Report its

A
Practical Training Report
On
“400 KV GRID SUB STATION
HEERAPURA JAIPUR”
Submitted for partial fulfillment of the requirements for the
award of the degree of
Bachelor of Technology
in
Electrical Engineering
Session: 2021-2022
Submitted to:
DR. SARFARAZ NAWAZ Submitted by:
Dept. of Electrical Engineering Divyanshu Agrey
18ESKEEO34
VII Sem, Electrical Engg.
Department of Electrical Engineering
Swami Keshvanand Institute of Technology Management
& Gramothan,Ramnagariya, Jagatpura, Jaipur

Department of Electrical Engineering/Skit
ACKNOWLEDGEMENT
I feel immense pleasure in expressing my regards to the chairman,
SKIT Shri Surja Ram Meel, Director Shri Jaipal Meel, Registrar
Smt. Rachna Meel, Director (Academics) Prof. (Dr.) S.L. Surana,
Director (D&W) Prof. (Dr.) Ramesh Pachar, Swami Keshvanand
Institute of Technology, Management and Gramothan, Jaipur for
proving me necessary facilities to complete this work.
I am grateful to my training guide in R.R.V.P.N.L., Shri D.K. Dixit
(Executive Engineer) and Mr. N.K. Gupta for providing me the valuable
support and guidance during my practical training at 400 kV GSS,
Heerapura, Jaipur.
I express my gratitude to the Head of the Department, Dr. Akash
saxena and Deputy Head of the Department, Mr. Ankush Tondon
for their valuable support.
I extent my thanks to our Seminar Incharge, Mr. Sarfaraz Nawaz,
Associate Professor and Mr. Jitendra Sharma, Assistant Professor,
Department of Electrical Engineering for their cooperation and guidance.
Yours sincerely,
Divyanshu Agrey

ABSTRACT
A practical training and comprehensive study of the State Load
Dispatch Centre (SLDC), RRVPNL, Jaipur (Rajasthan) was carried out. It was
a great opportunity to learn all the functionalities and operations of SLDC. We
gained quite immense theoretical knowledge about SCADA, RTU’s,Backup
System, Load Shedding, Tariff fixation etc. we have learned how andwhy the
data is monitored and the use for various communication system regarding
power transmission like PLCC etc.
The Load Despatch Department is the nerve centre for the operation,
planning, monitoring and control of the power system. Electricity cannot be
stored and must be produced when it is needed. It is therefore essential that
power system is planned and operated optimally & economically.

Contents
CERTIFICATE 3
ACKNOWLEDGEMENTS 4
ABSTRACT 5
LIST OF FIGURES 8
LIST OF TABLES
Chapter NO. PAGE NO.
1. INTRODUCTION 9
1.1. STATE LOAD DISPATCH CENTER (SLDC) 9
1.2. FUNCTIONS OF SLDC 10
2. EXISTING POWER SYSTEM AND LOAD DESPATCH FACILITY 11
2.1. GENERATION CAPACITY WITHIN STATE 11
2.2. INTER-STATE TRANSMISSION SYSTEM 12
2.3. LOAD DESPATCH FACILITY 12
3. SUBSTATION AUTOMATION 15
3.1. NEED FOR AUTOMATION 15
3.2. EARLIER METHODS USED TO ACQUIRE DATA 15
3.3. LIMITATIONS OF OLD METHODS 15
3.4. SCADA 15
3.5. WORKING OF SCADA SYSTEM 16
3.6. NEW CHALLENGES 17
4. RTU (REMOTE TERMINAL UNIT) 18
4.1. DIFFERENCE BETWEEN RTU AND PLC 19
5. WORKING OF SLDC 21
5.1. THE DIRECT BENEFITS OF A MODERN SCADA SYSTEM ARE: 21
6. CURRENT BLACK START AND SYSTEM RESTORATION PROCEDURES 23
6.1. OVERVIEW 23
6.2. NORTHERN REGIONAL GRID –SYSTEM RESTORATION PROCEDURE OVERVIEW 23
6.3. GENERAL GUIDELINES & PRECAUTIONS IN SYSTEM RESTORATION 24

6.4. SYSTEM SECURITY ASPECTS 25
7. DEMAND ESTIMATION AND CONTROL 26
7.1. OVERVIEW 26
7.2. DEMAND ESTIMATION 26
7.3. DEMAND CONTROL 27
7.4. LOAD CRASH 29
8. INTRA – STATE AVAILABILITY BASED TARIFF (ABT) 30
8.1. OVERVIEW 30
8.2. NEED FOR ABT 31
8.3. WHAT IS ABT? 31
8.4. PARTICIPANTS IN INTER-STATE ABT 32
8.5. BENEFITS OF ABT 33
8.6. UNSCHEDULED INTER-CHANGE (UI) CHARGES 33
9. FUTURE SCENARIO 35
9.1. OVERVIEW 35
9.2. ADVANCED TECHNOLOGY OF RTU’S 36
9.3. IRTU OFFERINGS 37
REFERENCES 39

List of Figures
Figure 1 Grid Diagram of Rajasthan 14
Figure 2 Substation Automation 16
Figure 3 Remote Terminal Unit 18
Figure 4 Working of SLDC 21
Figure 5 Future Scenario 35
Lists of Tables
Table 2 Capacity of Power Plants in Rajasthan
TABLE 1 UI TARIFF STRUCTURE

