PGVCL Training Report

PROJECT REPORT ON

POWER DISTRIBUTION

AT

PGVCL RAJKOT CITY CIRCLE-3

NANA MAVA SUB-DIVISON

&

VISIT AT

GETCO 66/11 KV LAKHSMI NAGAR SUB-STATION RAJKOT

PREPARED BY:

VASA PRITEN

DOBARIYA PRIYESH

DHARMESH SAKARIYA

FACULTY OF TECHNOLOGY & ENGINEERING

DEPARTMENT OF ELECTRICAL ENGINEERING

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THANKING LETTER

TO

Mr. BAKSHI

DEPUTY ENGINEER

NANA MOVA SDO RAJKOT

We are very thankful to PGVCL Nana Mava Sub divison for giving us a training & GETCO Laxmi Nagar Sub divison for providing a visit and it was such a great opportunity here and given a platform for us to nourish our technicality rich with the great exposure . We also greet the all the employees, Deputy Engineer ,Junior engineer including helpers and repairers for giving a guidance and core technical knowledge which will be helpful for us to build and establish strong career in this competitive field.

Thanking you

Vasa Priten

Priyesh Dobariya

Dharmesh Sakariya

SIGNED & CERTIFIED BY

MR K.H BAKSHI MR P.D PARMAR MR A.M SORATHIYA

DEPUTY ENGINEER JUNIOR ENGINEER JUNIOR ENGINEER

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BREIF OVER VIEW OF ELECTRICITY IN INDIA

The Gujarat Urja Vikas Nigam Limited (GUVNL) is an electrical services umbrella company in the state of Gujarat, India. It was set up in May 1999 and is registered under the Companies Act, 1956. The Company was created by the Gujarat Electricity Board (GEB) as its wholly owned subsidiary in the context of liberalization and as a part of efforts towards restructuring of the power sector with the aim of improving efficiency in management and delivery of services to consumers.As a part of Power Reform Process, the Electricity Act, 2003, was passed by the Central Government and Gujarat Electricity Industry (Re-organization & Regulation) Act, 2003, was passed by the Government of Gujarat to restructure the Electricity Industry with an aim to improve efficiency in management and delivery of services to consumers.

Under the provisions of the said Acts Govt. of Gujarat framed the Gujarat Electricity Industry Re-organization & Comprehensive Transfer Scheme, 2003, (the Transfer Scheme) vide Government Notification dated 24-10-2003 for transfer of assets/liabilities etc. of erstwhile GEB to the successor entities.

Accordingly erstwhile Gujarat Electricity Board (GEB) was reorganized effective from 1 April 2005 into Seven Companies with functional responsibilities of Trading, Generation, Transmission and Distribution etc.

The Companies incorporated are as under:

Gujarat Urja Vikas Nigam Ltd. (GUVNL) Holding Company

Gujarat State Electricity Corp. Ltd.(GSECL) Generation

Gujarat Energy Transmission Corp. Ltd.(GETCO) Transmission

Uttar Gujarat Vij Company Ltd. (UGVCL) Distribution

Dakshin Gujarat Vij Company Ltd. (DGVCL) Distribution

Madhya Gujarat Vij Company Ltd. (MGVCL) Distribution

Paschim Gujarat Vij Company Ltd. (PGVCL) Distribution

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FUNCTIONS OF GUNVLThe Company was incorporated to take over the assets, liabilities and personnel of the GEB in accordance with

Schedule G of the Main Transfer Scheme Notification dated 24 October 2003. The Company has to carry out the residual functions (including power trading) of the defunct GEB.

One of the functions of the Company includes coordination of the activities of its subsidiaries, business, and works to determine their economic and financial objectives and targets and to review, control, guide and

direct their performance with a view to secure optimum utilization of all resources placed at their disposal

SUBSIDARIES COMPANIES

Gujarat State Electricity Corporation Limited (GSEC) Gujarat Energy Transmission Corporation Limited (GETCO) State Load Dispatch Center (SLDC) Dakshin Gujarat Vij Company Limited (DGVCL) Madhya Gujarat Vij Company Limited (MGVCL) Paschim Gujarat Vij Company Limited (PGVCL) Uttar Gujarat Vij Company Limited (UGVCL) Gujarat Energy Training and Research Institute (GETRI)

BROAD OVER VIEW TO ELECTRICAL POWER SYSTEM

The table below presents the electricity generation capacity, as well as availability to India's end user and their demand

Of the 1.4 billion people of the world who have no access to electricity in the world, India accounts for over 300 million.

