What Are Substation Components?
Electrical substations play a critical role in the power grid, serving as vital hubs where electricity is transformed, regulated, and distributed to ensure reliable power delivery to homes and businesses.
Understanding how these complex systems operate, their components, and the safety measures necessary around them is essential for anyone working in the energy sector. In this blog, we explore the function, key components, and the crucial role electrical substations play in the transmission and distribution of electricity.
What Are Electrical Substations?
Electrical substations are the interface that lies between transmission and distribution systems. These are designed to reduce the voltage in transmission lines to levels that distribution systems can withstand.
In-built circuit breakers protect the distribution system and manage the current flow in different directions. These also manage fluctuations in voltage to manage heavy loads. An electrical substation is made up of the following components:
- Lighting arresters
- Conductors
- Insulators
- Instrument transformers
- Electrical power transformers
- Relays
- Circuit breakers
- Bus bars
- Capacitor banks
- Isolators
How an Electrical Substation Works
Electrical substations are the backbone of the power grid, ensuring the smooth transmission and distribution of electricity. The power flow through a substation begins with high-voltage transmission lines bringing electricity from power plants.
The power substation then steps down this voltage to a level suitable for distribution systems using transformers and other equipment. Voltage regulation is a key function of substations, as they maintain the appropriate voltage levels to meet demand. Regular maintenance is crucial to prevent disruptions and ensure the longevity of these essential systems.
What Is the Structure of an Electrical Substation?
Most above-ground substations, such as wooden poles, metal towers with lattice structures, and tubular steel frameworks, share common construction features. Cost-effective steel lattice towers typically support substations in larger areas, while smaller substations in suburban areas are often designed with aesthetics in mind to blend seamlessly with their surroundings.
Indoor substations, on the other hand, are either gas-insulated or encased in metal, particularly for low-voltage applications.
Regardless of their location, whether urban or suburban, these substations are carefully designed to integrate with nearby buildings and infrastructure. The smallest type, a compact substation, is usually located outdoors within a metal enclosure, with all components arranged side by side to maximize space efficiency.
What Are the Types of Substation Components?
Substations vary in voltage class, their specific role within the power system, the types of insulated connections they utilize, and the materials used in their construction. Here are some of the most common types of substations found within an electrical grid:
Transmission Substations
As the name suggests, this type of substation connects two or more electricity transmission lines that operate at the same voltage. To ensure safe operations, these substations are equipped with high-voltage switches that allow personnel to safely clear faults.
Typically, a transmission substation includes transformers for voltage adjustments, as well as capacitors, reactors, and other equipment that effectively manage power flow between systems.
The complexity of these substations can vary depending on the voltage level. A simple transmission substation may only require a bus and a few circuit breakers, while more complex substations, handling multiple voltage levels, require larger areas and a greater variety of equipment for protection and operation.
This equipment can include SCADA systems, relays, as well as voltage and current transformers.
Distribution Substations
As the name suggests, a distribution substation transfers power from the transmission system to the distribution system within a specific area.
This setup is cost-effective for power plants, as directly connecting individual consumers to the main transmission network would be prohibitively expensive and potentially hazardous due to the high power levels involved.
To safely and efficiently manage power distribution, these substations reduce the voltage to levels suitable for local distribution.
Typically, a distribution substation receives power from at least two transmission lines, with the output distributed through multiple feeders. The voltage levels are generally medium and adjusted according to the needs of the area served.
Feeders, which are often located underground or along streets, distribute the electricity, while distribution transformers positioned near homes and businesses further step down the voltage for safe use.
In addition to voltage transformation, these substations play a crucial role in isolating faults within both the distribution and transmission systems, as well as regulating voltage levels along extensive distribution circuits.
In large cities, distribution substations may be complex, featuring extensive switching equipment and robust backup systems to handle high power demands. In smaller areas, a simpler system may suffice, often consisting of a single transformer and minimal equipment to maintain voltage control.
Converter Substations
Converter substations are typically associated with traction current systems and HVDC (High Voltage Direct Current) converter plants.
These substations house powerful devices designed to alter the frequency of the current within the system. They play a critical role in converting alternating current (AC) to direct current (DC) and vice versa, depending on the specific requirements of the power network.
Safety Around Substations With 360training
Substations are high-voltage environments that require strict safety precautions. The dangers of being near a substation are significant, including the risk of electric shock or arc flash.
Therefore, both workers and the public need to maintain a safe distance from substations and adhere to all posted warning signs. Safety protocols, such as wearing protective gear and following proper lockout/tagout procedures, are vital for those working within or around these high-voltage areas.
Fortunately, for extra safety, 360training offers an 8008 Substations training course, where you’ll discover distribution substation fundamentals, including distribution reliability, switching procedures, and more. Practice workplace safety by learning everything there is to know about substations.
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Types of Substation Components
Different types of substations have their own voltage class, their use in a power system, insulated connections, and the material used in their construction. Here are some common substations that exist in a system:
Transmission Substations
As the name implies, this type of substation is used to join 2 or more transmission lines that have the same voltage running through them. That is why this substation also has high voltage switches to aid personnel in clearing faults safely. A transmission substation usually has transformers between the voltages, capacitors, reactors, and other equipment that can manage power flow between systems easily.
These can also be simple or complex depending on the voltage level. For instance, a transmission substation may just need a bus and some circuit breakers to work. Complex ones may require larger areas and a number of voltage levels, circuit breakers, and protection to work. The equipment it might need can range from SCADA systems and relays to voltage and current transformers.
Distribution Substations
As the name implies a distribution substation transfers power from the transmission system to the distribution system of any given area. This saves power plants a lot of money since it can be quite costly to connect electricity consumers to the main network.
It requires massive amounts of power which can also be hazardous.
An economical and safer alternative is to allow distribution systems to reduce voltage intensity to levels that can be distributed on a local level easily. Usually, a distribution substation gets at least two transmission lines and the output is usually through a number of feeders. The voltage levels are usually medium according to the area served and how it is used.
The feeders are usually based underground or along streets and the distribution transformers are usually near homes and offices of consumers. Besides transforming voltage, these substations also isolate faults in distribution as well as transmission systems. They also regulate voltage levels on distribution circuits that are several miles long.
This system can also be installed along the entire line to ensure voltage levels remain in control. Large cities may have several complex distribution substations complete with voltage-heavy switching and strong backup systems. In smaller areas, this system may only be made up of a single transformer and very few facilities to control voltage.
Converter Substations
These substations are usually associated with traction current and HVDC converter plants. Converter substations comprise powerful devices that can alter the frequency of the current running through the system. Converter substations are also used to convert alternate current to direct current and vice versa depending on need.
Structure of an Electrical Substation
Most substations that are located above ground have some things in common in their construction. These usually include wooden poles, a metal tower featuring latticework, and tube-based metal structures. Substations that are based on larger areas are usually supported by steel lattice towers which are low-cost. However, smaller substations are located in suburbs where their physical appearance is given preference.
Substations that are based indoors are either gas insulated or covered in metal for low voltages. However, whether these are located in urban or suburban areas, substations are designed to blend in with surrounding buildings. The smallest substation is a compact substation. This is usually based outside and enclosed in a metal cage. Each component is located side by side to save as much space as possible.
Power Distribution and Substation Training Courses
360training offers power distribution training courses, covering the operation and protection of distribution systems in three categories:
- Distribution system training
- System protection technology
- Electrical fundamentals.