1. INTRODUCTION
Rajasthan State Power System is the part of Northern Regional Grid which
operates in synchronous with Eastern, Western & Northern Eastern Grid.
Northern Regional Grid System consists of power systems of constituent
States of Haryana, Punjab, Rajasthan, Uttar Pradesh, Uttrakhand, Himachal-
Pradesh, Delhi, Jammu and Kashmir and Union Territory of Chandigarh. It
includes Inter-State Generating Stations of NTPC, NHPC, Nuclear Power
Corporation (NPC), Partnership projects, IPP’s, other generating companies,
Inter-State Transmission System of PGCIL and transmission system of BBMB.
Rajasthan State Power System consists of generating stations of RVUN,
Captive Power Stations, IPPs, other generating companies, partnership
projects, ISGS located within state, distribution network of three Discoms
namely JVVNL, AVVNL and JdVVNL.
1.1. STATE LOAD DISPATCH CENTER (SLDC)
The State Load Despatch Centre is the apex body to ensure integrated
operation of the power system in a State as per section 32 of EA 2003.
The State Load Despatch Centre is responsible for -
(i) optimum scheduling and despatch of electricity within State, in
accordance with the contracts entered with the licensees or the
generating companies operating in the State;
(ii) monitor grid operations;
(iii) keep accounts of quantity of electricity transmitted through the
state;
(iv) exercise supervision and control over the intra-state
transmission system;
(v) be responsible for carrying out real time operations for grid
control and despatch of electricity within the State through
secure and economic operations of the state grid in accordance
with the Grid Standards and the Grid Code (s).
Also, the State Load Despatch Centre which is responsible for
coordinating the scheduling of a generating station is also responsible for
(i) real- time monitoring of the station’s operation,
(ii) checking that there is no gaming in its availability declaration,
(iii) revision of availability declaration and injection schedule,
(iv) switching instructions,
(v) metering and energy accounting,
(vi) issuance of UI accounts,

Department Of Electrical Engineering / SKIT
(vii) collections/disbursement of UI payments,
(viii) outage planning, etc.
Role of SLDC towards open access suppliers and open access consumers
shall be as under: -
(i) Facilitating transactions of power under short term and long term
intra-state open access as approved by STU.
(ii) Issuing No Objection Certificate/Standing Clearance for inter-state
open access transactions and facilitating the same consequent upon
the approval from Nodal RLDC.
1.2. Functions of SLDC
(i) The State Load Despatch Centre shall be the apex body to ensure
integrated operation of the power system in a State.
(ii)The State Load Despatch Centre shall--
a) be responsible for optimum scheduling and despatch of electricity
within a State, in accordance with the contracts entered into with
the licensees or the generating companies operating in that State;
b) monitor grid operations;
c) keep accounts of the quantity of electricity transmitted through the
State grid
d) exercise supervision and control over the intra-State transmission
system; and
e) be responsible for carrying out real time operations for grid control
and despatch of electricity within the State through secure and
economic operation of the State grid in accordance with the Grid
Standards and the State Grid Code.
(iii) The State Load Despatch Centre may levy and collect such fee and
charges from the generating companies and licensees engaged in intra-
State transmission of electricity as may be specified by the State
Commission.

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2. EXISTING POWER SYSTEM AND LOAD
DESPATCH FACILITY
2.1. Generation Capacity within State
S.No. Name of
Generating Station
Unit Ratings &Nos
Total
capacity
MW
(A) RVUN
1 Kota Super Thermal Power Station 2 X 110 MW 1045 MW
(KSTPS) 3 X 210 MW
1 X 195 MW
2 Suratgarh Super Thermal Power
Station (SSTPS)
6 X 250 MW 1500 MW
3 Ramgarh Gas Thermal Power 1 X 3.0 MW 113.5 MW
Station (RGTPS) 1 X 35.5 MW
2 X 37.5 MW
4 Giral LTPS 1 X 125 MW 125 MW
5 Dholpur CCPP 3 X 110 MW 330 MW
6 Mahi Hydel Power Station-I (Mahi-
PH-I)
2 X 25 MW 50 MW
7 Mahi Hydel Power Station-II (Mahi-
PH-II)
2 X 45 MW 90 MW
(B) RVPN -Partnership Projects in State
1 Ranapratap Sagar Hydel Power
Station (RPS)
4 X 43 MW 172 MW
2 Jawahar Sagar Hydel Power Station
(JS)
3 X 33 MW 99 MW
(C) NTPC Projects in State
1 Anta Gas Power Station (Anta GPS) 3 X 88.71 MW
1 X 153.2 MW
419.3 MW
(D) NPC Projects in State
1 Rajasthan Atomic Power Station-A
(RAPS-A)
1 X 100 MW
1 X 200 MW
300 MW
2 Rajasthan Atomic Power Station-B
(RAPS-B)
2 X 220 MW 440 MW
TABLE 2 CAPACITY OF POWER PLANTS IN RAJASTHAN
Note: -
RPS and JS power stations are part of Chambal-Satpura Project in
partnership between Rajasthan & M.P. Rajasthan’s share is 50% in
hydel projects and 40% in Satpura TPS-stage-I. RPS and JS power

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stations are owned by RVPN but operated and maintained by RVUN and
two other power stations of partnership projects viz. GandhisagarHydro
power station (5x23 MW) and Satpura TPS -stage-I (5x62.5 MW) are
owned, operated and maintained by MP.
2.2. Inter-State Transmission System
Rajasthan Power System is inter-connected with Inter-State
Transmission System through following tie lines/ICT’s:-
i) 400 kV Bassi- Heerapura- I & II
ii) 220 kV Badarpur- Alwar
iii) 220 kV Bharatpur -Agra
iv) 220 kV Dadri- Khetri- I & II
v) 220 kV Hissar- Khetri
vi) 220 kV Kota-Badod
vii) 220 kV Modak- Badod
viii) 132 kV RPS-Gandhi Sagar I&II
ix) 2 Nos. 315 MVA, 400/220 kV ICTs At 400 kV GSS Bassi
x) 2 Nos. 315 MVA, 400/220 kV ICTs At 400 kV GSS Bhiwadi
2.3. Load Despatch Facility
The State Load Despatch Centre (SLDC) of Rajasthan is functioning at
Heerapura (Jaipur). The SLDC has communication links with NRLDC,
all major generating stations and important sub-stations for system
operation and load despatch function. Basic data, necessary for
System Operation, are available in the LD Control Room through the
existing ULDC system. PLCC is main communication channel between
Sub LDC and RTU stations. Microwave has been used as data
communication link between Sub-LDCs and SLDC at Heerapura. At
few locations OFC links, have also been provided for data transfer.
The communication link between SLDC and NRLDC is through optical
fibre cable. The on-line flow of MW, MVAR of the inter-state tie lines,
generating stations, 220 kV/132 kV Grid Sub- stations etc. is being
monitored at the SLDC Heerapura around the clock. On line data are
displayed on screen of operator consoles in the LD Control Room.
ULDC has facility for displaying the MW, MVARflows on single-line
diagram of respective stations along with digital status of breakers
and isolators etc. These online screens displaying data and single line
diagrams can be modified/ reprogrammed if required. The RTU’s are
time synchronized by GPS installed at SLDC Heerapura and Sub-Load
despatch centres at Kota, Ratangarh & Bhilwara.

