What is a transformer in a substation?
Transformers in substations are the core equipment used to raise and lower voltage in the power system, and they play a vital role in the transmission of electricity from power plants to homes and businesses. Before exploring the working principle of substation transformers in depth, we first need to understand the basic function and composition of substations.
1、Basic functions and composition of substations
Substation is the key node of the power network, its main role is to receive power from the power plant, through the transformer to raise or lower the voltage, and then the power is safely and efficiently distributed to the various users. According to its location and function in the power system, substation is divided into step-up substation and step-down substation.
– Boosting substation: Usually located near power plants, it is responsible for boosting power to a high voltage level suitable for long-distance transmission.
– Bucking substation: located near load centers, it is responsible for reducing high voltage electrical energy to a safe voltage level suitable for users.
The substation is equipped with a variety of electrical equipment such as transformers, circuit breakers, relays and other auxiliary systems such as cooling, lighting and communication to ensure the stable operation of the power system.
2、 Role of transformers
Transformers in substations are key equipment for ensuring the safe transmission and distribution of electricity. Their main roles include:
– Bucking: reducing the high voltage generated by power plants to a safe voltage suitable for use in homes and businesses.
– Boosting: raising the voltage to minimize energy loss during the transmission of electricity over long distances.
Without transformers, electricity would have to be transmitted at unsafe voltage levels, which would pose a significant safety risk to the public. Transformers are therefore an integral part of the power system and play a vital role in ensuring the stability and security of the power supply.
What is the function of station transformer in substation?
A substation transformer is an electrical device that utilizes the principle of electromagnetic induction to transfer electrical energy between two or more circuits, and consists of one or more coils (windings) wound on a magnetic core. There are several types of substation transformers, and the main focus here is on power transformers.Of the many types of substation transformers, power transformers are the most common and are primarily used to transfer electrical energy between high-voltage transmission lines and low-voltage distribution lines, with current ratings up to hundreds of megavolt-amperes (MVA). Typically used in power plants and substations, they are designed to handle large amounts of power and are able to withstand the demands of power transmission and distribution systems. The following are some of the main functions of a power transformer:
1、Voltage conversion: The most basic function of a transformer is to raise or lower the voltage level of an AC electrical signal to meet different power demands and transmission requirements.
2、Power Distribution: In the power grid, power transformers efficiently distribute the power generated by the power plant to the end-users at an appropriate voltage level.
3、Electrical isolation: Transformers provide electrical isolation between the primary and secondary windings, preventing direct electrical connections between different circuits, thereby increasing safety and reducing electrical risk.
4、Current Transformer: A current transformer is a special type of transformer used to measure high currents in power systems for protection and metering purposes.
How many transformers are in a substation?
The number of transformers in a substation is not fixed, but various factors have to be considered.
1、Determine the number of transformers according to the size of the substation
– Simple wiring of the substation, generally installed only 1-2 transformers.
– Large hub substation, especially the ultra-high voltage substation, in the same voltage level, the number of main transformer should not be less than two.
– For 330-500kV large substation, it is recommended to use 4 transformers.
2、According to the scale and the degree of connection with the grid system to determine the number of transformers
– Strong connection with the grid of large and medium-sized power plants, the main transformer is not less than 2 units.
– Smaller power plants with less connection to the grid, the main transformer may be installed only 1.
3、etermine the number of transformers according to the voltage level
In case of 35kV substation, 2 transformers are usually used, one for 35kV high voltage side and one for 10kV low voltage side. High-voltage level is usually not more than 3 units, unless there are special requirements.
According to the regulations, where a substation is equipped with 2 or more main transformers, after one of them is out of service in an accident, the capacity of the remaining main transformer should be ensured that 70% of the total load of the institute is not overloaded. Therefore, there is no fixed answer to the exact number of transformers in a substation.
What is the difference between a transformer and a substation?
Transformer and substation are two different concepts in the power system, which differ in their functions and roles, but are usually interrelated in the process of power transmission and distribution.
– A transformer is an electrical device that raises or lowers voltage.
– A substation is an integrated facility containing a variety of equipment for the reception, transformation, distribution, and control of electrical energy.
In practice, a transformer is an integral part of a substation, which usually contains several different types of transformers to meet different voltage conversion needs. Together, transformers and substations form a key node in the power transmission and distribution network, ensuring that power is delivered safely and efficiently to consumers.
Is it okay to live next to a substation?
Many people have concerns about the potential health risks of living near a substation. This worry mainly stems from misunderstandings and a lack of knowledge about electromagnetic radiation. So, what exactly is electromagnetic radiation?
Simply put, electromagnetic waves are generated when electric fields and magnetic fields interact and change. When these electromagnetic waves are emitted or leaked into the air, they form what we call electromagnetic radiation. In fact, the Earth itself is a huge magnetic field, and its thermal radiation and lightning also produce electromagnetic radiation. In our daily lives, whether it’s radio waves, microwaves, infrared, visible light, or ultraviolet, they all fall under the category of electromagnetic radiation.
For example, ultraviolet light is a type of electromagnetic radiation, but it brings us warmth; radio waves are essential for our communication; the light from a bulb is also a form of electromagnetic radiation; and the microwave oven heats food by relying on the energy of electromagnetic radiation.
However, when it comes to substations, the situation is different. The distribution equipment and other conductors within a substation do generate a power frequency electromagnetic field with a frequency of 50 Hz, classified as extremely low-frequency electromagnetic fields. These fields have weak spatial transmission capabilities and diminish rapidly with distance. The shielding effect of surrounding buildings further reduces their impact.
According to the WHO (World Health Organization) recommendations, the term “radiation” should not be used in the industry standards for power frequency electromagnetic fields. More accurately, transmission and transformation projects produce “power frequency electromagnetic fields”.
Regarding the health impacts of electromagnetic fields from substations, scientific research results are inconsistent. Some studies suggest that prolonged exposure to high-intensity extremely low-frequency electromagnetic fields may be linked to certain health issues, such as childhood leukemia, some types of cancers (like brain cancer and leukemia), and other health problems. However, these findings are not conclusive and remain controversial. The WHO and other health agencies continue to research and evaluate these risks.
Despite the insufficient scientific evidence, some countries and regions have taken precautionary measures to limit public exposure to electromagnetic radiation to reduce potential health risks and public concern. Common protective measures include:
1、Distance limitations: When planning new substations, the minimum distance from residential areas is considered to reduce residents’ exposure to electromagnetic fields.
2、Shielding and grounding: The design and construction of substations can include shielding measures to reduce electromagnetic field leakage. Proper grounding of equipment and work areas also helps to reduce electromagnetic radiation.
3、Environmental monitoring: Regular monitoring of electromagnetic field levels around substations to ensure they comply with national and international standards.
4、Public education: Providing the public with information about electromagnetic fields and health risks, as well as advice on how to reduce exposure.
5、Regulations and standards: Establishing and enforcing regulations and standards for electromagnetic field exposure to limit the intensity of electromagnetic fields that the public and workers may be exposed to.
6、Occupational health and safety: Providing training and safety guidelines for substation workers to reduce their exposure to electromagnetic radiation during their work.
It is important to note that the levels of electromagnetic field exposure for the general public in daily life are typically much lower than occupational exposure levels, so health risks are considered low. If you are concerned about electromagnetic radiation levels from a substation near your home, you can consult local environmental protection agencies or professional organizations for an assessment.
