1. Submitted By:
Sayak Chakraborty
3rd
year, B.E.
Electrical Engineering
IIEST,Shibpur.
Project Guide:
Mr. Santanu Sen
Manager
Distribution
Automation
Study of smart grid
In CESC Ltd.
2. Page | I
CERTIFICATE OF DECLARATION
This is to certify that Mr. Sayak Chakraborty, 3rd year undergraduate student of
Electrical engineering dept.,IIEST shibpur, has successfully completed the project titled
“Study of smart grid in CESC Ltd.” under my supervision and guidance during the
summer internship programme, UNMESH 2015.
Date: 04.07.2015 (Signature)
Mr. Santanu Sen
Manager
Distribution Automation
3. Page | II
ACKNOWLEDGEMENT
I take this opportunity to thank CESC Ltd. for their decision to undertake this exquisite
Summer Internship Program “UNMESH”. This has been a great learning curve for me at
Distribution Automation, CESC Ltd., 17 Auckland Square, Kolkata-17. Such a program not only
Opens to us a new arena of learning but alsohelps us have a peek into the professionalworld.
I am thankful to my project guide Mr. Santanu Sen (Manager, Distribution Automation) for
Considering me for this task.My project has been Study of Smart grid in CESC ltd. And a hands
on development of a Wireless intelligent electronic device for interfacing with RTU. This
Project would not have materialized without the supervision from my mentors
Mr. Arka ghosh , Mr. Shubhomoy halder, Mr. Dilip Banerjee and all the staff at CESC who, all
through my stay ,have been immensely helpful and co-operating.
4. Page | III
CONTENTS
Part----A (smart grid in CESC)
1. introduction………………………………..7
2. Smart grid : an overview……………10
3. CESC & Smart grid…………………….16
4. Path Forward……………………………..22
Part----B ( WIED --- RTU interface)
1. Introduction to current system..24
2. Possible solutions………………………26
3. ZIGBEE specs………………………………..30
4. General hardware Architecture 31
5. Software specifications….…………34
6. Proposed system design……………..36
7. Path forward……………………………….38
5. Page | IV
ILLUSTRATIONS
LIST OF DIAGRAMS
Sl. Description Page Number
1. IT-OT convergence in view of smart grid 10
2. Integrated EAI system view 14
3. Fiber optic communication network in CESC 17
4. Front view of an AMR 19
5. Front view of an AMI 19
6. Fault passage indicator 20
7. Street light controller 21
8. Front view of a RTU 25
9. Front view of an MDF 26
10. Infrared based communication 27
11. Rf communication 28
12. Wifi 29
13. Atmega256rfr2 front view 31
14. General networktopology 33
15. Abstraction layers of software stack 33
6. Page | V
LIST OF ABBREVIATIONS USED
1. OT Operations technology.
2. IT Information technology.
3. SCADA Supervisory control and data acquisition.
4. ERP Enterprise resource planning.
5. GIS Geographic information system.
6. CRM Customer relationship management.
7. DSM Demand side management.
8. TOD Time of demand.
9. DMS Distribution management system.
10. OMS outage management system.
11. ADMS Advanced DMS.
12. MDMS meter data management system.
13. AMI Automatic metering infrastructure.
14. AMR Automatic meter reading.
15. EAI Enterprise application integration.
16. PDH Plesiochronous digital hierarchy.
17. SDH Synchronous digital hierarchy.
18. NMS Network management system.
19. RMU Ring main unit
20. MCC Master control centre.
21. BCC Back up control centre.
22. RTU Remote terminal unit.
23. MDF Marshalling distribution frame.
24. HAL Hardware abstraction layer.
25. PHY RF physical layer
26. NWK Network physical layer.
7. Page | VI
Executive Summary
The goal for smart grid technology is to attain higher efficiency and reliable performance. A
smart grid platform implies the convergence of Operations Technology (OT) – the grid
physical infrastructure assets and applications–and Information Technology (IT) – the
human interface that enables rapid and informed decision making. This paper describes
practices for migrating to a scalable, adaptable, smart grid network and compares it to
CESC’s current scenario. Apart from that a hands on implementation of a new idea in the
communication side has been developed and portrayed in detail in this project.
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INTRODUCTION TO CESC:
The Calcutta Electric Supply Corporation or CESC is the flagship company of the RP-Sanjiv
Goenka Group. It is an Indian electricity generation and the sole distribution company Set
up in 1899 serving 567 square km administered by the Kolkata municipal corporation, in the
city of Kolkata, as well as parts of Howrah, Hooghly, 24 Parganas (North) and 24 Parganas
(South) districts in the state of West Bengal. It serves 2.8 million consumers which includes
domestic, industrial and commercial users. Some key features of this company can be
highlighted as below:
CESC is the 4th largest private sector power utility company in India.
The company has built its own fully integrated business model that combines
generation, distribution and coal mining.
The combined generating capacity of the 3 generating stations of CESC & one from
HEL is 1225MW.
The company has got a wide customer base of 2.8 million which is spread over 567
sq km.
80%+ demand of the consumers is met by its own generation and annual peak
demand lies around 1900+MW.
CESC has got 1700 HT consumers like Metro Rail, Electrosteel casting ltd. Etc. who
pay 36% of total annual revenue. Rest comes from commercial and domestic
consumers.
Besides all these CESC has got a portfolio of renewable energy projects across INDIA
that encompasses solar, hydro, wind & MSW.
Coal and gas based IPPs on a pan India basis is another growth plan that the
company has ventured in.
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INTRODUCTION TO PROJECT OBJECTIVES:
Smart grid is the hottest buzzword in today’s power sector industry. Most of the power
utilities proclaim to be smart grid compliant but in reality smart grid is an ever growing
concept which is getting refined day by day. A suitable and competent workforce is required
to adopt, improvise and implement smartness in existing conventional grid.