1
The various data such as MW and MVAR of various sub-stations, lines
are being transmitted to the SLDC at Heerapura through 73 Nos.RTUs
functioning at various stations. As per the scheme, under System Co-
ordination & Control– Northern Region Project four sub Load Despatch
Centres at Heerapura, Kota, Ratangarh and SLDC at Heerapura were
established for on-line transmission of electrical dataof various 400
/220/132 kV GSS and genera ting stations fallingunder each of Sub
Load Despatch Centre. As per scheme, following RTUs have been
installed at various SSs/Generating stations and integratedwith the
Sub Load Despatch Centres.
i) 26 RTUs at Sub LDC, Heerapura
ii) 11 RTUs at Sub LDC, Kota
iii) 12 RTUs at Sub LDC, Ratangarh
iv) 24 RTUs at Sub LDC, Bhilwara
In the present set-up, line flows on various important transmission lines with
the Northern Grid, generation data from major power stations as well as
mimic diagrams of 400 kV and several 220 kV Sub-Stations are availableon
the monitors which also display the scheduled drawl from NR Grid vis- a-vis
actual load flows on 400/220 kV lines. This enables monitoring of deviations
in injection and drawl with respect to schedule and estimates of energy in to
the grid, which is essential to enable the SLDC to regulate the generation of
various SGS or load of Discoms.
In addition to this, important on-line data of Central sector generating
stations & BBMB stations, relevant to RVPN, are being received from NRLDC.
The ULDC Scheme has provision of remote control operation of circuit
breakers etc. from SLDC/NRLDC ControlRoom but the operation thereof has
not been activated. Additionally, EMS function, Contingency Analysis,
Scheduling and weather based
load forecasting are available under ULDC Scheme which are also yet to be
activated.

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FIGURE 1 GRID DIAGRAM OF RAJASTHAN

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3. SUBSTATION AUTOMATION
3.1. Need for automation
 Improve information availability and better visibility
 Reduction of Fault Restoration times and adequate response to
customer query
 Real time and historical data for network analysis
3.2. Earlier methods used to acquire data
 PLCC network
 Wireless VHF sets
 P&T /FWP telephones
 Load pattern obtained in writing
 PTW Book etc...
3.3. Limitations of old methods
 Outage of telephone / PLCC network
 Non-clarity of speech
 Human factor
 No control on operations
 Huge time required to collect data
 No check on improper compliance of instructions
 Huge time required to pass instructions
3.4. SCADA
SCADA stands for supervisory controland data acquisition. It generally
refers to an industrial control system: a computer system monitoring
and controlling a process.
Benefits: -
 Reduced quantities of equipment, networks implemented with fibre-optic
cable, industry standard interface technology – Ethernet, Data
management, Metadata management, designing toward a seamless
architecture, Integration of digital information and functionality, Gradual
displacement of analog devices, new digital equipment capabilities and
Station HMI consoles.

1
 Substation automation benefits the utility staff, Maintenance staff,
Planner, Asset management personnel, Operators and operational
planners, Protection engineers, Operations engineers, Data
administrators.
 Control centre operations, SCADA/EMS systems, Contingency analysis
(security analysis), and intelligent alarm processing, Emergency response
etc.
3.5. Working of SCADA system
FIGURE 2 SUBSTATION AUTOMATION
SCADA software receives the information from remote terminal units (RTUs),
which in turn receive their information from the sensors or inputtedvalues
which we have given manually. SCADA in a power system is used to collect,
analyse and monitor the data effectively, which will reduce the waste
potentially and improve the efficiency of the entire system by saving money
and time.
As the power system deals with power generation, transmission and
distribution sectors, monitoring is the main aspect in all these areas. Thus,
the SCADA implementation of power system improves the overall efficiency
of the system for optimizing, supervising and controlling the generation and
transmission systems. SCADA function in the power system network provides
greater system reliability and stability for integrated grid operation.

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3.6. New challenges
SCADA systems have traditionally played a vital role by providing utilities
with valuable knowledge and capabilities that are key to a primary business
function - delivering power in a reliable and safe manner. A quality SCADA
solution is central to effective operation of a utility's most critical and costly
distribution, transmission, and generation assets.
The challenging issues for SCADA systems and projects today are not the
same as they were a few years ago, today, there is much more importance
placed on integration, use of new communication and network technologies,
access to information by more users, and other purposes.
Today’s SCADA systems, in response to changing business needs, have added
new functionalities and are aids for strategic advancements towards
interactive, self-healing smart grids of the future. A modern SCADA system
is also a strategic investment which is a must-have for utilities of all sizes
facing the challenges of the competitive market and increased levels of real
time data exchange that comes with it (independent market operator,
regional transmission operator, major C&I establishments, etc.). A well
planned and implemented SCADA system not only helps utilities deliver
power reliably and safely to their customers but also helps to lower costs and
achieve higher customer satisfaction and retention. Modern SCADA systems
are already contributing and playing a key role at many utilities towards
achieving:
 New levels in electric grid reliability – increased revenue
 Proactive problem detection and resolution – higher reliability
 Meeting the mandated power quality requirements – increased customer
satisfaction
 Real time strategic decision making – cost reductions and increased revenue
Business case justification is stronger now than ever before even for lower
density substations. The costs are declining with commercial off-the-shelf
(COTS) products built to international standards as opposed to legacy
proprietary solutions. Today, a utility can quickly gain these benefits by
implementing a low cost SCADA system and evolving it as its business needs
change

