Download bibliography

21, rue d’Artois, F-75008 PARIS
http : //www.cigre.org
B5-116
CIGRE 2010
IEC61850 9-2 Process Bus: Application in a real multivendor substation
J. CASTELLANOS*, I. OJANGUREN, I. GARCES, R. HUNT, J. CARDENAS, M.
ZAMALLOA, J. GARCIA, A. GALLASTEGUI, M. YUBERO, E. OTAOLA
Iberdrola, General Electric, Usyscom, Ingeteam T&D, Arteche, Sac, Ziv P+C
Spain
SUMMARY
New IEC61850 based pilot substations are being deployed all over the world, but few
attempts have been made so far to use the process bus to directly communicate with the
switchgear and measuring equipment of an electrical substation. This means that the IEC
61850-9-2 process bus has not yet been tested thoroughly in a real environment. In Spain, one
utility, a group of protection, control and communication equipment manufacturers and one
measurement transformer manufacturer are building a testing scenario in a real distribution
substation in order to test the feasibility of a multivendor IEC61850-9-2 process bus based
substation.
The work presented in this paper reflects the actual and future development of a pilot
installation in an existing high voltage substation. The main goal of the project is to review
the state-of-the-art process bus technology and evaluate it for practical use, including actual
interoperability between different manufacturers, degree of maturity, robustness, and possible
benefits. The lessons learnt will permit the participating companies to create the roadmap to
achieve the most efficient application and wide deployment of next generation of digital
Protection and Control systems based on IEC 61850 process bus and digital Ethernet
communications.
The paper also describes the key components of the project, the network configuration
alternatives, the different project stages, the technical challenges related to interoperability
and the required changes in the philosophy of protection and control engineering.
Finally the method for comparison of performance between the conventional P&C system and
the modern P&C system based on fiber optic IEC 61850 communications and non
conventional measurement transformers is presented, as well as the specific points that have
to be monitored.
KEYWORDS
Process bus, Merging Units, Remote Input Output units, Non-Conventional Current
Transformer, network architecture.
[email protected]
1. PROJECT DESCRIPTION
The project comprises the installation of a shadow P&C system for one 132kV line and one
power transformer on an existing substation, and the installation of several merging units, one
non-conventional current transformer with process bus interface and several remote
input/output units for digital signal acquisition, as is shown in figure 1.
Línea 132 kV
Vilecha
Man. 1
Manufacturer 1
Manufacturer 2
Manufacturer 3
Line Protection
Line Protection
Line Protection
Transformer
Protection
Transformer
Protection
Transformer
Protection
Line Bay Control
Line Bay Control
Line Bay Control
RIO
Man. 1
Man. 2
M.U.
(PIU)
M.U.
NCCT
F.O.
132 kV
Man. 1
F.O.
M.U.
Man. 2
RIO
F.O.
Man. 1
M.U.
Man. 1
F.O.
M.U.
Multivendor
Man. 3
Line Protection
RIO
45 kV
Line Bay Control
Transformer Bay Control
F.O.
Switchyard
SWITCH
Control Room
Figure 1: General scheme of Benavente process bus project
1.1 SELECTED LOCATION
The selected substation (located in Benavente, Spain) was built in the 70’s and is still in
service. It has been chosen due to the high number of faults experienced on its connected
overhead lines, especially in the summer season owing to the frequent occurrence of storms.
1.2 PROJECT KEY COMPONENTS
Remote Input/Output (RIO) units
The scope of the project includes the installation and interoperability tests of several small
intelligent units that provide the exchange of digital information to the IEDs that perform the
protection and control functions.
1
These units are located inside the outdoor control cubicles attached to power transformers,
circuit breakers, switches, etc, close to the source of information. The mechanical design is
based on low cost, compact and robust characteristics, easing their installation in the
switchyard.
The main goal is to achieve cost savings related to copper wiring. These modules have been
named Remote Input/Output (RIO) units.
