Comprehensive Analysis of 110 kV Oil-Immersed Power Transformers: Key Technologies and Application Areas

In modern transmission and distribution networks, voltage level conversion is crucial for efficient power transmission and stable grid operation. As a critical component connecting regional transmission networks and local distribution networks, the 110 kV oil-immersed power transformer directly influences grid reliability, safety, and operational efficiency. This article provides an in-depth analysis of its structure, working principles, core technologies, and application fields.

Structure and Working Principle

The core structure of a 110 kV oil-immersed transformer includes a laminated silicon steel core, primary and secondary windings, and insulating oil (mineral oil or synthetic ester oil) for cooling and insulation. Main components include the iron core and windings, oil tank, bushings, conservator, Buchholz relay, pressure relief valve, oil level gauge, temperature controller, and cooling system such as ONAN, ONAF, or OFAF.

The transformer operates based on electromagnetic induction: the alternating current on the primary side generates magnetic flux in the iron core, inducing voltage in the secondary windings and facilitating energy transfer.

Key Technologies of 110 kV Oil-Immersed Transformers

1. Insulation Technology

Oil-Paper Composite Insulation System: The combination of high-purity insulating oil and specially processed insulation paper ensures excellent dielectric strength, supporting 110 kV operating voltage, lightning impulse withstand capability, and stable long-term operation.

Drying and Vacuum Oil Injection: Thorough drying and vacuum oil filling eliminate moisture and air bubbles, enhancing insulation performance and extending service life.

2. Cooling Technology

Transformers generate heat due to copper and iron losses. Cooling technology is essential for maintaining operational stability:

ONAN: Natural oil and air convection cooling, suitable for medium-capacity transformers.

ONAF: Forced air cooling with radiator fans, commonly used in 110 kV transformer installations.

OFAF: Forced oil circulation with pumps, ideal for large-capacity units requiring enhanced cooling.

3. Voltage Regulation Technology

To manage voltage fluctuations, 110 kV transformers are equipped with an on-load tap changer (OLTC). This device adjusts the winding turns ratio under load without interrupting power, ensuring stable voltage quality.

4. Protection and Monitoring Technologies

Buchholz Relay: Detects minor internal faults by monitoring gas generation and oil flow disturbances.

Online Monitoring Systems: With the development of smart grids, modern oil-immersed transformers integrate IoT-based monitoring such as dissolved gas analysis (DGA), winding temperature sensors, partial discharge detection, and moisture monitoring. These systems enable predictive maintenance and reduce fault risks.

5. Energy-Saving and Environmental Technologies

Low-Loss Core Materials: Using amorphous alloy or high-grade silicon steel significantly reduces no-load losses, improving energy efficiency.

Environmentally Friendly Insulating Oils: Biodegradable synthetic ester oils offer high fire safety, strong thermal stability, and environmental friendliness, suitable for eco-sensitive and high-safety zones.

Application Areas of 110 kV Oil-Immersed Transformers

110 kV oil-immersed transformers are widely used across power generation, transmission, and industrial sectors. Their main functions include stepping up generator voltage for transmission and stepping down transmission voltage for distribution.

Power Plants: Step up generated power for long-distance, high-efficiency transmission.

Substations: Perform voltage conversion between transmission and distribution networks to ensure grid stability.

Industrial and Mining Enterprises: Provide stable power supply by converting high-voltage energy into usable voltage levels for industrial production.

The 110 kV oil-immersed transformer remains a key device in modern power systems due to its high reliability, strong adaptability, and favorable cost-performance ratio. During procurement and engineering design, focus should be placed on insulation solutions, cooling systems, OLTC performance, energy-saving materials, online monitoring functions, and life-cycle cost evaluation.

Adopting low-loss cores, environmentally friendly insulating oils, and intelligent monitoring technology can significantly reduce long-term operation and maintenance risks while improving grid efficiency and safety.