FIELD OF INVENTION:
[0001] The present disclosure relates to a Switchgear Control Unit (SCU) for substation
automation systems (SAS) and method to implement the SCU.
BACKGROUND OF INVENTION:
[0002] Electric power systems for supplying electric power to households, factories, or
buildings include an electric power plant for producing electric power, one or more
transmission lines for transmitting electric power, one or more substations for transforming the
amplitude of electric power into a desired amplitude, and one or more distribution lines for
distributing electric power to respective areas that require electric power.
[0003] A substation of the electric power systems generally includes electric power
equipment, such as a transformer, bus, line, and circuit breaker. The transformer is to transform
the amplitude of voltage to be transmitted, the bus is to connect transmission lines, and a circuit
breaker is to open and close the electric power flow through the transmission lines. Apart from
these electric power equipments, intelligent electronic devices (IEDs) are installed in the
substation and are configured to monitor, control, and protect various types of electric power
equipment. However, in case a fault occurs in such an IED, it is difficult to properly monitor,
control, and protect the electric power equipment, and thus it is difficult to smoothly supply
electric power.
[0004] In conventional substations, respective IEDs are directly connected to electric
power equipment and independently operated. The architecture is structured on three levels i.e.
Station level, Bay level and Process level. However, recently, in a substation automation
system (SAS) in which respective IEDs share information with each other has been adopted.
[0005] IEC 61850 is an international standard for substation automation communication
architecture that was proposed in order to implement effective communication between
heterogeneous IEDs installed in a substation. IEC 61850 has been established as the only
international standard for substation automation, and all IEDs are expected to follow this
international standard.
[0006] Efforts have been made in state of the art to implement the communication standard
IEC 61850 to the SAS and also to make conventional substation to digital substation. A few
related examples can be found in the earlier patents mentioned below:

[0007] EP2203754B1 2017-09-27 Operating a Substation Automation System (en): This
invention relates to a system and a method in which during maintenance, commissioning and
fault situations, when one or several IEDs are inoperable, the data that these IEDs would have
produced is substituted to ensure availability of the substation.
[0008] US8942970B2 2015-01-15 Method for Configuring an Intelligent Electronic
Device and a Substation Automation System (en) : This invention relates to a method for
configuring an intelligent electronic device (IED) that includes enabling dynamic capability of
the IED by a flexible data modelling technique to dynamically adapt a data model based on an
application requirement using a configuration tool. A Substation Automation system is also
disclosed which includes a local system equipment having a plurality of IEDs associated with
the local system equipment and an IED configuration tool configured to interact with the
firmware of each IED to configure the IED based on application requirements.
[0009] US20140025321A1 2014-01-23 System and Method for Performing Data
Transfers in an Intelligent Electronic Device (en): This invention relates to intelligent
electronic devices (IEDs) and, in particular, to a system and method for sending/receiving data
to/from intelligent electronic devices (IEDs) at high speeds over a network.
[0010] US9048697B2 2015-06-02 Intelligent Process Interface and Substation
Automation System (en): This invention is concerned with an intelligent and digitalized
process level interface which is referred to herein as an Intelligent Process Interface (IPI). The
input of the IPI includes both analog and digital channels and therefore the IPI can be used for
substations in transition or retrofit stages with both conventional and non-conventional primary
devices. The IPI acts not only as a digitalized interface, but also as an intelligent Supervisory
and control unit for switching functions.
[0011] US8327049B2 2012-12-04 Electrical process interface device (en): This invention
is concerned with an electrical process interface device for provision in a low control and
protection level of a Substation Automation or Distribution Automation system; the device
includes a process interface unit for interfacing the electrical process at the low control and
protection level, which unit has a number of parallel data connections on which I/O data related
to control and protective devices on higher control and protection levels may be transmitted.
The device also includes a signal conversion unit connected to the data connections, which unit
packets data of the data connections according to a communication standard used by control
and protective devices on the at least one higher control and protection level for allowing data

to be directly transmitted between the electrical interface device on the low control and
protection level and other devices on higher control and protection levels.
[0012] US9478973B2 discloses method for transfer of control between devices in a
substation system and a device thereof. This disclosure relates to the method and system for
coordinated transfer of control in a substation system having IED or logical devices/servers
using GOOSE messages with preconfigured data models with logical nodes containing one or
more data objects including private data objects (DO) connected in the substation
communication network.
[0013] All the prior arts are primarily based on electrical interfaces. There is a need of a
system and a method for implementing a process level architecture based on digital interfaces
between switchgear and bay level IEDs (Intelligent Electronic Devices) for controlling
switchgear operations.
OBJECTS OF THE DISCLOSURE:
[0014] It is an object of the present disclosure to provide a system and a method for
implementing a process level architecture based on digital interfaces between switchgear and
bay level IEDs (Intelligent Electronic Devices).
[0015] It is another object of the present disclosure to develop interfacing of the data
acquisition cards with a processor module, where the processor module may act as an interface
for data exchange between data acquisition cards and field communication.
[0016] It is another object of the present disclosure to provide a system and a method to
convey the information regarding the techniques involved in the implementation of the
information exchange between two elements in the substation automation systems employing
the IEC 61850 protocol.
[0017] Further object of this invention is the PC based configuration tool for configuring
the SCU functionalities. The PC based configuration tool provides for on-line and off-line
configuration, thus saving configuration time. The user-friendly screens with user management
allows for selective access and better control.

