Different Types of Substations Explained

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

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

Let’s dive from the basics,

What is a Substation?

The definition of substation:

An electrical substation is an integral part of power system mainly the generation, transmission and distribution power system.

The primary purpose of a substation is to provide continuous power from generating stations or transmission systems to consumer loads.

In layman’s terms, the substation is an assembly of electrical devices that are installed to control and facilitate the transmission and distribution of power.

And by electrical devices, I mean different types of transformers, several switchgear devices like as circuit breakers, fuse, busbars, lightning arresters, protective relays, control panels, and many more equipment are used for installing substations.

There are different types of substations designed as per the requirements.

Now let’s study at,

What are the different types of Electrical Substation?

There are parameters to classify substations into different categories.

Those parameters are construction, service requirement, operating load, working role, and power network.

Based on Construction Parameter

• Indoor Substation
• Outdoor Substation

Based on  Power Load Parameter

• High Voltage (HV) Substation
• Extra-High Voltage (EHV) Substation
• Ultra-High Voltage (UHV) Substation

Based on Working Parameter

• Primary Substation
• Secondary Substation
• Distribution Substation

Based on Service Requirement Parameter

• Transformer Substation
• Frequency Changer Substation
• Switching Substation
• Converting Substation
• Power Factor Correction Substation

Based on Power Network Parameter

• Grid Substation
• Town Substation

Let’s study the features and functions of each substation one by one.

1. Based on Construction and Design

On the basis of design, there are classified into two types. One is an indoor substation and another is an outdoor substation

• Indoor Substation

Indoor substations are usually found in urban areas.

These substations are constructed for low voltage requirements (for example 11 kV).

This type of substation takes less space.

• Outdoor Substation

The outdoor substations are installed where we need to generate a high voltage (for example 66 kV, 132 kV).

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 distribution substation.

It is placed and installed on an electric pole.

2. Foundation Mounted Substation

The foundation-mounted substation is placed in a secondary distribution system. It is also placed in the primary and secondary transmission systems.

This substation is preferred for the 33kV and above voltage requirement.

Outdoor substation enjoys scalability as an advantage. Because, it can be easily expanded to handle the increased load.

However, the disadvantage is an outdoor substation needs additional protection against lightning, dust, etc.

2. Based on Operating Voltage

Now based on power load requirement, there are three types of substations:

• High Voltage (HV) Substation

The high-voltage substation can handle high voltage in range of 11 kV to 66 kV.

• Extra-High Voltage (EHV) Substation

The extra high voltage substation can handle voltage in range of 132 kV to 400 kV.

• Ultra-High Voltage (UHV) Substation

This type of substation operates above the 400 kV voltage range.

3. Based on Working Role

• Primary Substation

This substation increases (or steps up) voltage from a lower level to an expected higher level. It works as a step-up substation.

This stepped-up load is directly fed to load centers for power transmission. It is associated with generating stations.

Step-up power transformer plays a vital role in stepping up voltage levels as per requirement.

• Secondary Substation

This substation balances the power generated and feeds power to load centers. It is located at the power generation system.

Mainly, the secondary substation operates at extra high voltage (i.e. above 66kV). The above primary and secondary substations are outdoor-type substations.

• Distribution Substation

A distribution substation is also known as a step-down substation. It is a part of the indoor type substation.

This is a pole-mounted type substation that is placed near the consumer ends.

The distribution substation receives high power from the secondary substation. And it converts in low voltage (near about 400 V) to the secondary distribution network.

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

Power requirement is ever changing phenomenon in real world. So to handle these changes, adaptive substations are commissioned.

Those are:

• Transformer Substation

This substation adjusts the voltage level as per voltage demand.

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

• Frequency Changer Substation

In industrial regions, specific frequency has to maintain and protect equipment from malfunctioning.

To overcome this risk frequency changer substation is installed to maintain frequency requirement.

• Switching Substation

In case of faulty or abnormal conditions, switching substation isolates and recovers faults in power system.

Switchgears are an integral component of this substation.

• Converting Substation

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

• Power Factor Correction Substation

To improve the power factor, the power factor correction substation is installed.

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

5. Based on the Power Network

The power network parameter is further classified into two categories. The grid substation and town substation are fundamental types of substation networks.

• Grid Substation

This grid substation is constructed or designed to transfer the bulk power from one point to another point in the grid. It is installed to handle power disturbance occurred while transferring power in the grid.

This substation is constructed at outdoor locations.

• Town Substation

This substation is installed for the town. It steps down extra high voltage to high voltage like 33 kV or 11kV.

This stepped-down power is distributed in town.

If there is any failure in these types of substations, results in a power cut off of the whole town.

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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Thanks for Reading!