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4. RTU (Remote Terminal Unit)
A remote terminal unit (RTU) is a multipurpose device used for remote
monitoring and control of various devices and systems for automation. It
is typically deployed in an industrial environment and serves a similar
purpose to programmable logic circuits (PLCs) but to a higher degree. An RTU
is considered a self-contained computer as it has all the basic parts
FIGURE 3 REMOTE TERMINAL UNIT
that, together, define a computer: a processor, memory, and storage.
Because of this, it can be used as an intelligent controller or mastercontroller
for other devices that, together, automate a process such as a portion of an
assembly line.
Remote terminal units are also known as remote tele control units.
Remote terminal units are more advanced versions of PLCs, which can only
follow specific programming called ladder logic. An RTU is sophisticated and
intelligent enough to control multiple processes without requiring user
intervention or input from a more intelligent controller or master controller.
Because of this capability, the purpose of the RTU is to interface with
distributed control systems (DCS) and supervisory control and data
acquisition (SCADA) systems by sending telemetry data to these systems.
But in most cases, even intelligent RTUs are connected to a more
sophisticated control system such as an actual computer, which makes their

1
reprogramming, monitoring and controlof the entire system easier for a user.
An RTU can also monitor a field's analog and digital parameters through
sensors and data received from connected devices and systems; it then sends
these data to the central monitoring station, as is the case in many industrial
facilities like power, oil and water distribution facilities. An RTU includes a
setup software that connects input and data output streams; the software
can define protocols and even troubleshoot installation problems.
Depending on the manufacturer, purpose and model, an RTU may be
expandable and custom fitted with different circuit cards including
communication interfaces, additional storage, backup power and various
analog and digital I/O interfaces for different systems. Because of their widely
varying applications, RTUs come in vastly different hardware and software
configurations and may not even be remotely compatible with each other.
For example, RTUs used in telecommunication automation may not be usable
at all for oil and gas applications as the processes and hardware systems
used would be completely different.
4.1. Difference between RTU and PLC
“RTU” stands for “Remote Terminal Units.” They are also referred to as
“Remote Telemetry Units.” An RTU is an electronic device which is controlled
by a microprocessor. The main function of an RTU is to interface the SCADA
to the objects present physically. “SCADA” stands for “supervisory control
and data acquisition.” The interface between objects and SCADA takes place
by using supervisory system messages to controlall the objects connected
and by transmitting to the system all the telemetry data.
The RTU does not support control loops and control algorithms. The
functionality of RTUs and PLCs has started overlapping because of cheaper
hardware, and thus the industry standardized the language for programs on
which RTUs run.
“PLC” stands for “programmable logic controller.” PLCs are digital computers.
They are used mainly for automating the electromechanical processes, for
example, assembly lines in factories, light fixtures, amusement rides, etc.
They are specially designed for output arrangementsand multiple inputs.
They have electrical noise immunity, vibration and impact resistance, varied
temperature ranges, etc.
Some of the functions of PLCs are; process control, relay control, motion
control, networking, etc. They have started matching the desktop computers
in storing, processing, communicating, and handling data.

RTU is different from a PLC because it is considered more suitable as it
uses wireless communication and is suited to a wider geographicaltelemetry
whereas PLCs are better with local controls, for example, production lines or
plants, etc. In plants and production lines, the systemis more based on
physical media.

5. WORKING OF SLDC
There are multiple agencies within a state engaged in generation,
transmission, and distribution of electricity. State Load Dispatch Centre
monitors these operations and keeps the account of quantity of electricity
transmitted through the state grid. SCADA is a part of it. Supervisory Control
and Data Acquisition System (SCADA) is a high-tech computer system with
associated communication network that enables supervision and control of
power system network. SCADA is the technology that enablesa user to collect
data from one or more distant operator to stay or visit frequently to the work
locations. It includes the man machine interface. It allows an operator to
make set point changes on distant process controllers,to open or close valve
or switches, to monitor alarms to collect measurement information SCADA is
best applicable to processes that are spread over large areas and it is suitable
for
1. groups of small hydroelectric generating stations that are turned on and
off.
2. oil and production facilities, pipelines for gas, oil, chemicals, water which
are located at far distances
3. electric transmission systems irrigation system etc.
FIGURE 4 WORKING OF SLDC
5.1. The direct benefits of a modern SCADA system are:
Constant access to RealTime picture of entire network showing power system
voltage, frequency, MW, MVAR, etc. Supervision, monitoring and control of
power in Real Time. Optimal operation of power system, i.e.

generation and associated resources. Minimum of outage and faster
restoration of the system in the event of Grid disturbances. Improvement
in the quality of supply through better controlof frequency, voltage and other
parameters. Less dependence on basic telephone system. When it comes into
existence.
Day by day the technology is changing, new trends are emerging which are
beneficial for utility side, power players and consumers too. In early days’
communication was done by the telephones only. All the changes,
information transfer, fault data, generation and demand side requirement
and all other data transfer depends upon the means which were not adequate
but somehow it was very difficult to keep the records of all the above said
things second to second as in many cases some information may get lost.
Hence a new technique named SCADA originates whichhelping the power
sector a lot by taking the form of load dispatch centre.A real-time expert
system now degrowing considerable fault case for restoration guidance. The
progress so far indicates a hopeful future for a quick and accurate fault
restoration support system. The system will continue to be thoroughly tested
in the field until it can be introduced into practical service. Also, automation
in communication process gives quick information and response and all this
happens at Load dispatch centre.

6. CURRENT BLACK START AND SYSTEM
RESTORATION PROCEDURES
6.1. Overview
A 'Grid Disturbance' denotes the situation under which a set of
generating units/transmission elements trip in an abrupt and
unplanned manner affecting the power supply in a large area and/or
causing the system parameters to deviate from the normal values in
a wide range. In the event of a grid disturbance, utmost priority is to
be accorded to early restoration/revival of the system. It is possible
that during such a situation the system may have to be operated with
reduced security standards and suspension of all commercial
incentives/penalties.
This chapter is based on System Restoration Procedures for Northern
Regional Grid brought out by NRLDC. This chapter describes theexisting
system restoration procedure for Rajasthan system and general
guidelines and precautions for system revival.
6.2. Northern Regional Grid –System Restoration Procedure
Overview
The Rajasthan Power System is the part of Northern Regional Grid
and therefore Northern Regional Grid restoration procedure applies for
Rajasthan System as well.
The Northern Region consists of a large network. In the event of a total
blackout, extending start-up power from one end of the region to the
other end is rather impractical. The restoration of the system back to
normal must be achieved in a sectionalized manner. Accordingly, the
Northern Region has been divided into 4 subsystems for system
restoration process so that in the event of total grid failure, initially
each subsystem is to be restored independently and once the
subsystems separately built-up, these can be synchronisedin stages
to integrate into a complete system.
1. Restoration of Eastern UP Sub-system
2. Restoration of North Central Sub-system
3. Restoration of Rajasthan Sub-system
4. Restoration of Western UP Uttrakhand Sub-system