SUMMARY:
[0018] This summary is provided to introduce concepts related to the architecture of
switchgear control unit for substation automation systems. The concepts are further described
below in the detailed description. This summary is not intended to identify key features or
essential features of the claimed subject matter, nor is it intended to be used to limit the scope
of the claimed subject matter.
[0019] In an embodiment, a switchgear control unit (SCU) for substation automation
system is described. The SCU includes one or more sensing modules to sense field input data
and includes a processor module having a data acquisition module coupled to the one or more
sensing modules. The data acquisition module is to receive the field input data from the one or
more sensing modules. The received field input data is then processed by the processor module
for communicating to an International Electrotechnical Commission (IEC) 61850 compliant
supervisory control and data acquisition (SCADA) system. Following the processing, the
processor module transmits the processed field input data to the IEC 61850 complaint SCADA
system as well as the status of the switchgear equipment’s to the Bay Control Unit (BCU) in
the bay level using IEC61850 GOOSE (Generic Object Oriented Substation Event). In response
to the transmission, the Bay Control Unit processor module receives commands from the
SCADA system, which then transmitted to Switchgear Control Unit (SCU) via GOOSE after
satisfying the interlock logics. Based on the received command, the data acquisition module of
the SCU processor module transmits digital outputs to a digital output/relay module.
[0020] In an aspect of the embodiment, a method for implementing a switchgear control
unit (SCU) for substation automation system is described. In an implementation, the method
begins with acquiring analog and digital field data using one or more sensing modules.
Following this, the acquired analog and digital field data are transmitted to a processor module
from one or more sensing modules. At the processor module, the acquired analog and digital
field data are processed by signal conditioning modules before digitizing the field data; and
mapping of computed value with International Electrotechnical Commission (IEC) 61850
substation automation protocols. The processed analog and digital field data are then
communicated to the IEC 61850 compliant supervisory control and data acquisition (SCADA)
system as well as the status of the switchgear equipment’s to the Bay Control Unit (BCU) in
the bay level using IEC61850 GOOSE (Generic Object Oriented Substation Events). In
response to the communication, the processor module receives control commands from the

SCADA system via Bay Control Unit over the IEC 61850 communication protocol based
network.
[0021] In an aspect of the further embodiment, after receiving the control commands from
the SCADA system, the processor module maps the control commands to the relay module via
base board and further hardwired to actual switchgear devices for operation.
[0022] Thus, with the present subject matter, a centralized process level architecture of
switchgear control unit having one processor module (microprocessor) and a number of data
acquisition modules (sensing modules) can be implemented. In such architecture, there would
be no data losses and at the same time accuracies would be increased, as all the data processing
is performed by a single processor module.
[0023] The configuration tool herein is loaded in the station PC and configuration can be
done in offline mode, without the need for SCU, thus saving time. There is no extra memory
requirement in SCU to store configuration utility. The user-friendly tool provides for easy
navigation and less dependency. The configuration tool allows us to connect the field Digital
Inputs, Digital Outputs, LEDs, 4-20mA signals, GOOSE Publish and Subscribe to the SCU
hardware terminals and also allows configuration of communication parameters, Hardware
Signal matrix for configuring channels in Digital Input Modules, Digital Output Modules,
Alarm configuration, Event and Alarm Viewer, Online display of sensor data, Digital channels
ON/OFF status and facility for firmware upgradation.
[0024] Various objects, features, aspects, and advantages of the inventive subject matter
will become more apparent from the following detailed description of preferred embodiments,
along with the accompanying drawing figures in which like numerals represent like
components.
Brief Description of Drawings:
[0025] The illustrated embodiments of the subject matter will be best understood by
reference to the drawings. The following description is intended only by way of example, and
simply illustrates certain selected embodiments of devices, systems, and processes that are
consistent with the subject matter as claimed herein, wherein:
[0026] FIG. 1 illustrates an exemplary arrangement of various modules housed in a single
rack compliant with electromagnetic-interference (EMI) / electromagnetic-compatibility
(EMC), in accordance with an exemplary embodiment of the present disclosure;

[0027] FIG. 2 illustrates an exemplary architecture of a switchgear control unit along with
field input(s)/output(s), supervisory control and data acquisition (SCADA) system, Bay Level
IED and PC based Configuration tool in accordance with an exemplary embodiment of the
present disclosure;
[0028] FIG. 3 illustrates an exemplary block diagram of an initialization routine, in
accordance with an exemplary embodiment of the present disclosure;
[0029] FIG. 4 illustrates an exemplary block diagram of IEC 61850 server, in accordance
with an exemplary embodiment of the present disclosure;
[0030] FIG. 5 illustrates an exemplary block diagram of Generic Object Oriented
Substation Event (GOOSE) publisher, in accordance with an exemplary embodiment of the
present disclosure;
[0031] FIG. 6 illustrates an exemplary block diagram of Generic Object Oriented
Substation Event (GOOSE) subscriber, in accordance with an exemplary embodiment of the
present disclosure;
[0032] FIG. 7 illustrates an exemplary flow diagram illustrating a method of implementing
control services for SCU for substation automation systems, in accordance with an exemplary
embodiment of the present disclosure.
[0033] Fig 8.1 – 8.8 shows the PC based Configuration Tool screens
DETAILED DESCRIPTION:
[0034] The following is a detailed description of embodiments of the disclosure depicted
in the accompanying drawings. The embodiments are in such detail as to clearly communicate
the disclosure. However, the amount of detail offered is not intended to limit the anticipated
variations of embodiments; on the contrary, the intention is to cover all modifications,
equivalents, and alternatives falling within the spirit and scope of the present disclosure as
defined by the appended claims.
[0035] As used in the description herein and throughout the claims that follow, the meaning
of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise.
Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the
context clearly dictates otherwise.
[0036] Each of the appended claims defines a separate invention, which for infringement
purposes is recognized as including equivalents to the various elements or limitations specified

