Comparative Evaluation of HVAC and HVDC

1.   Introduction

The transmission and distribution of electrical energy

started with direct current (DC) in the late 19th century, but

it was inefficient due to the power loss in conductors.

Alternating current (AC) offered much better efficiency,

since it could easily be transformed to higher voltages, with

far less loss of power. AC technology was soon accepted as

the only feasible technology for generation, transmission

and distribution of electrical energy.

However, high-voltage AC transmission links have

disadvantages and engineers were engaged in the

development of a technology for DC transmissions as a

supplement to the AC transmissions. The invention of

mercury arc rectifiers and the thyristor valves, made the

design and development of line-commutated current

sourced converters possible.

High Voltage Direct Current (HVDC) transmission finally

proved to be technically feasible. The world's first

commercial HVDC transmission link, was built in 1954

between the Swedish mainland and the island of Gotland,

with a rating of 20 MW, 200 A and 100 kV

Questions About Electric Power Transmission

Transmission of electrical power is commonly performed on high voltage, either using the HVAC (high voltage alternating current) and HVDC (high voltage direct current). the former uses an alternating current and this is contained in our country. The second course uses direct current. in this post, I will not touch such a question: Which is better, HVAC or HVDC? My problem is something more fundamental, namely concerning the reasons why the transmission done at a high voltage (even extra high) . it was clear from some college (khususnya high voltage engineering) that the transmission of electrical power carried on the high voltage to reduce losses associated with the transmission line impedance. but ... .Please refer to here to find out more about the various voltage values commonly used in transmission lines and its classification.

HVDC

Use of High Voltage Direct Current Transmission (HVDC) or in Indonesian terms is known as direct current power transmission (TDAS) actually started in the beginning of the first electricity was developed. Thomas Alva Edison made electricity network with a capacity of 6 x 100kW to power in 1200 using direct current light bulb in 1882. Although in its development, Edison developed dc system was 'lost' to compete with the ac system proposed by Westinghouse and Tesla, but these systems have been dc new era, the era of electricity. More than 70 years later, the dc transmission system came into use again after finding a mercury-arc tube at the end of the 1920s. Commercial HVDC project was first built in 1950 using a submarine cable to link Sweden with P. Gotland with a capacity of 20MW at 100kV voltage.
This paper briefly describes the technology, configuration, and application of direct current power transmission (HVDC).
HVDC technology started to be used again because the tube / mercury-arc already well established so that power converter ac / dc or dc / ac can be made, something that can not be done in the 1880s that resulted in the defeat of Edison's direct current alternating current system Westinghouse behind. Mercury-arc tube technology itself only lasted about 20 years until the invention of the thyristor at around 1970. This thyristor is the basis of the rapid development of HVDC technology because it can be made for the purposes of power, compared to the transistor / IGBT that with today's technology has a smaller capacity than the thyristor. The last decade, the development of IGBT technology allows for the HVDC converter is made by using IGBT (Figure 1), although its capacity is smaller than HVDC systems using thyristor converters. 

    Figure 1. Development of a static switch for HVDC