OUTLINE:
Designing
Substation Automation (SA) Systems
Objectives
· To learn how SA systems interact with the HV primary equipment in
transmission and distribution substation.
· To learn the main functions of SA from process connections to network
operation related functions.
· To learn the SA structure from station level to bay level and the
typical allocation of the various tasks including data
exchange between station level and bay level.
· To learn the various options of SA architectures their design features,
availability and reliability aspects as well as their typical
application areas.
· To
learn new change brought from IEC61850
Contents
Primary
Equipment in Substations
· Switching equipment
A
short description of the switching equipment like circuit
breakers, disconnectors, earthing switches and instrument
transformers as well as their typical interfaces for control
and on line condition monitoring.
The functions of SA
· Process
connections
Each
control and monitoring system needs input data from the
process and outputs to the control process. On one hand the
process interface allows to transfer information from the SA
system to the process on the other hand it is a barrier
between the control system and the hostile environment of the
process. The various types of sensors and actuators are
discussed as well as the pre-processing of data.
· System configuration and
maintenance functions
A
SA system consists of a set of software packages, running on a
distributed system containing a lot of substation and customer
specific configuration data, function parameters and
specifically developed software. The system configuration
functions are a subset of the engineering functionality, which
is needed during commissioning and maintenance.
· Communication Functions
Communication
functions are support functions which are necessary to support
a distributed system or the interaction between devices from
several manufacturers.
There
are devices supporting IEC61850
and devices not supporting IEC61850 when current communication
transit to IEC61850. How to integrate the two kinds of devices into one
SAS?
· Network related functions
Network
related functions are used for basic data acquisition and
control functionality and support the appropriate SCADA
functionality at network control level.
SA Structure
· Station Level
The
station level provides the Human Machine Interface (HMI) as a
central place for substation operation. Depending on the
complexity and reliability of the system station level
automatic functions may reside on separate station level IEDs. (Intelligent electronic device). It also contains the substation data base
and archive and provides the access to substation data.
· Time synchronization
A
lot of functions need time stamped data and time
synchronization is an important system support function.
· Remote control and
monitoring
This
chapter comprises communication gateway, remote control
functions and monitoring functions which rely on the data
exchange with bay level functions.
Now,IEC61850
is used at the
internal SAS,But IEC60870-5-101/104 are used between the SA
and control center.How to config and realize the conversion of
the two protocols in the gateway ?
· Bay level
The
physical bay level is close to the switchyard equipment.
Typical functions allocated to the bay level are bay level
control and protection functions, as well as local HMI to IEDs.
Introduction
of the inferface between bay and process by using IEC61850-9-1
and IEC61850-9-2.
· Process level
The
process level comprises hardwired cable connections, auxiliary
switches indicating the switchgear position,
electro-mechanical control relays sensors for non-electrical
measurements and serial communication links if applicable.
SA Architectures
· Communication within
substations
The
advent of microprocessors in substations allows to process
data in digital form. Therefore, data must be converted to
digital form before it can be processed. This is not a problem
for binary data form relay contacts, but it is not so easy for analog data as well as for serial communication
because of time delays. To ensure the same functionality and
performance as in conventional system appropriate SA
architectures have to be chosen. The various design aspects
and communication modes are discussed in this section.
· The integration of
protection and control systems
Historically,
there was one specific device per function. This is not only
valid for control and protection relays but for different
protection functions as well. Numerical devices, however, lead
to multifunctional devices that perform several protection
functions and even control functions in parallel. Only for
reliability and availability reasons more than one or two
devices are required. The safety and reliability aspects are
discussed to design appropriate systems.
· Allocation of functions
Most
of the SA functions are distributed. They consist of inputs
and outputs and data processing. The functional specification
of an SA system defines the implementation by means of logical
nodes and interfaces between logical nodes. In this section
the criteria for the allocation of functions are explained as
well as the availability criteria.
· Integration of primary
equipment
The
connection of SA systems to instrument transformers and
switchgear are either made via hardwired cables or via glass
fibre cable if modern electronic sensor provide the electrical
data in digital form. These glass fibre cables are called process
bus. The typical design aspects of a process bus is
discussed in this section.
· Asset management support
SA
systems can provide condition related data from the primary
equipment which can support modern asset management systems.
This means that the normal data acquisition, archiving and
logging facilities of a SA systems can be exploited as an
source for valuable information. The consequences and design
aspects of such an approach are discussed in this section.
· Dependability
All
hardware and software components of SA systems need to be of
very high quality to meet the high availability requirements.
In this section it is explained how short down times can be
achieved by extensive diagnostic functions, a modular hardware
design, fast reconfiguration and restart after repair combined
with an efficient repair as well with physical redundancies.
Prerequisites
Experienced developers and equipment manufacturers of SA systems
Duration
2 days
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