in the claims. Depending on the context, all references below to the “invention” may in some
cases refer to certain specific embodiments only. In other cases, it will be recognized that
references to the “invention” will refer to subject matter recited in one or more, but not
necessarily all, of the claims.
[0037] Groupings of alternative elements or embodiments of the invention disclosed herein
are not to be construed as limitations. Each group member can be referred to and claimed
individually or in any combination with other members of the group or other elements found
herein. One or more members of a group can be included in, or deleted from, a group for
reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the
specification is herein deemed to contain the group as modified thus fulfilling the written
description of all groups used in the appended claims.
Non-Limiting Definitions
[0038] Definitions of one or more terms that will be used in this disclosure are described
below without limitations. For a person skilled in the art, it is understood that the definitions
are provided just for the sake of clarity, and are intended to include more examples than just
provided below.
[0039] The term “Switchgear Control Unit” means a control unit used for control and
monitoring of switchgear equipment in electrical substations. It is applicable to all types of
busbar and switchgear arrangement in both gas and air-insulated substations. It is suitable for
use in the highest voltage level substations in which very high reliability is required, but can
also be applied for industrial substation and automation substations due to its flexible settings
and functions. The switchgear control unit facilitates the controlling remotely through the
communication network/bus.
[0040] The term “Substation Automation System” refers to a system using data from
intelligent electronic devices (IED) and control commands from remote users/devices to
control and automate power-system devices of a substation.
[0041] The term “intelligent electronic devices (IEDs)” is used in the electric power
industry to describe microprocessor-based controllers of power system equipment, such as
circuit breakers, transformers, and capacitor bank. The IEDs are generally responsible for the
protection, control, and monitoring of the primary devices of a substation.

[0042] To the extent a term used in a claim is not defined below, it should be given the
broadest definition persons in the pertinent art have given that term as reflected in printed
publications and issued patents at the time of filing.
Overview:
[0043] Exemplary embodiments of the present disclosure provide a switchgear control unit
for substation automation system which performs control functions for switchgear equipment’s
of an electrical power distribution substation, for example, a high and medium power
substation, without at least some of the disadvantages of known techniques. For instance,
exemplary embodiments of the present disclosure provide a centralized architecture of the
switchgear control unit having one processor module and a number of sensing modules, which
provide control functions, without the costs associated with duplication of the hardware
devices.
[0044] In an exemplary embodiment, a switchgear control unit (SCU) for substation
automation system is described herein. The SCU includes one or more sensing modules to
sense field input data and includes a processor module having a data acquisition module
coupled to the one or more sensing modules. Field connectivity is provided from the rear side
of the rack. The data acquisition module is to receive the field input data from the one or more
sensing modules. The received field input data is then processed by the processor module for
communicating to an International Electrotechnical Commission (IEC) 61850 compliant
supervisory control and data acquisition (SCADA) system as well as the status of the
switchgear equipment’s to the Bay Control Unit (BCU) in the bay level using IEC61850
GOOSE (Generic Object Oriented Substation Event). In response to the transmission, the Bay
Control Unit processor module receives commands from the SCADA system, which then
transmitted to Switchgear Control Unit (SCU) via GOOSE after satisfying the interlock logics.
Based on the received command, the data acquisition module of the SCU processor module
transmits digital outputs to a digital output/relay module.
[0045] In an aspect of the embodiment, a centralized process architecture of switchgear
control unit having one processor module (microprocessor) and a number of data acquisition
modules (sensing modules) can be implemented. In such architecture, there would be no data
losses and at the same time accuracies would be increased, as all the data processing is
performed by a single processor module. Also, as the single processor module is handling all