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800 million Indians use traditional fuels – fuelwood, agricultural waste and biomass cakes – for cooking and general heating needs

The five states with largest power demand and availability, as of May 2011, were Maharashtra, Andhra pradesh ,Tamil nadu, Uttar pradesh and gujarat

Problems

1) Government giveaways such as free electricity for farmers, partly to curry political favour, have depleted the cash reserves of state-run electricity-distribution system.

2) Shortages of fuel: despite abundant reserves of coal, India is facing a severe shortage of coal. The country isn't producing enough to feed its power plants. Some plants do not have reserve coal supplies to last a day of operations.

3) The giant new offshore natural gas field has delivered less fuel than projected4) hydroelectric power projects in India's mountainous north and northeast regions have

been slowed down by ecological, environmental and rehabilitation controversies, coupled with public interest litigations.

5) The July 2012 blackout, affecting the north of the country, was the largest power grid failure in history by number of people affected.

Government measures

India's Ministry of Power launched Rajiv Gandhi Grameen Vidyutikaran Yojana as one of its flagship programme in March 2005 with the objective of electrifying over one lakh un-electrified villages and to provide free electricity connections to 2.34 crore rural households

This free electricity program promises energy access to India's rural areas, but is in part creating problems for India's electricity sector

CONCEPT OF ENERGY GENERATION, TRANSMISSION , DISTRIBUTION

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• The purpose of the electric transmission system is the efficient interconnection of the electric energy producing power plants or generating stations with the loads.

• Main Parts of Power System

• Four Main Parts:

• Generation System

• Transmission System

• Distribution System

• Consumer (LOAD)

Simplified Diagram of Power System

• One-Line Diagram of Generating Station

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POWER DISTRIBUTION & POWER LOSS REDUCTION METHODS

CONTENTS

• Power Distribution System

• Equipment in Power Distribution

• Losses in the System

• Methods of Reducing Losses

Classification of Power Distribution

1. According to type of current

a. DC Distribution

b. AC Distribution

2. According to construction

a. Over head distribution system

b. Underground distribution system

3. According to service

a. General lighting and power

b. Industrial power

c. Street Lighting

4. According to number of wires

a. Two wire

b. Three wire

c. Four wire

5. According to scheme of connections

a. Radial system

b. Ring system

c. Inter connected system

CONNECTION SCHEMES OF DISTRIBUTION SYSTEM

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1. Radial system: In this system feeders radiate from single sub station and feed the distribution at one end only.

2. Ring system: In this system each consumer is supplied via two feeders. The arrangement is similar to two feeders in parallel on different routes.

3. Inter connected system: In this system the feeder ring is energized by two or more generating stations or sub stations

POWER DISTRIBUTION ATNFC

1. 132kV MAIN RECEIVING STATION

i. 132kV is step down to 33kV or 11kV over two 3 windings transformer of capacity 20/31.5MVA 132kV/33kV/11kV.

ii. The two feeders at 132kV are of 100% capacity iii. An ON LOAD TAP CHANGER (OLTC) which is controlled by automatic voltage regulator to

provide a constant secondary voltage of 11kV irrespective of primary incoming feeder voltage in a range of 138.6kV to 99kV.

2. 66 kV DISTRIBUTION SYSTEM

i. 66kV is step down to 11kV by two 15/20MVA, 66KV/11 transformer. ii. The step down secondary voltage is connected to the switch board through a closed

type bus duct 11kV switch board as 20 bulk oil circuit breaker to feed the 1250kVA, 11kV/433V transformer.

3. 11kV DISTRIBUTION SYSTEM

i. 11kV supply from 20/31.5MVA transformer is drawn to the switch panel through XLPE cables.

ii. SF6 gas circuit breaker

CAPTIVE POWER GENERATION PLANT (CPGP)

• Maximum demand of NFC made with APTRANSCO is 10MVA.

• Total capacity of 7.5MVA, consisting of 3 DG sets, each of 2.5MVA capacity.

• DG sets are connected to an 11kV bus of the power plant which is linked with the 11kV with board of MSDS-1 over to full capacity feeders.

