A substation is a full-fledged power plant to generate, transmit, and distribute the electricity to delegate locations.
A substation is the congregation of various electrical equipment aligned at a subsidiary station to generate electricity.
The 3 keys of substation are power generating plants, channelizing mediums, and consumer feeders points.
Solar systems are the most commonly used example of Substation.
Why do we need an electrical power substation?
It is crucial to understand the need for substations in highly advanced infrastructures.
Substations are your Christmas Santa and fulfil the following demands-
Step-Up and Step-Down the AC voltages-
These substations can transform the high voltages into the lower ones and vice versa to deliver the required form of power supply for domestic and commercial purposes.
Break the power flow-
Substation acts as a savior at the time of line fault removal in the supply system, because the whole supply needs to shut down & it is not possible to place a few switches to tolerate the high voltage supply. So, Substation can hold thousands of amperes until the fault removal.
Absorbs growth loads-
Areas on the extremes of the city do not have power supply infrastructures. So, substation is required in order to absorb the high voltage and growth loads from remote stations to supply the electricity for domestic and commercial purposes.
Types of substations-
The Substations classified into three categories-
Transmission substations-
They are also known as the bulk power system & it operates on the voltages above 138 kV. The major function of the transmission substations is to transfer the bulk power from its generating source and transmits it to bulk power delivery points. It is carried in a 3 phase power system.
The major benefit of Transmission substations are-
Power plants can be located away from the large populated centers.
Alternative sources can be accessed when primary sources are not available.
Low electrical energy costs.
Sub transmission substations-
It operates at high voltages between 33kV and a 138kV voltage level. So, they can be transmitted for longer distances with the help of the grid to the substation transmission voltage levels.
These supply lines are called radical readers which means they connect substations to a smaller number of distributing substations. The sub-transmission substations are more cost-effective for delivering the power supply to nearby locations.
There are two types of configurations for sub-transmission substations.
Dual-source sub-transmission configurations– Faults on the radical circuits of sub-transmission do not cause interruptions to substations.
Single sourced radical substation configurations– Faults on the radical circuit of sub-transmission causes interruptions to many substations.
Most of the sub-transmission types of substations are overhead and are planted alongside roads and streets. The newer kind of sub-transmission substations is set up underground too. The usage of solid insulated cables had reduced the overall cost.
Distribution substations-
It operates at 811 kV and 0.4 kV voltage levels. These substations are set up near the consumer substations. They are most fitted for delivering electric electricity e Tu to industrial and residential customers for domestic and commercial uses.
These substations use a high power transformer for increasing voltages for transmission to distant areas.
Challenges to a substation–
Several challenges arise while establishing a substation. Few of them are mentioned below-
Land availability-
The substation can not set up wherever you want. There are certain concerns you need to check out like the proximity to the areas, availability of adequate areas which are difficult in the urban areas, and the substation equipment is really large enough to be installed in small areas. It is really difficult to establish a substation in areas with trees and tall buildings.
Environment concern-
There are various environmental factors that you should take care of pollution, drainage, and road traffic. Setting up the substations is of great challenge for the wildlife also because many of the transformers still use polychlorinated biphenyls which is very harmful to live beings.
Cost-
There are numerous components in the substation that can’t even be stated. These equipment are very expensive. Since many upgrades have been made till now to reduce the costs but still the cost is too high. So you must check out the full enclosures to establish the substations.
Safety-
A substation is dangerous in itself. The incoming and outgoing points the danger potential is very high in terms of electric shocks from live components. You need to create a structure that includes safety measures for personnel, the public, and wildlife.
Substation equipment
Substations in the group of electrical equipment. The equipment installed in substations is highly expensive.
Power transformer and distribution transformer-
Transformers are an important part of substations. Transformers can vary from small to large sizes depending upon their needs in a substation. For the widespread distribution of electric power in distant locations “AC transformers” fit best. The major function of a transformer is to convert electricity to higher voltages so that they can be transmitted for long distances and converted back to lower voltages at the consumer’s feed points. A transformer is a three-phase unit and it is the most expensive component in a substation specifically in the distribution substation.
Circuit breakers-
Circuit breaker controls the high voltage supply and protects other equipment in the substation. The oil-filled circuit breakers contain oil so whenever any fault or damage happens, the contact points are broken and separated with insulating oil and thus do not conduct the power anymore and thus protect further damage in substations.
Relays-
Relays disconnect the circuits manually or automatically. Relay is made up of a coil which is energized. Relay is used for activating the circuit breakers. There are many types of relay used power substations- overcurrent relays, voltage relays, auxiliary relays, definite time overcurrent relays, solid-state relays, inverse time overcurrent relays, reclosing relays, microcontroller relays.
Insulators-
Insulators restrict the movement of free electrons or electricity. Hence, the insulators have higher resisting property. Different types of insulators used in power substations are- strain type, shackle type, stray type, pin type, and so on.
Isolators-
Isolators are manually operated to isolate the faulty section from the entire substation to repair the fault. It is also known as the disconnecting switch. There are different isolators used in substations like single break isolator, bus silencer, later line isolator, double break isolator.
Busbars-
Busbars collect electric power from incoming feeders and distribute it to the outgoing feeders. The common schemes for substation- single busbar, Main Busbar, auxiliary busbar, double busbar.
Convertor Stations-
Convertor stations are installed at the end of the DC transmission line. One of the major functions of a converter station is to connect the AC terminal to the entire substation and connect the DC line to other converter stations.
There are several types of equipment that are used in the substations, I have mentioned the most important ones.