the functions, there are no data transfer delays, in addition to better accuracies and no
dependencies.
[0046] In an aspect of the embodiment, the one or more sensing modules further includes
an isolator module to sense and provide a 4-20 mA sensor signal to the data acquisition module.
[0047] In an aspect of the embodiment, the one or more sensing modules further includes
a digital input module for providing a status signal from a switchgear in the form of binary
data. The Digital Input modules provide isolation and level translation to the status inputs signal
to 5V level. Each DI module has a provision for reading 24 status inputs.
[0048] Accordingly, the analog sensing modules will acquire the analog field data and send
it to processor module for further communication. Similarly, digital sensing module will
acquire the digital field data and sent it to the processor module for further communication.
Such fixed functionality modules are advantageous from the point of view of fault diagnosis
and easy maintenance. Further, in an example, the analog sensing modules and digital sensing
modules can be configured using a configuration tool known in the art.
[0049] In an aspect of the embodiment, the SCU includes a power supply module to supply
power to all the modules of the SCU from a single power source. All the modules are powered
by 24V DC, which is derived from a universal input power supply.
[0050] In an aspect of the embodiment, the one or more sensing modules are coupled to
the processor module through Flat Ribbon Cable (FRC), while the power supply module
supplies the power separately through a power cable to one or more sensing modules and the
processor module. The separation of power cable and data cable (FRC) provides less
interference to the data signals and improve the reliability.
[0051] In an aspect of the embodiment, all the modules of the SCU are housed in a single
rack compliant with electromagnetic-interference (EMI) / electromagnetic-compatibility
(EMC), and a common power supply is used to power all the modules. Further, as there is no
differentiation in the modules for medium voltage and low voltage, the modules are generic
and can be used interchangeably. Such configuration of the modules provides modularity and
ease of maintenance.
[0052] In an aspect of the embodiment, a PC based configuration tool allows for
configuring the communication parameters, Hardware Signal matrix for configuring channels
in Digital Input Modules, Digital Output Modules, Alarm configuration, Event and Alarm

Viewer, Online display of sensor data, Digital channels ON/OFF status and facility for
upgrading the application code.
[0053] In a further aspect of the embodiment, the SCU facilitates Generic Object Oriented
Substation Event (GOOSE) messaging between bay level and process level Intelligent
Electronic Devices (IEDs).
Exemplary Embodiments:
[0054] Various embodiments are further described herein with reference to the
accompanying figures. It should be noted that the description and figures relate to exemplary
embodiments, and should not be construed as a limitation to the subject matter of the present
disclosure. It is also to be understood that various arrangements may be devised that, although
not explicitly described or shown herein, embody the principles of the subject matter of the
present disclosure. Moreover, all statements herein reciting principles, aspects, and
embodiments of the subject matter of the present disclosure, as well as specific examples, are
intended to encompass equivalents thereof. Yet further, for the sake of brevity, operation or
working principles pertaining to the technical material that is known in the technical field of
the present disclosure have not been described in detail so as not to unnecessarily obscure the
present disclosure.
[0055] FIG. 1 illustrates an exemplary arrangement of all modules of a switchgear control
unit (SCU) (100) in a single rack compliant with electromagnetic-interference (EMI) /
electromagnetic-compatibility (EMC), in accordance with an exemplary embodiment of the
present disclosure.
[0056] As can be seen from FIG. 1, the single rack includes a single processor module
(102), three digital input modules (104), two digital output modules (106), one 4-20mA module
(108), one filter module (110), and a power supply module (112).
[0057] The details of the SCU (100) are described with reference to FIG. 2. FIG. 2
illustrates a centralized architecture of the SCU (100) in accordance with an exemplary
embodiment of the present disclosure.
[0058] FIG. 2 illustrates various components of a proposed SCU (100). In an example, the
SCU (100) may be implemented in a computing device which can communicate with other
computing devices through a Local Area Network (LAN) communication network.

[0059] In an example implementation, the SCU (100) may include a processor module
(102). The processor module (102) may be implemented as one or more microprocessors,
microcomputers, microcontrollers, digital signal processors, central processing units, logic
circuitries, and/or any devices that manipulate data based on operational instructions. Among
other capabilities, the processor is configured to fetch and execute computer-readable
instructions stored in a memory (not shown) of the processor module (102). The memory may
store one or more computer-readable instructions or routines, which may be fetched and
executed to acquire or share the field data over a network service. The memory may include
any non-transitory storage device including, for example, volatile memory such as RAM, or
non-volatile memory such as EPROM, flash memory, and the like.
[0001] The processor module (102) may also include an interface(s) (not shown in figures).
The interface(s) may include a variety of interfaces, for example, interfaces for data input and
output devices referred to as I/O devices, storage devices, and the like. The interface(s) may
facilitate communication of the processor module (102) with various devices coupled to the
processor module (102). The interface(s) may also provide a communication pathway for one
or more components of the processor module (102). Examples of such components include,
but are not limited to, the data acquisition module (202).
[0002] The data acquisition module (202) may be implemented as a combination of
hardware and programming (for example, programmable instructions) to implement one or
more functionalities of the data acquisition module (202). In examples described herein, such
combinations of hardware and programming may be implemented in several different ways.
For example, the programming for the data acquisition module (202) may be processor
executable instructions stored on a non-transitory machine-readable storage medium and the
hardware for the data acquisition module (202) may include a processing resource (for
example, one or more processors), to execute such instructions. In the present examples, the
machine-readable storage medium may store instructions that, when executed by the
processing resource, implement the data acquisition module (202). In such examples, the
processor module (102) may include the machine-readable storage medium storing the
instructions and the processing resource to execute the instructions or the machine-readable
storage medium may be separate but accessible to the processor module (102) and the
processing resource. In other examples, the data acquisition module (202) may be implemented
by electronic circuitry.

