HVDC TRANSMISSION Subject Code: 10EE751

HVDC TRANSMISSION Subject Code: 10EE751

HVDC TRANSMISSION
Subject code: 10EE751

UNIT 1- LECTURE 1

Text Books:

Direct current Transmission by EDWARD WILSON KIMBARK (Wiley interscience, New york,1971).

High Voltage D.C.Power Transmission system by K.R.PADIYAR IISc Bangalore, New Age International Publishers Ltd.

Overview:

General Aspects of DC transmission and comparison of it with AC transmission.

Converter Circuits

Analysis of the Bridge converter

Control of HVDC Converters and Systems.

Protection.

PART A (Unit 1 & 2)

General Aspects of DC Transmission and comparison of it with AC Transmission

Historical Sketch

Constitution of EHV AC and DC links.

Limitations and Advantages of AC and DC transmission.

Historical Sketch:

Evolution of Power Systems:

Late 1870s- Commercial use of electricity.

In 1882- First Electric power system which includes Generator, Cable,fuse,Load designed by Thomas Edison at Pearl Street station in New york.

It was DC System (Low Voltage 110V),underground cable is used to distribute the power to consumers. Only 59 consumers are benefited by this low voltage DC system. Incandescent lamps are used as a load.

In 1884-Motors were developed by Frank Sprague. After the invention of motors electricity is used more effectively or it was appreciated.

In 1886 -Limitation of DC

High losses and Voltage Drop

Transformation of Voltage required.

Transformer and AC distribution (150 lamps) developed by William Stanley of Westing house.

In 1889- First AC transmission system in USA between Willamette falls and Portland, Oregon. It was 1-Phase,4KV,Over 21 Km.

Before that in the year of 1888-N.Tesla developed Poly Phase system and had patents of Generator,Motor,Transformer, transmission lines. Later Westing House bought it.

In 1890-Controversy on whether industry should standardize AC or DC.

Edison-DC System Westing House-AC System

Later because of features of AC System, its dominated

  1. Voltage increase is possible
  2. Simpler and cheaper generators and motors.
  3. In 1893-First 3-Phase line ,2.3KV,12 Km in California .
  4. Improvement in voltages year by year,

1922-165KV

1923-230KV

1935-287KV

1953-330KV

1965-500KV

1966-735KV

1969-765KV

1990-1100KV

Standard voltages are 115,138,161,230KV preferred for High Voltage (HV)lines.

Remaining 345,500,765KV are Extra High Voltage(EHV) lines.

For interconnection of AC systems, We need fixed frequency.

60Hz-US and Canadian countries

50Hz-Europe and Asian countries

Entry of HVDC system:

HVDC transmission was designed by a French Engineer, RENE THURY. Simultaneously AC system was also developed slowly.

In between 1880-1911,atleast 11 Thury system were installed in Europe. The prominent was Mouteirs to Lyons(France) in 1906. It comprises 180Km(4.5 km underground cable),4.3MW,57.6KV,75A.

Features:

DC series generators were used.

Constant control current mode.

In1920-Transverter(Mechanicalconverter-polyphase transformer)were developed. Again AC system dominated.

In 1938-All the Thury system were dismantled. Because in DC system, we need frequent maintenance, cost also is not effective.

Again AC revolution back till 1950. In the year of 1950, Mercury arc valves (Bulky converter) it was possible to convert AC to DC.

In 1954, first HVDC System between Sweden and Gotland island was commissioned by cable. Conversion carried out by Mercury arc rectifier. Again people think about DC transmission because of the limitation in AC system.

Limitations of HVAC

Reactive power loss

Stability

Current carrying capacity

Skin and Ferranti effect

Power flow control is not possible.

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