AN INDUSTRIAL TRAINING ON

HIGH VOLTAGE DIRECT CURRENT (HVDC) TRANSMISSION TECHNOLOGY

( 500 kV RIHAND-DADRI LINK)

POWERGRID, DADRI

Arundhati Yadava (1273920005)

Power Grid Corporation of India Limited

Contents

About POWERGRID

The War of Currents

HVDC: A Simple Explanation

Why HVDC?

Types of HVDC links

The Converter Station

500 kV Rihand-Dadri Link

List of HVDC Projects in India

Need of HVDC in India

References

1) About POWERGRID

Reputed transmission utility of India

Headquarters: Gurgaon, Haryana

Founded: 29th October, 1989

Chairman & MD: Shri R. N. Nayak

Milestone: set up the 500 kV Rihand-Dadri link (the first HVDC link in India)

Awards: Environmental and Sustainable Development Award by Indian Chamber of Commerce (ICC) in 2011 Microsoft Windows Server 2003 Challenge Winner

Completed 25 glorious years in 2014

2) The War of Currents

Thomas Alva Edison (in favor of DC)

Nikola Tesla

George Westinghouse

in favor of AC

3) HVDC: A Simple Explanation

RihandConverter Station

NTPC,Rihand

Dadri ConverterStation

Delhi

4) Why HVDC?

Asynchronous grid connection

Low running cost

30-50% less losswhen compared to EHV AC

HVDC towers require less space (Right of Way)

5) Types of HVDC link

MONOPOLAR

BIPOLAR

HOMOPOLAR

6) The Converter Station

Switchyard (AC and DC)

Converter Transformer

The Valve Hall

Control Room

Battery System

i. Switchyard (AC and DC)

Lightning ArresterProtects equipments from lightening

Diverts high voltages to the earth

Installed in DC as well as AC switchyard

Wave TrapPrevents high frequency carrier signals from going elsewhere

Connected in series with transmission line

Installed in DC as well as AC switchyard

Circuit BreakerAutomatic operation

Operates when fault occurs in a system

Usually used in the breaker and a half scheme

IsolatorManual operation

Isolates a part of circuit from system when needed

Usually used for maintenance purpose

Current TransformerSeries connected instrument transformer

Types: live tank dead tank

Potential TransformerParallel connected instrument transformer

Types: electromagnetic capacitor optical

AC FilterProvide reactive power consumed by the converter

Eliminates harmonics

Consists of series RLC series circuit connected in parallel with the bus-bars

DC FilterHarmonic voltages (on DC side) cause AC currents which are superimposed on the direct current in the transmission line

DC filter circuits are connected in parallel

DC Smoothing ReactorAir core type

Smooths DC

Avoids fault current

Large inductive coil

Provided with surge arresters

Capacitor Voltage TransformerSteps down extra high voltage signals

Provide a low voltage signal, for metering or operating a protective relay

Consists of two capacitors, an inductive element and a voltage transformer

ii. Converter Transformer

It is the interface between the AC system and the thyristor valves

Have AC supply on primary side and DC load of valve on the secondary side

Undergoes AC and DC stress

The AC voltage stress is predominantly in the insulating oil and defined by the geometry and permittivity of the materials

DC stress is governed by the resistivity of the insulating materials

iii. The Valve Hall

Consists of quadruple thyristor valves

Usually a twelve pulse converter

Thyristor valves are suspended from the roof of the building

Low voltage: closest to the roof

High voltage: lowest point on the valve

iv. Control Room

iv. Control Room

v. Battery System

Ni-Cd battery

220 V system is used to operate circuit breaker motor

48 V system is used for Power Line Carrier Communication (PLCC)

24 V

7) 500 kV Rihand-Dadri Link

ConfigurationBipolar

Transmission voltage 500 kV

Maximum transmission power1500 MW (2 X 750 MW)

Transmission line length810 km

Number of towers2140

Type of conductor usedBersimis

Right of way46 m

Frequency rating47.5 - 51.5 Hz

Short-time overload1000 MW per pole (for 5 s)

Thyristor valves6.5 kV, 1568 A

Converter transformer305 MVA

AC filters 3 x 230 MVAR (11/13, 3/36, 5/27)

DC filters 2 x (12, HP 24)

8) List of HVDC Projects in India

S. No.ProjectYearof commission RegionPower rating(MW)AC transmission voltage(kV)DC transmission voltage(kV)

1.Rihand-Dadri1991ER-WR1500400500

3Chandrapur-Padge1999CR-WR1500400500

3.Talcher-Kolar2003ER-SR2000400500

4.Ballia-Bhiwadi2010ER-NR2500400500

5.Mundra-Mohindergarh2012WR-NR1500400500

6.Biswanath-Agra2015NER-ER6000400800

9) Need of HVDC in India

Abundance of energy resources in North-East India

Biswanath Chariali, Assam

Agra, Uttar Pradesh

HVDC

(1900 km)

10) References

http://www.siemens.com/press/pool/de/feature/2013/energy/2013-08-x-win/factsheet-hvdc-e.pdf

https://en.wikipedia.org/wiki/HVDC_converter#/media/File:12_pulse_bridge_with_thyristor_valves.png

http://www2.ee.ic.ac.uk/patrick.sterling10/yr2proj/HVDC%20Circuit%20Breakers%20Report.pdf

http://www.skm-eleksys.com/2011/09/substation-bus-schemes.html

http://epaper.kek.jp/p01/EXHIBIT/HITEC.PDF

THANK YOU!