[0003] Further, the processor module (102) is communicatively coupled to an International
Electrotechnical Commission (IEC) 61850 compliant supervisory control and data acquisition
(SCADA) system (204).
[0060] In operation, one or more sensing modules (data acquisition modules) periodically
acquire analog and digital field input data.
[0061] For acquiring analog field input data, the one or more sensing modules include an
isolator module to sense and provide a 4-20 mA sensor signal to the data acquisition module
(202).
[0062] For acquiring digital field input data, the one or more sensing modules include a
digital input module (104) for providing a status signal, from switchgear, in the form of binary
data to the data acquisition module (202).
[0063] In an exemplary implementation, all the inputs from the field are subjected to
required signal conditioning before digitizing.
[0064] Once the analog and digital field input data is acquired, the processor module (102)
processes the field data and mapping the computed value with IEC 61850 substation
automation protocols for communication with the IEC 61850 compliant SCADA system (204).
Those skilled in the art can appreciate that although the communication protocol is described
for the communication standard IEC 61850, the present disclosure is not restricted to IEC
61850. In an exemplary implementation, the recent versions of IEC 61850 can be implemented
in the present subject matter without deviating from the scope of the present disclosure.
[0065] In an exemplary implementation, all the modules of the SCU (100) are powered with
a 24V DC which is derived from a universal input supply module (112).
[0066] Continuing with the present disclosure, following the processing, the processor
module transmits the processed field input data to the IEC 61850 complaint SCADA system
(204) as well as the status of the switchgear equipment’s to the Bay Control Unit (BCU) (206)
in the bay level using IEC61850 GOOSE (Generic Object Oriented Substation Event). In
response to the transmission, the Bay Control Unit (206) processor module receives commands
from the SCADA system (204), which then transmitted to Switchgear Control Unit (SCU)
(100) via GOOSE after satisfying the interlock logics. Based on the received command, the
data acquisition module (202) of the SCU processor module (102) transmits digital outputs to
a digital output/relay module (106). In an exemplary implementation, each digital module (106)
caters 16 digital outputs.

[0067] In an exemplary implementation, the SCU (100) may utilize a communication module
having 2 number of LAN ports for communicating with bay level devices (206) and high-end
SCADA system (204) as well as Configuration tool (208).
Exemplary Implementations:
[0068] Further, the SCU (100) for substation automation systems may be implemented using
application code developed in C language in Real-Time Operating System (RTOS) environment,
as RTOS provides greater timing accuracy. Herein, the application is designed as multiple
processes with multiple threads. Each thread is designed to perform a particular task. For an
application, algorithms have been developed for analog and digital data acquisition, measurement,
sequence of events (SOE) recording, alarms recording, and data transfer over IEC 61850
substation protocol.
[0069] In an exemplary implementation, the entire implementation of IEC 61850 in the
proposed architecture is divided into the following subsystems:
i. IEC 61850 Server module: This module provides all IEC 61850 communication as well
as data model of IED for external IEC 61850 clients. When client requests for any of the
IEC 61850 services, this module facilitates all the validation and provides accession of
data through IEC 61850 data models configured via Substation Configuration Language
(SCL) eXtensible Markup Language (XML) file. All IEC 61850 client requests are
addressed via pre-registered leaf functions. This module passes the logical control to IED
interface module whenever it needs access to IED data. This is the first threaded module
of IEC 61850 server implementation.
ii. IEC Generic Object Oriented Substation Event (GOOSE) Publisher: This module
facilitates the publishing of multi-cast GOOSE packets to media access control (MAC)
addresses according to SCL definitions. Hence, it provides GOOSE data to external IEC
GOOSE subscribers via IEC GOOSE communication. Whenever there is any change in
GOOSE data from IED, this module facilitates all the validation and provides
publication of data through IEC GOOSE publisher control blocks configured via SCL
XML (SCD) file. This module uses shared memory data copy to identify the changes
in GOOSE data. This is the second threaded module of IEC 61850 server
implementation.
iii. IEC Generic Object Oriented Substation Event GOOSE Subscriber: This module
facilitates subscribing of multicast GOOSE packets from MAC addresses according to the

External Reference in SCL definitions. Hence, it provides GOOSE data from external IEC
GOOSE publishers to the defined IED. Whenever there is any changed GOOSE data from
the subscriber module, it informs the IED via the shared memory. This is the third threaded
module of IEC 61850 server implementation.
Initialization Module
[0070] FIG. 3 shows a block diagram of an initialization routine/module which describes
the basic flow of initialization sequences of IEC 61850 server driver. As can be seen from Fig.
3, SCD file (302) is the main configuration file. BCU-IEC Map file (303) is a configuration
file concerned with IED application and IEC 61850 application put in a configuration text file
consisting of shared memory type (IN & OUT data types) and shared memory index for each
of the IEC 61850 data in the IED section of the SCD file (302). IEC 61850 application
internally loads the configuration file (303) at start-up and reads-and-writes shared memory
data according to the configuration.
[0071] Further, a StartUp.cfg file (301) is provided to the IED user to facilitate the parsing
of SCD file (302) using SCL parser (305) compliant with IEC 61850 Edition 2.0 SCL schema
for this user’s IED.
[0072] Yet further, the IED Data Mapping module (308) is using the configuration file
(303) provided by the IED User to identify the mapping information related to the IED and IEC
61850 data objects. The IED Data Mapping module (308) fills the IEC 61850 server index and
shared memory address and type information to the respective IEC 61850 data structures (313).
At runtime, this information is used by IED Data Mapping module (308) to feed data from the
IED shared memory to IEC 61850 server database.
[0073] Yet further, a dynamic object creator takes the IEC 61850 - MMS (Multimedia
Messaging Service) configuration file as an input to initialize the MMS connections as well as
the MMS global objects (304). The MMS global objects (304) also configure the logging and
initialize a memory subsystem.
[0074] Yet further, the SCD file (302) gets parsed further to decode the type information
details. Also, logical device instance(s) (309) are created along with the logical node instances
(310) using SCL data type information (307).
[0075] Control blocks (311), such as buffered report control blocks, un-buffered report
control blocks, and GOOSE control blocks are initialized further by supervisory LN objects
(315).