According to IEEE Smart grid can be defined as, “The "smart grid" has come to describe a
next-generation electrical power system that is typified by the increased use of
communications and information technology in the generation, delivery and consumption of
electrical energy”. Western power utilities have started long back implementing advanced
technologies for monitoring and control purpose of their system to ensure reliable power
supply but in India’s perspective the concept is relatively new and Indian power utilities
initiated their smart grid initiative years ago.
CESC is no exception to them. Being a forerunner in the power sector of India it has
successfully implemented several Technologies for control and monitoring purpose of their
system and the process is still going on.
Here, in these project we’d study and evaluate the current status of CESC smart grid in
nation as well as world’s perspective , its future plan and suggest some improvements that
are technically feasible to incorporate. At last we’ll show the development of a Wireless
intelligent electronic device for interfacing with RTU which might be considered as a small
contribution towards a smarter system. However, this project will only focus on the
automation of distribution side of a power utility in context of smart grid. Other important
aspects of smart grid like renewable energy utilisation are not taken into consideration here.
10. Page | 9Chapter XXX : Chapter Name
SIGNIFICANCE OF THE PROJECT:
The study of current status of smart grid will bring out the pros and cons of the prevalent
systems and the suggestions that are made after technical feasibility study can be
considered to be implemented for betterment of the existing grid systemof CESC.
In the latter part this project gives a demonstration about one of its suggestions i.e wireless
connectivity between switchgear panel and the RTU which largely eliminates the
requirement of wired connection in distribution stations or substations. The cost of cable,
carrier tray, MDF can all be eliminated with the installation of this smart device, which itself
is pretty cheap, inside the switchgear panels. This gives the company an idea to carry out a
pilot project that whether this device will be suitable to serve in their systemenvironment.
A detailed study of economic and other benefits of the company with the installation of this
device can be found later on .
11. Page | 10Chapter XXX : Chapter Name
Smart grid in CESC
1.Definition of smart grid:
A smart grid is a modernized electrical grid that uses analogue or digital information and
communications technology to gather and act on information - such as information about
the behaviours of suppliers and consumers - in an automated fashion to improve the
efficiency, reliability, economics, and sustainability of the production and distribution of
electricity. Electronic power conditioning and control of the production and distribution of
electricity are important aspects of the smart grid.
2. Executive summary:
The goal for any utility that invests in smart grid technology is to attain higher efficiency and
reliable performance. A smart grid platform implies the convergence of Operations
Technology (OT) – the grid physical infrastructure assets and applications–and Information
Technology (IT) – the human interface that enables rapid and informed decision making.
This paper describes practices for migrating to a scalable, adaptable, smart grid network and
compares it to CESC’s current scenario.
Fig 1: IT OT convergence in SMART GRID
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3.Smart grid in the view of IT--- OT convergence:
Operations Technology (OT) represents a broad category of components that utilities
depend on for safe and reliable generation and delivery of energy. OT encompasses
operating gear, from oil circuit breakers and sectionalizers to solid-state relays, and many
devices in between. OT also often includes control room applications, such as supervisory
control and data acquisition (SCADA) systems that monitor the network.
If OT is the purview of the few, Information Technology (IT) is just the opposite. IT systems
are in place to allow machines to exchange information directly with humans, usually within
a second or longer. The utilities industry has experienced an exponential increase in both
quantity and quality of IT systems. Improved Enterprise Resources Planning (ERP),
Geographic Information Systems (GIS), and Customer Relationship Management (CRM)
systems, along with office-based productivity tools and mobile computing devices, have
permeated the utility workplace. Yet, until recently, the growth in IT stood independent of
the hidden OT equipment quietly humming along in the field, serving and protecting the
grid.
4. Integrated communication technology:
Some communications are up to date, but are non-uniform because they have been
developed in an incremental fashion and not fully integrated. In most cases, data is being
collected via modem rather than direct network connection. Areas for improvement
include: substation automation, demand response, distribution automation, supervisory
control and data acquisition (SCADA), energy management systems, wireless mesh
networks and other technologies, power-line carrier communications, and fibre-
optics Integrated communications will allow for real-time control, information and data
exchange to optimize systemreliability, asset utilization, and security.
5. Demand Side Management:
demand side management (DSM), is the modification of consumer demand
for energy through various methods such as financial incentives and behavioural change
through education. Usually, the goal of demand side management is to encourage the
consumer to use less energy during peak hours, or to move the time of energy use to off-
peak times such as night time and weekends.
It essentially reduces the need of investment to improve network or power plant equipment
to meet peak demand.
Different approaches that has been made are:
1. Using less power to perform the same tasks. This involves a permanent reduction of
demand by using more efficient load-intensive appliances such as water heaters,
refrigerators, or washing machines.
2. Any reactive or preventative method to reduce, flatten or shift demand. Historically
demand response programs have focused on peak reduction to defer the high cost of
constructing generation capacity. However, demand response programs are now being
looked to assist with changing the net load shape as well, load minus solar and wind
13. Page | 12Chapter XXX : Chapter Name
generation, to help with integration of Variable renewable energy Demand Response
includes all intentional modifications to consumption patterns of electricity of end user
customers that are intended to alter the timing, level of instantaneous demand, or the total
electricity consumption. Installation of TOD meters is one such approach.
It is an Energy meter which measures the energy consumed and also the time of day it
was consumed. TOD meter gives it output in the form of slabs with the energy units and
the time. The utility then applies the cost per unit depending on the time and the
customer gets the final bill.
