main ppt.pptx

7/27/2019 main ppt.pptx

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D. Babu(101798)


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The first central electric station was

installed by Edison in Newyork in1882 which is operated at 110v DC

It is interesting to know as to why

then AC almost replaced all DC lines

and why DC is again being used forsome high voltage transmission lines


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Reasons for power generated,

transmitted, distributed andconsumed as alternating current

Transformer

Induction motors

Commutators


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Strong technical reasons for direct

current transmission

High charging currents in AC Asynchronous interconnection

Economical after break even distance


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Cost comparison of ac and dc

transmission

Cost of DC terminal

Cost of AC terminal

Cost

Break even distance

Distance in km

Cost of AC Line

Cost of DC Line

500 700 km


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Types of HVDC links

Monopolar

Bipolar

Homopolar


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Monopolar line

Usually the line is operated with negative

polarity as the corona loss and radio

interferences are less


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Modes of Operation

DC OH Line

Converter

Transformer

Thyristor

Valves

400 kVAC Bus

AC Filters,

Reactors

Smoothing Reactor

Converter

Transformer

Thyristor

Valves

400 kVAC Bus

AC Filters

Smoothing ReactorBipolar

Current

Current


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Modes of Operation

DC OH Line

Converter

Transformer

Thyristor

Valves

400 kVAC Bus

AC Filters,

Reactors

Smoothing Reactor

Converter

Transformer

Thyristor

Valves

400 kVAC Bus

AC Filters

Smoothing ReactorMonopolar Metallic Return

Current


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Modes of Operation

DC OH Line

Converter

Transformer

Thyristor

Valves

400 kVAC Bus

AC Filters,

Reactors

Smoothing Reactor

Converter

Transformer

Thyristor

Valves

400 kVAC Bus

AC Filters

Smoothing ReactorMonopolar Ground Return

Current


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Homopolar link

Two or more conductors with same polarity usually

negative for the reason of corona and radio interference

and always operate with ground as the return


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Parallel and series connections ofthyristor

o Parallel -Current rating will increase

o Series voltage ratings will increase


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Parallel operation of DC link with

AC network

Stability of AC network can be increased if it iskept in parallel with DC line


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POWERGRID (Engg-HVDC)

Single Line Diagram

DC OH Line

ConverterTransformer

DC Filter:

DT 12/24

DT 12/36

DC Filter:

DT 12/24

DT 12/36

ThyristorValves

400 kVAC Bus

AC Filters,

Reactors

Talcher ConverterStation

Smoothing Reactor

ConverterTransformer

DC Filter:

DT 12/24

DT 12/36

DC Filter:

DT 12/24

DT 12/36

ThyristorValves

400 kVAC Bus

AC Filters

Kolar ConverterStation

Smoothing Reactor


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6-Pulse Convertor Bridge

3

6

CiLs

4

E1 L

s

Ls

Bi

iA

1

2

I

V'd

5

Vd

IddL

d


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12-Pulse Convertor Bridge

Y


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Salient Features

Rectifier Talcher, Orissa

Inverter Kolar, Karnataka

Distance 1400 km

Rated Power 2000 MW

Operating Voltage 500 kV DC

Reduced Voltage 400 kV DC


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Simplified SLD at Talcher

Y

YACF3 ACF1

Y

Y ACF2

Meramundali-I

Meramundali-II Rengali-II

Rengali-I

Rourkela-II

Rourkela-I

ICT

BS 1B

BS 1A

Gen 1Gen 2Gen 3Gen 4Gen 6

BS 2B

BS 2A

BS 3A

BS 3B

Pole2 Pole1

ICTGen 5


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Bus # 3 Bus # 5

Bus # 4 Bus # 6

STAGE-II POWER FLOW SINGLE LINE DIAGRAM

GENERATOR # 6GENERATOR # 5GENERATOR # 4

ST # 2

GENERATOR # 3

ST # 3

HVDC # 1 HVDC # 2

GT # 5

HVDC # 3 HVDC # 4

HVDC POLE-2HVDC POLE-1

400 KV BUS-1

400 KV BUS-2

TO FILTER-2

MWT-6MWT-5MWT-4MWT-3

GT # 3 GT # 4

TO FILTER-1

GT # 6


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Simplified SLD at Kolar

Y

YACF2ACF1

Y

Y ACF3

Future

ICT

BS 1A

BS 1B

ICT

Pole1 Pole2

Chennai Hosur

I

Hosur

I

Hosur

II

Hoody

I

Hoody

II Bangalore

Cuddapah Future

Line


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Logic for unit tripping during HVDC single

pole outage

block

blockdeblock

deblock

Pole 1 Pole 2

S

Power

>

1750

Trip

Identified

Unit

TSTPP Stg II all four Units running with full capacity

Ex-bus Generation shall be around 1850 MW or less.

While all four Units running, if one HVDC pole isblocked & NTPC Ex-bus Generation is more than 1750

MW, one identified unit shall trip instantaneously.


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Logic for unit tripping during HVDC

Both pole outage

block block

Pole 1 Pole 2

S Power> 550

S Power> 1100

Trip Unit # 5

Trip Unit # 4

250 ms

500 ms

Trip

Unit # 6

T1

T2


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Logic for unit tripping during HVDC Both pole

outage

Both HVDC poles blocked & TSTPP Stg II Ex-bus generation is morethan 550 MW & less than 1100MW.

Unit # 5 shall trip instantaneously.

Unit # 4 shall trip after time delay of 250 m sec.


Both HVDC poles blocked & TSTPP Stg II Ex-bus generation is more than 1100

MW.

Unit # 5 & 6 shall trip instantaneously.



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Existing HVDC in INDIA

1 Rihand-Dadri (1500MW)

2 - Vindyachal (500MW)

3 - Chandrapur-Padghe (1500MW)

4 - Chandrapur-Ramagundam(1000MW)

5 Barsoor-Lower Sileru(100MW)

6 Gajuwaka (500MW)

7 - Sasaram (500MW)

8 - Talcher-Kolar (2000MW)


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HVDC Bipolar LineChandrapur-PadgheRihand-Dadri

Talcher-KolarBalia-BhiwadiBiswanath-Agra

HVDC Back-to-backVindhachalChandrapurGazuwakaSasaram

HVDC Monopole LineBarsur-Lower Sileru

Existing HVDC projects in INDIA


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Advantages

Power per conductor

Power per circuit

No charging current

No skin effect

Less corona loss and radio interference

No stability problem

Less short circuit currents

No compensation


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Disadvantages

Expensive converters and transmission lines

Voltage transformations

DC circuit breaking is difficult


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