• Every production unit is provided with a diesel generator set of capacity 40kVA or 180kVA or 500kVA according to their emergency demand.

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EQUIPMENT IN POWER DISTRIBUTION

• Bus bars: Bus bars or buses are conductors to which several local feeders or sources are connected. • Outdoor Bus bars • Indoor Bus bar • Compound Immersed Bus bar

• Various types of bus bar arrangements:

Single Bus bar Arrangement

Duplicate Bus bar Arrangement

Sectionalization of Bus bar

Ring Bus

• Circuit breakers: Circuit breaker requires the separation of contacts in a presence of a dielectric medium which serves two functions as

1. It extinguishes arc between two contacts.

2. Provides adequate insulation between the contacts and from each contact to earth.

Classification of Circuit Breaker:

1. Air Circuit Breakers

2. Oil Circuit Breakers

3. SF6 Circuit Breakers

• Surge Arresters:

Surge arresters are used to protect the apparatus insulation from lightning surges and switching surges.

Surge arresters are usually connected between phase and ground in distribution system; near the terminals of the large medium voltage machines and in HV, EHV, HVDC substations.

Two types of Surge Arresters:

1. Gapping Silicon Carbide Surge Arresters

2. Zinc Oxide Gapless Arresters.

EQUIPMENT IN POWER DISTRIBUTION

S.No Equipment Functions

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1 Bus bars Incoming and outgoing circuits are connected to bus bars

2. Lightening arrestors To discharge lightning over voltages and switching over voltages to earth

3. Shunt reactor in E.H.V substations To provide reactive power compensation during low loads.

4. Series reactors To reduce the short circuit currents or starting currents.

5. Neutral Grounding Resistor To limit the earth fault currents.

6. Coupling Capacitor To provide connection between high voltage line and line carrier currents equipment.

LOSSES IN THE POWER DISTRIBUTION

• Distribution Line Losses

• Transformer Losses:

i. Core Lossesii. Copper Losses

iii. Dielectric Lossesiv. Stray Magnetic Losses:

• Losses due to Harmonics

• Losses due to low power factor

• Miscellaneous losses

IMPROVEMENTS IN POWER DISTRIBUTION IN AN INDUSTRY

• Energy Management System

• Power Factor Correction

• High Efficiency Transformers

i. Dry Type Transformerii. Amorphous Core Type Transformer

• Lighting

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Energy Management System

Industrial Energy Management systems are key factors in energy cost conservation.

i. Monitoring and reports

ii. Load shedding

iii. Load forecasting

Monitoring and Report

i. Monitoring and reports also reveal at what times there were particularly high loads.

ii. From here strategies can be developed to avoid such critical situations.

iii. Load Shedding

iv. Load shedding modules in an energy management system offer the possibility of specifying a "turn-off strategy" which states precisely which consumers may be turned off at all and in which order.

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Industrial load forecasting:

• Load forecasting gives you a preview of your company’s load curve, it stores knowledge about the production processes’ behavior in typical production situations from several hours to several days ahead.

o Forecasting can be done in three modes:

i. Assistance Mode

ii. Semi-automatic Mode

iii. Automatic Mode

• DRY TYPE TRANSFORMER• Rating ranges from 100 to 20000 KVA

• They make use of flame-retardant inorganic insulating materials which free these transformers from all restrictions that apply to oil-filled electrical equipment, such as oil-collecting pits, fire walls, fire extinguishing equipment, etc.

• Dry Type Transformers are installed wherever oil-filled units cannot be used

• Their efficiency is rated at 99.02%

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AMORPHOUS TRANSFORMERS

• Amorphous Transformer has become well known after "Super amorphous transformer" produced by Hitachi Ltd.,

• Amorphous transformer uses amorphous alloy in the core.

• Core material is an alloy of Fe,B,Si.