3. Advance or delay appliance operating cycles by a few seconds to increase the Diversity
factor of the set of loads. The concept is that by monitoring the power factor of the power
grid, as well as their own control parameters, individual, intermittent loads would switch on
or off at optimal moments to balance the overall system load with generation, reducing
critical power mismatches. As this switching would only advance or delay the appliance
operating cycle by a few seconds, it would be unnoticeable to the end user.
6 .Advanced Monitoring system:
6a. Advanced dms:
Leading utilities and their vendor partners take is to integrate distribution operational
applications into a single platform. This helps to streamline the management of the overall
system and offers improved workflow, and simplifies task execution. Often referred to as
Advanced DMS (ADMS), this approach merges DSCADA, OMS, and DMS into a single
platform. By giving users a single tool that presents an integrated flow of information in a
unified, straightforward user experience, operations and analysis of the distribution grid are
simplified for the operator, and high-speed, high-quality decisions are enabled.
Outage management system:
The Outage Management System (OMS) at many sites has migrated away from the
enterprise and towards the operations domain. Once considered by many to be an
extension of a call centre application, modern OMS deployments now embed network
intelligence to support restoration and switching. The more accurate and up-to-date the
OMS network model is, the more likely it is to be integrated into the other applications and
workflow of the operations centre. It might seem obvious, but the convergence of IT and OT
has far-reaching implications for the operational applications that model, monitor, and
manage the distribution network.
6b. Meter data management system:
An MDM system is the IT interface of AMR & AMI system which themselves are key
components of a smart grid. An MDM system performs long term data storage and
management for the vast quantities of data delivered by smart metering systems. This data
consists primarily of usage data and events that are imported from the head end servers
14. Page | 13Chapter XXX : Chapter Name
that manage the data collection in Advanced metering infrastructure (AMI) or Automatic
meter reading (AMR) systems.
An MDM systemwill typically import the data, then validate, cleanse and process it before
making it available for billing and analysis. Solutions based on meter data include Smart
meter deployment planning and management; Meter and network asset monitoring and
management; Automated smart meter provisioning (i.e. addition, deletion and updating of
meter information at utility and AMR side) & billing cutover; Meter-to-Cash system,
workforce management system, asset management and other systems. Furthermore, an
MDMS may provide reporting capabilities for load and demand forecasting, management
reports, and customer service metrics.
6c. IT INFRASTRUCTURES:
Other discrete areas of IT development for smart grid includes mainly:
1.GIS
2.CRM
Utility operators will need GIS to make the best decisions about key issues such as collecting
data, managing smart meter and sensor installation, analysing customer behaviour, and
incorporating renewable energy. When viewed in the context of geography, data is quickly
understood and easily shared. Furthermore, GIS technology can be integrated into any
enterprise information systemframework. Simply put, GIS makes it possible for utilities to
build and operate a smart grid.
WORKFORCE AUTOMATION &SITUATION AWARENESS are two main advantages the system
takes care of.
7. Enterprise application integration:
Driving the increase for integration on the front end for many SCADA, DMS, and OMS
applications is the need for accurate network models. Maintaining an up-to-date view of the
network is a challenge for many legacy SCADA, DMS, and OMS applications.
The performance requirements of an OMS or DMS – and to some extent Distribution SCADA
(DSCADA) – dictate that the up-to-date network model, or at least relevant parts of it, be
available immediately. When an outage occurs or an emergency switching operation is
imminent, grid operators require the model be in its most accurate, current state. Sourcing
that current, high-performance model can be a challenge.
Most utilities today use a geographic information system(GIS) as a critical part of their
network and asset management toolset. GIS-based network models can furnish an
important representation of the as-built network, but that model must be more complete,
correct, and current than ever before. In order to support performance and current state
15. Page | 14Chapter XXX : Chapter Name
requirements, a new level of network model integration is required. Modern integration
technology and architecture can make it possible for SCADA, DMS and OMS to share a
common model sourced from the GIS as-built network. The single, unified environment and
user experience – in effect, ‘a single version of the truth’ – can be achieved without
sacrificing data freshness or speed.
Fig 2: integrated EAI system view
In CESC there’re no such integrated platform till date to put all these data together for
access but different platform are discretely merged and work in accordance with one
another. It’s highly recommended to bring them under a single shade as a leading utility-like
practice.
8. Ami & AMR SYSTEMS:
A smart grid often replaces analogue mechanical meters with digital meters that record
usage in real time. Often this technology is referred to as Advanced Metering Infrastructure
(AMI) since meters alone are not useful in and of themselves and need to be installed in
conjunction with some type of communications infrastructure to get the data back to the
utility (wires. fibre, WiFi, cellular, or power-line carrier). Advanced Metering Infrastructure
may provide a communication path extending from power generation plants on one end all
the way to end-use electrical consumption in homes and businesses. These end use
consumption devices may include outlets, (smart socket) and other smart grid-enabled
appliances such as water heaters and devices such as thermostats. Depending on the utility
16. Page | 15Chapter XXX : Chapter Name
program, customers may be contacted or devices may be shut down or have their setting
modified automatically during times of peak demand.
AMI extends current advanced meter reading (AMR) technology by providing two way
meter communications, allowing commands to be sent toward the home for multiple
purposes, including “time-of-use” pricing information, demand-response actions, or
remote service disconnects.AMI differs from traditional automatic meter reading (AMR)
in that it enables two-way communications with the meter.
9. Smart grid sustainability:
The improved flexibility of the smart grid permits greater penetration of highly variable
renewable energy sources such as solar power and wind power, even without the addition
of energy storage. Current network infrastructure is not built to allow for many distributed
feed-in points, and typically even if some feed-in is allowed at the local (distribution) level,
the transmission-level infrastructure cannot accommodate it. Rapid fluctuations in
distributed generation, such as due to cloudy or gusty weather, present significant
challenges to power engineers who need to ensure stable power levels through varying the
output of the more controllable generators such as gas turbines and hydroelectric
generators. Smart grid technology is a necessary condition for very large amounts of
renewable electricity on the grid for this reason.