6.3. General guidelines & precautions in system restoration
The general guidelines and precautions to be followed during system
revival are mentioned below:
a. SLDC shall at all time have the latest amended copy of this document
available in the Control Room.
b. The Shift In charge, SLDC shall inform the Head of SLDC about the
situation and request assistance in the restoration process.
c. During total grid collapse/ failure of supply at the GSS, the In- charge
of the shift will inform about grid failure to the XEN/ AEN In- charge
of the GSS and also to SLDC controlroom and wait for the instructions
from SLDC control room. The shift In-charge will get all the incoming
(if no power is available) & outgoing feeders including circuit breakers
controlling main power transformers openedimmediately. On load tap
changers (OLTCs) of the transformers would be brought down to
normal tap position by local manual control. This should be
completed within 10 minutes of the grid failure by each Shift
Duty In charge. The In-charge ofthe GSS shall reach the
Control room as soon as the information regarding disturbance
is conveyed to him.
d. During total grid collapse/failure of supply at any power station the
in-charge of the shift will inform about grid failure to the in charge
of the power station and also to SLDC control room, Heerapura and
wait for the instructions from SLDC control room.
e. During revival of the system, In-charge of sub stations, powerstations
and SLDC would remain present in control rooms of substations so as
to expedite restoration of the system.
f. In order to maintain a balance between load - generation at the time
of grid contingency the list of generating stations with black start
facility, interstate/inter-regional ties, synchronizing points and
essential loads to be restored on priority, should be prepared and
updated regularly and must be available at all times in SLDC.
g. While building up the system, it would be ensured that the voltage at
the charging end remains within limits. Before switching next section,
essential load of substation shall be connected to enable charging of
battery, shunt reactor shall be connected and a small loadmay be
switched on at each sub-station to ensure charging end voltage.
However, the ultimate objective, viz. building up of the network
should not be lost sight of, while connecting the loads and large loads
shall not be switched on. If charging end voltage dips at any
substation, non-essential load or shunt reactor at intermediate
stations may be switched off.
h. Security of the network being built up would be strengthened at the
earliest by closing the parallel lines available in the restoration path.

i. Priority would be accorded for extending supplies to railway traction
and installations where safety is of paramount importance such as
nuclear power stations.
j. All switching instructions for a system must emanate from SLDC,
Heerapura. For synchronization of two systems, NRLDC would be the
coordinating agency.
k. In line with Clause 5.8(e) of IEGC, during system revival all
communication channels required for restoration process shall be used
for operational communication only, till grid normalcy is restored.
l. Synchronizing facility should be available at following grid
substations to have maximum flexibility in choosing the point of
synchronization.
6.4. System Security Aspects
While restoring the system, load generation balance is to be
maintained in each subsystem and all efforts to be carried out by
all the users to maintain the parameters within the subsystem
near nominal values for security of operation of the restored
subsystem as well as for ease of synchronisation.

7. DEMAND ESTIMATION AND CONTROL
7.1. Overview
Demand estimation plays a very important role in system operation. In
the long term, it constitutes important input for generation and
transmission network planning. In the medium term, say one year, it
constitutes an important input for outage planning of generating units
and transmission lines and short term bilateral agreements for power
purchase. In the short
term, it is an important input for generation and drawl scheduling, load
shedding & bilateral power purchase agreements. Variation in demand
in real time operation from the estimated values could either be
absorbed by
the grid or affect it adversely. Even if the estimates are accurate, the
generation could vary from scheduled values adversely affecting the
grid. Demand control thus play an important role in arresting these
adverse effects on the grid.
Demand estimation and control is essentially the responsibility of
SLDCs and NRLDC would generally not have a major role in this area.
NRLDC would give instructions to SLDCs on demand control whenever
the same has a bearing on the security of the regional grid & such
instructions would have to be complied forthwith by all SLDCs.
7.2. Demand estimation
SLDC shall be responsible for assessing the availability andrequirement
in kW, kWH & kVAr for one year on monthly basis. The SLDCs would
forecast demand (MW peak & energy in MWh) on an annual, quarterly,
monthly, weekly and ultimately on daily basis, which would be used in
the day-ahead scheduling. SLDC will maintaina historical database for
the purpose and be equipped with the state- of-the-art tools such as
Energy Management System (EMS) for demand forecasting. Ideally,
the forecasts should be on hourly basis (8760, 720 & 168 values
respectively in the annual, monthly and weekly forecasts) rather than
mentioning only the peak MW and energy requirements for the period.
Discoms shall submit its power requirement to SLDC for the ensuing
year by 31st October on monthly basis as per their entitlement and
share in generating stations and contract signed with the generating
companies and the traders.

Discoms shall provide to SLDC estimates of load that may be shed
when required, in discrete blocks with the details of arrangements of
such load shedding.
Discoms shall also furnish realistic category-wise demand and energy
requirement for their respective companies along with details of
essential loads, supply hours to be maintained in rural areas, details
of power cuts imposed or to be imposed and specific requirements, if
any.
The above demand estimation covers only active power. It is also
important that, the reactive power requirements are also forecasted
right from substation level by each SLDC. The reactive power planning
exercise and programme for installation of reactive compensation
equipment’s should take care of these requirements also and would be
carried out by STU in consultation with NRPC and Discoms.
The SLDC would forecast the demand (in MW as well as MWh) on
quarterly, monthly, weekly and ultimately on daily basis on the basis
of requirement received from Discoms, which would be used in the day
ahead scheduling of Rajasthan as a whole.
Attention shall also be paid by SLDC in demand forecasting for special
days such as important festivals and National Holidays having different
crests and troughs in the daily load-curve as compared to normal
weather conditions & days, The Discoms may negotiate short term &
spot power purchase as per their requirement.
SLDC shall furnish data for and participate in deliberations of load
generation balance, Annual Demand, ‘availability’ and shunt capacitors
requirement studies of NRPC. It shall take into consideration their
reports for demand estimation.
7.3. Demand control
Primarily the need for demand control would arise on account of the
following conditions: -
1.Variations in demand from the estimated or forecasted values,
which cannot be absorbed by the grid, and
2.Unforeseen generation / transmission outages resulting in
reducedpower
availability, and
3. Heavy reactive power demand causing low voltages, and
4. Commercial reasons.

