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Substations


Wed Jun 15, 2022

Substations

Pictured:  Russian Substation 110/35kV

Substations are the link between different parts of the grid that have different voltage. They also ensure the quality of electricity, the safety of the electricians that repair the grid and the safety of the average person. Substations monitor several different measurements of the grid:
  1. Voltage
  2. Current
  3. Frequency
  4. Load
  5. cosfi (Power Factor)

How does a substation control the grid and is it automated?

Substations use a thing called "Relay Defense" . Relay defenses are circuits made of mostly different kinds of relays aka Current relays, Voltage relays, and so on. There are several kinds of Relay Defenses but we will not look into them for now as we are going over the simple things.

What is inside a substation?

Substations have a set of equipment, which is divided into 4 categories: Comutational, _________

Comutational: Those are the breakers and switches. (There is a difference between the breakers and switches as the switch provides a visible break in the line while the breaker does not.)

Pictured: Switchgear from a outside 20kV substation.

Measuring: In this category we have measuring transformators and measuring tools.


Transformation and transformator control: Transformators that either Step-up or Step-down the Voltage and the equipment that controls them.

Pictured: Transformator 35/6kV.

Safety: Grounding, lightning strike protection, Reactors (they lower the current incase of a short circuit)

Are there different kinds of substations?

Yes there are! It depends on what they do.
They can be categorised into either step-up or step-down. 

They can also be categorised into normal, control, traction, converter and mobile.
Normal
Control: Control the grid but not transform it, mostly seen above 110kV
Traction: Used for electrical transport
Converter: Used to convert any of grid properties. Example: Frequency for arc furnaces.
Mobile: They are build on trailers and used mainly for temporary supply.

Pictured: Mobile substation 110/20kV.

They are also sorted based on what voltage they work with.

System (they work with voltages above 110kV and connect the grid)
Regional (they work with voltages below 110kV)

Lastly, substations can be different depending on whether the instrumentation is inside or outside (control circuits do not count)
Covered - That’s a substation located inside a building and is often under 110kV
Uncovered - That’s a substation located outside in the open. They are the most common and is above 110kV.

Pictured: The inside of a Covered substation 20/0,4kV

There is actually a lot more to substations. We only brushed the surface of what it takes to keep us safe and to ensure we get the best out of the electrical grid.

Radi
Subject: Basics of Electricity

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