17. Page | 16Chapter XXX : Chapter Name
Current status of smart grid in CESC:
So far we have given the reader an idea about the current status of smart grid in the leading
power utilities of the world where operation technology (OT) merges with information
technology (IT) and vice versa. With regard to that knowledge we’ll move forward and
compare CESC’s current status to state-of-the-art smart grid and will suggest suitable
modifications, if any.
Integrated communication technology:
CESC has its own optical fibre rich network and
The major hardware equipment used to set-up this OpticalFiber Communication Network are
(i) Access Multiplexer (PDH)
(ii) Transport Multiplexer (SDH STM-4)
Equipment of ABB make are installed. They are integrated to meet our traffic requirement.
For each system, there are NMS for monitoring, configuration and testing of various Network
components from the Communication Control Centre.
Voice 2W from central EPABX at CESC House
18. Page | 17Chapter XXX : Chapter Name
VoIP VLAN
Exchange to Exchange E1 connectivity
Tx SCADA data (19.2kbps,E,8,1)
Emergency Trip & Budge Budge Lock Out
DMS VLAN
Tx SCADA VLAN
Dist. SCADA VLAN
Protection VLAN
RMU Automation
Future provisions for CCTV, Videoconferencing
RF Mesh Communication:
A pilot project for RF Mesh based communication has been rolled out and it’s actually used in
a small scale basis in select areas for below mentioned purposes:
1. AMI &AMR READING TRANSFER
2. Data transmission from FRTUs installed beside RMUs.
19. Page | 18Chapter XXX : Chapter Name
Fig 3: fiber optic communication N/W in CESC
Demand Side Management:
CESC has installed TOD meters in LT commercial, industrial and for other part of the
consumer base. Special rebated tariff scheme for different power factor and load factor
slabs are being implemented. There are also some roll out pilot projects where remote load
switching at consumers’ end are being done on the concerned customer’s consent. Works
on further advanced technology adoption is going on even though CESC has immense room
for improvement in this specific sector.
Different Slabs for power and load factor can be found in the appendices that are currently
in use.
Advanced monitoring system:
1. Except the offline DMS system currently functional, i.e SIEMENS SINAUT SPECTRUM 4.5
CESC has its own home grown software DISTRIBUTION TRANSFORMER MANAGEMENT
SYSTEM that help to manage entire life cycle procure management, storing, testing,
installation are also monitored. This systemis integrated with DREAMS system. Another
homegrown LCC system SLIM help to track, control T&D loss. But a complete integrated
ADMS systemis not yet in the place.
2. In CESC the OMS/FMS is integrated with the DREAMS software. It also works in
accordance with other systemsoftware like DLTMS & DPMS.
MDMS:
In CESC the existing systemthere is a web based systemthat keeps track of different
parameters from static meters/AMRs & as well as those from DTRs and can download them
in .XML format. This’s a SUN SOLARIS 10 based software. this systemis integrated to a
consummated ERP GL module & supports CIS Features like transferring post billing data at
desired granularity.
GIS INFRASTRUCTURE:
CESC consumer base has been divided into 10 areas and district wise maps are being
prepared. At present 2 district maps are made. A web based systemhas also been launched
for viewing and updating the database. Options for network tracing will also be
incorporated. In future it’ll be incorporated with CESC’s CRMsystem for smoothening of
operation.
CESC in AMI & AMR:
Preparation for AMR:
20. Page | 19Chapter XXX : Chapter Name
From 1995 CESC has a working meter reading system, through which all information
of static meters were retrieved through smart HHUs. CESC has also developed its
own MDMS even in those early days of IT exposure. This strong framework helps
the system achieve efficient, effective, intelligent meter to cash recovery cycle.
These serves as the launching pad of future AMR system. these meters have
following features
1. GPRS/GSM modem installed inside.
2. Readings from all these meters are being downloaded by a server with a powerful
software named INTEGRATOR developed by secure meters.it runs on ORACLE 10G
platform and is capable of downloading data from 15000 meters of 90 days within 5
hours.
3. Communication platform used for data traffic is the GPRS cloud from the remote
meters end modem to the server of service provider. The GSM (Data over voice
channel) are kept as a back-up plan.
Other AMR PURPOSES:
1. Pilferage detection:
AMR for DT metering is used to identify pockets having high distribution loss due to
pilferage of electricity.
2. Improved customer service:
Through SMS based alarm systemfrom the DT,by letting the call centres know of any fuse
failure cases in DT LT side or at feeder pillar box end, even before the customer calls to
inform about his power failure
3.Proactive action and health monitoring of the transformers were also possible by the
same device.
Fig 4: front view of an AMR installed in DTr
AMI FIELD TRIALS:
The meter utilises a remote consumer display unit operated through PLC & has bidirectional
communication with a router. This router can in turn communicate and can be reached
through GPRS/GSM modem from the base station. The meter has connect disconnect
features based on threshold values of voltage current &power factor thresholds as well as on
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demand switching operation. The meter can be converted to a pre/post payment meter based
on customers’ choice.
FIG 5: State of the art AMI systems.
Current developments in Feeder Automation:
1. Installation of Automated and semi-automated RMUs helped reduce power restoration
period by a substantial amount.
2. Fault Passage indicator:
Can sense both short circuit and earth fault separately
•Sensors may be coupled to the unit through metallic/OF cable or through radio
•Supports local display and manual reset facility
•Provides fault detection contacts and remote reset contact for interface to FRTU
•Equipped with batteries (Lithium)
Except these features, recently installed modules have a GSM modem via which it can
communicate to the networking monitoring system about its current status.
