Different Types of Substations Explained

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In this post, we are going to study the important topic from electrical power system i.e. power substation.

The power substation is an integral part of the generation, transmission, and distribution of power systems.

Let’s dive from basics,

What is a Substation?

The definition of substation:

An electrical substation is an assembly of electrical devices that are installed to control and protect the transmission and distribution power system.

The substation has different types of transformer and several switching, controlling, and protecting types of substation equipments.

The main purpose of a substation is to serve the continuous electricity or power source from generating stations or transmission systems to the consumer ends.

For successful operation of the power system, the different types of substations are designed.

Let’s see the classification of electrical substations with features and functions.

What are the different types of Electrical Substation?

Based on the construction, service requirement, working; the substations are classified into different categories.

Keep scrolling to get more about each substations.

1. Based on Construction and Design

  • Indoor Substation

Indoor substations are usually found in urban areas. These substations are constructed where 11 kV voltage range is required.

A small space is needed to set up the required types of equipment for the indoor substation.

  • Outdoor Substation

The outdoor substations are installed where we need to generate around 66 kV voltage. To set-up or install the outdoor substation’s equipment, large space is required.

According to the construction and service, outdoor substations are further classified into two subclasses.

  1. Pole Mounted Substation

Pole mounted substation is a type of distribustion substation. It is placed and installed on pole.

In this substation, the transformer and other equipment are installed on the overhead of an H-type pole or 4-pole type structure.

  1. Foundation Mounted Substation

The foundation-mounted substation is placed for the 33kV and above its voltage range.

The main advantage of an outdoor substation is that we can easily expand the installation of connected electrical equipements.

The installed pieces of equipment of the outdoor substation need additional protection against lightning, dust, etc.

  • Underground Substation

Under some situations (like scarcity of land or high cost of land), the underground substation is sufficient to install this required equipment for transmitting power.

2. Based on Operating Voltage

These substations are classified into three types based on voltage level.

  • High Voltage (HV) Substation

High voltage substation serves voltage in range of 11 kV to 66 kV.

  • Extra-High Voltage (EHV) Substation

Extra high voltage substation serves voltage in range of 132 kV to 400 kV.

  • Ultra-High Voltage (UHV) Substation

High voltage substation operates above 400 kV voltage range.

3. Based on Working Role

  • Step-up Substation

The step-up substation helps to increase or step up generating voltage level (from 11 kV up to 220 kV). It is constructed for a powerhouse or power station.

  • Primary Grid Substation

From the step-up substation, 220 kV voltage is received to the primary grid substation. This voltage is transmitted over a three-phase three-wire of the overhead system.

This grid substation reduces the voltage level (near about 66kV) and provides it to the secondary substation.

  • Secondary Substation

The secondary substation takes 66 kV from the primary grid substation. The main function of the secondary substation is to step down the voltage range (from 66kV up to 11kV).

  • Distribution Substation

A distribustion substation is a pole-mounted type substation which is placed near to the consumer ends.

This substation gives input voltage (11 kV) from the secondary substation. And it serves the low voltage (near about 400 V) to the consumer through the three-phase four-wire (star connection).

Read more: Star connection vs Delta conncetion of power system

The above three (step-up, primary, secondary) substations are the outdoor type substations. And distribustion substation is part of the indoor type substation.

4. Based on Service Recruitment

  • Transformer Substation

The substation which use to change the voltage level of the electrical supply is called an electrical transformer substation.

In this substation, electrical transfomer plays the major role to step up and step down the voltage.

  • Frequency Changer Substation

A substation that changes the supply frequency is called a frequency changer substation. It is used in an industrial environment.

  • Switching Substation

The substation which performs the switching operations for incoming and outgoing power lines is called a switching substation.

This substation does not change incoming and outgoing voltage levels. It helps to isolate the faulty portion of the power system in the short duration.

  • Converting Substation

The substation that changes the AC power source into a DC power source is known as converting substation. The converting substation is used in traction, electroplating, electric welding, etc.

  • Power Factor Correction Substation

The substation which is used for improving the power factor of the system is known as the power factor correction substation.

In this substation, the synchronous condenser is used as power factor improvement equipment.

5. Based on the Power Network

Grid substation and town substation are fundamental types of substation network.

  • Grid Substation

A grid substation are constructed or designed to transfer the bulk power. It is constructed at outdoor locations.

  • Town Substation

The town substation is used at the distribution place in the town. It operates under the voltage at 33/11 kV.

I have described all basic classifications of substations based on multiple working roles, voltage transmitting ranges and usage.

If you have any queries regarding types of substations, write me in the comment section.

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