[0076] After creating the base objects, the corresponding functions are attached to each of
the leaf variables in the form of leaf functions (312). This information is used at run-time for
reading/write operations. The initialization of IEC 61850 server structures helps in the entire
implementation module for easy and fast access to IEC 61850 and IED data at runtime.
IEC 61850 Server
[0077] FIG. 4 shows a block diagram of IEC 61850 server routine which describes the
basic operation of IEC 61850 server functionality. As can be seen from FIG. 4, IEC 61850
server module handles all the IEC 61850 operations. The operations include servicing client
requests (401) with client specific responses (408), validation of client requests (401), and
passing read-write indications (402, 403) to internal data structures (404, 405). The other
important operation or functionality of this IEC 61850 server module is to handle control blocks
(406) according to client specified parameters. This handling includes handling of buffered and
un-buffered report control blocks, setting group control blocks, and log control blocks.
[0078] Providing data information into IEC 61850 server module is done by the data
structures (404, 405). Hence, these structures (404, 405) are referred dynamically by the IEC
61850 server module for any transactions with external clients.
[0079] There are specific functions for handling report data and log data. Such specific
functions are performed by report servicing module (407). Log file recycling of entire system,
limiting of maximum size and acting as a circular file is managed by this report servicing
module (407). This functionality helps entire system to not use disk capacity in an unlimited
manner.
IEC GOOSE Publisher
[0080] FIG. 5 shows a block diagram of the GOOSE publisher which describes IEC 61850
GOOSE publisher functionality. As can be seen from FIG. 5, the IEC GOOSE publisher
module (501) handles all the GOOSE data publishing operations and enable/disable of GOOSE
control blocks by any external clients. This IEC GOOSE publisher module (501) detects the
data changes (503) in GOOSE dataset variables and trigger new GOOSE publishing (504) for
that specific GOOSE control block. Retransmission (505) of the triggered GOOSE, packets are
handled by a separate function which takes care of fast and slow publishing of GOOSE packets
into subnet interface (506).
[0081] GOOSE module demands more performance than IEC 61850 server in terms of its
functionality of putting packets to Ethernet interface bypassing many intermediate MMS

layers. This makes GOOSE a connectionless protocol, which in turn demands retransmissions.
This ensures the receiving of GOOSE packets at the other end even if there is any packet loss.
Subscribers who are interested in SCU’s GOOSE packets will be receiving the same in an
efficient manner because of this retransmission mechanism of IEC GOOSE module.
[0082] Further, in accordance with an exemplary implementation, a fixed number of
GOOSE control blocks are dedicated for GOOSE publishing. Accordingly, the user can assign
any dataset to these GOOSE control blocks while creating ICD / CID files. The user can also
create new dynamic datasets for these publisher GOOSE control blocks.
IEC GOOSE Subscriber
[0083] FIG. 6 shows a block diagram of GOOSE subscriber which describes IEC 61850
GOOSE Subscriber functionality. With reference to FIG. 6, IEC GOOSE subscriber module
(601) handles all the GOOSE data receiving operations and enable/disable of GOOSE control
blocks by any external client. The IEC GOOSE subscriber module (601) detects the data
changes in GOOSE dataset variables received and updates the same to pre-configured shared
memory data structure blocks (604). This IEC GOOSE subscriber module (601) also
simultaneously updates the status in a GOOSE supervision logical node module (605) for any
client to monitor the status.
[0084] In an implementation, subnet interface module (605) is registered to receive
GOOSE packets only for the required MAC addresses. The IEC GOOSE subscriber module
(601) demands more performance than IEC 61850 server in terms of its function of receiving
packets from Ethernet interface by avoiding many intermediate MMS layers. The configuration
of subscriber GOOSE control blocks are handled in the following manner:
i. External inputs section in the SCD File (302) provides information of remote data
attributes that may come from remote Publishers.
ii. During the creation of an SCD file (302), the SCL user should know about the details
of all remote GOOSE control blocks and their respective datasets, to which the IED is
going to subscribe.
iii. As per Edition 2 of IEC 61850, the remote IED details should be present in the SCD
file (302).
iv. The dataset elements in the subscribed GOOSE datasets are mapped to digital output
values of the shared memory using SCU - IEC 61850 map file (303).

