Hvdc

High Voltage Direct Current Transmission –
Proven Technology for Power Exchange

Answers for energy.
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Contents

Chapter
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Theme
Why High Voltage Direct Current? Main Types of HVDC Schemes Converter Theory Principle Arrangement of an HVDC Transmission Project Main Components Thyristor Valves Converter Transformer Smoothing Reactor Harmonic Filters AC Harmonic Filter DC Harmonic Filter Active Harmonic Filter Surge Arrester DC Transmission Circuit DC Transmission Line DC Cable High Speed DC Switches Earth Electrode Control & Protection System Studies, Digital Models, Design Specifications Project Management

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5 5.1 5.2 5.3 5.4 5.4.1 5.4.2 5.4.3 5.5 5.6 5.6.1 5.6.2 5.6.3 5.6.4 5.7 6

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Why High Voltage Direct Current ?

1.1 Highlights from the High Voltage Direct Current (HVDC) History The transmission and distribution of electrical energy started with direct current. In 1882, a 50-km-long 2-kV DC transmission line was built between Miesbach and Munich in Germany. At that time, conversion between reasonable consumer voltages and higher DC transmission voltages could only be realized by means of rotating DC machines. In an AC system, voltage conversion is simple. An AC transformer allows high power levels and high insulation levels within one unit, and has low losses. It is a relatively simple device, which requires little maintenance. Further, a three-phase synchronous generator is superior to a DC generator in every respect. For these reasons, AC technology was introduced at a very early stage in the development of electrical power systems. It was soon accepted as the only feasible technology for generation, transmission and distribution of electrical energy. However, high-voltage AC transmission links have disadvantages, which may compel a change to DC technology: • Inductive and capacitive elements of overhead lines and cables put limits to the