SLDC shall match the consolidated demand with the consolidated
generation availability from SGS, ISGS, IPP/CPP and other sources and
shall exercise the Demand Control such that there is a balance between
the energy availability and the Discoms demand plus losses plus the
required reserve.
As per section 6.4.8 of the IEGC, the SLDC shall regularly carryout the
necessary exercises regarding short-term demand estimation to plan in
advance as to how the load would be met without overdrawing from the
grid. The following deviations from the schedule and other violations
would be controlled by the SLDC.
• Over drawls/ under injection at frequencies below 49.2 Hz.
• Under drawls/ over injection at frequencies above 50.3 Hz.
• Reactive power drawls/injections causing low/high voltage
respectively.
If the demand estimation and generation availability figures published by
the SLDC indicate a significant shortfall or demand gap, in any Discom
then that Discom shall work out a plan to meet the shortfall. If the
shortfall is not met out, a manual load shedding program shall be
announced by the Discom well in advance.
SLDC shall advice the STU to plan Automatic Load Shedding Schemes
and rotational load shedding by installing Under Frequency Relays.
The guidelines for under frequency load shedding shall be prepared by
the Technical Committee, and approved by the SPC. A copy of the
approved guidelines can be made available on demand and on payment
as may be decided by the SPC.
The details of feeders or group of feeders at a particular EHV sub-station
scheduled to be tripped through under-frequency load shedding scheme
whether manually or automatic on rotational basis or otherwise shall be
displayed on the Notice Board and at the sub-station for the information
of consumer(s).
NRPC Secretariat formulates under frequency load shedding scheme for
the Northern Region in consultation with all the constituents and NRLDC.
The scheme considers the largest single credible contingency occurring in
the system and load shedding is based on tripping by fixed under
frequency as well as fixed frequency and rate of change offrequency
relays.
Demand control so exercised under these conditions by the SLDC, could
be done manually or through the under-frequency relays including those
working on rotational / sequential basis or through direct circuit breaker
tripping effected from SLDC/ Sub LDC using RTUs on under frequency

detection by SLDC/Sub-LDC computer or through telephonic instructions.
Each user shall endeavour to restrict their drawl within their drawl
schedule or entitlement whenever the system frequency is below 49.5 Hz.
When the frequency falls below 49.2 Hz. requisite load shedding (manual)
shall be done by the concerned Discom/user to curtail the over- drawl.
During the demand control by manual disconnection of loads by
staggering among different groups, the changeover from one group to
another shall be carried out in a gradual and scientific manner so as to
avoid excursions in the system parameters.
The SLDC would also identify feeders drawing heavy quantum of reactive
power and disconnect the same under low voltage conditions. Necessary
metering arrangements/transducers for identifying such feeders shall be
provided by the RVPN.
Sudden reduction in generator output by more than one hundred (100)
MW unless under an emergency condition or to prevent an imminent
damage to the equipment, shall be avoided, particularly when frequency
is falling below 49.2Hz.
Sudden increase in load by more than 100 MW by any SLDC, particularly
when frequency is falling below 49.2Hz and reduction in load by such
quantum when frequency is rising above 50.3 Hz. Shall be avoided.
No demand shed by operation of under frequency relays shall be restored
without specific directions from SLDC.
7.4. Load Crash
In the event of load crash in the system due to weather disturbance or
any other reasons, the situation would be controlled by the SLDC by the
following methods:
(i) Back down or close down of generating units of SGS except CPP & non-
conventional sources commensurate with system frequency &
transmission constraints by giving SLDC Code.
(ii)Lifting of the load restrictions, if any. While implementing the above, it
shall be ensured that the provisions in frequency control under clause
6.8 shall not be violated. Further, in case of Hydel generation linked
with irrigation requirements, the actual back down or close down of
such Hydel units shall be subject to limitations on such account & to
avoid spillage of water.

8. INTRA – STATE AVAILABILITY BASED
TARIFF (ABT)
8.1. Overview
Availability Based Tariff (ABT) is a frequency based pricing mechanism
applicable in India for unscheduled electric power transactions. The ABT falls
under electricity market mechanisms to charge and regulate power to achieve
short term and long term network stability as well as incentives anddis-
incentives to grid participants against deviations in committedsupplies asthe
case may be.
Through this scheme, the Central Electricity Regulatory Commission (CERC)
looks forward to improve the quality of power and curtail the following
disruptive trends in power sector:
 Unacceptably rapid and high frequency deviations (from 50 Hz) causing
damage and disruption to large scale industrial consumers
 Frequent grid disturbances resulting in generators tripping, power outages
and power grid disintegration.
The ABT scheme has now been expanded to cover the Intrastate systems as
well. The power generation or grid capacity has increased substantially inlast
fifteen years particularly after the Electricity Act 2003 by introduction of
competition and unbundling of vertically integrated utilities (SEBs) into
separate entities in charge of electricity generation, electricity transmission,
and electricity distribution. Deregulation and competition has facilitated
participation of private sector on large scale in electricity generation,
transmission and distribution. Of late, Indian electricity sector is transforming
from perennial deficit to surplus electricity availability. The volume of
purchased electricity that could not be transmitted to the buyers due to
transmission lines congestion is only 0.3% of the total electricity consumed
in the financial year 2013-14. It means that the actual power deficit in India
is less than 1% excluding underpriced electricity demand. ABT/DSM
mechanism needs improvements to address the requirements of all stake
holders (including final electricity consumers) for encouraging least cost
electricity generation / tariff based on demand verses availability in thegrid.
There is a need of well represented Electric Reliability Organization to involve
all the grid participants for framing guidelines for power system operation
and accreditation which is presently looked after by the CEA.
Bulk power purchasers can buy electricity on daily basis for short, medium
and long term duration from reverse e-auction facility. In reverse e-

