All you need to know about substation

 

Substation

Introduction

A substation is a part of an electrical power system that provides access to electric power from high-voltage transmission lines. A substation may contain transformers, switches and circuit breakers, but does not generate power or even transmit it beyond its own site. This means that at a large substation, all the lines have been brought together to allow efficient transfer of huge amounts of electrical energy over long distances. Substation can be divided into different types depending on the voltage level they operate on: low voltage (LV), medium voltage (MV) and high voltage (HV). LV/MV substations are used for local distribution while HV substations are mainly used for long distance transmission.

Power Substation

A power substation is a collection of electrical equipment housed in a building, which provides an interface between the transmission and distribution system. Substations are used to change voltages from high transmission voltages to lower distribution voltages, or increase or decrease the current in alternating current systems.

Types of Substation

Substation is a station or substation where the electrical power is generated and transmitted. There are three types of substations:

• High voltage substation

• Medium voltage substation

• Low voltage substation

The transformers used in these types of stations are referred to as high-voltage, medium-voltage and low voltage transformers respectively.

Packaged Substations

Packaged substations are small, compact and easily installed. They can be configured to meet the needs of a wide range of applications including telecommunications, industrial/commercial facilities, rail networks and laboratory testing.

They're lightweight and portable which makes them ideal for remote locations or areas with limited space.

Packaged substations are built to withstand harsh conditions like high winds and lightning strikes that can occur in the utility industry.

High-Voltage Substations

High-voltage substations contain medium-voltage substations. They are used to connect high voltage transmission lines to medium voltage distribution lines.

High-voltage substations are usually located in rural areas, away from populated areas.

Medium-Voltage Substations

Medium-Voltage Substations

Medium-Voltage substation is used to step down the voltage of the transmission line. It is used to connect the high-tension line to the low-tension line and also it is used to connect two or more high-tension lines like 230 kV, 400 kV, 500 kV etc. The equipment found in Medium Voltage Substation includes transformers, switchgear, circuit breakers and control panels etc.

Low Voltage Substations

Low-voltage substations are used to distribute power from the main transmission line to the distribution network.

In contrast, medium-voltage substations usually carry power between high voltage substations and low voltage substations or directly to consumers (e.g., industrial plants). In addition, they can be used as a transfer point between two lines carrying different voltages or even between two lines carrying similar voltages but with different frequencies (typically 50 Hz vs 60 Hz).

Circuit Breaker

Circuit breakers are used to protect the electrical equipment from overcurrent, short circuit and overload.

Circuit breakers are also called fuses and are connected in series with the load. If excessive current passes through a circuit breaker, it will trip and interrupt current flow. Circuit breakers have three main functions:

• To limit the amount of current flowing into an electrical system by opening if too much energy is drawn from it (and thus protecting equipment from overheating)

• To disconnect an overloaded circuit that may cause damage to your home

• To stop a fault when an abnormal surge occurs

Busbars

Busbars are steel beams that connect the generator and circuit breakers to form a complete electrical circuit. The busbar is made of copper or aluminum. Busbars are generally used in high-voltage substations, but they can also be found in medium-voltage stations.

A busbar tie is a piece of equipment used to connect the generator's main busbar to its switchgear, including step-up transformers, disconnecting switches/breakers, capacitors and other devices that may be installed at the substation.

Capacitor Voltage Transformer (CVT)

A capacitor voltage transformer (CVT) is a step-up transformer used to convert the voltage of an alternating current (AC) power source. CVTs are integral parts of high-voltage AC transmission systems, where they are used to convert transmission voltages between 69 kV and 765 kV.[1]

CVT is also known as HVDCIs or HVDC converters.

Current Transformer (CT)

A Current Transformer (CT) is used to measure current in the power system. It is connected in series with the load, or parallel with it. These connections are shown on a CT diagram as:

• Series connection

• Parallel connection

In addition to these connections, you may also see CTs connected in parallel with other CTs and/or series with other CTs.

Lightning Arrestor (LA)

Lightning arrestors are used to protect the transformer from lightning strikes.

They are made up of air gaps and spark gaps.

Lightning arrestors are installed close to the transformer, in parallel with it.

Control, Relay, and Metering Panel Board (CRMPB)

Control, Relay, and Metering Panel Board (CRMPB)

Control Panel Board

Relay Panel Board

Metering Panel Board

Power Transformers(PVs)

Power Transformers (PVs)

Power transformers are the devices that transfer electrical energy from one circuit to another through electromagnetic induction. They consist of two or more windings, called primary and secondary windings. The input winding is called the primary winding, while the output winding is called the secondary winding.

Conclusion

This is all you need to know about power substations.