[0085] FIG. 7 illustrates example method (700) for implementing switchgear control unit
(SCU) (100) for substation automation system. The order in which the method (700) is
described is not intended to be construed as a limitation, and any number of the described
method blocks may be combined in any order to implement the method (700), or an alternative
method. Furthermore, method (700) may be implemented by processing resource or computing
device(s) through any suitable hardware, non-transitory machine-readable instructions, or
combination thereof.
[0086] It may also be understood that methods (700) may be performed by programmed
computing devices, such as computing device(s) or processor module (102) as depicted in
FIGs. 1-2. Furthermore, the method (700) may be executed based on instructions stored in a
non-transitory computer-readable medium, as will be readily understood. The non-transitory
computer-readable medium may include, for example, digital memories, magnetic storage
media, such as one or more magnetic disks and magnetic tapes, hard drives, or optically
readable digital data storage media. The method (700) is described below with reference to the
processor module (102) and the SCU (100) as described above; other suitable systems/devices
for the execution of the method (700) may also be utilized. Additionally, implementation of
the method (700) is not limited to such examples.
[0087] At block (702), analog and digital field input data are obtained using one or more
sensing modules. In an example, the analog field input data may be obtained using modules
including, but not limited to, 4-20mA module (108), and isolator module (110), while the
digital field input data may be obtained using modules including, but not limited to, digital
input modules (104).
[0088] At block (704), the acquired analog and digital field input data are transmitted from
the one or more sensing modules to a processor module.
[0089] At block (708), the processor module communicates the processed analog and
digital field input data to the IEC 61850 compliant supervisory control and data acquisition
(SCADA) system (204).
[0090] At block (710), the processor module receives control commands from the SCADA
system (204) through bay level IED (206) after satisfying the interlock logics over the IEC
61850 communication protocol based network.
[0091] At block (712), the processor module issues the control command for controlling
the operations of one or more electrical devices of the substation.

[0092] A PC-based configuration tool (208) allows for configuring the following
parameters of switchgear control unit and its configuration screens are shown in Fig 8.1 to 8.8.
- SCU Project Explorer [Fig.8.1]
- Digital Inputs Signal names [Fig.8.2], allows rename of the signal names
- Digital Inputs terminal page [Fig.8.3], use to visualize the digital signals in the field
terminal
- Analog input matrix [Fig.8.4], allows to configure the 4-20mA signals in the field
terminal
- Alarm Configuration [Fig.8.5], allows to configure the alarms to be generated based
on the limit
- Event viewer [Fig. 8.6], for viewing of stored events in the switchgear control unit
IED
- Measurement page [Fig.8.7], online monitoring of 4-20mA analog values
- Digital signals Runtime [Fig.8.8], online monitoring of Digital signals
[0093] Thus, with the present subject matter, a centralized bay architecture of switchgear
control unit having one processor module (microprocessor) and a number of data acquisition
modules (sensing modules) can be implemented. In such architecture, there would be no data
losses and at the same time accuracies would be increased, as all the data processing is
performed by a single processor module. Also, as the single processor module is handling all
the functions, there are no data transfer delays, in addition to better accuracies and no
dependencies.
[0094] The above description does not provide specific details of manufacture or design of
the various components. Those of skill in the art are familiar with such details, and unless
departures from those techniques are set out, techniques, known, related art or later developed
designs and materials should be employed. Those in the art are capable of choosing suitable
manufacturing and design details.
[0095] Note that throughout the following discussion, numerous references may be made
regarding servers, services, modules, interfaces, portals, platforms, or other systems formed
from computing devices. It should be appreciated that the use of such terms are deemed to
represent one or more computing devices having at least one processor configured to or

programmed to execute software instructions stored on a computer-readable tangible, non-
transitory medium or also referred to as a processor-readable medium. For example, a server
can include one or more computers operating as a web server, database server, or another type
of computer server in a manner to fulfill described roles, responsibilities, or functions. Within
the context of this document, the disclosed devices or systems are also deemed to comprise
computing devices having a processor and a non-transitory memory storing instructions
executable by the processor that cause the device to control, manage, or otherwise manipulate
the features of the devices or systems.
[0096] It should be understood, however, that all of these and similar terms are to be
associated with the appropriate physical quantities and are merely convenient labels applied to
these quantities. Unless specifically stated otherwise, as apparent from the discussion herein,
it is appreciated that throughout the description, discussions utilizing terms such as “acquiring”
or “receiving” or “communicating” or “processing” or the like, refer to the action and processes
of a computing machine, or similar electronic computing device, that manipulates and
transforms data represented as physical (electronic) quantities within the computer system's
registers and memories into other data similarly represented as physical quantities within the
computer system memories or registers or other such information storage, transmission or
display devices.
[0097] The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of the present disclosure. It will be
appreciated that several of the above-disclosed and other features and functions, or alternatives
thereof, may be combined into other systems or applications. Various presently unforeseen or
unanticipated alternatives, modifications, variations, or improvements therein may
subsequently be made by those skilled in the art without departing from the scope of the present
disclosure as encompassed by the following claims.
[0098] The claims, as originally presented and as they may be amended, encompass
variations, alternatives, modifications, improvements, equivalents, and substantial equivalents
of the embodiments and teachings disclosed herein, including those that are presently
unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and
others.
[0099] While the foregoing describes various embodiments of the invention, other and
further embodiments of the invention may be devised without departing from the basic scope

thereof. The scope of the invention is determined by the claims that follow. The invention is
not limited to the described embodiments, versions or examples, which are included to enable
a person having ordinary skill in the art to make and use the invention when combined with
information and knowledge available to the person having ordinary skill in the art.