• Low iron loss, High permeability, Low stress sensitivity

POWER FACTOR CORRECTION

i. The input power factor is the real power divided by the apparent power ii. BENEFITS

a. Released System Capacity b. Reduced Power Losses c. Voltage Improvement

ELECTRICITY THEFTA MAJOR ISSUE IN POWER INDUSTRY

CONTENTS

• Introduction

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• India’s generation capacity

• India’s consumption capacity

• Deficit

• Electricity theft

• Major causes of electricity theft

• Measures to control theft

• Conclusion

INTRODUCTION • Many developing countries confront widespread theft of electricity from government owned power

utilities. • In India electricity theft leads to annual losses estimated at US$4.5 billion, about 1.5 percent of GDP.• Who are the losers??• Honest consumers, poor people, and those without connections, who bear the burden of high tariffs,

system inefficiencies, and inadequate and unreliable power supply.• India is the seventh-largest country by area, the second-most populous country with over 1.2 billion

people, and the most populous democracy in the world.• Who are the losers? Honest consumers, poor people, and those without connections, who bear the

burden of high tariffs, system inefficiencies, and inadequate and unreliable power supply.

While 80% of Indian villages are electrified, only 44% of rural households have access to power.

DEFICIT India has been facing growing shortages over the past five years

1. During the year 2007-08

peak deficit:8,000 MW (16.5%)

average energy shortage:73 Billion kWh (10%).

2. During the year 2008-09

peak deficit 13,000 MW (12%)

average energy shortage: 86 Billion kWh (11%).

3. During the year 2009-10

peak deficit:5,157 MW (12.7%) average energy shortage:84 Billion kWh (10.1%).

ELECTRICITY THEFT

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WHAT IS ELECTRICITY THEFT….???

• It is the use of electrical power without a contract with a supplier with total or partial bypassing metering system

OR

• Interfering this system in the way to adulterate its measurements.

MAJOR CAUSES OF ELECTRICITY THEFT • Absence of accountability.

• Inadequate and ineffective enforcement of law.

• Political protection to employees and influential customers.

• Customer attitude: “Immoral to steal from neighbor but legitimate to steal from state’’.

WHERE DOES ELECTRICITY THEFT OCCUR MOST COMMONLY ?

ELECTRICITY THEFT METHODS

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Meters:

• Tampering with meters and seals

• By-passing the meters

• Damaging or removing meters

Wires/ Cables:

• Illegal tapping to bare wires or underground cables

Transformers:

• Illegal terminal taps of overhead lines on the low side of the transformer

Billing irregularities made by meter readers.

Unpaid bills by individuals, government institutions and “untouchable” VIPs.

FEW OTHER WAYS FOR POWER THEFT

• Use of single phase supply from three phase supply.

• Disconnected neutral from both the ends.

• Used earth/separate neutral for return circuit.

• Connecting phase voltage to neutral of used single phase supply. Potential difference w.r.t. neutral of

used single phase supply is zero. Hence power product of voltage and current, will be zero.

• Isolating neutral from both ends.

THEFT OCCURS WHEN:

• An illegal consumer(not a registered customer) steals directly from the distribution lines or from another legal customer.

• A legal customer(registered customer) steals either bypassing the meter (connecting around the meter to a live cable on the company side of the meter) or tampering with the meter to make it read less or no consumption.

• There is a collusion between the customer and a company employee to reduce the amount paid to the company (with lower side payments to the employee in return).

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METER TAMPERING

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ILLEGAL WIRING

OTHER WAYS TO STEAL ELECTRICITY

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HOW CAN ELECTRICITY THEFT BE REDUCED

NON TECHNICAL SOLUTIONS Financial rewards:

Utility companies encourage consumers to report electricity theft

Periodic checks:

Electricity theft frequently takes place after service has been disconnected. Some utility companies periodically check disconnected meters if the customer has not contacted them to reconnect service.

Enforcement of law: Fines should be imposed by the government for stealing electricity.

• Taps, makes or causes to be made any connection with overhead, underground or under water lines or cables, or service wires, or service facilities of a licensee;

• Tampers a meter, installs or uses a tampered meter, current reversing transformer, loop connection or any other device or method which interferes with accurate or proper registration, calibration or metering of electric current or otherwise results in a manner whereby electricity is stolen or wasted.

• Damages or destroys an electric meter, apparatus, equipment, or wire or causes or allows any of them to be so damaged or destroyed as to interfere with the proper or accurate metering of electricity, so as to abstract or consume or use electricity shall be punishable with imprisonment for a term which may extend to three years or with fine or with both.