Fig 6: fault passage indicator
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STREET LIGHT CONTROLLING SYSTEM:
Street lights are a major source of revenue drain for all cities and can result in lot of
inconvenience to the citizen if not maintained properly. System from siemens and genus has
been procured to control the street lighting in a fitting manner. It’s a complete street light
management solution having following features:
Low cost wireless control
Efficient and effective energy accounting
Increased lamp life, configurable overload settings.
Powerful software with GPS mapping
Extensive MIS report based on performance and energy saving
Integration with legacy billing system.
Fig 7: street light controller
CESC in sustainable development:
CESC, even though, does not possess any renewable energy generating unit within its
distribution licenced area but have opportunity for customers who intend to release the
burden of conventional energy like most of the leading power utilities do
CESC is encouraging such interconnection and has already allowed interconnection in the
following cases. • Sir Nripendra Nath Girls’ High School – 3 kWp • Raj Bhavan – 50 kWp •
RKM Seva Pratisthan – 6.9 kWp.
There are quite a few more cases viz. Writer’s Building (15 kWp), Shaid Minar (4.5 kWp),
Bidhan Sabha (20 kWp), Rama Krishna Mission Vidyamandira, Belur (15 kWp) etc. where the
roof-top Solar PV Plants are to be interconnected with CESC’s distribution system. Supply of
electricity to the consumer(s) from CESC’s System and that to the CESC’s System from the
roof-top Solar PV sources should be measured for net metering arrangement. This may be
done either by two separate meters, or alternatively by an export-import type meter
suitable for directly measuring the net exchange. Availability of whole current export-import
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meter is as major issue and CESC has developed an arrangement for the purpose. However,
for CT operated meters, export-import meters are available.
CESC have already set up few green energy plants outside west Bengal e.g: Arunachal
Pradesh, Maharashtra etc.
Path forward
Based on above system study we are going to evaluate current standing of CESC smart grid
and suggest some features that are technically feasible to incorporate in CESC’s scenario.
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1. Islanded SCADA/DMS or MDMS system is not suitable for data exchange hence an
integrated data storage systemhas to be formed to enable more efficient monitoring on the
network. A state of the art enterprise integration application (EAI) is suggested to be formed
that will integrate other datum like ERP, EAM, FMS, GIS etc.
2. SCADA/DMS currently operational are not ready to support advanced DMS (ADMS)
features that support several systems running in parallel, where each system consists of a
set of services needed to successfully run distinguishable roles of the control centre like
Production System, Test System, Data Entry System, Training System, and Emergency
Backup System. Therefore, control centre hardware consists of several computer groups
and networking equipment: data acquisition servers, application servers, engineering data
servers, UI clients, redundant LAN, time system(GPS), printers, network devices (routers).
Scalability is an important architectural aspect and the system supports various
deployments - from many pairs of redundant servers to a single computer hosting
everything. Also, such computer groups can be placed in different security zones and sites
(for disaster recovery or other) where methods for sending data across different security
zones are important in order to comply with customer’s strict security rules.
3. Current disaster recovery system in BCC needs enhancement.
4. GIS needs functional enhancement.
5. Twin communication infrastructure is required for ensuring uninterrupted system
performance.
6. Synchrophasor technology, which uses devices called phasor measurement units (PMUs)
to measure the instantaneous voltage, current, and frequency at substations, is being
deployed to enhance wide-area monitoring and control of the transmission system.
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Part B: Wireless intelligent electronic device for interfacing
with RTU:
Current working system:
The systemthat’s presently deployed to interface with the RTU can be described below:
What are RTUs?
RTUs are microprocessor controlled intelligent electronic devices used in the field through
which the central SCADA systemfrom a remote location controls the field instruments. It
acts as a standalone data acquisition and control unit, which processes field instruments,
carries data acquired from the field to the control center, and performs control tasks issued
from the control centre. In short, it interfaces objects in the physical world to SCADA
system.
The field inputs of the power utility required at the remote manned station are of two
types:
1. Digital inputs, which can have only two states, 0 or 1. Following are the digital inputs
taken by the RTU:
a. Status of Circuit Breakers (whether on or off)
b. Status of Isolators (whether on or off)
c. Mechanism position (ex. Spring charge)
d. Bus selection position
e. Test/ Service position
f. Tap position indication of power transformers read in binary code
g. Bay level alarms (ex. ‘low SF6’)
h. Transformer tripping and non-tripping relay indications
i. Station level alarms
j. Local/ Remote position status for RTU
2. Analogue measurands, which include:
a.Current, voltage, frequency
b. Active power, reactive power, power factor and kWh
c. Transformer tap position
d. Station battery voltage
e. Oil and winding temperatures
f. Output of transducers (ex. Leg current in double cable box CBs)
hardware :the field interface
The I/Os to and from the MDF which are hardwired to the field are called Hard I/Os whereas
those from MFMs and transducers are called Soft I/Os. The Marshalling Distribution Frame
or MDF acts as the junction box between the RTU and switchgear. The input/ output signal
cables from the I/O modules are connected to a termination block (AVT). The termination
points are taken to the adjacent MDF panel through signal cables of different sizes. Separate
cables are used for analog, digital and command signals. The MDF contains a large number
of terminal blocks where the 10P (10 pair) cables from the field terminate, and from the
26. Page | 25Chapter XXX : Chapter Name
MDF, 50P (50 pair) and 10 cables carry the signals to and from the Remote Terminal
Unit.Depending on the type of RTU (i.e. on the number of I/Os needed in a particular
Distribution station), the MDF has a fixed number of Terminal Blocks (TBs), each of which
has a fixed number of terminals which are wired to the corresponding terminals of the RTU.