The connection between IEDs and RIO modules is made by means of a standard point to
multipoint communication bus. In this way, the same IED is able to communicate with several
RIO modules developed by different manufacturers.
IEC61850 8-1 Goose messages have been selected to communicate the value of the inputs to
the IEDs installed in the substation. The same format of message has been selected to operate
the outputs.
Merging Units (MUs)
One of the main elements in the project is the Process Interface Unit (PIU), which is a process
bus merging unit as per IEC 61850 9-2, combined with contact inputs and outputs to form a
complete protection and control interface to primary equipment in the switchyard. This PIU is
a rugged device designed for outdoor mounting in a switchyard. This unit uses connectorized
cables (for copper cables to interface with equipment, and fiber optic cables for
communications) to allow simple installation, removal, and replacement.
The PIU contains 4 merging units using the same data to provide a star connection to 4
different devices.
The purpose of this design is to have the same physical interface both for the protection and
control systems, a PIU connected to a fiber optic cable, for all applications and zones of
protection. The only variability in design is where to place the PIUs, and how to lay out the
fiber optic cables.
The use of a standard, rugged PIU, with connectorized cables, provides many benefits: there
is a small list of standard components (PIU, copper cables, fiber optic cable) for the
installation, the system can be designed by engineers and installed by field personnel with no
high-level training required, the system is successfully commissioned using standard testing
tools and methods.
Additionally, operation, maintenance, and life cycle costs should be considerably less than
with conventional installations and replacement, refurbishment, repair, or upgrade to the
system requires only replacing individual components using only simple hand tools.
MUs to be connected only to conventional CTs and VTs, without contact inputs and outputs,
are also planned to be tested.
2
Non-Conventional Current Transformers (NCCTs)
Within this project a set of three NCCTs will be installed in the Vilecha line bay (132 kV).
The most important challenges for the NCCTs are, on one hand, the direct publication of the
sampled values by the transformer, without needing intermediate elements like merging units
between the measurement and its users (protections and meters), and on the other hand, the
use of optical sensors to perform the measurements. The implications and improvements of
these two facts are numerous, besides the ones of the use of the process bus.
With the optical technology, the need to distinguish between windings with class of precision
of metering or protection disappears, since the class of metering precision stays (or it
improves) in all the dynamic range of the sensor. Therefore, the sampled values published by
the sensor can be used by so many “clients” as it is demanded, independent of the dynamic
range of the application. Future needs will not be limited by the availability of free
measurement windings as one sensor is able to satisfy all the present and future needs for
measurement.
From this point of view, the best communication topology is point to multipoint and thus
compatibility between the different vendors becomes essential.
Since the terminal unit of the NCCTs only has to publish the sampled values corresponding to
the three currents of the substation position, and in order to interoperate with as many
manufacturers as possible, it has been chosen to implement 61850-9-2 LE (Lite Edition)
recommended by the UCA for the instrument transformers. This implementation is
characterized by its simplicity and the unidirectionality of the communications.
There are other advantages derived from the use of NCCTs that justify its inclusion in this
project, like the following:
 The absence of elements like oil and SF6.
 The elimination of some failure mechanisms in the conventional transformer like:
overheating, overvoltages, failures of isolation, etc, resulting in electrically robust
equipment.
Intelligent Electronic Devices (IEDs)
IEDs that will be installed in Benavente substation will fully support the requirements of
process bus, in accordance with IEC61850-8-1 and also IEC61850-9-2 LE. At the same time,
these IEDs will support the widely tested station bus according to the IEC61850 standard and
also to the utility’s iSAS specification for Substation Automation.
Assuming that for every IEC61850 system, interoperability between different manufacturers
is a must, some technical challenges arise at the time of implementing the process bus in a
multivendor environment:
 Merging units and non-conventional current transformers will provide IEDs with
sampled values. These units are replacing conventional CTs and VTs, and their
dynamic behavior becomes one of the biggest challenges. Due to the fact that the
3
response of these non-conventional transformers and merging units is not standardized
and that protection algorithms are designed according to the dynamic behavior of
relay’s analogue inputs, there are some uncertainties about the performance of these
new IEDs when they get sampled values from a different vendor’s measurement
device.