TECHNICAL SOLUTIONS Electronic tamper detection meter

Pre payment meters

Plastic meter encasements

Anti theft cable

Using GSM

Using PLCs

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Electronic Tamper Detection MetersAutomatic detection of :

•

• Meter tamper

• Meter Bypass

• Meter disconnection

Pre-Payments Meters

• Credit added to the meter on the keypad.

• Credit is purchased on the recharegable token and entered to the meter with disconnection ability

Plastic meter encasements

Hard plastic encasements are a type of meter seal. These transparent plastic covers serve as a warning.

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• Anti theft cable

DISTRBUTION SYSTEM FAULT MANAGEMENT

AGENDA

Introduction.

Currently Existing System.

New Fault Management System.

Advantages, Applications, Improvements.

DISTRIBUTION SYSTEM.Distribution system is that part of the power system which distributes power from distribution substation to local use .

Generally the higher voltage for distribution is 11000v and the lower voltages are 400 v and 220v.

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TYPES OF FAULTS IN DISTRIBUTION SYSTEM• LINE TO LINE FAULT .

• LINE TO GROUND FAULT .

• 3 PHASE FAULTS.

• OVER CURRENT FAULTS

LINE TO LINE FAULT. It’s The Fault Which Occurs Between Any Of The 2 Lines .

At This Fault The Voltage Across Two Lines Will Be Zero, And Current Is Maximum.

V=0,I=∞

LINE TO GROUND FAULT IT IS THE FAULT OCCURS BETWEEN ANY LINE TO GROUND.

AT THIS FAULT THE VOLTAGE ACROSS LINE TO GROUND IS ZERO, AND CURRENT IS MAXIMUM.

V=0,I=∞

THREE PHASE FAULTS Over Current Faults

In Overcurrent Faults The Current Is Maximum ,That Is More Than Rated Value.

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OVERVIEW OF CURRENT FAULT MANGEMENT SYSTEM

DIFFICULTIES IN CURRENTLY EXISTING SYSTEM

• Fault Identification takes too much time.

• At the time of raining it is too difficult find and correct faults.

• With the human error fatal accidents are common .

• L.V. distribution faults(after the secondary of distribution transformer) are cannot be identified from existing relays, faults like conductor down, overloading, short circuiting of conductors etc. which unexpected and very difficult identify.

OBJECTIVE OF FAULT MANAGEMENT SYSTEM

To improve reliability and quality of service of distribution system by

Reducing frequency and duration of power interruptions to targets consistent with best international practice

To operate efficiently and safely by

Minimizing power losses

Applying manpower resources effectively

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METHOD INVOLVED

It will be consisting of control room with a signal indicating system it may be a computer monitor or big screen

Which will be indicating the status of all section voltage and current with alarm for any abnormal conditions .

After I identifying the fault feeder all loads are removed from the network and network will be charged idly with full voltage and limiting current through a current limiter which may be a saturable reactor so it limits the fault currents.

After charging the line idly , all sections current and voltage status will be absorbed and faulty section is identified.

after identifying faulty section, it will be isolated from the healthy one from remotely .

After clearing the fault the section will be closed.

Fault cleared successfully.

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Advantages

The new fault management system has a wide and verity range of applications and advantages .

The down time is got reduced.

Less interruption system can be ensured to the customer.

Revenue loss is got reduced.

With moves toward deregulation and open competition, access to accurate and timely outage

information is critical in order to maximize operational efficiency, minimize customer complaints, and

maintain electric system reliability

Implementing same system to the L.V. distribution the transformer secondary side faults can be

identified and cleared immediately which ensures the safety for men and machines.

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IMPROVED FAULT MANAGEMENT SYSTEM

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APPLICATIONS

Fault Location, Isolation, and Service Restoration

◦ Can detect and locate fault, isolate the faulty section, restore power to “healthy” feeder segments

Load Shedding

◦ Can shed one feeder section if necessary

Cold Load Pickup

◦ Can pick up feeder load one section at a time

Feeder Reconfiguration

◦ Can balance load between feeders and reduce losses

“Intelligent” Substation Bus Transfer

◦ Can transfer load to another substation following transformer failure

. DIFFERENT PROVISIONS FOR THEFT OF ELECTRICITY IN EA, 2003 & COMMENTS

2.1 Focus on revenue realization rather than criminal proceedings.

(Sections 126, 135) The real focus after the identification of the activity of electricity theft by any class of consumer is on the collection of revenue which is chargeable to the offender according to the financial gain incurred by him brought out by the assessment of the assessment officer. There are very low measures for severe punishments so that it is ensured that the same crime does not take place again. The tempting condition behind collection of revenue as a fine at the first place may be because of the poor financial condition of the distribution utilities. There is no act of imprisonment to a consumer with a load of less than 10 kilowatts. These are mainly the retail customers and many cases have been found with these customersleading to a huge loss to the utilities. Theft by these consumers is majorly done by tapping an electric cable/pole or by tampering of meters. Also, to the consumers above the load of 10 kilowatt imprisonment clause is only after the repeated offence.