From the MDF panel, signals are distributed to the individual Relay/ Control/ Indication
panels through different signal cables. ––
fig 8: front view of an RTU
27. Page | 26Chapter XXX : Chapter Name
Fig 9: Marshalling distribution frame
WIRELESS SOLUTION:
As the project objective suggests,the wires that carry signals from RTU to switchgear panel
and vice versa are to be eliminated & a suitable wireless solution has to be found.The
approximate amount of cost that the utility has to bear in laying these cables and their
carriers is approximately 3-4 lakhs.So,the cost of wireless solution that we’re going to
propose has to be less than that to lower the expenditure.
The possible wireless solutions available in the market are listed below along with their
merit and demerit.We have to choose one among these as the need demands.
In general there are 6 wireless technologies available in the market & they are respectively:
28. Page | 27Chapter XXX : Chapter Name
1.Infrared communication:
communicates information in a device or systems through IR radiation. IR is
electromagnetic energy at a wavelength that is longer than that of red light. It is used for
security control, TV remote control and short range communications. In the electromagnetic
spectrum, IR radiation lies between microwaves and visible light. So, they can be used as a
source of communication.
Merit:
1. It is pretty cheap
Demerit:
1.The data transmitted is not very secure and can be easily tapped.
Fig 10: IR communication system
2. Radio Frequency Communication:
The first wireless communication technology is the open radio communication to seek out
widespread use, and it still serves a purpose nowadays. Radio uses a transmitter which is
used to transmit the data in the form of radio waves to a receiving antenna. Radio
broadcasting may be done via cable FM, the net and satellites. A broadcast sends
information over long distances at up to two megabits/Sec (AM/FM Radio).
Radio waves are electromagnetic signals that are transmitted by an antenna. These waves
have completely different frequency segments, and you will be ready to obtain an audio
signal by changing into a frequency segment.
Merit: Cheap and suitable for medium Range communication
Demerit: Data transmission might be hampered by weather condition.
29. Page | 28Chapter XXX : Chapter Name
Fig 11: RF communication system
3. Microwave communication:
an effective type of communication, mainly this transmission uses radio waves, and the
wavelengths of radio waves are measured in centimeters. In this communication, the data
or information can be transfers using two methods. One is satellite method and another one
is terrestrial method.
Merit: perhaps the most effective system.
Demerit: costly than other solutions
4. Wifi :
It is a low power wireless communication device that is used by various electronic devices
like smart phones, laptops, etc.In this setup, a router works as a communication hub
wirelessly. These networks allow users to connect only within close proximity to a router.
WiFi is very common in wireless networking portability wirelessly. These networks need to
be protected.
merit: suitable for high data rate application like internet service.
Demerit: security is of utmost concern.
30. Page | 29Chapter XXX : Chapter Name
Fig 12: WIFI system
5.Mobile communication system:
The advancement of mobile networks is enumerated by generations. Many users
communicate across a single frequency band through mobile phones. Cellular and cordless
phones are two examples of devices which make use of wireless signals. Typically, cell
phones have a larger range of networks to provide a coverage.But, Cordless phones have a
limited range. Similar to GPS devices, some phones make use of signals fromsatellites to
communicate.
6.Bluetooth:
The main function of the Bluetooth technology is that permits you to connect a various
electronic devices wirelessly to a system for the transferring of data.Cell phones are
connected to hands free earphones, mouse, wireless keyboard. By using Bluetooth device
the information from one device to another device. This technology has various functions
and it is used commonly in the wireless communication market.This’s not very secure.
System requirements:
1.Range:
The range over which our data is to be transmitted is either medium or short range i.e
devices that can communicate in LOS of few metres to 100 metres would be suitable for our
requirement.
2.Data Rate:
The requirement of data rate is also not very high.We have to transmit several digital and
analogue signals to the RTU end as per our requirement.Even though the data is sampled in
real time but with proper software adjustment of microcontroller function our requirement
can be customized to transmit data in a suitable fashion.
3.Ambience:
Our requirement is completely in-house where the modules will be placed within switchgear
panels.So there’d be possibly not much hazard that would bother data transmission.To
avoid metallic and other obstructions external antenna might be used.That can help
increase the gain and link budget also.
31. Page | 30Chapter XXX : Chapter Name
4.Band:
As determined by ISM there are several free bands but most popular radio band for short
range communication is 2.4 GHz band and its already in use in different wireless sensor
network application having scenario kind of similar to ours.Most devices operating in this
freqency offers an adjustable range of 100 MHz.
5.Interference immunity:
As the devices would be operating in the vicinity of High voltage circuits as well as some
similar modules of the other kind they have to be made with suitable interference guard to
protect the signals fromelectromagnetic or radio frequency interference.
6.Security:
The data that are to be transmitted has to be properly encrypted such that safe
transmission is ensured.
With the above technical constraints in mind we have chosen the radio
modules that use zigbee standard for our purpose.This choice also takes into account the
budget reduction of utility in this particular sector as Rf modules along with antenna are
pretty cheap
Zigbee specification:
ZigBee is a specification for a suite of high-level communication protocols used to create
personal area networks built from small, low-power digital radios. Zig-Bee is based on an
IEEE 802.15.4 standard.
1. Though its low power consumption limits transmission distancesto 10–100 meters line-of-
sight, depending on power output and environmental characteristics, ZigBee devices can
transmit data over long distances by passing datathrough a mesh network of intermediate
devices to reach more distant ones.
2. ZigBee is typically used in low data rate applications that require long battery life and
secure networking (ZigBee networks are secured by 128 bit symmetric encryption keys.)
ZigBee has a defined rate of 250 kbit/s, best suited for intermittent data transmissions from
a sensor or input device.Further data encryption can be done by writing APIs that can
interact with NWK layer.
