Medium and High Voltage Transformer Stations: Role and Applications in the Power System

Medium and high voltage transformer stations play a crucial role in power systems, from power distribution to transmission across great distances. These two types of stations serve different purposes, depending on specific needs and terrain.

Concept and Voltage Range of Medium and High Voltage Transformer Stations

Medium voltage transformer stations are tasked with receiving and converting electricity from medium voltage levels, usually ranging from 6kV to 35kV, down to low voltage. High voltage transformer stations primarily serve to upgrade or downgrade voltage within the range from 66kV upwards. The goals and scales of these two types of transformer stations vary significantly, depending on the design of the power distribution system in a particular region or country.

Transformer stations are indispensable in modern power supply systems, playing a vital role in electricity transmission and ensuring effective power delivery to consumers. In particular, both medium and high voltage transformer stations are core components for adapting voltage levels to meet usage requirements.

1. Concept of Transformer Station

A transformer station is a stationary electrical device using electromagnetic induction to transform voltage levels, ensuring reasonable power transmission within the power supply system.

2. Voltage Range of Medium Voltage Transformer Stations

• Medium Voltage: Defined within the range of 6kV to 35kV, including important levels such as 10kV, 15kV, 22kV, and 35kV.
• Applications: Primarily serves to transmit power from high voltage transformer stations to smaller distribution stations or residential areas.

3. Voltage Range of High Voltage Transformer Stations

• High Voltage: Voltage from 66kV to 220kV, utilized in high voltage transformer stations, while voltage above 500kV is used for ultra-high voltage stations.
• Applications: Used for transmitting power over long distances, minimizing loss due to high voltage levels.

4. Functions and Structural Diagram

Medium and high voltage transformer stations not only meet voltage transformation requirements but also include components such as transformers, busbar systems, isolating switches, grounding lightning protection systems, and internal power systems. These components ensure efficient and safe power transmission within the system.

5. Importance in the Power System

The importance of transformer stations in power supply systems cannot be overstated. They help reduce energy loss during long-distance transmission and flexibly meet electricity usage needs of specific areas. Choosing the correct type of transformer station concerning voltage heavily depends on the system design and requirements of each geographical area.

Applications of Transformer Stations in the Power System

Medium voltage transformer stations primarily serve power distribution to residential, business areas, aiming to minimize losses during transmission. On the other hand, high voltage transformer stations are implemented to transmit power over large distances, connecting power plants with the national grid. This optimizes resource use and minimizes costs of power generation and transmission.

Transmission and Distribution of Power

Transformer stations play a key role in power transmission and distribution. Intermediate transformer stations receive electricity from 110kV–220kV, lowering it to 22kV–35kV for distribution to nearby regions, optimizing operational capacity by reducing transmission line losses.

• Medium voltage transformer stations: Serve power consumption needs of residential and business areas through adjusting voltage levels, suitable to the technical requirements of these electrical systems regularly.
• Power Distribution: From medium voltage stations, the voltage is lowered from 22kV–35kV to 0.4kV–0.22kV, serving households and industrial facilities.

Industrial Power Systems and Grid Stability

Transformer stations greatly contribute to stabilizing the national grid and meeting large power demands of industrial power systems.

• Industrial Power Systems: Transformer stations provide accurate voltage supply for hospitals, shopping centers, and heavy industries thanks to efficient voltage provision and adjustment.
• Grid Stability: The role of isolating circuits prevents widespread incidents and ensures system safety by adjusting load to real demands.

Urban Areas and Smart Grids

Transformer stations not only have the task of stepping down electricity for domestic consumption but also integrating modern technologies to serve smart grids.

• Smart Grids: Use automatic monitoring technology to optimize power distribution processes, reduce losses, and enhance system reliability.
• Household Low Voltage: Voltage is reduced to 220V/110V to meet electricity needs of household devices.

Multi-tier Power Grid Structure

A multi-tier power grid structure is the foundation of modern electrical systems, including three stages:

1. High Voltage Transmission: Power is transmitted with high voltage from 110kV–500kV to reduce loss over long distances.
2. Medium Voltage Distribution: Power at 22kV–35kV level serves the connection between intermediate stations and distribution stations.
3. Low Voltage Consumption: Meeting end-user consumption needs with voltage from 0.4kV–0.22kV.

This model ensures continuity and stability for the entire power system from production to consumption.

Safe Distances in Transformer Station Operation

Safe Distances in Transformer Station Operation

During transformer station operation, safe distances are of utmost importance. For medium voltage transformer stations, required safe distances vary according to voltage, from 0.7m for voltages 1kV to 15kV and 1.0m for voltages 15kV to 35kV. Meanwhile, at high voltage transformer stations, a larger safe distance must be maintained: from 2.5m for voltages 110kV to 220kV, and 4.5m for voltages from 220kV to 500kV.

Safe distances around transformer stations are critical technical requirements to protect people and vehicles from the risks in grid operation. These distances are strictly regulated depending on the voltage of the transformer stations.

General Regulations on Safe Distances

• 110 kV Transformer Stations: Safe distance should be about 1.5 meters from electrical wires to protected points or 15 meters in front and 12 meters on the sides of transformer stations.
• 220 kV Transformer Stations: Required safe distance ranges from 2.5 meters to 6 meters depending on specific situations.
• 500 kV Transformer Stations: Safe distance ranges from 4.5 meters to 6 meters.

High Voltage Power Line Safety Corridor

According to Article 10 of Government Decree 14, the high voltage grid protection corridor includes safe discharge distance, applicable to people and vehicles. This distance varies by voltage to ensure safety for vehicles and construction close to transformer stations. This is an important part of safety regulations.

Provisions for Flying Vehicles

Flying vehicles must maintain a minimum distance of 100 meters from the nearest parts of high voltage grid structures, except in special cases.

Provisions for Waterways and Railways

Safe distances for waterways and railways depend on static clearance height and technical grade of surrounding vehicles or structures near transformer stations.

Electromagnetic Radiation from Transformer Stations

Although transformer stations generate electromagnetic radiation, safe distances are often established to prevent discharge, rather than to manage radiation. This ensures no contact with high voltage areas, maintaining safety for the surrounding environment and power grid system.

Safe distances are one of the decisive factors for stable and safe grid operations, contributing to productivity protection and community health.

Medium and high voltage transformer stations are the pillars in the power system, ensuring efficiency and stability in the distribution and transmission processes. Investment in these two types of stations brings long-term benefits in cost savings and operational efficiency for the power industry.

Contact QuangAnhcons for transformer station solutions and services at hotline: +84 9 1975 8191.

QuangAnhcons specializes in providing design and construction services for medium and high voltage transformer stations, delivering optimal and safe solutions for your power distribution system.