Electricity plays very important role in our daily routine life from using fan, tv, washing machine to run electric trains and operations of industries. So, It is necessary to have an Idea that How electricity flows from generating station to the consumer?
Electrical power system consists of three main components which are as follows:
1). Generation
2). Transmission
3). Distribution
As we all know that AC system is widely accepted all over the world, Hence we are going to study the power system structure of AC system only in this particular post.
AC power is generated at various types of power plants like solar, wind, hydro, thermal and nuclear with the help of turbines and generators.
We will discuss about these power plants in detail later.
Generating plants are situated at very long distances from main city due to lack of availability of raw material near urban areas. So, that’s why Power must be transmitted over large distances through Transmission lines and then finally Distribution is done to supply power to the consumer.
You can see the whole power flow structure from generating station to the end consumer in the picture given below. I will explain it step by step now. Do not put much attention to this diagram as I am going to make it easy for you in further discussion.
Generating Station
At generating station power is generated at voltage level of around 11kV (in some case it is higher as 16.5kV or 25kV). To Transmit this power over long distances, we need higher voltage level so that we can send power with minimum losses.
But, We do not generate the power at higher Voltage level such as 66kV, 132kV or 400kV because to generate power at this much high voltage level, we need very very large generators and other equipment, the cost and maintenance will not be feasible. Already we have very bulky Generators to generate the power at 11kV voltage level.
To Transmit the power at higher voltage level we simply use Step-up transformer at generating substation. This step-up transformer converts the voltage level from 11kV to 132kV (or 220kV or 400kV).
Transmission of Power at higher Voltage level reduces the voltage losses and increase the Voltage regulation and efficiency.
Primary Transmission
The Primary transmission of electric power at voltage level of 132kV is done with the help of 3-phase Transmission lines and giant Steel Transmission Towers.
Read: Why power is generated and Transmitted in 3-phase only? Why not other phase system?
These transmission towers take this power over long distances and brings to Receiving substations which are located outside the city area.
At receiving substation, the step-down Transformer reduces the Voltage level from 132kV to 33kV (or 66kV) only.
To supply the Rail OHE network the voltage level is reduced to 25kV from 132kV at Traction substation.
Now secondary Transmission of Electric power starts from here.
Secondary Transmission
The 3-phase power at voltage level of 33kV (or 66kV) then goes to another substation which is located inside the city area. You might have seen these substations in your nearby area.
A step-down transformer further reduces the voltage level from 33kV to 11kV only.
A substation consists of many equipment along with transformer, but as our focus is only on the power flow structure so we will learn about substations in different post.
Distribution of Power starts from here (11kV).
Primary Distribution
The three-phase power at voltage level of 11kV serves the Primary Distribution. This power goes to pole mounted substation as shown below, where Voltage level is further reduced to 415V by a Step-down Transformer.
Large Industries or plants who need Bulk power takes direct power from these lines and they step-down the voltage level by their own transformers.
Secondary Distribution
At pole mounted substation the step-down transformer reduces the voltage level from 11kV to just 415V. The Primary side of this Transformer is connected in Delta which is also called as 3phase 3 wire system, but the secondary side of this transformer is connected in star connected which is also called 3phase 4 wire system because at Star point, we get an extra wire which is known as Neutral wire.
This Neutral wire helps to supply Single phase power to the residential consumers who do not have heavy loads.
The consumers who have heavy loads or three phase loads can take direct 3 phase connection.
We will discuss the AC distribution system in detail in another post.
I hope that this topic ” How electricity flows from generating station to consumer?” is clear to you.
You can read more such interesting topics related to electrical engineering here,
Why the colourful marker balls are used in transmission lines?