auction, availability based tariff is applied to settle the failed commitments
by the electricity sellers or buyers. The electricity prices transacted under
reverse e-auction facility are far less than the prices agreed under bilateral
agreements.
8.2. Need for ABT
Prior to the introduction of Availability Based Tariff, the regional grids were
operating in a very undisciplined and unsystematic manner. There were large
deviations in frequency from the rated frequency of 50 cycles per second (Hz)
leading to low and high frequency situations. The low frequency situations
resulted due to a higher consumer load than the total generation available in
the grid and high frequency resulted as a result of insufficient backing down
of generation when the total consumer load fell during off-peak hours. This
continued functioning at non-standard frequency resulted in long-term
damages to both generation and end use equipment resulting in hidden costs
that ultimately had to be borne by the end consumers.
Apart from this, the earlier regime did not provide any incentive for either
backing down generation during off-peak hours or for reducing consumer
load/enhancing generation during peak-load hours. The reasons for the same
were that the full fixed charges were payable at achieving a PLF of 68.49%
and an incentive was payable for each unit of electricity generated above this
PLF which made it profitable to go on generating at a high level even when
the consumer demand had come down. Further, if a beneficiary decided not
to draw any energy, he could escape payment of the fixed charges, which
were paid by the person drawing energy. Also, there wasno provision of
penalizing any consumer who was overdrawing power. The new increased
cost of electricity was covered by other beneficiaries.
8.3. What is ABT?
The term Availability Based Tariff, particularly in the Indian context, stands
for a rational tariff structure for power supply from generating stations, on
an availability basis. It is a performance based tariff structure for the supply
of electricity by generators owned and controlled by the central government
that provides for a new system of scheduling and dispatch which mandates
the generators and beneficiaries to commit to day ahead schedules through
a system of reward and penalty. The defaulters are liable to paya penalty
which entails payment of prescribed charges, non-payment of which will call
for appropriate action under sections 44 and 45 of the ERC Act. The most
significant aspect of ABT is the splitting of the existing rigid energy charges
into three components viz. capacity charges/ fixed charges,

variable charges and a third charge viz. the unscheduled interchange (UI)
charges.
 Capacity charges/ fixed charges: The fixed charge (FC) in case of
ABT is payable every month by each beneficiary to the generator for
making generation capacity available for use. However, it is not the
same for each beneficiary and varies with the share of a beneficiary in
a generators capacity. It also vary with the level of availability achieved
by a generator. As per the ABT mechanism, FCs excluding RoEis payable
on a proportionate basis for 30% availability. Pro-ratedRoE is payable
from 30- 70% availability and beyond this level, an incentiveis payable
to generating station at 0.4% of equity for each percentageincrease in
availability in the 70- 85% range. Thereafter the incentive falls to 0.3%
in order to discourage generating facility from overloadingthe units at
the costofmaintenance and equipment life. It is a functionof ex-bus MW
capability of the power plant for the day declared in advance, paid by
beneficiaries proportionate to their respective % sharein the plant.
 Variable charges: It is the energy charge per kwh of energy supplied
as per a pre-committed schedule of supply drawn upon a daily basis
by LDCs. Under the earlier regime, fixed and variable charges were
bundled together and payable in proportion to the actual energydrawn
by the consumer. The splitting under the new regime will promote
power trading which is discussed later on in this paper. Energy charges
are calculated as:
 Energy Charge = MWh for the day as per drawl schedule for the
beneficiary finalized in advance x Energy Charge rate for the plant
(OR) Energy Charge = Scheduled Energy X Energy Rate
 Unscheduled Interchange: Under the earlier regime, no penalty was
applicable for deviation from generating/drawal schedule by an entity.
An attempt has been made to do away with this drawback under the
ABT regime through introduction of UI charge. Here, for any withdrawal
of power other than the schedule, the beneficiary has to pay an
unscheduled interchange (UI) charge for deviation from the day ahead
schedule which is linked to the frequency. The relationship between the
UI rate and grid frequency, for the inter-state system,is specified by
Central Electricity Regulatory Commission. UI charges are calculated
using the following relationship:
 A generator generates more/less than the schedule causing grid
frequency to deviate upwards/ downwards.
 Beneficiary draws more/ less than the schedule causing grid frequency
to deviate downwards/upwards.
8.4. Participants in Inter-state ABT

 Interstate generating station (ISGS) from generating side
 SEB/ State/ Union territory from load side
 Other regions for import and export
 Regional grid for transmission
8.5. Benefits of ABT
 Rational recovery of fixed costs from beneficiaries.
 It provides a fiscal mechanism to encourage high availability of plants
to meet the peak demand.
 Merit order and most economic generation is encouraged as a result
of which low cost power gets a priority in generation.
 Rationalization of the contractual demand between the SEB’s and the
generators.
 Fiscal disincentives for over drawl during low frequency conditions and
under drawl during high frequency conditions.
8.6. UNSCHEDULED INTER-CHANGE (UI) CHARGES
The UI for a Generating Station shall be equal to its actual generation minus
its scheduled generation. UI for States shall be equal to its total actual drawl
minus its total scheduled drawl.
UI shall be worked out for each 15 minutes’ time block. Charges for all UI
transactions are based on average frequency of the time block.
The UI Tariff structure w.e.f., 07/01/2008 is as under.
Average Frequency of time-block UI Rate (P/kWh)
50.5 Hz and above 0.00
Below 50.50 Hz and upto 50.48 Hz 8.00
Below 49.02 Hz 1000.00
Between 50.50 Hz and 49.80 Hz Linear in 0.02 Hz steps
@ 8 P/kWh for each step
Below 49.80 Hz Linear in 0.02 Hz steps
@ 18P/kWh for each step
TABLE 3 UI TARIFF STRUCTUR E
The rates are decided by using the formula:
UIS = UIR / (1-L)

Where, UIS is Intra State ABT rate for a frequency step
UIR is UI rate applicable for Northern Region for that frequency step
L is the Inter-State transmission losses of NR in per unit