2.2 Penalties linked to the connected load and quantum of energy and financial gain

involved in theft.

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(Section 135) For the case where the load abstracted, consumed or used/attempted does not exceed 10 kilowatt, the fine imposed on first conviction will not be less than three times the financial gain realized due to such an activity. For second conviction the fine has not to be less than six times the financial gain realized out of such activity. For the case where the load abstracted, consumed or used/attempted exceeds 10 kilowatt, the fine imposed on first conviction is not less than three times the financial gain derived from such activity. Upon second conviction the consumer can be imprisoned for a period not less than six months and which may extend to five years along with the penalty of six times the financial gain realized. Here, if the period of theft/pilferage cannot be ascertained it is taken to be 12 months from the date of noticing the theft. There is no proper method to reach to the actual

(Section 126)

The officer in-charge, if by inspection of any place or equipments comes to the conclusion that there is some unauthorized use of electricity, he can provisionally access to the best of his judgment the electricity charges payable by the person benefited by such use. An order of provisional assessment shall be served on the person who owes the premise. The person may accept the assessment and deposit the assessed amount with the licensee within seven days of the assessment order. After assessment if the person is found guilty the assessment has to be done for the entire period for which the activity has been carried out. In cases where this cannot be ascertained the period of theft is takes as twelve months from the date of first inspection and this assessment shall be at the rate twice the tariff rates applicable for the particular class of consumer.

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AN OVERVIEW OF TRANSMISSION SUBSTATION LAYOUT AND ITS EQUIPMENTS

“SUBSTATION LAYOUT”

• Single line diagram

Substation Switchyard Accessories

• Lightning Arrestor

• CVT

• Earthing switch

• Wave trap

• Isolator

• Current transformer

• Circuit Breaker

• Power Transformer

• Current transformer

• Reactors and capacitors

• Other Switchyard Equipments

• PLCC

• SCADA

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SWITCHYARD LAYOUTING

CLASSIFICATION OF SUBSTATIONS

• Based on working

I. Generating substation (step up s/s)

II. Grid substation

III. Switching substation

IV. Secondary substation -- a) sub transmission voltage

b) primary distribution c) distribution substation

• Based on structure

I. Outdoor conventional air insulated substation (AIS)

II. Indoor substation

III. Compressed air insulated

IV. G I S

LIGHTNING ARRESTORS

A lightning arrester is a device used on electrical power systems to protect the insulation on the

system from the damaging effect of lightning.

Metal oxide varistors (MOVs) have been used for power system protection since the mid 1970s.

The typical lightning arrester also known as surge arrester has a high voltage terminal and a ground

terminal.

Current from the surge is diverted around the protected insulation in most cases to earth.

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CVT

Capacitor Voltage Transformer (CVT), Capacitance Coupled Voltage Transformer(CCVT)

o To step down extra high voltage signals and provide a low voltage .For measurement or to operate

a protective relay

EARTHING SWITCH

• Earth Switch is used to discharge the voltage on the circuit to the earth for safety.

• Earth switch is mounted on the frame of the isolators.

• It is located for each incomer transmission line and each side of the busbar section.

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LINE TRAP (WAVE TRAP)

Connected in series with the power (transmission) line.

It blocks the high frequency carrier waves (24 KHz to 500 KHz) and let power waves (50 Hz - 60 Hz) to pass through.

It is basically an inductor of rating in Milli henry (approx 1 milli Henry for 220 KV 1250 Amp.).

It has three main components:-

1. Main coil.

2. Tuning Device.

3. Lightning Arrestor.

ISOLATOR

• Disconnector or Isolator switch is used to make sure that an electrical circuit can be completely de-energised for service or maintenance.