3. Applications include wireless light switches, electrical meters with inhome-displays, traffic
management systems, and other consumer and industrial equipment that requires
shortrange low-rate wireless data transfer.That pretty much match with our operations
where we will have to take digital indications from Circuit breakers,Transformer tap position
and analog data from MFMs to transmit to a remote end module.
4. The technology defined by the ZigBee specification is intended to be simpler and less
expensive than other wireless personal area networks (LoWPAN).A switch to WPAN from
the current daisy-chained adam module based signal transmission will make the network
more flexible for both operation and modification as any change can be done via firmware
alteration.
32. Page | 31Chapter XXX : Chapter Name
5. Besides all these ZIGBEE devices offer an open source cluster library that makes it easier
to customize your application programming interface upon protocol layers as par your
requirement demands.
6. While designing a system based on Zigbee protocol a designer can make his firmware so
optimized that 3 types of devices exist on a single network 1.CO-ORDINATOR 2. ROUTER
3.END DEVICE.As the name suggests a co-ordinator is to set up a network and acts as a
central node.Data from different nodes come to co-ordinator for further processing or
transmission.Whereas a router is an intermediate device responsible for data transmission.
An end device is not very different from router except that it can not directly talk to the
parent node.That allows it to be asleep for a significant amount of time for power
management purpose.
7. The current ZigBee protocols support beacon and non-beacon enabled networks. In non-
beacon-enabled networks, an unslotted CSMA/CA channel access mechanism is used. In this
type of network, ZigBee Routers typically have their receivers continuously active, requiring
a more robust power supply. However, this allows for heterogeneous networks in which
some devices receive continuously, while others only transmit when an external stimulus is
detected. That actually fits with our application where we can use a MAC enabled BEACON
for end devices.
8. ZigBee uses 128-bit keys to implement its security mechanisms. A key can be associated
either to a network, being usable by both ZigBee layers and the MAC sublayer, or to a link,
acquired through pre-installation, agreement or transport. Establishment of link keys is
based on a master key which controls link key correspondence. Ultimately, at least the
initial master key must be obtained through a secure medium (transport or pre-installation),
as the security of the whole network depends on it. Link and master keys are only visible to
the application layer. Different services use different one-way variations of the link key in
order to avoid leaks and security risks
General architecture of Wireless solution:
As we have proposed so far we are going to use wireless radio modules that use zigbee
standard for communication.Therefore the Hardware specification will be like:
A module that needs to have a RF transceiver chip and a microcontroller for programming
that chip.External antenna may or may not be added according to our system
requirements.other secondary equipment like resistor,capacitor or crystal oscillator has to
be added after final design has been done.
After a lot of market research it’s been found that theirs is an available product from ATMEL
that actually matches to all our requirement as mentioned before and also offer another
important feature and that is a single chip SoC solution with both MCU and RF transceiver
that helps fater data reception and transmission and processing thus making it a Robust
industrial module.The complete system with Its features is described as below (Features
that we’ll use only) :
• Network support by hardware assisted Multiple PAN Address Filtering
• Advanced Hardware assisted Reduced Power Consumption
• High Performance, Low Power AVR® 8-Bit Microcontroller
- Up to 16 MIPS Throughput at 16 MHz and 1.8V – Fully Static Operation
• Non-volatile Program and Data Memories
33. Page | 32Chapter XXX : Chapter Name
- 256K/128K/64K Bytes of In-System Self-Programmable Flash
• Endurance: 10’000 Write/Erase Cycles @ 125°C (25’000 Cycles @ 85°C)
8 KBytes EEPROM
• Endurance: 20’000 Write/Erase Cycles @ 125°C (100’000 Cycles @ 25°C)
- 32KBytes Internal SRAM
• Peripheral Features
- Multiple Timer/Counter & PWM channels
- 10-bit, 330 ks/s A/D Converter; Analog Comparator; On-chip Temperature Sensor
- Master/Slave SPI Serial Interface
- Two Programmable Serial USART
- Byte Oriented 2-wire Serial Interface
• Fully integrated Low PowerTransceiver for 2.4 GHz ISM Band
- High Power Amplifier support by TX spectrum side lobe suppression
- Supported Data Rates: 250 kb/s and 500 kb/s, 1 Mb/s, 2 Mb/s
- -100 dBm RX Sensitivity; TX Output Power up to 3.5 dBm
- Hardware Assisted MAC (Auto-Acknowledge, Auto-Retry)
- 32 Bit IEEE 802.15.4 Symbol Counter
- SFD-Detection, Spreading; De-Spreading; Framing ; CRC-16 Computation
Antenna Diversity and TX/RX control/ TX/RX 128 Byte Frame Buffer
• PLL synthesizer with 5 MHz and 500 kHz channel spacing for 2.4 GHz ISM Band
• Hardware Security (AES, True Random Generator)
• Integrated Crystal Oscillators (32.768 kHz & 16 MHz, external crystal needed)
• I/O and Package
- 38 Programmable I/O Lines
• Temperature Range: -40°C to 125°C Industrial
• Ultra Low Power consumption (1.8 to 3.6V) for AVR & Rx/Tx: 10.1mA/18.6 mA
- CPU Active Mode (16MHz): 4.1 mA
- 2.4GHz Transceiver: RX_ON 6.0 mA / TX 14.5 mA (maximum TX output power)
- Deep Sleep Mode: <700nA @ 25°C
• Speed Grade: 0 – 16 MHz @ 1.8 – 3.6V range with integrated voltage regulator.
34. Page | 33Chapter XXX : Chapter Name
Fig 13: pointed diagram of an ATMEL RF transceiver
The external headers protruding outside the board are different pins of the microcontroller
ATmega256RFR2.For a detailed description of the external headers please look into the
datasheet of the ATmega256rfr2 xplained pro, of which the link has been mentioned in
bibliography.