 Sampling rate is another factor that will have to be addressed in Benavente. Most
likely, IED’s current sampling rates won’t match up with sampling rates established in
IEC61850-9-2 LE.
1.3 NETWORK DESIGN
Point to Multipoint vs. Point to Point network architecture
Both Point to Multipoint and Point to Point network architectures were initially considered for
the implementation of the process bus.
In a Point to Multipoint process bus architecture all the IEDs, MUs, RIO units, etc, can be
connected in a star topology using a managed IEC61850 compliant Ethernet switch. Using the
Parallel Redundancy Protocol (PRP) could be a way to guarantee link redundancy for the
IEDs connected to the process bus (all the IEDs should be connected to this bus using two
physically independent network interfaces).
With Point to Point network architecture each protection IED can be directly connected to the
merging units (point to point) and to the substation bus. An Ethernet switch would be the
device responsible of allowing data communication between the IEDs and any other device
connected to the process bus such as non-conventional transformers and RIO units. VLANs
could be used for substation bus and process bus traffic segmentation. For doing so, IEDs
should be able to handle different VLAN tags for substation bus and process bus traffic.
Implementation in Benavente project
Due to the diversity of physical interfaces of the bay level devices and the lack of PRP
capable IEDs, at the beginning of the first phase of the project the Point to Point architecture
was chosen.
A managed IEC 61850 compliant Ethernet switch was initially deployed in the control room
at substation bus level. The protection and control IEDs were directly connected both to this
switch and to the merging units.
The 3rd phase (depicted with broken lines in figure 2) of the project comprises the use of a
process-bus-switch to which all the RIOs units and non-conventional transformers will be
connected. MUs and protection IEDs can also be connected to this switch so the system
performance can be compared with the performance of a “pure” point-to-point architecture
(direct MU-IED connection).
VLANs are defined at the switch in order to separate network management traffic, substation
bus traffic and process bus traffic.
4
Remote access is necessary for troubleshooting, management and monitoring. A cellular
router was chosen for this task. Special care was needed due to security concerns related to
the use of public network infrastructure (such as UMTS/GPRS) for accessing critical
installations. The use of an IP tunnel based Virtual Private Network provided the required
security level.
Figure 2: Logical Network Architecture (phase 3 connections depicted with broken lines)
1.4. PROJECT TIME SCHEDULE
 Phase 1:
During 2009, four MUs and three IEDs from one manufacturer, and two RIO
from two different manufacturers have been installed in Benavente substation.
Commissioning was finished in September.
 Phase 2:
Line and transformer protection and line bay controllers from two more
manufacturers (to be connected to already fitted MUs) will be installed before
June of 2010.
A set of three NCCT will also be installed in the Vilecha line bay before June
of 2010, together with a recorder provided by the same manufacturer in order
to monitor the behavior of the transformer during normal and abnormal
conditions.
 Phase 3:
In the last stage, RIOs from three different manufacturers and IEDs capable to
subscribe to RIOS, NCCTs, and MUs will be installed at the end of 2010. MUs
from a different manufacturer will also be mounted.
5
2. TESTING AND MONITORING CONSIDERATIONS
Each of the devices installed according to the IEC61850 standard has to be previously tested
by each manufacturer. Once the solution has been installed in field, the testing tasks
concentrate on the analysis of the reliability of the global system during real situations (trips,
recloses, etc.) by forcing the system to work under the worst possible communication
conditions (communications network extremely loaded, sudden loss of communication
channels, etc.).
In order to compare results between the different devices installed, it is necessary to have a
common synchronization source using a GPS device that will generate an IRIG-B or SNTP
synchronization signal.