9. FUTURE SCENARIO
9.1. Overview
The main things are make load dispatch centre operations more complex than
earlier years are changes in system network, growth in consumer population,
mix of fuel used etc. also problems related to security, integration of various
grids, forces the load dispatcher to attain new dimensions. Load dispatch
centre has to handle and face no. of problems regarding the electricity
changes. In earlier days the methods used to communicate oral instruction
and manual intervention were somewhat unreliable in critical situations. And
this thing make necessary to adopt the new methods
1) techniques like automatic control on generating units as well as
important load centres. This is for effective and timely control to avoid the
major occurrences of black out. This aspect will also require the fool proof
arrangement of reliable interlocks and back up protection to ensure safe grid
working.
2) Also the transmission switchyard will be properly equipped and no
interference of local staff except the experts.
3) Control actions taken by load dispatcher cannot be bypassed.
4)The remote control of generation should be done through the
governor controls to improve generation. In recent years, the automatic
governor control does it.
Now a-days, as we have seen SCADA is in use to control and monitor all the
things Which is the most effective communication media. Also, a regular and
timely communication about power supply schedule and generation
FIGURE 5 FUTURE SCENARIO

schedule is the heart of healthy power system and this happens only when
there is a proper communication.
9.2. Advanced Technology of RTU’s
By leveraging the powerful embedded technology, RTU can be integrated
increasingly functionality and become a new intelligent iRTU to fulfil the
application in IoT (Internet of Things) Era. It can not only replace the PLC to
complete the local tasks faithfully, but also communicate with the centre
master through the available channels with the pre-designed behaviour. Face
the big data application, iRTU can also help on the data pre- treatment, not
only reduce the loading of cloud but also reduce the communication
bandwidth. Self-awareness is also a very important improvement as an
intelligent remote terminal. As key element of IoT solution, iRTU is usually
used to master all the conditions in the field site. However, the most
important is the health status of iRTU itself, this factor related to the system
stability directly.
With the evolution of the era of big data, IoT technology is being more and
more used and its architecture includes cloud computing and intelligent
terminals which are dispersed geographically over a wide regional area.
Examples are traffic monitoring networks as well as industrial applications in
the oil, gas, and water industry. In all cases, intelligent RTUs aredistributed
across the area (oil wells, water pumping stations, gas pipelines). Their main
task is to ensure a constant delivery process (of water, oil or gas) and safe
and cost efficient plant operation to perform, optimize and monitor these
tasks, relevant (big) data must be collected and in some cases pre-processed
by the terminals and RTUs respectively. The information is then sent to the
cloud through wireless communication using Wi-Fi / 3G/ZigBee technologies.
Major advantages are:
Plant efficiency: Rapid integration of information in the cloud allows to
remotely monitor the production process, data reporting, online planning,
equipment diagnosis and so on, effectively improving efficiency and reducing
costs.
System reliability: Intelligent RTUs are responsible for collecting and
analysing local data, reducing the load of centre handling data, workingwith
the other devices, taking the initiative to report data, status and provide
alarms. iRTU can also communicate with each other, quickly handle I/O
correlation and collaborate on emergencies to reduce the loss. All is
contributing to an overall increased system reliability and availability.

Rapid and cost efficient maintenance: In the remote and wide ranging
oil, gas and water applications site maintenance and updating procedures are
extremely costly. Intelligent RTU can perform remote monitoring, operation,
maintenance, and updates via the Internet. iRTU’s can perform update,
complete delivery tasks at the site, and upload data to the cloud the cloud
server is used to accumulate the huge amount of data and conduct high-
speed parallel computing to generate important operation and
– if required - preventive strategies and solutions. This may include
improvement of production efficiency, monitoring machine operation and
distribution state or localizing pipeline leaks. In the past, workers were
needed to supervise plant operation. The use of intelligent terminal units can
help to install unmanned supervision and controlconcepts and greatly reduce
costs.
9.3. iRTU OFFERINGS
iRTU is an intelligent device, mainly used in the oil, gas, and water industries.
Intelligent network nodes in the IoT can controlthe downstream field devices
to complete delivery tasks, transfer data to upstream devices wired or
wirelessly. It is the key to connecting devices to the Internet of Things
architecture. The ADAM-3600 has a high performance but low power
processor, adopts 20 local I/O points and provides wired and wireless
communication. Users can collect, process and distribute the local
information. ADAM-3600 has a built-in real-time operating system and a real-
time database, providing customers with an open interface and supports
diverse programming languages. It can be used for outdoor controlcabinets
and therefore must be able to withstand the heat ofsummer and the cold of
winter.
FIGURE 6 INTELLIGENT RTU: ADAM-3600-C2G

The ADAM-3600 supports an operating temperature range of - 40℃ to
+70℃. The selected components are industrial grade, and have been tested
with the strictest environmental control, to ensure that the products have
a long life and, stable working in harsh environments. The ADAM-3600
contains a variety of I/O ports and different models provide different local
I/O functions. It can provide four expansion slots for multipoint I/O
applications and lets users have more rapid and flexible I/O solutions.
Important features include:
 Wide array of on-board I/O and flexible expansion I/O modules supporting
different acquisition requirements and providing cost efficiency
 Powerful communication:
o Wireless: Wi-Fi/ 3G/ GPRS/ ZigBee
o Wired: Ethernet / RS 232 / RS 485
 Support for Modbus RTU/TCP and DNP3 protocol
 -40° to +70°C operating temperature for use in harsh environments
 USB drive and SD card allow to update the firmware without computer and
configuration program
 Intelligent Connectivity Diagnosis Manager (iCD Manager) to remotely
monitor the serial and Ethernet ports status and send alarm information to
prevent the loss of important data.

REFERENCES
 Load_dispatch_manual
 NRREPORT201711
 DISCOMENERGY201711
 scadasubstationautomation-120908161924-phpapp02 (1)
 https://www.techopedia.com/definition/1033/remote-terminal-unit-rtu
 http://www.ijcaonline.org/journal/number7/pxc387276.pdf
 www.srldc.org/Roles%20And%20Functions%20Of%20NLDC.aspx
 https://www.sldcguj.com/aboutus/Functions.asp
 http://www.factorysystemes.fr/media/siteV2/brochures/M2M/Intelligent -
RTU-advantech-livre-blanc.pdf

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