Everything about HVDC - Explained by an Engineer - Introduction

Description

HVDC is powering some of the most ambitious energy projects on Earth — from interconnectors between countries to proposals linking entire continents. But why do we use DC instead of AC for these ultra-long connections?

In this video, I break down how HVDC actually works — from the physics of AC vs DC, to the limitations of cables, and why effects like capacitive charging currents, the Ferranti effect, and skin effect make AC unsuitable for long-distance subsea transmission.

We then dive into converter technology, explaining:

How LCC (thyristor-based) systems operate
How VSC (IGBT-based) systems build waveforms using modular multilevel converters (MMC)
What submodules, capacitors, and valve stacks actually do
Why thousands of semiconductors are used instead of just a few

We’ll also compare LCC vs VSC, explore power control, black start capability, harmonics, ripple frequency, and why HVDC enables asynchronous interconnection between grids.

By the end, you’ll understand:

Why HVAC cables are limited to ~100 km
How HVDC overcomes those limits
Where each technology is used today — and what’s coming next

If you’re interested in power systems, grid engineering, or the future of global energy infrastructure, this is everything you need to know for a moderately in depth overview and there's more videos to come so get subscribed!

Links:
Patreon: www.patreon.com/TheElectricBrit
Website: www.electricbrit.co.uk
Store: https://shop.electricbrit.co.uk/

Chapters:
0:00 Intro
2:36 History of DC
5:10 Physics Recap
5:53 Skin Effect
7:50 Capacitive Charging Currents
10:23 Ferranti Effect
11:33 Asynchronous Interconnection
13:51 Power Flows
14:56 Converter Configurations
16:30 Dynamic Power
17:00 LCC Explained
19:30 VSC Explained
23:03 LCC Bridges
25:55 Harmonics
27:22 12 Pulse Bridge
29:26 LCC vs VSC
33:55 Cost and Projects
36:30 Conclusion
37:46 Out Takes
41:20 Cat Takes

Corrections:
4:06 The 160 MW, 100 kV Cross Channel Project actually preceeded this back in 1961, built by ASEA which later became ABB.

6:10 Eddy Currents aren't the sole cause, see Maxwell's Equations: The changing magnetic field induces opposing electric fields inside the conductor itself. These oppose current flow more strongly in the centre than at the surface.

9:25 In the formula, the letter V should actually be U, meaning RMS Voltage. V is the unit of measurement so I was inconsistent here in making the formula. f for frequency can also be substituted for ω for angular frequency.