Power stations play a pivotal role in the electrical transmission and substation networks, and a key component within them is the power transformer.
Universal Power Transformers, a seasoned manufacturer in the field, specializes in crafting a range of transformers conforming to international standards and boasts a wealth of experience in diverse global electrical projects.
So, what types of transformers are integral to power stations? Dive into this article for insights.
Types of Power Substations
Substations are categorized into various subsets based on their voltage class, function as well as internal position.
In voltage class, substations can be labeled as super high voltage, high voltage, medium voltage, and low voltage. Super high voltage denotes levels over 330kV, high voltage spans from 10kV to 330kV, medium voltage ranges from 1kV to 10kV, and low voltage is below 1kV.
Substations serve distinct purposes: village/town, industrial, and agricultural. In the power system hierarchy, they function as hubs, intermediates, regionals, enterprises, and end-users.
- Hub Substation: Positioned at the heart of the power system, hub substations generally operate at 330kV and above, are associated with multiple power sources, with extensive capacity, and play a crucial role in ensuring power system stability and reliability.
- Intermediate Substation: Located at the junction of the main ring line or main trunk line, this type of substation usually functions at 220kV to 330kV, serves as a convergence point for 2-3 power sources and several lines, and impacts regional grid operation when out of service.
- Regional Substation: This type of substation serves as the primary substation in a region or medium-sized city, typically operating at 220kV. Regional substations are critical for regional or city power supply.
- Enterprise Substation: A specialized substation for medium and large-scale enterprises, enterprise substations work with a voltage range of 35kV to 220kV and 1-2 incoming lines.
Types and Roles of Power Plant Transformers
- Main Transformers for Power Plants: These transformers elevate the voltage emitted by power plant motors (generally below 20kV) to system bus voltage for efficient power transmission and distribution.
- High Voltage Transformers for Power Plants: These transformers adapt generator output voltage to high voltage for the power plant’s high voltage motors and low voltage transformers.
- Low Voltage Transformers for Power Plants: These transformers lower the high-voltage busbar voltage for use in powering low-voltage single-phase and three-phase loads.
- Power Plant High Voltage Backup Transformer: Acts as a backup power source for high-voltage busbars in power plants.
- Power Plant Low Voltage Backup Transformer: Functions as a backup power supply for the power plant’s low-voltage bus.
- Isolation Transformer: Ensures system isolation and safety, commonly used for supplying power to remote mortar pumping stations.
Additionally, various specialized transformers such as dust removal transformers, excitation transformers, running light transformers, and rectifier transformers serve specific functions within the power plant ecosystem.
Selection Principles for Main Power Plant Transformers
- Determination of the Number of Phases: Choice between single-phase and three-phase transformers, considering economic factors and manufacturing conditions.
- Determination of the Number of Transformer Windings: Based on the maximum unit capacity, choose between three-winding, double-winding, self-coupling, and split-winding transformers, optimizing for economic viability.
- Selection of Tap Changer: Decide on the voltage regulation mode, on-load or no-load, based on system requirements and voltage fluctuation conditions.
- Determination of Winding Connection: Select the appropriate winding connection method, ensuring compatibility with system voltage phase.
- Selection of Transformer Impedance: Weigh impedance values on each side address various factors such as system stability, power flow, reactive power distribution, protection, short-circuit current, and voltage regulation methods.
- Selection of Cooling Method: Choose from cooling methods such as natural air cooling, forced air cooling, forced oil circulation, and forced oil circulation with water, depending on transformer type and capacity.
- Selection of Voltage on Each Side: Tailor the voltage levels to match the power supply or grid requirements for end-users.
Which transformer is used in the power stations?
Dry-Type Transformers for Solar Power Stations
Dry-type transformers are commonly employed in solar power plants for safety and insulation. Unlike traditional oil-immersed transformers, dry transformers are flame-resistant and explosion-proof. To ensure their safety and longevity, it is recommended to install these transformers within protective cabinets. These cabinets shield the transformers from the elements and potential contact with small animals while maintaining a safe distance for humans.
Pad-Mounted Transformers for Wind Turbine Solar Power Stations
Wind turbine solar power plants extensively use oil-immersed pad-mounted transformers, similar to substation transformers. However, a distinct feature of pad-mounted transformers is their underground bushing connection, which enhances safety. Furthermore, the installation process is more straightforward, and these transformers occupy less space.
Enhanced Safety with KNAN/KNAF Cooling Power Transformers
For projects demanding the highest safety standards, customers may opt for KNAN/KNAF cooling transformers, which are immersed in vegetable oil. Vegetable oils possess a higher flash point compared to mineral oils, making them a safer choice. Although these transformers come at a higher cost, they offer an added layer of safety and security.
High-voltage, pad-mounted, and dry transformers serve power plants, meeting specific requirements and safety considerations in diverse applications.
In Conclusion
In the world of electrical power generation and distribution, transformers bridge the gaps and facilitate the smooth flow of electricity. Transformers in traditional and renewable power are key for efficiency and safety in a changing energy landscape.
Advancing technology and environmental focus elevate the importance of specialized transformers, like dry-type and pad-mounted transformers, in various applications. These transformers not only ensure the secure operation of power systems but also contribute to the overall eco-friendliness of energy generation.