SOFTWARE SPECIFICATION:
As we have mentioned earlier that ZIGBEE specification suite provides us with some cluster
library or software development kits that makes the job of a design engineer easy to
customize the firmware for his own application. Here we are going to use an available
software stack LIGHTWEIGHT MESH that is a low power, proprietary wireless mesh network
protocol. One can build his own APIs to communicate with each abstraction layer of the
stack. Several features can be looked into of this software stack …..
• Simplicity of configuration and use
35. Page | 34Chapter XXX : Chapter Name
• Up to 65535 nodes in one network (theoretical limit)
• Up to 65535 separate PANs on one channel
• 15 independent application endpoints
• No dedicated node is required to start a network
• No periodic service traffic occupying bandwidth
• Two distinct types of nodes:
• Routing (network address < 0x8000)
• Non-routing (network address ≥ 0x8000)
• Once powered on node is ready to send and receive data; no special joining procedure is
required. power management of node can be done by programming.
• No child-parent relationship between the nodes
• Non-routing nodes can send and receive data to/from any other node (including non-
routing nodes), but they will never be used for routing purposes
• Route discovery happens automatically if route to the destination is not known
• Routing table is updated automatically based on the data from the received and
transmitted frames.
• Optional support for AODV routing
• Optional support for multicast communication
• Duplicate frames (broadcast or multipath unicast) are rejected & basic security.
Network Topology:
Network topology and possible device types are illustrated by Figure. Nodes shown in blue
are routing nodes; they form a core of the typical network and expected to be mains-
powered. Nodes shown in green are non-routing nodes; they are part of the network and
they can send and receive data as long as they are in range and have the radio turned on,
but they are not expected to be available all the time (they can be sleeping nodes, mobile
nodes going out of range, etc). Non-routing nodes will not be used for routing purposes, so
they cannot act as range extenders, and typically will be located at the edge of the network.
In our application end devices might not be required right now but can be added if one
needs to remotely monitor other important data like a station battery or temperature etc.
on a regulatory basis.
36. Page | 35Chapter XXX : Chapter Name
Figure 14: Network topology of the proposed system
Software stack architecture:
The architecture of the software stack is shown below.
Fig 15: Abstraction layers of software stack
The above figure gives a brief idea about different abstraction layers that the protocol uses to
set up a PAN based communication system.
37. Page | 36Chapter XXX : Chapter Name
• Hardware Abstraction Layer (HAL) provides basic hardware dependent functionality, like
hardware timer, sleep control, GPIO access for the radio interface
• Radio physical layer (PHY) provides functions for radio transceiver access. Some of them
are accessible only by the network layer (request to send data, data indication); some of
them can be used from the application (channel selection, random number generation,
energy detection, etc.)
• Network layer (NWK) provides core stack functionality.
• System services provide common functions for all layers, which are necessary for normal
stack operation. System services include basic types and definitions, software timers,
default configuration parameters, encryption module access, etc.
• Application services include modules that are not required by the stack, but are common
for most applications. Currently the only service of this type is Over-The-Air upgrade
(OTAU).
Proposed System Design:
The proposed system to replace currently functional wired connection between MDF and
RTU is described as below.
1. Each Switchgear panel will have an installed ATMEL make ATMega xplained PRO256rfr2
with external antenna within it.It’ll mainly serve two purposes.
a .Take several Digital Inputs from switchgear panels via its digital I/O pins and transmit
them In data byte form to the remote end module. That module can communicate with the
RTU via its virtual COMport.
b. Ask the MFMs to pass several analogue measurands (voltages, current, real power of 3
phase) via MODBUS protocol and send them to remote end RTU via the same module
mentioned above.
2. The remote end RTU will receive these data via its serial port which is connected to the
serial com port of a similar ATMega256rfr2 device. it’ll process the data and can send it to
telecontrol processor for further transmission or can give instructions to switchgear panel
modules based on received data. MCUs in switchgear will actuate those instructions with
suitable device (e.g circuit breaker on/off etc.)
4.In polled mode data transfer RTU can ask for data to a MCU via an interrupt based request
and MCU will answer its query with most recent data.
5.Suitable care has to be taken for system security as these data are very important to utility
for reliable remote operation of breakers and the software stack provides a basic Auto-
encryptio engine security (AES) of 128 bits and international CRC polynomial of order16
for error free data transmission.
6. Key distribution is one of the most important security functions of the network. A secure
network will designate one special device which other devices trust for the distribution of
security keys: the trust center. Ideally, devices will have the trust center address and initial
master key preloaded; if a momentary vulnerability is allowed, it will be sent as described
above. Typical applications without
special security needs will use a network key provided by the trust center (through the
initially insecure channel) to communicate.
38. Page | 37Chapter XXX : Chapter Name
Path forward:
This systemis subject to more experimentation before implementation as it caters a very
important service in SCADA system. But after primary evaluation it seems that the system
might be a working solution for data transmission to RTU for RTU based SCADA system. If
the system works properly It can further be exploited to utilize more of its features like ADC
channel, On board Temperature sensor etc. That’ll enable us to design a more efficient
system where we will no more need a central processor in RTU but rather divide its job to
several parallel MCUs which are already installed in the switchgear panels. Thus we will also
be able to save the cost of AI & DI cards for RTU. The transceiver modules will pass the data
to telecontrol processors so that they can communicate these datum to the servers for
storage and display to the HMI systems. As we move forward, technologies shall only
become faster and faster.
Older protocols shall make way for new ones. But one must remember that the ultimate aim
is economic, stable and sustainable management of the system. With this aim in mind we
move Forward.