The protection relays are installed in parallel with the original devices of the substation,
therefore a first proof level consists in checking that their behavior is similar to the
conventional devices. The behavior of the relays will be monitored during disturbances in the
network (faults, recloses, transformer energizations, power swings, etc.). The expected result
is that the relays will operate in a similar way to the conventional devices.
The monitoring is focused on the following aspects:
 Global synchronization of all the devices.
 Sample synchronization differences between different merging units and conventional
CTs
 Reaction times similar to a conventional solution.
 Correct running of the communication network.
 Running of communication planned redundancies.
The installation can be accessed remotely as the internal network is connected with the
outside with a GPRS modem router that manages communications. The access to the IP
direction of this modem enables individual access to the IEC61850 elements connected to the
substation bus, in order to verify if its behavior is correct. Each project member is able to
access with its own tools the status and configuration of its devices as well as accessing the
rest of the devices using IEC61850 communication tools.
The internal reports of IEDs are used to record the performance of the elements of the system
in order to find out about internal and external trips, the functioning of the RIO modules,
communication failures, etc.
3. CONCLUSIONS
Development of protection and control systems for the next decade should be approached
from the utility enterprise perspective, recognizing and addressing the present needs of
today’s utilities – cost reduction and speed of deployment, remaining at the same time reliable
and secure.
Substantial cost is associated with copper wiring: designing, documentation, construction,
commissioning, and troubleshooting of tens of thousands of individual terminations in a
6
substation. Therefore, the next generation Protection and Control (P&C) solution is often
viewed as completely eliminating “copper” from substations and replacing it with “fiber”.
Non-conventional cost-effective measurement transformers will become a reality in the
future, due to the important benefits that this technology will bring.
The Spanish project described in this paper will allow testing in a real substation of the
equipment from different manufacturers in the process bus, in order to achieve the following
final goals:










Cost saving
Reducing project duration and outage windows
Shifting cost from labour to pre-fabricated material
Targeting copper wiring as main area for cost optimization
Reducing skill set requirements
Supporting optimum work execution
Improving system performance and safety
Using open standard communications
Migration to truly digital substations including primary and secondary equipment
Keeping testing and maintenance process at similar reliability and quality levels of the
present systems, minimizing the impact on the Operation of the Power System.
BIBLIOGRAPHY
[1]
[2]
[3]
[4]
[5]
[6]
M. Adamiak, D. McGinn, V. Muthukrishnan, “Designing Copper Wiring Out of High
Voltage Substations: A Practical Solution and Actual Installation”. Proceeding of 63rd
Annual Georgia Tech Protective Relaying Conference, Atlanta, USA, 2009
D. McGinn, S. Hodder, B. Kasztenny, D. Ma, “Constraints and Solutions in Testing
IEC 61850 Process Bus Protection and Control Systems“, 42 CIGRE Session, Paris,
August 24-29, 2008, paper B5-206.
D. McGinn, M. Adamiak, G. Maciej, J. Cardenas, “Reducing Conventional Copper
Signaling in High Voltage Substations with IEC 61850 Process Bus System “, 2009
IEEE Bucharest PowerTech, Romania, June 29-July 2, 2009, paper 576.
Cardenas J., Goraj M. (GE, Spain), Adamiak, M. (GE, USA), Ojanguren, I.(Iberdrola,
Spain), Castellanos, J. (Iberinco, Spain), “Reducing the Costs of Maintenance of
Secondary Systems in High Voltage Substations with the use of Process Bus “,CIGRE
Colloquium, Korea, October 19-24, 2009, paper 106.
José Miguel Yarza (ZIV P+C, Spain), Rafael Quintanilla (ZIV P+C, Spain) y José
Miguel Arzuaga (ZIV uSyscom, Spain), “Implicaciones de la implementación del bus de
proceso en las subestaciones eléctricas”, XIII ERIAC de Puerto Iguazú - 2009
(Encuentro regional Iberoamericano de Cigré).
IEC 61850 Standard Series, Communication Networks and Systems in Substations.
7