs a minimum of time after the first 10 steps are
finished. Following this approach will result in an open system within your
company resulting in the benefits as in paragraph 1 and 4.
Of course not restricted to but
especially a must for utilities or areas that have not started a migration path
yet (because they can start really from scratch).
7. Structured project approach in practice.
Is this a theoretical approach or are
there also parties following this approach with success? It is being used in
practice and an indicator of this is the increasing number of utilities
following this approach
and – partly derived from it – the
increasing number of IEC 60870-5-101/103/104 (conformance) tested
implementations by KEMA over the last few years.
Putting a telecontrol connection into operation requires only a minimum of time
if protocol problems are eliminated by a passed protocol conformance test. Users
of the equipment tested confirm this compared to equipment that has not been
conformance-tested. For more than 60% of the tested equipment a retest is
necessary because of a) non-conformant behaviour; b) a reasonable cause for
expecting interoperability problems and c) a reasonable cause for expecting
operational problems.
The communication protocol is a small but
important part of ‘utilities’ system that controls and monitors its core
activities. Costs involved of not having a proper and consistent implementation
of the protocol, has a range up to millions of euros. E.g. a complete area may
become without power after sending a break-off command by the control centre
(which means ‘do not switch’) and false interpreted by the substation control
system as a normal command and executed.
8. Conformance testing centre
What are the requirements to be set to a
test centre? Is it necessary to have a government-approved notified body that
is allowed to perform the tests and issue a “certificate” or “attestation of conformity”?
The costs for setting up such an official body must be borne by either the
government or the party ordering the test. On the other hand, it may not be
commercially interesting because of the market size. The market is relatively
small and it is expensive to equip, set up and maintain the necessary
requirements for such a service, as we know. The best option depends of a lot
of factors and it too complicated to go into detail within the scope of this
article. It is an interesting subject for further discussion and if applicable,
I invite you to start this discussion.
For the IEC 60870-5 series, but also for
IEC61850, from their publication up to the present time, KEMA created
conformance test equipment and corresponding test plans, during its consultancy
and testing activities. The “Attestation of Conformity” is accepted by a lot of
utilities internationally as tangible proof that the protocol implementation in
the delivered device/system complies to the standard and PID. It is granted by
KEMA and accepted only because of the supplier-independent role and its
reliable name within the international utility industry. In fact, the KEMA test
plans form the basis for the IEC 60870-5-6 test plans, which are currently
under construction.
Besides assisting utilities and supplier
from initiative up to operation phase, KEMA can also assist governments or
other parties in setting up and equipping (supplier-independent) test centres
by offering services and facilities.
