Here, we intend to explain the types of electrical substations and their applications for you. Please continue reading along with Electrosheil to achieve the best results from this article. First, let’s move on to the definition of an electrical substation.
An electrical substation, or in other words, the power infrastructure, is one of the most important and crucial elements in the process of generation, transmission, and distribution of electricity.
This structure is capable of establishing voltage at different times and points to required levels. The transmission and distribution of electricity take place through power plants, and therefore, it can play a very important role in consumption centers.
The power system is capable of transferring and distributing electricity between production and consumption centers using several substations, with appropriate voltage management. We will discuss the practical aspects and maintenance performance of these equipments further.
Electric substations act as interfaces between distribution network components and transmission systems. These points are usually fenced for environmental security and may be observed around cities.
Different types of power substations reduce the voltage of transmission lines to suitable levels for the distribution network. Moreover, these substations are equipped with protective circuits for the distribution system and have the ability to control current flow in different directions. The power substation is also responsible for smoothing and filtering voltage fluctuations caused by increased load.
Components of an Electrical Substation
Electrical power can be transferred from generating units to distribution through various components of an electrical substation. These components include insulators, conductor rods, power transformers, and other elements that are interconnected within the substation.
The components of an electrical substation are crucial for its installation and commissioning. Designing electrical substations is a complex and highly engineered process.
The key stages in the design of various types of electrical substations include switching system, equipment planning and placement, component selection, as well as ordering, engineer support, structure design, electrical layout design, relay protection, and device grading. The main components of an electrical substation are as follows:
1. Power Transformer
The primary purpose of a power transformer is to increase transmission voltage at the generating unit and decrease transmission voltage at the distribution unit. These types of transformers operate under full load conditions and are disconnected under light load conditions. Therefore, power transformer efficiency is maximized under full load conditions.
2. Instrument Transformer
The primary purpose of an instrument transformer is to reduce high currents and regulate voltages to a certain and accurate level. These values can be calculated using standard devices.
3. Surge Arresters
These are the first components in various types of electrical substations, and their main function is to protect substation components against high voltage surges and to limit the magnitude and duration of electrical currents. These components divert electrical current and surges to the ground and act as the shield of the system, protecting against damage from the electrical substation.
– Surge Arrestor
The surge arrester is positioned at the input lines to trap high-frequency signals. These signals, or waves, come from remote stations and can interrupt current and voltage signals.
– Circuit Breaker
This tool is a type of electrical switch used to open or close a circuit in case of a system fault. It consists of two movable parts that are usually closed. When a fault occurs in the system, the relay transfers the signal to the circuit breaker, activating its components separately.
– Conducting Rods
Conducting rods are recognized as vital components in various types of electrical substations. These rods are made of a type of conductor carrying electrical current, creating numerous connections within them. In other words, these rods are a type of electrical connection where input current and output current flow.
When a fault occurs in this component, all related circuit components must be separated. Over time, complete isolation is established to prevent faults from being ignored due to heating of the conductors for connections.
In power plants or large substations, the function of lighting, relay systems, or control circuits is provided by batteries. These batteries are connected to a specific battery cell based on the DC voltage of the particular circuit.
Batteries are classified into two types: acid-alkaline and lead-acid. Lead-acid batteries are very cost-effective for substations and power plants due to their high and low voltage capabilities.
– Switching
Switching is used to transfer electrical power from a substation at the desired voltage level to transmission lines or a power station close to the generation source.
– Relay
A relay is an electrical device whose main role in various types of electrical substations is to protect network components against undesirable conditions such as faults. One type of relays are detection devices used to detect and locate faults, then send a signal to the circuit breaker.
After receiving a signal from the relay, the circuit breaker removes a portion of the network. Relays are essentially useful for protecting devices against hazards and damages.
Key Points in the Design of Various Types of Electrical Substations
Electrical substations are part of the electrical network system, so their proper design is crucial. Before installing a substation in an area, it is necessary to obtain information about that area to make the best choice for it.