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• Isolator is an off-load device.

• Types of Isolators are

1. Central rotating, horizontal swing

2. Centre-Break

3. Vertical swing

4. Pantograph type

CURRENT TRANSFORMER

Current transformers are used for Stepping down current for measurement, protection and control.

Current transformers are of two types

1. Protective CT

2. Measuring CT

CIRCUIT BREAKERS

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A Circuit breaker is an automatically operated electrical switch designed to protect an electrical

circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition

and, by interrupting continuity, to immediately discontinue electrical flow.

All circuit breakers have common features in their operation, although details vary substantially

depending on the voltage class, current rating and type of the circuit breaker.

Once a fault is detected, contacts within the circuit breaker must open to interrupt the circuit.

Small circuit breakers may be manually operated; larger units have solenoids to trip the mechanism,

and electric motors to restore energy to the springs. HIGH-VOLTAGE BREAKERS ARE BROADLY CLASSIFIED BY THE MEDIUM USED TO EXTINGUISH THE ARC

• Bulk oil

• Minimum oil

• Air blast

• Vacuum

• SF6

BUSBARS

Busbars receive power from incoming circuits and deliver power to outgoing circuits

REACTORS

The majority of the load in a typical AC power system is inductive; the current lags behind the voltage. Since the voltage and current are out-of-phase, this leads to the emergence of an "imaginary" form of power known as reactive power. Reactive power does no measurable work but is transmitted back and forth between the

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reactive power source and load every cycle. This reactive power can be provided by the generators themselves, through the adjustment of generator excitation, but it is often cheaper to provide it through capacitors, hence capacitors are often placed near inductive loads to reduce current demand on the power system (i.e, increase the power factor), which may never exceed 1.0, and which represents a purely resistive load. Power factor correction may be applied at a central substation, through the use of so-called "synchronous condensers" (synchronous machines which act as condensers which are variable in VAR value, through the adjustment of machine excitation) or adjacent to large loads, through the use of so-called "static condensers" (condensers which are fixed in VAR value).

Reactors consume reactive power and are used to regulate voltage on long transmission lines. In light load conditions, where the loading on transmission lines is well below the surge impedance loading, the efficiency of the power system may actually be improved by switching in reactors. Reactors installed in series in a power system also limit rushes of current flow, small reactors are therefore almost always installed in series with capacitors to limit the current rush associated with switching in a capacitor. Series reactors can also be used to limit fault currents.

Capacitors and reactors are switched by circuit breakers, which results in moderately large steps in reactive power. A solution comes in the form of static VAR compensators and static synchronous compensators. Briefly, static VAR compensators work by switching in capacitors using thyristors as opposed to circuit breakers allowing capacitors to be switched-in and switched-out within a single cycle. This provides a far more refined response than circuit breaker switched capacitors. Static synchronous compensators take a step further by achieving reactive power adjustments using only power electronics.

SHUNT REACTORS

• Shunt Reactors are used for long EHV transmission lines to control voltage during low – load period.

• Shunt reactors is also used to compensate shunt capacitance of transmission line during low load periods.

• Usually Shunt reactors are unswitched.

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SHUNT CAPACITORS

• Shunt capacitors are used for compensating reactive power of LPF.

• They are used for improving the power factor. It is also used for voltage control during heavy lagging power factor loads.

• They are located at the receiving stations and distribution substations.

• They are switched on during heavy loads and switched off during low loads.

NEUTRAL GROUNDING EQUIPMENT

• Neutral Grounding Equipment are Resistors and reactors.

• They are used to limit the short circuit current during ground fault.

• They are connected between neutral point and ground.

WHAT IS SCADA ?

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• SCADA stands for Supervisory Control And Data Acquisition.

• It is not a full control system, but rather focuses on the supervisory level.

• It is a purely software package that is positioned on top of hardware to which it is interfaced. ( via Programmable Logic Controllers(PLCs)) .

The SCADA systems are arranged to perform the following tasks.

• Data Collection (Data Acquisition)

• Data transmission (telemetry)

• Scanning, Indication, Monitoring, Logging.

• Control and indication.

• Ensure sequential events.

• Data presentation, display, reporting

• Execution of operating, commands: on/off,raise/lower.

• Network supervision, alarms and report any uncommon

change of state.

Thank you

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