We claim:
1. A switchgear control unit (SCU) (100) for substation automation system, comprising:
a plurality of sensing modules (104, 108, 110) to sense field input data; and
a processor module (102) comprising a data acquisition module (202), coupled to
the plurality of sensing modules (104, 108, 110), and a digital output module (106),
the acquisition module configured to receive the sensed field input data from the plurality
sensing modules (104, 108, 110);
the processor module configured to process the received field input data for
communicating to an International Electrotechnical Commission (IEC) 61850 compliant
supervisory control and data acquisition (SCADA) system (204); and transmit the
processed field input data to the IEC 61850 complaint SCADA system (204) and transmit
the status of the switchgear equipment’s to a Bay level Intelligent Electronic Device (IED)
(206) using IEC61850 GOOSE (Generic Object Oriented Substation Event)
communication;
the Bay Level IED (206) configured to receives commands from the SCADA system
(204) in response to the transmission and transmitted the commands to SCU (100) via
GOOSE after satisfying the interlock logics and the processor of the SCU (100) transmit
digital outputs corresponding to the received commands to the digital output module
(106); and
the digital output module (106) configured to receive the commands for controlling
operation.
2. The SCU (100) as claimed in claim 1, wherein the processor module (102) processes the
received field input data by:
amplifying and correcting the field input data;
extracting fundamental component from the amplified and corrected field input data
using Discrete Fourier Transform (DFT) technique; and
mapping a computed value of the extracted fundamental component with IEC
61850 substation automation protocols for communication with the IEC 61850 compliant
SCADA system (204).

3. The SCU (100) as claimed in claim 1, wherein the plurality of sensing modules (104, 108,
110) include an isolator module (108) to sense and provide a 4-20 mA sensor signal to
the data acquisition module (202); and a digital input module (104) for providing a status
signal from a switchgear in the form of binary data.
4. The SCU (100) as claimed in claim 1, further comprising a power supply module (112)
to supply power to sensing modules (104, 108, 110) and the processor module (102) from
a single source.
5. The SCU (100) as claimed in claim 4, wherein the power supply module (112) supplies
the power to sensing modules (104, 108, 110) and the processor module (102) through a
power cable.
6. The SCU (100) as claimed in claim 1, wherein the plurality of sensing modules
(104,108,110) are coupled to the processor module (102) through Flat Ribbon Cable
(FRC).
7. The SCU (100) as claimed in claim 1, wherein the processor module (102) periodically
provides output data which is sought by an IEC 61850 compliant external client device.
8. The SCU (100) as claimed in claim 1, wherein the plurality of sensing modules (104, 108,
110), processor module (102) and digital output module (106) are housed in a single rack
compliant with electromagnetic-interference (EMI) / electromagnetic-compatibility
(EMC).
9. The SCU (100) as claimed in claim 1, wherein, digital output module (106) is transmit
the commands to PC based configuration tool (208) for configuring the SCU.
10. The SCU (100) as claimed in claim 9, wherein, the PC based configuration tool provides
for on-line and off-line configuration.
11. A method for implementing switchgear control unit (SCU) (100) for substation
automation systems, the method comprising:
acquiring analog and digital field input data using a plurality of sensing modules
(104, 108, 110);
receiving, at a processor module (102), the acquired analog and digital field input
data from the plurality of sensing modules (104, 108,110);

processing, at the processor module (102), the acquired analog and digital field data
for communicating to an International Electrotechnical Commission (IEC) 61850
compliant supervisory control and data acquisition (SCADA) system (204);
transmitting, by the processor module (102), the processed field input data to the
IEC 61850 complaint SCADA system (204) and transmitting the status of the switchgear
equipment’s to a Bay level Intelligent Electronic Device (IED) (206) using IEC61850
GOOSE (Generic Object Oriented Substation Event) communication;
receiving, by the Bay Level IED (206) commands from the SCADA system (204)
in response to the transmission and transmitting the commands to SCU (100) via GOOSE
after satisfying the interlock logics;
receiving, at the processor module (102) of the SCU (100), the commands and
transmitting digital outputs corresponding to the received commands to the digital output
module (106); and
receiving by the digital output module (106) the commands for controlling
operation.
12. The method as claimed in claim 11, wherein the processing at the processor module
comprises:
signal conditioning before digitizing the field input data;
extracting fundamental component from the amplified and phased corrected field
input data using Discrete Fourier Transform (DFT) technique; and
mapping a computed value of the extracted fundamental component with
International Electrotechnical Commission (IEC) 61850 substation automation protocols
.
13. The method as claimed in claim 11, wherein before transmitting digital outputs
corresponding to the received commands to the digital output module (106), the method
further comprising:

mapping, at the processor module (102), the control command received from the
SCADA system (204) through bay control unit (206) using GOOSE to actual switchgear
devices for operation; and
forwarding the mapped control commands comprises the digital outputs
corresponding to the received commands, to a digital output module (106)
communicatively coupled to the processor module (102).