Daily Concept Booster Electrical Engineering: HVDC Transmission Systems Part-01

HVDC Transmission Systems

HVAC v/s HVDC

In AC Transmission, the direction of voltage and current change continuously which causes overheating in the lines, thus resulting in significant power loss. Unlike AC transmission, current and voltage flow in one direction only in DC Transmission. So, when we convert HVAC into HVDC we observe a significant reduction in power loss hence increasing the efficiency of the transmission lines.

Comparison of AC and DC Transmission

The merits of two modes of transmission (AC & DC) should be compared based on the
following factors.
1. Economics of transmission
2. Technical Performance
3. Reliability

Classification of HVDC Links

The high voltage dc links may be classified into:

1. Monopolar Link: monopolar link has only one conductor and return path is provided by permanent earth or sea.

2. Bipolar Link: This is the most widely used dc link for overhead long-distance HVDC transmission systems and also for back-to-back HVDC system. This link has two conductors— one operating with positive polarity and the other with negative polarity with respect to the earthed tower structure.

3. Homopolar Link: A homopolar link has two or more conductors having the same polarity.