What are the advantages and disadvantages of high-voltage DC transmission lines
Hello dear guests and subscribers of my channel!
We continue to get acquainted with energy with you, and today I want to tell you about high-voltage direct current lines and explain why, despite all the advantages, they are extremely reluctant to be introduced. Interesting? Let's start then.
The loads are growing every year, and the requirements for the reliability and quality of power supply are increasing.
One of the promising directions in ensuring reliable and high-quality power supply is the construction of high-voltage direct current power lines.
What is the peculiarity of DC lines
The main feature of DC lines is that the transmitted power is extremely active. And the inductive and capacitive components in such circuits are absent a priori.
In addition, in such lines there is no influence of wave processes and for power flow, only the potential difference at the ends of the line is sufficient.
Also, in order to calculate the required conductor cross-section, it is enough to take into account the heating temperature, which depends on the ohmic resistance of the conductor.
That is why, with the same conductor cross-section, the throughput will be significantly higher if it (the conductor) is used for constant voltage.
But what about the dynamic and static stability of the system? In networks with DC lines, such concepts simply do not exist. And all because there is no phase shift (as at break).
All this makes high-voltage DC lines ideal for transmitting energy over great distances.
There are a number of other factors that play in favor of direct current. Well, if everything is so good, then why is recess reigning supreme in our country? Let's figure it out.
What is the main disadvantage of DC lines
So, despite all the advantages, DC has one disadvantage, which crosses everything out. And this is the high price of equipment for DC substations.
In order to connect AC systems with DC lines, it is necessary to use devices such as rectifiers and inverters.
The rectifiers are three-phase bridge circuits with controlled thyristors as semiconductor elements.
In this case, one group is used in the arms of each phase, which can consist of hundreds of thyristors.
It is the complexity and overestimation of this equipment that dictates the conditions for profitability. And at the moment, direct current transportation becomes profitable when the line length is from 800 to 1100 km for lines without taps and in the range from 1100 to 1400 km for lines with taps.
In this case, the power range should be from 600 to 3000 MW. For cable lines with direct current, profitability occurs at a length of more than 75 km.
Conclusion
So, summarizing all of the above, we get the following:
Advantages of DC lines:
- The transmitted power is independent of transients.
- It is possible to transfer energy between non-synchronized systems.
- Inertialess control of voltage and power at the output of substations.
- Long cable lines can be used.
Cons of DC lines:
- Equipment price.
That's all I wanted to tell you about DC power lines. If you liked the material, then do not forget to rate it like and repost.
Thanks for attention!