1. Environmental Information including:
– Temperature
– Altitude above sea level
– Wind speed
– Earthquake
– Ice accumulation
– Air pollution
– Amount of precipitation
2. Electrical Information including:
– Nominal voltage
– Maximum equipment voltage
– Rated current
– Nominal frequency
– Phase connection type and vector group
– Temporary and transient overvoltages
Types of Electrical Substations
Now is the appropriate time to introduce the types of electrical substations. Electrical substations are categorized into three sub-branches based on voltage, which are explained below:
1. Transmission Substation
The task of this substation is to connect two lines with the same voltage. Transmission substations are divided into two categories: simple and complex.
2. Distribution Substation
The task of this substation is to receive power from a transmission substation and transfer it to another distribution system. This substation reduces the voltage to a level suitable for consumers. When there is a need for two distribution substations, this type of substation is used. Each country has its own specific voltage standard, which is applied to distribution substations. The next task of the distribution substation is to isolate the distribution network to reduce the error rate.
Power Plant Substation (Sub-transmission Substation)
This type of electrical substations is responsible for establishing output voltages from generators at a level suitable for transmission. These substations are typically used for high powers and over long distances.
Another classification of types of electrical substations is Switching Substations, which we will explain below. The duty of these substations is to disconnect and connect transmission lines or consumers from the main network. This can be planned in advance or done entirely accidentally in case of a problem.
In case of damage, it is necessary to inspect and troubleshoot the devices or, if necessary, implement an extension in the system, but this power substation does not disconnect the entire system and only cuts off the relevant part that needs repair.
If we categorize types of electrical substations based on their function and role, we can arrive at the following classification:
1. Boosting Substation:
As you know, the voltages generated by generators are limited, and for economical transmission, there is a need to increase the voltage at various intervals. These types of substations are mainly used by power plants that are far from consumption centers.
Step-down Substation:
The voltage generated in substations must be reduced to a level suitable for consumers. This reduction is achieved using step-down substations or distribution substations to provide the appropriate electrical voltage for consumption.
Distribution Substation:
Distribution substations regulate voltages between distribution and transmission substations. Complex distribution substations can be observed in large cities. These substations provide suitable voltage for domestic and industrial consumption.
Important Note: If you have enough information about electrical substations, you will realize that these substations can be divided into two types: outdoor and indoor substations, which are observable around cities.
Indoor Substations:
These substations are housed within rooms and halls and are not visible to the general public.
Outdoor Substations:
These substations are located on the ground and are exposed to weather conditions. You have seen these types of substations around your cities. These substations are divided into two categories: conventional substations and Gas Insulated Substations (GIS).
Conventional Substations:
These substations are constructed when land constraints are not an issue, and maintaining safe and permissible distances within them is crucial.
Gas Insulated Substations:
All high-pressure equipment in gas substations is housed within a metal enclosure. These substations use hexafluoride gases as insulation, which is suitable for electrical purposes.
Advantages of Gas Insulated Substations:
These substations are not affected by weather conditions, so they have lower chances of connection and accidents. Also, due to their insulation, they have higher safety levels.
Disadvantages of Gas Insulated Substations:
In cold conditions and temperature reductions, gas turns into liquid. Additionally, the high cost of these substations is considered a weakness.
In another general categorization, types of electrical substations can be classified differently, as we will discuss below:
Ground Distribution Substation:
This substation has two cells; the first cell is designed for protection against short circuits and overload, and the second cell, or measuring cell, includes two or three transformers with a hundred-watt output.
Public Utility Substation:
This substation is used to supply electricity to consumers with low consumption, such as household networks and similar setups.
Dedicated Power Substation:
This type of substation is designed for electrical branches with initial voltages of 250 kilowatts and primary Diamond voltages.
Public-Dedicated Substation:
This substation is designed for public use and alongside Diamond subscribers, combining features of the two previous types of substations.
Passage Substation:
Installed near the consumption location when the power plant and the consumption site are far apart.
Power Distribution Substation:
In this substation, a feeder is divided into several branches.
Pre-fabricated Compact Power Substations (Kiosks):
These substations are easy to transport and operate. Their main feature is ease of use and high safety.
Aerial Distribution Substation:
Economically, using these substations is easier than underground substations due to less space occupation and fewer consumables in these substations.
In summary, a power substation is a place where energy transmission equipment is installed, converting energy and delivering it to the consumption cycle.
Overall, substations act as voltage converters and switches, combining these two features in many types of power substations. Substations are categorized based on their function, insulation, and installation location, as discussed in the articles.
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